Lidé

doc. Ing. Zdeněk Müller, Ph.D.

Garant programu Electrical Engineering and Computer Science

Všechny publikace

Stand-alone Solar Photo-voltaic Systems for Off-grid Electrification

  • DOI: 10.22044/rera.2023.13015.1218
  • Odkaz: https://doi.org/10.22044/rera.2023.13015.1218
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Electric energy is necessary to meet the daily needs of the population, as it is used in cooking, heating, irrigation, lighting, and others. There are many residential areas far from the public electricity network, hence the importance of solar energy in meeting the needs of these residents. This paper will study the design of a solar photo-voltaic system with a capacity of 131.6 kwh. The needs and requirements will be studied first, then a design will be made for the parts of this system such as inverters, batteries, and photo-voltaic panels. The results that we will obtain will confirm that this energy system is able to meet the necessary needs with high efficiency, and will also confirm that it is environmentally friendly in terms of carbon emissions. We will take Tanzania as a case study; the designed system contains 108 panels and about 8 kw battery bank to supply the load.

Autonomní zdroje rozptýlené výroby pro napájení kritické infrastruktury v podmínkách ostrovního provozu

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Fungující systém kritické infrastruktury je zásadní pro mnoho průmyslových odvětví, včetně energetiky. Transformace energetického sektoru přináší určité nové dopady na systém kritické infrastruktury. Předložený příspěvek se zaměřuje na hodnocení vlivů malých rozptýlených fotovoltaických elektráren (FVE), které v současnosti zažívají značný rozvoj. Konkrétně se jedná o posouzení dopadů při vzniku ostrovního provozu ve vybraném území s cílem co nejrychlejšího obnovení napájení zařízení zařazených do systému kritické infrastruktury. Specifikem uvažovaných malých FVE elektráren je jejich autonomie. Prezentovaná případová studie porovnává možné přístupy k obnovení napájení na jedné straně a dopad rozptýlené výroby (FVE) na straně druhé. Výsledky poskytují důležité závěry pro očekávaný rozvoj systému kritické infrastruktury v souvislosti s nárůstem autonomních rozptýlených zdrojů elektrické energie.

Effective Criteria in the Public-private Partnership in Developing Countries to Apply the Sustainable Development Goals: GAN-based Decision Support System for the Renewable Electrical System

  • DOI: 10.1016/j.heliyon.2023.e21422
  • Odkaz: https://doi.org/10.1016/j.heliyon.2023.e21422
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The cost of generating electricity in developing countries surpasses the government's ability to sustain it, necessitating the involvement of the private sector in this service provision through public-private partnerships (PPPs) contracts. In Syria, the electricity system has been highly susceptible to damage as a result of the ongoing crisis, leading to frequent and prolonged blackouts. This research focuses on addressing the need for a comprehensive system that aids decision-making for PPPs contracts in the country. By employing a combination of studies, reports, and interviews with domain experts, significant general and exclusive factors that guide decision-makers in PPPs contracts are identified and organized into questionnaires. These questionnaires are then filled out by professionals engaged in PPPs contracts. The collected data is analyzed and validated using SPSS software. However, due to insufficient data collected, generative adversarial neural networks (GAN) are utilized to enhance the research data. Additionally, Expert Choice and the analytic hierarchy process are employed to calculate weights for each factor. Remarkably, the calculated weights for both general and exclusive factors align with real-life strategies. General factors primarily address the financial and commercial considerations associated with PPPs, while exclusive factors primarily focus on the operational aspects of the electrical power system. These factors are arranged in descending order of effectiveness, enabling stakeholders to determine whether the private sector should be engaged in the project or if it should remain within the public sector's purview. The proposed system has demonstrated its reliability and can serve as a promising starting point for PPPs contracts.

A novel scheme for control by active and reactive power utilized in gearless variable speed wind turbine system with PMSG connected to the grid

  • DOI: 10.20998/2074-272X.2022.2.09
  • Odkaz: https://doi.org/10.20998/2074-272X.2022.2.09
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    As a result of increasing fossil fuel price and state-of-the-art technology, more and more residential and commercial consumers of electricity have been installing wind turbines. The motivation being to cut energy bills and carbon dioxide emissions. Purpose. The main goal of this work is developing a control scheme for a variable speed wind turbine generator in order to produce utmost power from varying wind types, and variable wind speed. Novelty. This research paper presents an IGBT power converter control scheme for active power in relation to wind speed and reactive power by adjusting Q-reference (Qref) value in a gearless variable speed wind turbine with permanent magnet synchronous generator. Methods. An effective modelling and control of the wind turbine with the suggested power converter is executed by utilizing MATLAB/Simulink software. The control scheme consists of both the wind turbine control and the power converter control. Simulation results are utilized in the analysis and deliberation of the ability of the control scheme, which reveals that the wind turbine generator has the capability to actively sustain an electric power grid network, owing to its ability to independently control active and reactive power according to applied reference values at variable wind speed. Practical value. This research can be utilized for assessing the control methodology, the dynamic capabilities and influence of a gearless variable-speed wind energy conversion system on electric power grids. A case study has been presented with a (3·10 MW = 30 MW) wind farm scheme.

Elektrické napájení kritické infrastruktury vybrané oblasti

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zaměřuje na problémy spojené s dodávkami elektřiny do kritické infrastruktury v krizových situacích. V úvodních pasážích se článek zaměřuje na metodiku výběru objektů kritické infrastruktury. Následně je pozornost věnována vybraným aspektům spojeným s provozem výroby elektřiny za krizových situací. Využitím vhodných typů výrobních jednotek (plynových turbín) je možné postupně spustit ostrovní provoz v okolním regionu, a to především pro objekty kritické infrastruktury, jejichž hlavním úkolem je ochrana obyvatelstva. V praktické části se článek zaměřuje na problematiku stability ostrovního režimu provozu. Výsledky případové studie ukazují, že pro plán zapnutí je nutné zohlednit dynamické vlastnosti ostrovního provozu postupným napájením objektů kritické infrastruktury po malých krocích elektrického výkonu.

The Impact of Cyber Attack on Emergency Energy System

  • DOI: 10.11648/j.epes.20221106.12
  • Odkaz: https://doi.org/10.11648/j.epes.20221106.12
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    An emergency energy system is a backup power system used in critical situations with the aim of protecting lives and property from the consequences of energy loss, as is the case in hospitals (heart monitors, Ventilator,...etc), and also in sensitive facilities (military industries and government buildings). The emergency power system can contain batteries of all kinds, in addition to solar and wind energy equipment and other cheap types of energy. The concept of cyber security arose several decades after the invention of the computer. At first, there was no need for cyber security, as it was difficult for electronic attacks to occur, because access to computers was limited to specific numbers of users, as the devices were giant confined to a room with certain specifications and were not Linked to networks at the time, Energy sectors expose themselves to a range of cyber threats that can damage control systems. So management, engineering, and IT must adhere to a comprehensive approach that includes threat prevention, detection, and elimination. In this research we will try to mitigate the effects of the cyber attack on these systems by applying some algorithms in order to detect, identify and prevent such attacks, and we will see through the results we obtained that we have made remarkable progress in this field.

The Impact of Distributed Autonomous PV Installations on Critical Infrastructure in Crisis Situations

  • DOI: 10.1109/ACCESS.2022.3203197
  • Odkaz: https://doi.org/10.1109/ACCESS.2022.3203197
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Ensuring a functioning critical infrastructure system is crucial for many industries, including energy. Due to the transformation of the energy sector, it is necessary to take into account the impact of the induced changes on critical infrastructure. The presented paper focuses on the assessment of the effects of small dispersed photovoltaic power plants (PV), which are gaining in popularity both in households and in other buildings. Specifically, it is an impact assessment within the emergence of island operation in the selected area with the aim of restoring power to the facilities included in the critical infrastructure system as soon as possible. The specificity of the considered small photovoltaic power plants is their autonomy and impossibility of control from the superior control system. The presented case study compares possible approaches to power recovery on the one hand and the impact of different levels of dispersed PV on the other. The results provide important conclusions for the expected development of the critical infrastructure system in connection with the increase in autonomous distributed electricity sources.

Zvyšování resilience kritické infrastruktury v kontextu energetického sektoru

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek je zaměřen na kritickou infrastrukturu, konkrétněji na její resilienci. Úvodní části příspěvku definují koncepty kritické infrastruktury, resilience kritické infrastruktury a definují související legislativní bázi. Dále následuje definice typických kritických stavů z oblasti elektroenergetiky. Pozornost je ve velké míře věnována také metodám ochrany kritické infrastruktury a posilování odolnosti kritické infrastruktury. V rámci vybraného území byl proveden průzkum možností kritické infrastruktury, který byl vyhodnocen. Na základě výsledků bylo identifikováno několik doporučených kroků v dílčích oblastech, kterým bude věnován další výzkum.

A Comparative Analysis of a Power System Stability with Virtual Inertia

  • DOI: 10.3390/en14113277
  • Odkaz: https://doi.org/10.3390/en14113277
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper investigates the stability of a power system with synchronverters. A synchronverter is a control strategy for voltage source converters that introduces virtual inertia by mimicking synchronous machines. The authors picked a commonly known IEEE 9 bus and IEEE 39 bus test case systems for the test case studies. The paper presents the power system's modal analysis with Voltage Source Converters (VSCs) controlled as synchronverters, vector control, or Rate of Change of Frequency-based Virtual Synchronous Generator, thus comparing different approaches to VSC control. The first case study compares selected control algorithms, the IEEE 9 bus system, with one VSC in the paper. The results demonstrate the benefits of synchronverters over other control strategies. The system with synchronverters has a higher minimal damping ratio, which is proven to be the case by numerical simulations. In the second case study, the effects of virtual inertia placement were investigated. The computations showed that placement is indeed important, however, the control strategy is as important. Besides, the system with synchronverters exhibits better stability characteristics. The paper demonstrates that the application of synchronverters is feasible and can meet the demand for algorithms that bring the benefits of virtual inertia.

An improved SVC control for electric arc furnace voltage flicker mitigation

  • DOI: 10.1016/j.ijepes.2021.106831
  • Odkaz: https://doi.org/10.1016/j.ijepes.2021.106831
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The work focuses on the possibilities of improving the Static Var Compensator (SVC) control system for more effective reduction of the flicker effect. The studied SVC control system consists of an open control loop, which provides a fast response to dynamic changes in Electric Arc Furnace (EAF) power, and a closed control loop, which provides precise control to ensure the required value of the power factor in the Point of Common Coupling (PCC). The improvement consists in the use of alternative techniques for signal processing of input control variables. The first alternative technique is the use of Second Order Generalized Integrator (SOGI), which is also used in other related applications. The second alternative technique is to use the flicker weighting function, which corresponds to the function used to measure the flicker effect using a standardized flicker meter. Experimental laboratory equipment and theoretical model in frequency domain was used to verify the properties of the proposed techniques. To simulate the dynamic behavior of EAF, data measured from real operation were used, which were implemented into an experiment using VSC. Analysis of measured data and data obtained from laboratory apparatus shows high similarity. The experiments were carried out in several variants to reflect the differences in the various stages of the production process in the EAF. For all variants, the resulting flicker effect was evaluated and the individual techniques were compared with each other and with the results of other works.

Blackout!? Zvládání rozsáhlých výpadků dodávek elektrické energie

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Blackouty, plošné dlouhodobé výpadky elektrické energie ve velké městské aglomeraci, byly zaregistrovány v řadě států světa a představují závažný potenciální problém i pro Českou republiku. V nedávných letech proběhla u řady krajských samospráv komplexní cvičení, která poukázala na jejich možné negativní dopady na život v kraji a nutnost všestranné technologické i organizační přípravy na zvládání těchto stavů. Jako důležitý závěr z těchto cvičení se ukazuje nutnost těsněji koordinovat opatření technicko-energetická s opatřeními krizového řízení a ochrany obyvatelstva. Pro poskytnutí odborné pomoci orgánům krizového řízení kraje byl podán společný výzkumný projekt dvou fakult ČVUT – Fakulty elektrotechnické (oblast energetiky) a Fakulty biomedicínského inženýrství (krizové řízení a ochrana obyvatelstva). Řešitelský tým projektu, který vyváženě obsahuje odborníky z akademického prostředí i z praxe.

Dispečerský trenažér

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Stále komplikovanější provozní stavy v distribuční soustavě vedou k nutnosti zajistit kontinuální výcvik pracovníků dispečerského řízení. Pro řešení této problematiky se vytvořil mezi ČVUT v Praze, Fakultou elektrotechnickou (Katedrou elektroenergetiky), a ČEZ Distribuce, a. s., společný výzkumný tým, který podporuje tvorbu nových algoritmů a procedur. Tato spolupráce zvyšuje užitnost nového dispečerského trenažéru.

Dynamic stability improvement of power system by means of STATCOM with virtual inertia

  • DOI: 10.1109/ACCESS.2021.3106236
  • Odkaz: https://doi.org/10.1109/ACCESS.2021.3106236
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper investigates the application of Static Synchronous Compensator (STATCOM) with synchronverter control to enhance dynamic stability. Synchronverter is a control strategy for voltage source converters that emulates a synchronous generator, therefore providing virtual inertia. A thorough analysis of system stability with STATCOM controlled using synchronverter is presented. Furthermore, a comparison to vector control is provided. The analysis was conducted for a commonly known Single Machine Infinite Bus (SMIB) test case. The authors also compare the synchronverter and vector control performance using different mathematical tools such as eigenvalue analysis, numerical simulation, and lyapunov theory. Synchronverter algorithm improves the damping of the system, as small-signal analysis shows. The results of numerical simulations demonstrate the improvement of dynamic stability. Besides, the stability region also improves in the case of synchronverter. Finally, the paper demonstrates on the IEEE 39 bus system that the operation of STATCOM with a synchronverter control strategy is feasible and improves dynamic stability. Synchronverter brings the advantages of artificially adding inertia to the system, an essential issue in modern power systems.

The impact of COVID-19 on electricity prices in Italy, the Czech Republic, and China

  • DOI: 10.3390/app11198793
  • Odkaz: https://doi.org/10.3390/app11198793
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    COVID-19 is likely to be the 2020s’ deadliest pandemic according to the World Health Organization (WHO). There have been more than 3.7 million confirmed deaths after 15 months spread. Besides the loss of human lives, COVID-19 has other unfavorable impacts on society, education, and the economy. Due to successive lockdowns and the continuous quarantines, the demands on power resources have reduced. Therefore, there is a need to investigate the impacts of the COVID-19 pandemic on electricity prices (EP). In this paper, a set of six economic factors that are affected by COVID-19 and affect EP are considered. These factors were fed into a functional link artificial neural network (FLANN) to model the relationships between them and the EP. An empirical equation was formulated to help decision makers and strategic developers in the electricity markets come up with more appropriate plans. Italy, the Czech Republic, and China were used as case studies in this research. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

A comparative study of synchronverter stability

  • DOI: 10.1109/EPE51172.2020.9269194
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269194
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Electric grids, after a large scale installation of renewable energy sources, have dramatically changed. One of the major concerns in the operation of the modern power system is low grid inertia. Different approaches are being proposed to overcome this challenge. However, the prevalent idea is to introduce virtual inertia to the system using a sophisticated control strategy of power electronics in the electric grids. This paper investigates the synchronverter, which is a possible solution to the mentioned problem. The first chapter briefly describes the problem and the synchronverter control strategy of power converters. The second chapter provides a mathematical model of the synchronverter in d-q frame connected to an infinite bus. Furthermore, it analysis the small signal stability of the synchronverter. The third chapter gives a brief overlook of small signal stability of traditional vector control. Moreover, this chapter provides a comparison between the researched approach and the conventional one.

A New Algorithm for Detecting Failure to Clear Mode of Circuit Breakers Using Fundamental Frequency Component of Voltage Signals

  • Autoři: Feizifar, B., doc. Ing. Zdeněk Müller, Ph.D., Usta, O.
  • Publikace: IEEE Transactions on Power Delivery. 2020, 35(2), 794-801. ISSN 0885-8977.
  • Rok: 2020
  • DOI: 10.1109/TPWRD.2019.2927102
  • Odkaz: https://doi.org/10.1109/TPWRD.2019.2927102
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper introduces a new algorithm for the early detection of abnormal arcing conditions of circuit breakers (CBs). Any interruption with a higher arcing time compared to maximum permissible arcing time of CB is defined as a CB failure to clear mode. Measuring CB arcing time is not easy because there is no control on the mechanical opening and closing instants of CB contacts. Nevertheless, there is a correlation between the spectral energy densities of CB arcing voltages and arcing times of CB. This correlation is used by calculating the spectral energy densities of the instantaneous system voltage and the instantaneous CB voltage across its terminals utilizing discrete Fourier transform for two periods of the system frequency. The difference between the spectral energy densities at the fundamental frequency is defined as a criterion for identifying a failure to clear mode. Whenever this criterion exceeds a predefined trip level, it indicates the occurrence of a failure to clear mode. In this situation, a trip signal is initiated for adjacent CBs to isolate the faulted CB and the fault. The results obtained from computer simulations and measurements show that the algorithm discriminates between normal and abnormal arcing conditions of CB.

A supervisory MPC for synchronverter

  • DOI: 10.1109/EPE51172.2020.9269232
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269232
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The adoption of renewable energy sources leads to lower grid inertia, which brings more complications to operators of electrical grids. New control strategies for power electronics try to cope with that problem by introducing virtual inertia. Sychronverter is one of the promising algorithms. Furthermore, other control techniques combined with synchronverter might improve stability. Model predictive control (MPC) has proven to be a good tool in real applications. Therefore, the authors present a simplified mathematical model of a PV power plant with a synchronverter. The paper also proves that the presented model can be applied to MPC for synchronverter. Depending on the stated objective, MPC for synchronverter can bring different advantages to the control of grid converters.

Bioenergy Electricity on Internet of Renewable Energy (IoRE) Framework for Sustainable Electricity Grid Integration in the European Union (EU)

  • Autoři: Igbinovia, F.O., Krupka, J., Hajek, P., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J.
  • Publikace: 2020 21st International Scientific Conference on Electric Power Engineering (EPE). Prague: Czechoslovakia Section IEEE, 2020. ISSN 2376-5623. ISBN 978-1-7281-9479-0.
  • Rok: 2020
  • DOI: 10.1109/EPE51172.2020.9269180
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269180
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Climate change and the finite nature of traditional electricity production sources have resulted in the increasing utilization of renewable electricity sources in today's electricity grid architecture. Which is hoped to eventually lead to a hundred percent renewable electricity grid architecture. A purely renewable electricity grid will bring about the implementation of the Internet of Renewable Energy (IoRE). The European Union (EU) in an attempt to stimulate and strengthen the integration of electricity grid architecture of member states has set in motion several strategies. A great strategy should be a purely renewable electricity grid assets integration in the region. Besides hydro and wind energy, bioenergy is following on the listing of vital renewable energy sources consumed in the European electricity generation mix. Bioenergy electricity combined with other renewables on the IoRE framework will lead to a sustainable electricity grid integration in the EU. The anticipated utilization of IoRE technology in the short-term and long-term in the region will lead the way to assess a hundred percent renewable electricity product by consumers in each member country. It will as well bring about cleaner electricity product production in the EU.

Critical infrastructure and the possibility of increasing its resilience in the context of the energy sector

  • DOI: 10.1109/EPE51172.2020.9269175
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269175
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper focuses on critical infrastructure and its resilience. The introductory parts of the paper define the concepts of critical infrastructure and resilience of critical infrastructure and further define its legislative basis. Then follows the definition of typical critical states in the field of power engineering. To a large extent, attention is also focused on methods for critical infrastructure protection and methods for strengthening critical infrastructure resilience. Within the selected area, a survey of the possibilities of critical infrastructure was carried out, which was evaluated. Based on the results, several recommended steps were identified in the sub-areas to which further research will be devoted.

Electricity Storage in Internet of Renewable Energy (IoRE) Domain for Sustainable Smart Cities

  • Autoři: Igbinovia, F.O., Krupka, J., Hajek, P., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J.
  • Publikace: 2020 21st International Scientific Conference on Electric Power Engineering (EPE). Prague: Czechoslovakia Section IEEE, 2020. ISSN 2376-5623. ISBN 978-1-7281-9479-0.
  • Rok: 2020
  • DOI: 10.1109/EPE51172.2020.9269241
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269241
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Electricity storage is essential to permitting the advocacy of a purely renewable electricity grid architecture. This will be the utmost resolution for devoting only random renewable electricity resources like wind and solar plants, to only meet utility base load demand of electricity consumers. Electricity storage is one of the key facilitating equipment's for the future purely renewable electricity grid architecture. Which when intelligently controlled using Internet of Renewable Energy (IoRE) has the attributes that will reward both residential/industrial electricity consumers, and electricity utility authorities. Thereby making it possible to initiate new electricity market models and smart management of cities. This write up is influenced with the desire to give perception into the prospective utilization of electricity storage technology in IoRE domain for clean and sustainable smart city implementation.

Emergency situations in the transmission grid and opportunities for their prevention through the intraday electricity market

  • Autoři: Šrom, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: 2020 21st International Scientific Conference on Electric Power Engineering (EPE). Prague: Czechoslovakia Section IEEE, 2020. ISSN 2376-5623. ISBN 978-1-7281-9479-0.
  • Rok: 2020
  • DOI: 10.1109/EPE51172.2020.9269167
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269167
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The intraday electricity market is increasing its importance within the electricity markets. This article introduces real life examples of the contribution of the intraday electricity market towards the prevention and resolution of emergency situations in the electricity system. The article also emphasizes the positive contribution of the integration of the intraday electricity market into the single intraday electricity market in Europe.

Experience with Reconstruction of Industrial SVC Analogue Controller

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper focuses on the lifetime of the 90 MVAr SVC system in the steel plant with 60 ton UHP EAF + 60 ton LF. The system is powered from the 110 kV primary distribution system, which is powered from transmission system substation 400/110 kV (220 kV in the past). The system was commissioned in 1994. During the operation of the facility, several major changes occurred. The first major change was the intensification of the steel production. This change of the SVC operation was not significantly influenced by the sizing of the equipment. Another major change was the gradual change of short-circuit conditions at the PCC point (reconstruction of the transmission system node from the 220 kV system to the 400 kV system). There was a need to monitor the 110 kV system voltage to avoid damaging the higher harmonic filter capacitors. One major accident occurred during operation due to failure of the thyristor block cooling system. The crash was eliminated by a complete replacement of thyristor blocks and protection extensions that identify similar types of faults in time. Periodic inspections of the equipment also resulted in replacement of higher harmonic filter capacitors (vessel leakage, deteriorated tg δ, capacity drop).

Methodology of electricity supplying of critical infrastructure in crisis situations

  • DOI: 10.1109/EPE51172.2020.9269257
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269257
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper focuses on the issues associated with the supply of electricity to critical infrastructure in crisis situations. In the introductory passages, the paper focuses on the methodology of selecting objects of critical infrastructure. Subsequently, attention is paid to selected aspects associated with the operation of electricity generation during a crisis situations. By using suitable types of production units (gas turbines), it is possible to gradually start island operation in the surrounding region, primarily for critical infrastructure facilities, whose main task is to protect the population. In the practical part, the paper focuses on the issues of stability of the island operation mode. The results of the case study show that for the switch-on plan it is necessary to take into account the dynamic characteristics of island operation by feeding the objects of critical infrastructure gradually after small electrical power steps.

Modelling of AC Electric Railway System using PSCAD/EMTDC

  • Autoři: Elbelkasi, M.S., Badran, E.A., Abdelwahab, M., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: 2020 21st International Scientific Conference on Electric Power Engineering (EPE). Prague: Czechoslovakia Section IEEE, 2020. ISSN 2376-5623. ISBN 978-1-7281-9479-0.
  • Rok: 2020

Potential of technical losses reduction in low voltage feeder using small photovoltaics

  • DOI: 10.1109/EPE51172.2020.9269214
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269214
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Efficiency of electricity systems is currently a high priority for the society. Our article focuses on the area of low voltage distribution system, where we focus more deeply on the possibilities of reducing technical losses. To achieve this goal, many traditional methods are known which require modification and intervention in the distribution system. Our concept is based on the possibility of reducing active losses using small photovoltaic systems installed at low voltage customers. For this purpose, a low voltage feeder model of the corresponding structure was created in this work. Using this model, a case study based on real data (solar irradiation data and typical daily diagrams of low voltage customers) was performed. The results of the simulations show considerable potential for reducing technical losses using the described concept.

Primary energy reduction using small CHP systems

  • DOI: 10.1109/EPE51172.2020.9269204
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269204
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This work deals with the creation of a control model for a system with CHP units, heat pump and energy storage. By simulating such system, it can be designed and optimized for primary energy consumption and investment. The model also enables extrapolation of the monitored quantities from energy consumption over a known period of time.

The KRG GRID Network Comparison between Two Different Years 2013 and 2019

  • Autoři: Khudhur, D., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: 2020 21st International Scientific Conference on Electric Power Engineering (EPE). Prague: Czechoslovakia Section IEEE, 2020. ISSN 2376-5623. ISBN 978-1-7281-9479-0.
  • Rok: 2020
  • DOI: 10.1109/EPE51172.2020.9269166
  • Odkaz: https://doi.org/10.1109/EPE51172.2020.9269166
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The development of national electric power network infrastructure in the Kurdistan region of Iraq has shown substantial growth in the last decades. The goal of this paper is to show the difference in the electric power network between two different years, and how gradually the demand for energy consumption was increasing. The growth includes the generation, transmission lines, Substation, and load demand. Furthermore, it is good to present the expansion plans concerning the factors mentioned above.

The Role of Renewable Energies in the Sustainable Development of Post-Crisis Electrical Power Sectors Reconstruction

  • DOI: 10.3390/en13236326
  • Odkaz: https://doi.org/10.3390/en13236326
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The electric power sector in countries suffering from crises and wars such as Syria, Iraq, Yemen, Libya, etc., is among the most affected infrastructures. Since this sector plays a vital role in the economic growth and in improving people's quality of life, the post-crisis reconstruction of this sector must take into account the requirements and concepts of sustainable development (SD) in addition to technical and economic considerations. This article discusses the role that renewable energy sources (RES) can play in achieving SD in the post-crisis reconstruction phase of the Syrian Electric Power Sector (SEPS) as a case study. Based on the available data, the study period was chosen from 2005 to 2017 and divided into two periods. In the first period (2005-2010), which is the pre-crisis period, the structure of the SEPS and its main characteristics were described while the adoption of RES solutions and SD concepts were investigated. In the second period (2011-2017), the crisis period, the satiation of the SEPS and impact of the crisis were evaluated. The challenges that faced the adoption of SD concepts and RES solution were also addressed at this stage. Based on analysis and comparison of the available data, several scenarios were discussed to evaluate the role of RES in achieving SD in the post-crisis reconstruction phase of the SEPS. EnergyPLAN software was used for the techno and socio-economic evaluation of these scenarios. Our results emphasize the importance of the adoption of RES solutions in the reconstruction phase, as these can help promote SD concepts (reducing greenhouse gas emissions, protecting the environment, increasing energy efficiency, creating jobs, etc.) and securing the electric supply of the SEPS while enhancing its stability.

A Collective Condition Monitoring Algorithm for On-Load Tap-Changers

  • Autoři: Feizifar, B., doc. Ing. Zdeněk Müller, Ph.D., Ing. Ghaeth Abdulhamid Fandi, Usta, O.
  • Publikace: Proceedings of 19th IEEE International Conference on Environment and Electrical Engineering (EEEIC) / 3rd IEEE Industrial and Commercial Power Systems Europe Conference (I and CPS Europe). New York: IEEE, 2019. ISBN 978-1-7281-0652-6.
  • Rok: 2019
  • DOI: 10.1109/EEEIC.2019.8783320
  • Odkaz: https://doi.org/10.1109/EEEIC.2019.8783320
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Transformer units are widely utilized to transfer the electric power over transmission and distribution networks efficiently. These units can be equipped with an on-load tap-changer (OLTC) to regulate the voltage level of power grids by tap changing operations between different steps of transformer winding to compensate unpredicted fluctuations of voltage. An OLTC is the solely moving and switching component of power transformers, thus it is highly prone to electrical, mechanical, and dielectric defects. Some international surveys indicate that the majority of the failures and outages with respect to power transformers are originated from malfunctions of OLTCs. This paper contains an analytical review of the existing methods for condition monitoring (CM) of OLTCs and proposes a collective CM algorithm, which considers the mechanical, electrical, and dielectric defects and degradations of OLTCs. The algorithm is designed to provide a comprehensive CM output for OLTCs by collecting different types of measurements from certain sensors used by different CM methods.

Improvement of transient stability using STATCOM combined with optimization

  • DOI: 10.1109/EPE.2019.8778105
  • Odkaz: https://doi.org/10.1109/EPE.2019.8778105
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Further improvement of FACTS (Flexible Alternating Current Transmission System) control can help to increase the transient stability of a power system without adding extra grid inertia. Sophisticated optimization algorithms and modern Computer Algebra Systems provide new means of controller synthesis for power systems. The paper presents an approach of enhancement of transient stability using FACTS devices, particularly STATCOM (Static Synchronous Compensators), combined with optimization. Furthermore, chapter 3 describes different ways of defining the objective function. Different approaches are compared using the case study model that was implemented in MATLAB/Simulink.

Optimized use of the steam accumulator in the combined heat and power production

  • DOI: 10.1109/EPE.2019.8778141
  • Odkaz: https://doi.org/10.1109/EPE.2019.8778141
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper presents technical analysis of the usage of steam accumulator in the combined heat and power production and also in all general steam production. Created mathematical model is possible to use for evening on wanted slope of steam flow change.

Utilizing the synchronous condenser for robust functioning of wind farm implanted electric grid

  • DOI: 10.2478/jee-2019-0022
  • Odkaz: https://doi.org/10.2478/jee-2019-0022
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Present-day electricity grids are equipped with sophisticated devices that allow to meet various grid code requirements. These include reactive and active power controls to ensure robust functioning of the grid. Robust operation of the electricity grid entails favourable voltage and frequency profile adjustments that can be achieved through reactive and active power controls. This study presents the synchronous condenser capability of providing voltage regulation and reactive power output, and the active power possibility path of a type-3 wind machine for dynamic state conditions and voltage stability issues. Simulations carried out in the MATLAB/Simulink environment prove the efficiency of the proposed methodology.

Voltage Quality and Power Factor Improvement in Smart Grids Using Controlled DG Units

  • DOI: 10.3390/en12183433
  • Odkaz: https://doi.org/10.3390/en12183433
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The increased penetration of renewable energy sources in the electrical grid, due to the rapid increase of power demand and the need of diverse energy sources, has made distributed generation (DG) units an essential part of the modern electrical grid. The integration of many DG units in smart grids requires control and coordination between them, and the grid to maximize the benefits of the DG units. Smart grids and modern electronic devices require high standards of power quality, especially voltage quality. In this paper, a new methodology is presented to improve the voltage quality and power factor in smart grids. This method depends on using voltage variation and admittance values as inputs of a controller that controls the reactive power generation in all DG units. The results show that the controller is efficient in improving the voltage quality and power factor. Real data from an electrical network have been used in the simulation model in MATLAB Simulink to test the new approach.

A Novel Power Losses Reduction Method Based on a Particle Swarm Optimization Algorithm Using STATCOM

  • DOI: 10.3390/en11102851
  • Odkaz: https://doi.org/10.3390/en11102851
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    In the modern electric power industry, Flexible AC Transmission Systems (FACTS) have a special place. In connection with the increased interest in the development of smart energy, the use of such devices is becoming especially urgent. Their main function is the ability to manage modes in real time: maintain the necessary level of voltage in the grids, control the power flow, increase the capacity of power lines and increase the static and dynamic stability of the power grid. The problem of system reliability and stability is related to the task of definitions and optimizations and planning indicators, design and exploitation. The main aim of this article is the definition of the best placement of the STATCOM compensator in case to provide stability and reliability of the grid with the minimization of the power losses, using Particle Swarm Optimization algorithms. All calculations were performed in MATLAB.

Design of an Emergency Energy System for a City Assisted by Renewable Energy, Case Study: Latakia, Syria

  • DOI: 10.3390/en11113138
  • Odkaz: https://doi.org/10.3390/en11113138
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Electrical energy is one of the most important daily needs. Shortage of energy can be very dangerous for any society. This can affect the standard of living and quality of life of the people and even endanger the lives of those in hospitals, and so forth. Developed countries do not face such risks in general because they have well organized electrical systems and high energy security. The developing countries are faced daily with electric system collapses, especially in the case of wars, where many parts of the electrical grid in the country can be damaged and fuel transmission lines for generators cut off. Urban areas in developing countries should have a strategic plan to deal with any unexpected occurrence of energy shortages using any available renewable energy sources. City of Latakia is located in the region which has been suffering from the consequences of war for more than six years. The fact that a high number of migrants from other cities have come to Latakia along with a lack of fuel makes the energy shortage in the city worse. An emergency system could use the cheapest available renewable energy sources in addition to few big portable generators to provide an acceptable energy supply for the most needed requirements of daily life.

Elektroenergetické systémy v jihoafrickém regionu

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek popisuje výrobu elektřiny a elektroenergetický systém v jihoafrickém regionu. Výroba elektrické energie, přenos a distribuce elektřiny v tomto regionu jsou provozovóny jako monopol společnosti ve vlastnictví čIenských států s instalovaným výkonem 52 GW, se skladbou zdrojů:72 % uhelných elektráren, 18 % vodních elektráren, 10 % naftových a plynových elektráren a jaderných elektráren. Počítá se, že využívání obnovitelných zdrojů energie a velkých vodních elektráren se bude podílet na celkové výrobě elektrické energie v roce 2030 47 % (podíI velkých vodních elektráren bude 22 % a obnovitelných zdrojů energie 25 %), což sníží zóvislost na fosilních palivech (uhlí a jádro), která mají negativní vliv na životní prostředí. Spolehlivá přenosová soustava v regionu jižní Afriky umožní členským zemím exportovat a importovat do/ze sousedních zemí elektrickou energii za přijatelnou cenu.

Improvement of Voltage Profile and Mitigation of Power Losses in Case of Faults Using DG Units

  • DOI: 10.1109/EPE.2018.8395984
  • Odkaz: https://doi.org/10.1109/EPE.2018.8395984
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Distributed generation (DG) units has become an essential part of the smart grid due to increased penetration of renewable energy sources. These units help to improve power quality according to their position and control. Grids could face unexpected faults which affects power quality most especially voltage profile and power losses. This paper presents the potential application of (DG) units as a solution for improving voltage profile and mitigating power losses in loop distribution systems in case of faults for different positions of DG unit. Load flow analysis of a 66/20 kV distribution line network is performed to calculate the various values of voltage and power flow at each bus for different faults in each position of DG unit. Simulation of this distribution substation network with DG units have been developed in the MATLAB/Simulink Environment. The objective of this study is enhancement of voltage profile at various buses and the improvement in power flows in the distribution network with reduction in branch losses in the presence of fault.

Micro Hydro Power for Off Grid Electrification: A Case Study of Hhaynu River - Mbulu,Tanzania

  • Autoři: Melkior, U., Tlustý, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: 2018 19th International Scientific Conference on Electric Power Engineering (EPE). Brno: Czech Section of the IEEE VUT, 2018. ISSN 2376-5631. ISBN 978-1-5386-4612-0.
  • Rok: 2018
  • DOI: 10.1109/EPE.2018.8395983
  • Odkaz: https://doi.org/10.1109/EPE.2018.8395983
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Designing of Hydro Power Plant needs reliable water throughout the year. Determining amount of water in the stream/river is important step before implementing HEP project due to recent demand in irrigation. Two methods of determining amount of water in the river that is historical data and measured data have been used. It is found that maximum flows occurred in April with discharge of 2.3 m(3)/s and the lowest is in October with discharge of 0.6 m(3)/s. therefore, for system design 0.4 m(3)/s would be used for electricity generation while 0.2 m(3)/s would be for environmental flowing at length of penstock. Using discharge of 0.4 m(3)/s, head of 25 m the gross power generated by the hydro power plant would be 98.1 kW.

Model Predictive Direct Power Control of Four-Switch-Based Inverter Connected to Unbalanced Grid System

  • DOI: 10.1109/ICSEE.2018.8646186
  • Odkaz: https://doi.org/10.1109/ICSEE.2018.8646186
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    A model based predictive direct power control with finite set of control variables for the three phase four-switch-based converter B4 connected to an unbalanced grid is introduced. The instantaneous active and non-active powers are outputs of the controlled system. The alternative instantaneous non-active power theory is used that preserves harmonic free grid currents not only for a symmetrical but also unsymmetrical voltage system. Simulation results for the L grid filter are presented and analyzed.

Modeling and simulation of the anticipated effects of the synchronous condenser on an electric-power network with participatingwind plants

  • DOI: 10.3390/su10124834
  • Odkaz: https://doi.org/10.3390/su10124834
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Installing a synchronous condenser (SC) onto an electricity grid can assist in the areas of reactive power needs, short-circuit strength, and, consequently, system inertia and guarantees better dynamic voltage recovery. This paper summarizes the practical potential of the synchronous condenser coordinated in an electric-power network with participating wind plants to supply reactive power compensation and injection of active power at their point of common coupling; it provides a systematic assessment method for simulating and analyzing the anticipated effects of the synchronous condenser on a power network with participating wind plants. A 33-kV power line has been used as a case study. The results indicate that the effect of the adopted synchronous condenser solution model in the MATLAB/Simulink environment provides reactive power, enhances voltage stability, and minimizes power losses, while the wind power plants provide active power support with given practical grid rules. © 2018 by the authors.

Progressive usage of the synchronous machine in electrical power systems

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    In traditional electric-power systems, synchronous generator based center electric-power plants have been the main origin of dynamic reactive power sustenance, but owing to the steady growth in the number of renewable power generating plants across the globe and the concurrent dismantling of these rotating synchronous machines principally driven by the demand to decrease carbon emission and reliance on fossil fuels, the need for grid-stabilizing systems is increasing. Also, traditional electric-power generating units are approaching the end of their useful operational life and utility authorities are faced with a difficult resolution of retiring electric-power plants. One way of resolving these issues is the refurbishment of these machines that is the electric-power plants to synchronous condensers. This paper presents a brief assessment of the synchronous machine and the motivation for this research work. It discusses the importance of the synchronous machine in electrical power systems, and the progressive trend in the use of the synchronous machine in electric-power networks. It stresses the need for the use of the synchronous machine for reactive power compensation purposes, with a vivid description given with MATLAB/Simulink simulation model. When the synchronous condenseris connected to the power system model at the terminating end of the network and switched ON, the medium voltage (MV) electrical power network simulation model effectively allows the control of reactive power, which improves voltage stability and power flow control of the proposed network.

Reputation of the Synchronous Condenser Technology in Modern Power Grid

  • DOI: 10.1109/POWERCON.2018.8601540
  • Odkaz: https://doi.org/10.1109/POWERCON.2018.8601540
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The synchronous condenser nowadays contributes an essential share of resources for generating reactive power to ensure voltage stability in modern power systems. Such resource has to be taken care of by owners of electricity infrastructures. In any case, real projects, experiments and simulation results have shown need to use the synchronous condenser for enhancing power quality of the grid. Hence, traditional generators are being retrofitted to synchronous condensers in order for them to serve a better purpose of voltage stabilization after they are retired and new synchronous condensers are installed by electricity utility managers to serve same purpose too. This paper presents the synchronous condenser technology. It discusses the experience and lessons learnt from the use of the synchronous condenser in real projects. It also provides an outlook on the development of the use of the technology in modern power grid using two simulation study scenarios. These developments include Scenario One: utilizing only the synchronous condenser for voltage regulation on a power grid. And Scenario Two: Installing the synchronous condensers with Type-3 wind farm for voltage support on an electricity network, such contextualization is towards voltage stability in modern power grids.

Use of Renewable Energy for Electrification of Rural Community to Stop Migration of Youth from Rural Area to Urban: A Case Study of Tanzania

  • Autoři: Melkior, U., Tlustý, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Dependability Engineering. London: IntechOpen Limited, 2018. ISBN 978-1-78923-258-5.
  • Rok: 2018
  • DOI: 10.5772/intechopen.74956
  • Odkaz: https://doi.org/10.5772/intechopen.74956
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Rural electrification is the key in developing countries to encourage youth and skilled personnel to stay in rural for production activities. Lack of grid network in Tanzania currently discourages youth and skilled personnel to live in rural areas. Tanzania has diverse renewable energy which needs to be developed for electricity generation. Most of these sources are found in rural areas but they are not developed and grid network are not extended because of low population density. The government has put in place policy which encourages small power producers to develop renewable energy resources. Energy produced would be sold to the community directly or to the government owned company for grid integration. This paper discussed three major renewable energy sources such as wind, solar and hydro power. Electrifying rural areas will encourage youth to reside in their communities and engaging themselves in production activities like farming and livestock keeping. Also communication among communities and networks between rural - urban would be improved. Establishment of small industries would lead more farm products and earn more money. Therefore, the strong links between rural - urban communities would be strengthened; hence youth migration would be stopped naturally.

Voltage Regulation and Power Loss Minimization in Radial Distribution Systems via Reactive Power Injection and Distributed Generation Unit Placement

  • DOI: 10.3390/en11061399
  • Odkaz: https://doi.org/10.3390/en11061399
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Distributed Generation (DG) has become an essential part of the smart grids due to the widespread integration of renewable energy sources. Reactive power compensation is still one of most important research topics in smart grids. DG units can be used for reactive power compensation purposes, therefore we can improve the voltage profile and minimize power losses in order to improve the power quality. In this paper two methods will be used to accomplish the mentioned tasks; the first technique depends on the reactive power demand change of the proposed network loads, whereas the second technique uses an algorithm to control DG units according to the measured voltage values in the feeders to generate the needed reactive power. Both methods were applied to different scenarios of DG unit positions and different reactive power values of loads. The chosen DG unit is made up of a Type-4 wind farm which could be used as a general unit where it is able to control reactive power generation in a wider range separately from active power. The simulation results show that using these two methods, the voltage profile could be improved, power losses reduced and the power factor increased according to the placement of DG units.

Effect of average environmental conditions in Slovakia at the current conductor capacity of overhead transmission line

  • Autoři: Špes, M., Kosterec, M., Beňa, L., Márton, M., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Proceedings of the 9th International Scientific Symposium on Electrical Power Engineering ELEKTROENERGETIKA 2017. Košice: Technical University of Košice, 2017. p. 702-707. ISBN 978-80-553-3195-9.
  • Rok: 2017
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Current capacity of conductors is defined as the maximum amount of current that can flow without damaging the conductor. It depends primarily on the electrical and mechanical properties of the conductor, their ability to spread the heat generated and the ambient conditions. The proposal of powerlines as each electricity device are subject to the valid standards. Standard EN 50341 defines the environmental conditions for calculating the maximum current capacity. In general, the environmental conditions are not constant over time. Depend on the climatic conditions of the country, area, that are different climatic nature. This paper deals with the calculation of the maximum current capacity of conductor of overhead transmission line based on ambient climatic conditions according to the equations defined in the IEEE Std 738-1993. The article describes average weather conditions in Slovakia and its impact on the determination of the maximum current capacity. Article compares the maximum current capacity given by ambient conditions referred to a standard and current capacity determined by average weather conditions.

Effect of improved electricity product development on the business performance of a public electricity transmission company

  • DOI: 10.1109/PowerAfrica.2017.7991198
  • Odkaz: https://doi.org/10.1109/PowerAfrica.2017.7991198
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Improved electricity product development is becoming more significant to the business performance of electricity transmission companies. Despite the fact that the term improved/new product development is not new, very few studies have investigated the effect of improved electricity product development on the business performance of a public electricity transmission company, most especially in a developing country such as Nigeria. This paper present means by which improved electricity product development can be used to assist electricity transmission company's business performance in order to improve customers' electricity product adoption and other stakeholder's satisfaction in the industry. It is based on a case study of the Transmission Company of Nigeria (TCN), it provide guidelines to stakeholders in the industry in utilizing improved electricity product development to better support electricity transmission companies: it allows transmission companies to launch improved electricity products to end-users; it helps transmission companies to determine the weaknesses of the electricity product delivered to end-users; it allows improved quality of electricity product that customers are willing to pay a premium for, while eliminating epileptic electric-power supply end-users do not want.

Impact of environmental conditions on the capacity of power lines

  • Autoři: Špes, M., Beňa, Ľ., Kosterec, M., Kruželák, L., doc. Ing. Zdeněk Müller, Ph.D., Wachta, H., Márton, M.
  • Publikace: Acta Electrotechnica et Informatica. 2017, 11(3), 3-7. ISSN 1335-8243.
  • Rok: 2017
  • DOI: 10.15546/aeei-2017-0018
  • Odkaz: https://doi.org/10.15546/aeei-2017-0018
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This article deals with determining the value of maximum permissible current with consideration of ambient conditions. Each ambient conditions and their influence on the value of current ampacity for ACSR conductor 350/59 in comparison with ampacity given by calculation accordance the standard EN 50341 are described in this article. Static ambient conditions are given in this standard and change in the ambient conditions was neglected in calculation of the resulting value. The aim of this article is to refer the influence of the change of ambient environment and ambient conditions to the maximum permissible current.

Method of Calculating the Correction Factors for Cable Dimensioning in Smart Grids

  • Autoři: Simutkin, M., Tuzikova, V., Tlustý, J., Tulsky, V., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: IOP Conference Series: Materials Science and Engineering. Bristol: Institute of Physics Publishing, 2017. vol. 189. ISSN 1757-8981.
  • Rok: 2017
  • DOI: 10.1088/1757-899X/189/1/012028
  • Odkaz: https://doi.org/10.1088/1757-899X/189/1/012028
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    One of the main causes of overloading electrical equipment by currents of higher harmonics is the great increasing of a number of non-linear electricity power consumers. Non-sinusoidal voltages and currents affect the operation of electrical equipment, reducing its lifetime, increases the voltage and power losses in the network, reducing its capacity. There are standards that respects emissions amount of higher harmonics current that cannot provide interference limit for a safe level in power grid. The article presents a method for determining a correction factor to the long-term allowable current of the cable, which allows for this influence. Using mathematical models in the software Elcut, it was described thermal processes in the cable in case the flow of non-sinusoidal current. Developed in the article theoretical principles, methods, mathematical models allow us to calculate the correction factor to account for the effect of higher harmonics in the current spectrum for network equipment in any type of non-linear load.

Modeling and simulation of a gearless variable speed wind turbine system with PMSG

  • DOI: 10.1109/PowerAfrica.2017.7991200
  • Odkaz: https://doi.org/10.1109/PowerAfrica.2017.7991200
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Wind turbine designs and production is an advance high-tech technology when considering design features from different manufacturers. The design of a wind turbine gearbox is demanding owing to loading and environmental circumstances in which the gearbox must function, Hence, the need for gearless wind turbine designs. As a replacement for gearbox, gearless wind turbine technology can be used, this actually causes the turbine to be more reliable, by reducing downtime and repair costs, an important special consideration for offshore turbines, a place or terrain some more costly to dispatch skilled workers to carry out maintenance operations. This paper analysis a gearless variable speed wind turbine system with Permanent Magnet Synchronous Generator (PMSG). Modelling and simulation of the gearless variable speed wind turbine scheme with PMSG is implemented by utilizing MATLAB/Simulink software. Results shows that the wind turbine has the capability to sustain an electric-power scheme. This research work is beneficial to Model, simulate and analyze the influence of changes in wind speed and Q-reference of a variable speed wind turbine system with permanent magnet synchronous generator.

A Matlab-Simulink model of network reactive power compensation based on binary switchable capacitors and thyristor-controlled reactor

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J., Beck, Y., Berkovich, Y.
  • Publikace: IEEE International Conference on the Science of Electrical Engineering. Tel Aviv: IEEE, 2016. ISBN 978-1-5090-2152-9.
  • Rok: 2016
  • DOI: 10.1109/ICSEE.2016.7806150
  • Odkaz: https://doi.org/10.1109/ICSEE.2016.7806150
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper considers a Matlab-Simulink Model of a system for a load reactive power compensation with consisting of a thyristor-controlled binary switched capacitors (TBSC) and a thyristor controlled reactor (TCR). The capacitors ensure stepwise compensation of reactive power, while the controlled inductance makes it possible to achieve smooth changing of the resulting compensating power within the limits of the minimal capacity in the binary capacitors series. The model uses a very simple algorithm of capacitor control, provided with a logical system that prevents current surges in the moments when capacitors are being connected to the network. The switching of capacitors is set by a closed system for maintenance of the maximal power coefficient. To regulate the inductance in TCR, an invariant system of phase control is used, which maintains the unit value of the power coefficient in the network irrespective of load changes. The realization of the system in the model is maximally close to its possible hardware realization. The functioning of the model has been tested in a wide range of variation of the reactive load power, and the testing confirmed the efficiency of combining a switchable series of binary capacitors and a thyristor-controlled inductance when using the proposed control algorithms.

Advantageous Positioning of Wind Turbine Generating System in MV Distribution Network

  • Autoři: Ing. Ghaeth Abdulhamid Fandi, Igbinovia, F., Švec, J., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J.
  • Publikace: 2016 17th International Scientific Conference on Electric Power Engineering (EPE 2016). New York: IEEE, 2016. International Scientific Conference on Electric Power Engineering. ISBN 978-1-5090-0907-7.
  • Rok: 2016
  • DOI: 10.1109/EPE.2016.7521807
  • Odkaz: https://doi.org/10.1109/EPE.2016.7521807
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper presents a new method for achieving voltage stability and reduction of power losses with renewable wind turbine generating system (WTGS) installed at different position on a Medium Voltage (MV) distribution system. The proposed network is a three-phase system consisting of 0.4 kV low voltage (LV) feeder with an active power (P) of 8 MW and a negative VAR (QC) of 0.5 MVAR. And a 20 kV MV feeder with an active power (P) of 22 MW and a negative VAR (QC) of 1.5 MVAR. The 0.4 kV and 20 kV feeders has varying positive VAR values of 2, 2.25, 2.5 and 6, 6.5, 7 MVARs respectively. Three sets of data's were observed; data 1, 2, and 3, the feeders are connected to a 20 kV MV distribution network, which is then linked to a 20 kV substation. Thereafter, a 20 kV MV renewable WTGS energy source with IGBT converters is integrated to the network for effective reactive power compensation. Three different Cases have been analyzed; First is the case with the proposed power system network analyzed without any WTGS attached to the network, in other words when the WTGS is switched off (this is designated as Case 1). Second is the situation with the WTGS positioned at the terminal end of the 20 kV MV distribution network (point 1, which is designated as Case 2) and Third is the situation when the position of the wind energy source is changed and stationed at the beginning of the terminal of the 20 kV MV power line (point 2, which is designated as Case 3). Matlab/Simulink software is used for the simulation of the system model. Simulation results for each of the case studies is analyzed and it is observed that research findings for Case 2 is more efficient in achieving improved voltage stability and power losses reduction in medium voltage electric-power distribution network.

Application of generalized non-active power theory for parallel hybrid compensation of periodic a nd non-periodic disturbances

  • DOI: 10.24084/repqj14.543
  • Odkaz: https://doi.org/10.24084/repqj14.543
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    A strategy of decomposition of detrimental current components in electric power syst ems is presented. The method is based on the non-active power theory with different averaging time intervals. These individual current components can be used as the reference signals for the devices compensating periodic as well as non-periodic and stochastic currents generated by non-linear unbalanced loads connected to an unsymmetrical non-sinusoidal voltage power source. The use of an appropriate set of parallel compensation devices for mitigating individual detrimental load current components with different dynamics can lead to the substantial reduction of the power rating and cost of such a hybrid compensator.

Contribution to control strategies for converter connected to unbalanced grid

  • DOI: 10.1109/SETIT.2016.7939886
  • Odkaz: https://doi.org/10.1109/SETIT.2016.7939886
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with developed and experimentally tested effective synchronization and power control techniques for grid-connected converter. A new FLL (Frequency Locked Loop) technique is developed that incorporates advantages of both the cascaded delayed signal cancellation and dual second order generalized integrator schemes. Experimental results are evaluated in terms of quality of the positive voltage sequence, frequency and phase angle identification for the grid voltage disturbed by harmonic, subharmonic, and negative sequence components as well as for amplitude, frequency, and phase angle jumps in the voltage. A novel power control technique for grid-connected converter under unbalanced voltage conditions is referred as well. The current positive and negative sequences during grid voltage sags are controlled to assure a proper exchange of active and reactive powers without substantial power ripples, and especially, without current harmonics.

Control of Flying Capacitor Multilevel Converter in Fault State after Grid Disturbance

  • DOI: 10.1109/IGBSG.2016.7539444
  • Odkaz: https://doi.org/10.1109/IGBSG.2016.7539444
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    An effective HW reconfiguration of a FCM (Flying Capacitor Multilevel) converter and also of its control algorithm in case of a fault of one element in the converter phase is presented. A strategy starts from the theory of FCM converters with unequal distribution of voltages on converter capacitors. The use of additional switching elements and capacitors with higher rated voltage is a necessary condition for the presented approach. Because a number of redundant switching states in faulted phases is limited, joint-phase redundancies are recommended to be used to balance capacitor voltages. The case of a 4-level FCM converter is analyzed in detail as an example.

Cost Implication and Reactive Power Generating Potential of the Synchronous Condenser

  • Autoři: Igbinovia, F., Ing. Ghaeth Abdulhamid Fandi, doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J.
  • Publikace: The Proceedings of the 2nd International Conference on Intelligent Green Building and Smart Grid (IGBSG). Praha: IEEE Czechoslovakia Section, 2016. p. 212-217. ISBN 978-1-4673-8473-5.
  • Rok: 2016
  • DOI: 10.1109/IGBSG.2016.7539450
  • Odkaz: https://doi.org/10.1109/IGBSG.2016.7539450
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The objective of this study is to examine the cost implication and reactive power generating potential of the synchronous condenser. Universally, increase in electricity demand constitutes new issues for power generation, transmission and distribution. Synchronous condenser solutions are being initiated globally to be instrumental in the best usage of power resources and offer grid systems support for todays and future sustainable, stable and reliable electrical grid network. This research x-rays the cost implication of the synchronous condenser in today's challenging environment. A vivid description of the reactive power generating potential of the synchronous condenser is shown with Matlab/Simulink environment simulation of a medium voltage (MV) power system network. It is observed that the synchronous condenser is cost-effective as compared to other reactive power generating equipment's and sources. Furthermore, Matlab/Simulink simulation results of the MV electric-power network shows an effective scheme for reactive power generation.

Intelligent system for safe and reliable power supply

  • Autoři: Štefan, J., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J.
  • Publikace: 2016 17th International Scientific Conference on Electric Power Engineering (EPE 2016). New York: IEEE, 2016. International Scientific Conference on Electric Power Engineering. ISBN 978-1-5090-0907-7.
  • Rok: 2016
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper introduce project TA04021240 „Intelligent system for safe and reliable power supply“. Its aim is to find technical solution for medium-term emergency power supply.

Novel method of optimization of losses in power grid

  • DOI: 10.1109/ICSEE.2016.7806044
  • Odkaz: https://doi.org/10.1109/ICSEE.2016.7806044
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper describes theoretical and practical applications of FACTS devices such as STATCOM for voltage control and active power losses optimization. The idea and development with applying STATCOM for the optimization is presented. STATCOM provides an improvement in power quality and active power consumption stabilization. This effect could be used in applications where a variable load voltage should be compensated. It would result in a power stability improvement and decrease a risk of critical events caused by those sources. Using STATCOM, we are able to control the voltage at the node to which this device is connected and at the same time it is possible to reduce active power losses. The shown simulation provides information for STATCOM design and placement in power grids. Applying Particle Swarm Optimization showed the potentials to use this method in power grids to improve their operation and selected criteria.

Optimal Location of the Synchronous Condenser in Electric-Power System Networks

  • Autoři: Igbinovia, F., Ing. Ghaeth Abdulhamid Fandi, doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J.
  • Publikace: 2016 17th International Scientific Conference on Electric Power Engineering (EPE 2016). New York: IEEE, 2016. International Scientific Conference on Electric Power Engineering. ISBN 978-1-5090-0907-7.
  • Rok: 2016
  • DOI: 10.1109/EPE.2016.7521731
  • Odkaz: https://doi.org/10.1109/EPE.2016.7521731
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    In this paper, authors focus on the use of the synchronous condenser device for voltage stability and power flow control on a three-phase 33 kV Medium Voltage (MV) electric-power system network. Matlab/Simulink is used for the simulation of the proposed system model. To test the validity of the system, measured and calculated power factor values were obtained. Two scenarios were studied; Firstly, is the scenario with the synchronous condenser located at the terminal end of the 33 kV MV network (position 1). And secondly, is the scenario with the synchronous condenser placed at the beginning of the 33 kV MV power Line (position 2). Simulation results obtained from the study are compared in order to determine the most appropriate location for situating the synchronous condenser device. It is observed that the locations of the synchronous condenser equipment have different impacts on the electric-power system network. However, the proposed study of the simulation model base on the location of the synchronous condenser at the terminal end of the 33 kV MV electric-power system network (position 1) demonstrate a more effective and suitable scheme of the electric-power network concerning issues of voltage stability and power flow control.

Smart region - Automation of distribution system

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Smart Region is a smart grid project implemented by ČEZ Distribuce (DSO) in the north part of the Czech Republic. It is focused on automation of distribution system. The overall challenge of the project is to assess the potential of automation equipment together with new communication infrastructure and upgrades of grid control systems to optimize network operation on MV, LV levels and enablethe island operation.

The Reliability of the System with Wind Power Generation

  • Autoři: Melkior, U., Ing. Martin Čerňan, Ph.D., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J., Kasembe, A.
  • Publikace: 2016 17th International Scientific Conference on Electric Power Engineering (EPE 2016). New York: IEEE, 2016. International Scientific Conference on Electric Power Engineering. ISBN 978-1-5090-0907-7.
  • Rok: 2016
  • DOI: 10.1109/EPE.2016.7521833
  • Odkaz: https://doi.org/10.1109/EPE.2016.7521833
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Electricity supply is a fundamental need of a modern society. A crucial property of electricity supply reliability, is achieved by keeping a power system in a secure state most of the time. A secure state means that the risk of a disturbance to spread further and endanger the system integrity, resulting into supply interruption, is minimal. Large wind power integration can also lead to problems on the voltage control and power quality at large. Voltage control when wind turbines are used can usually be achieved by changing the amount of reactive power compensation (by shunt capacitors installation). The lack of control on the active and reactive powers can disturb the voltage on the Point of Common Coupling (PCC).

A probabilistic approach to power electric systems analysis

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The contribution deals with probabilistic approach to distribution system analysis. This method is suitable for the development and planning of the system with decentralized renewables sources and electro mobility etc. The transition to a probabilistic approach can lead to higher quality of analysis and increase the predictive ability of power flow computation and provides reliable information for decision-making processes.

A Probabilistic Approach to Power Flow Analysis

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper shows some opportunities offered by new approaches to processing planning and distribution network management data. The increasing amount of phenomena that are difficult to predict (e.g. decentralized sources, electromobility etc.) decreases the informative value of currently used calculation methods. These methods also require accurate input data. Using methods from the probability theory allows us to describe the reality more accurately in the conditions with increased amounts of uncertainty.

Calculation of magnetic and electric field under OHL and its reduction

  • Autoři: Ehrenberger, J., doc. Ing. Zdeněk Müller, Ph.D., Švec, J.
  • Publikace: Proceedings of the 8th International Scientific Symposium on Electrical Power Engineering ELEKTROENERGETIKA 2015. Košice: TU Košice, 2015. pp. 117-120. ISBN 978-80-553-2187-5.
  • Rok: 2015
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper describes calculation methods of magnetic and electric field under overhead transmission line (OHL), and a possible way of its reduction. The reduction is obtained by auxiliary shield conductors placed under phase conductors. All aforementioned calculations are derived generally in an analytical form and presented for one example model. The model consists of one tower with one transmission line, and RMS values of magnetic and electric fields are calculated for the control level at a given height above the ground to obtain both the fields profiles under the line. In case the field is too high, auxiliary conductors are placed under the line, and the original field is reduced. Reduction of original field depends on the number and placement of these auxiliary conductors or conductor loops, and a corresponding sensitivity analysis is performed. RMS values of electric and magnetic fields are calculated at control height above the ground and depend directly on the distance from the line. That means RMS values of fields depend directly on the conductors sag which depends on the conductor temperature and hence the current flowing through the line. Thus both the electric and magnetic fields are affected by conductor currents. Aforementioned facts are presented for one example. Sensitivity analysis of the current flowing through the line to magnetic and electric fields is performed, and reduction of fields by addition of auxiliary conductors under the line is calculated.

Comparative review of reactive power compensation technologies

  • Autoři: Igbinovia, F., Ing. Ghaeth Abdulhamid Fandi, Švec, J., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J.
  • Publikace: 2015 16th International Scientific Conference on Electric Power Engineering (EPE). Ostrava: VŠB - Technical University of Ostrava, 2015. p. 2-7. ISSN 2376-5623. ISBN 978-1-4673-6788-2.
  • Rok: 2015
  • DOI: 10.1109/EPE.2015.7161066
  • Odkaz: https://doi.org/10.1109/EPE.2015.7161066
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The quality of electrical power in a network is a major concern which has to be examined with caution in order to achieve a reliable electrical power system network. Reactive power compensation is a means for realising the goal of a qualitative and reliable electrical power system. This paper made a comparative review of reactive power compensation technologies; the devices reviewed include Synchronous Condenser, Static Var Compensator (SVC) and Static Synchronous Compensator (STATCOM). These technologies were defined, critically examined and compared, the most promising technology is recommended for the realisation of an effective, efficient, sustainable, qualitative and reliable electrical power network.

Dynamic behaviour of overhead line under icing conditions

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with dynamic model of overhead line mechanics. Dynamical modelling are useful to study many different transient states and it is also possible used for determination of an effects of various influences. The analysis thus allows to detect potentially dangerous situations and can be prevented by performing the corrective actions. In contrast to the static model, dynamic model also allows to simulate the shock forces and determine the peak exceeding the allowable limits of safe state of operation of overhead lines. The mechanical model of the power line is based on modeling each elements and interaction of its neighbors. This method allows the description of complex structures. Each element has mass, length, rigidity and damping. Each model function is modelled as block with internal interaction. In case study is transient state with conductor ACSR 350/59 analyzed. Transient state is induced fall icy.

Ferroresonance Phenomena in Medium Voltage Systems

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with the analysis of the formation of ferroresonance in MV systems. The analysis is focused on ferroresonance caused by instrument voltage transformer (IVT) connected to the outlet of the tertiary winding 10,5 kV autotransformer 400/110 kV. A non-linear element in this case is the magnetic circuit of IVT Ferro-resonance, in this case exhibits similar to the imperfect ground connection. The two phases may arise overvoltages in two phases and undervoltage in one phase. The rate of these adverse events is given by the initial conditions and load of switched circuits when circuit is switched on. Similarly, other exhibit nonlinear chaotic circuits. The main adverse effects include overvoltage that can damage the power system components well as a significant harmonic distortion. For prevent this problem the authors conducted the case study resonant circuit as a whole. In this case it is magnetic circuit of the IVT, in which saturate a hysteresis the magnetic flux depending on the winding currents. In the article before are described two approaches to determine hysteresis curves. The first approach is based on laboratory measurements of the properties of IVT, the second approach, developed by the authors is based on the measurement of nonlinear resonant circuit as a whole. The developed method additionally incorporates speech hysteresis. A non-linear circuit is described by the set of differential equations. Based on the knowledge of the basic parameters of the individual elements of the system is possible to analyze the resulting ferroresonance by solution system of differential equations in software Wolfram Mathematica. The analysis shows that the circuit can be for certain parameters even behave chaotically. It is, however, only certain ranges of the parameters. The simulation also confirms that ferroresonance is manifested like ground failure. To limit the exposure of ferroresonance is based on the analysis carried out several possible actions.

Flexible grid power control for distributed sources

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The formulaes for the calculation of reference current components using the Instantaneous Active-Reactive Control and Balanced Positive Sequence Control strategies have been combined to make a selection of the contribution of a negative voltage sequence to the formation of the reference current vector possible. Thus, the demands laid on a maximum magnitude of the grid current, current unbalance factor, and an instantaneous active power distortion can be considered and an appropriate compromise selected.

Icing influence simulation using 3-DOF overhead line modelling

  • DOI: 10.1109/EPE.2015.7161158
  • Odkaz: https://doi.org/10.1109/EPE.2015.7161158
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper describes a dynamic model of overhead line mechanics and its utilization for icing influence evaluation. The case study is performed for AlFe350/59 wire and for real overhead line. The case containing several connected fields is threated as conjunction spans using partially hinged insulator strings.

Increase of Voltage Quality in Industrial Distribution Systems

  • DOI: 10.24084/repqj13.459
  • Odkaz: https://doi.org/10.24084/repqj13.459
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper deals with the solution of the issue of exceeding the permissible levels for long-term flicker effect Plt in industrial distribution systems. Flicker effect in distribution systems is often exceeded as a result of the connection of electric arc furnaces, which exhibits high variable electrical power in-take. The article shows the benefits of measures on the steel plants, the distribution system operator and the transmission system operator. The main benefits were the installation SVC device and reconstruction of substation 220/110 kV to substation 400/110 kV. Measurements have shown that the flicker has a major impact and configuration system 110 kV. In some cases, exceeded values flicker effect, and therefore the final part of the article deals with the possibility of deployment of active filters low power.

Overhead Line Mechanical Behaviour - Dynamic Model

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with overhead line motion problems. The dynamic model is derived from string equation. The main contribution of the developed model is complex mechanics simulation in 3D. The result consist of a continuous description of the position of the wire along its length in both space and time domains. The model thus allows calculations of un-even effects of forces along overhead line length. The model is actually a combination of discrete and continuous calculations. The dynamic model is, according to its complexity, also useful to simulate various mechanical wave phenomena such as galloping. Each model function block is described in equation form. In the case study ACSR 350/59 wire is analyzed. In this part an auxiliary model of wind influence was integrated into the global model.

Power Control at Grid Connected Converters and Analytical Solution of Steady States

  • DOI: 10.1155/2015/601916
  • Odkaz: https://doi.org/10.1155/2015/601916
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper presents a power control technique at grid connected converters under unbalanced voltage conditions. The current positive and negative sequences during grid voltage sags are controlled to ensure a proper exchange of active and reactive powers without power ripples. An analytical solution in a closed form of the B6 and B4 converters working with an optimized half a period switching symmetry is presented. The analytical solution may be applied for the converters connected to highly unbalanced grids and for different grid filter topologies.

Srovnání různých přístupů ke zlepšování parametrů SAIFI a SAIDI v distribučních sítích vysokého napětí

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zaměřuje na analýzu přínosů prvků automatizace v distribučních sítích VN. Pro automatizaci a zvyšováni spolehlivosti bylo uvažováno nasazení recloserů, automatických úsečníků s inteligencí a indikátorů průchodu zkratového proudu (FPI – Fault Passage Indikator). Jako hlavní hodnotící ukazatele byli zvoleny parametry SAIFI, SAIDI a nedodávky elektrické energie. Přínosy jednotlivých prvků byli analyzovány na zjednodušených sítích a to ve dvou případech. Variatny se odlišovali možností záložního napájení. Požadavky na vstupní hodnoty obsahují průměrný roční počet permanentních poruch, počet odboček delších jako 1 km, celkový počet zákazníků, průměrné roční nedodávky energie a doby dojezdu, lokalizace a odstranění poruchy pro jednotlivé vývody. V závěru příspěvku jsou ukázány technicky odlišná řešení pro typově odlišné VN vývody.

Using renewable MV wind energy resource to supply reactive power in MV distribution network

  • Autoři: Ing. Ghaeth Abdulhamid Fandi, Igbinovia, F., doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J.
  • Publikace: 2015 16th International Scientific Conference on Electric Power Engineering (EPE). Ostrava: VŠB - Technical University of Ostrava, 2015. p. 169-173. ISSN 2376-5623. ISBN 978-1-4673-6788-2.
  • Rok: 2015
  • DOI: 10.1109/EPE.2015.7161146
  • Odkaz: https://doi.org/10.1109/EPE.2015.7161146
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper deals with the use of Medium Voltage (MV) renewable wind energy source to optimize reactive power in a distribution network, it describes the increase of power factor when the reactive power is controlled at a wind farm increase in power factor allows improvement in the stability of distribution networks, and the increase in power factor is used as new methodology to reduce power losses, Matlab/Simulink program is used to show the results of the analysis.

3-DOF overhead line mechanical dynamic model

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with overhead line motion problems. The line model is based on dynamic description of catenary curve. Benefits of dynamic modeling in this field are decrypted and one of the used models is consequently explained. The dynamic model is derived from string equation. The main contribution of the developed model is complex mechanics simulation in 3D. The model of overhead line shaking is generally based on the superposition of harmonic components in particular spatial coordinates. Each individual harmonic component is solved separately in one step of calculation and than combined with other solutions. The results consist of a continuous description of the position of the wire along its length in both space and time domains. The model thus allows calculations of un-even effects of forces along overhead line length. The accuracy of the calculation is determined by the number of harmonics calculated and other parameters (e.g. step size, simulation time etc.). The model is actually a combination of discrete and continuous calculations. Each model function block is described in equation form. In the case study ACSR 350/59 wire is analyzed. In this part an auxiliary model of wind influence was integrated into the global model.

Analytical closed-form solution of current responses of multilevel converter connected to unbalanced grid

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    An analytical closed-form solution of ac current responses of a multilevel converter connected to the unbalanced grid in steady state is proposed in the contribution. The method of the solution can be used for different grid filter topologies and for unsymmetrical grid voltages and/or currents to analyze easily converter current responses in steady states.

FACTS Devices Influence on Power Losses in Transmission Systems

  • DOI: 10.1109/EPE.2014.6839431
  • Odkaz: https://doi.org/10.1109/EPE.2014.6839431
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Since there are still higher efforts for transmission systems equipment utilization, more control mechanisms and devices are integrated to the systems and their dispatch centers and these will be also in future. FACTS devices purpose is preferably to maintain voltage levels and to control active and reactive power flows. Their implementation in the grid can result from the necessity to improve the system capabilities in a longterm period or to solve some extraordinary states. The paper deals with the implementation of shunt and series FACTS devices into electrical transmission systems and their influence on active power losses. There are provided comparison analyses of how different FACTS types have a potential to changes power losses in the system either in a negative or in a positive way. There are explained basic principles and the results are presented on the IEEE/CIGRE transmission system model.

Inteligentní systém pro bezpečné a spolehlivézásobování oblasti elektrickou energií

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Proceedings of ELEN 2014. Praha: ČVUT FEL, Katedra elektroenergetiky, 2014. ISBN 978-80-01-05654-7.
  • Rok: 2014
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek obsahuje stručné shrnutí informací o projektu TA ČR "Inteligentní systém pro bezpečné a spolehlivézásobování oblasti elektrickou energií".

Optimized half a period switching symmetry applied at grid connected four-switch converter and analytical solution of steady states

  • DOI: 10.1109/EPEPEMC.2014.6980662
  • Odkaz: https://doi.org/10.1109/EPEPEMC.2014.6980662
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    An analytical solution in a closed form of the B4 converter working with a proposed optimized half a period switching symmetry is presented. The proposed switching strategy provides a good current tracking capability and minimum switching frequency. The analytical solution may be applied for the B4 converter connected to highly unbalanced grids. The method enables to analyze quickly B4 converter current responses in steady states for different grid filter topologies.

Particle Swarm Based Optimization of Power Losses in Network Using STATCOM

  • DOI: 10.24084/repqj12.337
  • Odkaz: https://doi.org/10.24084/repqj12.337
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The main goal of this paper is to define the best location for the STATCOM compensator in order to minimize active power losses in the grid, using Particle Swarm Optimization algorithm.

Power Quality Enhancement using STATCOM with Energy Storage

  • DOI: 10.24084/repqj12.336
  • Odkaz: https://doi.org/10.24084/repqj12.336
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper describes an advanced approach to power quality enhancement, mainly to flicker mitigation. There is described the standard STATCOM device added by an energy storage in its DC circuit. Its function is then discussed and modelled for active power compensation in addition to the classical reactive power compen sation. A case study is provided for an industrial plant with 60 MVA electric arc furnace producing power disturbances, namely flicker.

Quality of Service and Experience – Business Driven Standardisation for Interoperability in Internet of Things

  • Pracoviště: Katedra elektroenergetiky, Katedra telekomunikační techniky
  • Anotace:
    The phenomenon of the Internet of Things (IoT) brings not only new opportunities in services, but also the requirements for interoperability of various existing technologies and technological systems in converged world. Complex system IoT thus forms a kind of umbrella, allowing more business opportunities. Implementation of modern communication and technology brings great potential especially in the telecommunications, energy, transport and logistic. This article is devoted to the description of opportunities and threats that arise from a new comprehensive system of IoT in individual sectors. It will be also shown that the main measurable criteria to provide the services required in this complex system are to meet the quality of service QoS and quality of experience QoE. It will be shown that these two main criteria are common to all sectors roofed under the umbrella of the Internet of Things in future converged world.

STATCOM Effect on Voltage Stability in Ghanaian Electrical Grid

  • Autoři: Essilfie, J., doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J.
  • Publikace: Proceedings of the 2014 15th International Scientific Conference on Electric Power Engineering. Brno: Vysoké učení technické v Brně, 2014. p. 235-240. ISSN 2376-5623. ISBN 978-1-4799-3807-0.
  • Rok: 2014
  • DOI: 10.1109/EPE.2014.6839445
  • Odkaz: https://doi.org/10.1109/EPE.2014.6839445
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper deals with using STATCOM for voltage stability purposes which is analyzed on the Ghanaian power system development. Preliminary studies have shown that the northern sector is vulnerable to voltage instability which has led to the proposed installation of STATCOM in a key substation Tamale. It is therefore necessary to assess the performance of the device when put in operation. Comparison had therefore been made between the use of STATCOM and a fixed compensator. Line and generator contingencies as well as small signal disturbances analysis have been carried out. Voltage stability is improved with the installation of STATCOM but do not affect the interconnection between Ghana and Burkina Faso. Further evaluation focused on the inter-tie is proposed.

Vliv nových trendů v elektroenergetice na zatížení a napětí v reálné síti nn PREdistribuce, a.s.

  • Autoři: Tlustý, J., doc. Ing. Zdeněk Müller, Ph.D., Votruba, S., Lžičař, P.
  • Publikace: Konference ČK CIRED 2014. Praha: CIRED, 2014. ISBN 978-80-905014-3-0.
  • Rok: 2014
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Pod vlivem rozvoje nových trendů v elektroenergetice byla vytvořena analýza dopadů těchto trendů (fotovoltaika, mikrokogenerace, systémy s tepelnými čerpadly – topení a klimatizace, elektromobilita) ve vybraných částech NN sítě v městské aglomeraci s využitím nových progresivních metod a přístupů. Pro vytvoření potřebných simulací a analýz byl zvolen stochastický přístup, pro dosažení výsledků s dostatečnou mírou věrohodnosti bylo vytvořeno dostatečné množství scénářů a průchodů výpočtu (řádově stovky). Tento příspěvek popisuje postup zpracování analýzy a vybrané výsledky.

Advances in Distribution System Architecture

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    An analysis of the distribution network structure and its influence on the power system functions is critical for the Smart Grid concept. It creates a base framework for the implementation of the Smart Grid concept into the distribution network environment including a compliance with all relevant links. The basic structure of the networks and facilities and transmission and distribution system are described in EC breakdown showing the interface between the transmission (TS) and distribution system (DS). This interface is one of the key points of the balance control system of the observed distribution network. Other nodal points create connection with all the resources within the analyzed part of the distribution network. Customer management functions are realized as the link between processes of Smart Grid and Smart Metering in the general concept. The paper analyses new trends and advances in the power system architecture.

Assessment of Power Systems with Doubly Fed Induction Generator Based Wind Turbines

  • DOI: 10.1166/asl.2013.4872
  • Odkaz: https://doi.org/10.1166/asl.2013.4872
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Connection and system integration of large scale wind power into the network systems has rose a number of important issues that must be evaluated in order to continually keep the power systems operation secure. It is therefore very important in planning and operation phases of power systems to perform and investigate the impact of wind power on the transient and small-signal stability. This paper briefly explores critical clearing time as a transient stability margin to evaluate the tested power systems without and with doubly fed induction generator based wind turbines. Maximum amplitude of the power swing, its settling time and voltage recovery in the system are also studied as margins. Simulations for transient stability analysis in this paper are performed using the Power System Simulator for Engineering software tools.

Dopady nových trendů na distribuční sítě

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek vychází ze závěrů studie ČVUT FEL zabývající se dopady nových trendů (převážně nárůstem drobných FVE na střechách budov a rozvojem "elektromobility") na distribuční síť Hlavního města Prahy. Ve vybrané oblasti jsou pomocí několika různých scénářů modelovány možné dopady, které budou vyžadovat změnu koncepce provozu DS. Jedině tak bude možné ve střednědobém horizontu nadále zajistit požadovanou kvalitu a spolehlivost dodávky elektrické energie.

Elektromobilita - Technologie a možnosti implementace v městských sítích

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    V příspěvku jsou v úvodních částech zmíněny základní technologické součásti elektromobilu. Jsou popsány základní prvky infrastruktury sloužící k provozování a nabíjení elektromobilů. Popsány jsou dva možné koncepty provozu elektromobilů v energetické soustavě. Případová studie, uvedená v závěrečné části, popisuje provedené simulace možného vlivu vozidel na elektrický pohon na městskou distribuční soustavu.

Elektromobilita a její možnosti využití v ČR

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek se zabývá elektromobilitou a jejími možnými vývoji v ČR. Jsou popsány základní technologie a infrastruktura potřebná k úspěšnému provozu nabíjecích stanic a pro nabíjení elektrických vozidel. V další části jsou popsány základní koncepty elektromobility ve vztahu k energetické soustavě a budoucím koncepcím smart grid. Ke konci článku je uvedena simulace vlivu možného rostoucího podílu elektrovozidel v městských sítích a možný vliv na tyto sítě.

Hybrid power filter for advanced power quality in industrial systems

  • DOI: 10.1016/j.epsr.2013.05.013
  • Odkaz: https://doi.org/10.1016/j.epsr.2013.05.013
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper presents the structure and control strategy of the hybrid power filter (HPF) with a split passive part. Its impedance is divided into two parts tuned to 50 Hz and 250 Hz. The HPF topology is very efficient to mitigate harmonic currents. The fundamental frequency voltage at the converter terminals is remarkably small in comparison with the grid voltage at the same moment. The HPF functionality is only negligibly influenced by the grid inductance changes. The HPF characteristics were compared with those for standard HPF topologies and the classical passive compensation by means of simulations done in the Matlab/Simulink environment. The voltage and current responses and their harmonic spectra were also measured in an industrial plant under different conditions.

Overhead Line Mechanical Behaviour - Dynamic Model

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper presents modelling of overhead line dynamics. The model of overhead line (OHL) shaking is generally based on the superposition of harmonic components. Individual harmonic coordinate components are finally composed together. The accuracy of the calculation is determined by the number of harmonics calculated and other parameters. The model is actually a combination of continuous and discrete calculations. In the case study OHL ACSR 350/59 is analyzed.

Provoz elektrárny v ostrovním režimu pro zásobování kritické infrastruktury

  • Autoři: Kůla, J., Linhart, T., doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J., Karafiát, P.
  • Publikace: CIRED 2013. Praha: CIRED, 2013. ISBN 978-80-905014-2-3.
  • Rok: 2013
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zabývá problematikou provozování ostrovního provozu elektrárny Kladno při rozsáhlém výpadku elektrické energie a návrhem metodiky pro vytvoření ostrovního provozu k zásobování kritické infrastruktury. Je popsána legislativa nouzových stavů v energetice, energetický zákon s navazujícími vyhláškami a pravidla provozování přenosových a distribučních soustav. Pro vybrané objekty kritické infrastruktury, které budou v ostrovním provozu napájeny, jsou navrženy varianty konfigurace distribuční sítě. Jako zdroj pro ostrovní provoz slouží plynová jednotka TG8 elektrárny Kladno II. Pro ověření schopnosti zdroje TG8 zásobovat zvolenou síť jsou provedeny výpočty zatěžování. V závěru jsou shrnuty výsledky navržených variant a doporučení pro další postup vedoucí k realizaci krizového ostrovního provozu.

The Converter Choice and its Control Circuit Design for Synchronous Generators

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Wind power plants equipped with synchronous generator without a gearbox and with a static converter will increase in quantity in future. To decrease the investment costs and plant maintenance it is important to choose the suitable converter for this plant and to improve the plant control strategy which depends on this chosen converter. The whole system was simulated using Matlab/Simulink program so that to get results for making sure this system is functional.

Advanced Applications of FACTS in Industrial Distribution Systems in Middle Europe

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with the possibilities of FACTS devices installation and operation in the Middle European distribution systems. A voltage fluctuation that results in flicker is caused by Electrical Arc Furnace (EAF) power fluctuation. The UPQC can be an effective means to suppress voltage fluctuation connected with the function of the EAF. Hitherto, the flicker has been compensated for mainly by using Static Var Compensators (SVC), whose capability to eliminate voltage subharmonics is limited by the frequency up to 10 Hz at maximum. A model of a power system with an electric arc furnace was developed for a typical metallurgical plant. The paper would like to emphasize that FACTS devices should have their position not only in large transmission system but for specific tasks also in local distribution systems. This is all connected with technical-economical decision how to approach to solving all partial electrical systems operational issues.

Advanced Method of Phasors Identification in Electrical Grids

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    As far as synchronized phasor measurement systems have emerged as a powerful tool to improve power systems performance and reliability and e.g. fault localization possibility, the need of precise, robust and fast method of phasor identification occurred. The authors present the SW and HW implementation of their original mathematical method of frequency and phase angle assessment. Statistical methods minimizing standard deviation of moving averages of the window lengths corresponding to possible frequency values for frequency assessment and numerical quadrature for phasor are used. The algorithm has been developed and tested using Mathematica SW. Microchip implementation using C language was realized and tested in laboratory conditions.

Dispersed Generation Impact on Faulted Currents in Distribution Systems

  • Autoři: Mareček, P., Šrom, J., Švec, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Proceedings of the 13th International Scientific Conference EPE 2012. Brno: VUT v Brně, Fakulta elektrotechniky a komunikačních technologií, 2012. pp. 749-752. ISBN 978-80-214-4514-7.
  • Rok: 2012
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with dispersed generation connected to the distribution grid on current flowing in the grid lines during faults - mainly short-circuits. There is shown at current changes in distribution systems, especially lines with dispersed generation but also some near ones. These changes can influence protective systems sensitivity very significantly. The calculations in the paper monitor the dispersed generation size, character and location influences on the static and dynamic fault conditions in the systems. There are also described some possibilities how to face the mentioned phenomena during grids operation and protection.

Evaluation of IRP, FBD, SD, and Generalized Non-Active Power Theories

  • DOI: 10.1109/EEEI.2012.6376914
  • Odkaz: https://doi.org/10.1109/EEEI.2012.6376914
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Most of modern power equipments connected to the grid must be viewed as non-linear loads producing voltage and current harmonics, subharmonics, and quasi-periodic and stochastic disturbances even under normal operation conditions. An analysis and comparison of usage of different power theories for the parallel compensation of periodic and non-periodic disturbances is presented in the paper. Different reference voltage vectors and averaging time intervals are applied in the power theories.

Generalized Non-Active Power Theory for Non-Periodic Disturbances

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper presents the principles and the utilization analysis of the generalized non-active electrical power theory for the parallel active power filter compensation of periodic and non-periodic current disturbances. There are studied mainly frequency characteristics of residuum currents after the applied compensation to show its effectiveness. A non-linear unbalanced load is considered which generates periodic and stochastic non-periodic currents. This load is connected to an unbalanced nonsinusoidal voltage source.

Methodology for Lightning Protection of Medium and High Voltage Networks

  • Autoři: Soibelzon, H., Vernieri, J., Salzman, C., doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J.
  • Publikace: ELEN 2012. Praha: vydavatelství ČVUT v Praze, 2012. pp. 1-10. ISBN 978-80-01-05096-5.
  • Rok: 2012
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper critically analyses different theoretical methods of medium (MV) and high (HV) voltage networks in order to prevent damages caused by lightning. Medium voltage networks distances suggested by international standards and recommendations (CIGRE, IEEE, etc) are critically scrutinized. Shielding protection techniques in high voltage networks are risk assessed emphasizing successful examples of uses in the Argentinean network & power generation market. The MV approach is assessed by means of a critical ex-post analysis of the work performed in the City Bell MV grid in order to evaluate the maximum admissible distance between arresters and transformers including transformer voltage (Ua) and maximum distance (L). Calculations are detailed, as well as, usual configuration levels to establish the practical links between lightning arresters and protected appliances. The HV approach is considered by means of two critical studies: an existing 132 kV power line with triangular disposition with its mounted and reinforced 2.50 meters of concrete poles and phase conductors of ACSR 240/40 mm2 in which the classic methods of angles is used, and a second study of a much higher order power line (i.e. 500 kV) in which a shift from the traditional method of angles to the modern EGM method is applied using CIGRE and IEEE recommendations. One of the originalities of this paper is to show by means of real life examples that while CIGRE recommendations seem to be adequate for high voltage power lines, IEEE recommendations are flawed, and may even put at risk the sustainability of the power line.

Migration of the IT Technologies to the Smart Grids

  • DOI: 10.5755/j01.eee.123.7.2390
  • Odkaz: https://doi.org/10.5755/j01.eee.123.7.2390
  • Pracoviště: Katedra elektroenergetiky, Katedra telekomunikační techniky
  • Anotace:
    This paper describes the migration of the traditional IT technologies to the Industrial Control Networks for Power Grids (ICNPG), characteristics of the typical ICNPG network and the differences between them and ICT network. We define the availability and reliability of the ICT networks and describe the current trends of the IT technologies in the ICNPG network with regarding its use in the Smart Grids. Finally, we describe the Smart Grid technology and summarize the availability and reliability of the ICNPG networks from technical studies. The comparison of ICNPG and ICT networks show that the utilization rate of ICT technologies must be determined in the Smart Grids with regard to the required availability and reliability. Ill. 1, bibl. 7, tabl. 2 (in English; abstracts in English and Lithuanian).

Stability of Operation with Small Hydropower Plants in Islanded Network

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The objective of the paper is to provide verification of power network behaviour with a new Hydropower Plant installation (HPP). The network is operated as an island, powered with the existing diesel generator sets. The generator sets are located in a factory which is representing the main consumption of the network contemporarily - Factory Power Plant (FPP). The paper is analyzing both single HPP operation and parallel operation of HPP and with the existing FPP. For this purpose there was developed the network model in MATLAB Simulink. Computations made hereinafter are evaluating reference load changes (including motor start-ups) in order to determine system responses (frequency change) on specified load changes at different operation states. The paper main aim is to specify proposals on stability improvements in case of unsatisfactory solutions (possible modifications are supposed to be GD2 or Tw changes on HPP part). All the simulations have to respect that frequency deviation shall not be greater than ± 3 Hz.

Synchronous Phasors Monitoring System - Testing Project in the Czech Republic

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper focuses on the issues of advanced methods to achieve security and reliability of electrical power systems, mainly focusing on transmission systems. Advanced principles and techniques in monitoring systems are discussed. The key part of the paper deals with application possibilities of PMUs (Phasor Measurement Unit) and their integration into WAMPaC systems (Wide Area Monitoring, Protection and Control). Assessment criteria are explained in a mathematical form and demonstrated in terms of case studies. Significant power system states were analyzed in the case studies. PMUs usage for voltage phase monitoring is demonstrated for three cases - usual system state, high-load state and islanding. In this context the attention is paid to the possibilities of power system observability improvement using measuring chain error elimination.

Synchronous Phasors Monitoring System Application Possibilities

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with some tasks of advanced methods to achieve security and reliability of transmission power systems. There are discussed advanced principles and techniques in monitoring systems. The paper main part is devoted to possible applications of PMUs (Phasor Measurement Unit) and their integration into WAMPaC systems (Wide Area Monitoring, Protection and Control). Significant transmission system states were analyzed in several case studies. PMUs utilization for voltage monitoring is demonstrated for three cases - standard system state, high-load state and islanding. Here the attention is paid to the possibilities of power system observability improvement using measuring chain error elimination. Other possible applications in transmission systems include ampacity determination of transmission corridors, the calculation of line electrical parameters using synchrophasor measurement, state estimation issues and power system stability. The power system model was established for methods and algorithms verification purposes. The appropriate algorithms and their parameters were found using simulation outputs to create the local automatics, e.g. Automatic Power System Stabilizer (PSS).

The Use of Regression Methods for Measurement and Diagnostics in Electrical Power Engineering

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper presents the principles and the utilization of regression methods for measurement using electrical quantities samples. Direct electrical devices parameters measurement in operation can be sometimes a hard or even impossible task. The presumption of electrical circuits linearity and harmonic signal component orthogonality allows us to determine the circuit parameters using the sampled data and the least-square regression method. Examples of the developed method utilization are given in the paper. The first example is devoted to harmonic filters equivalent circuit data assessment. The second one deals with the measurement of active losses in highly reactive devices e.g. arc-suppression coils.

UPQC application for EAF flicker mitigation

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with the possibilities of utilizing series and shunt active filters compensation in order to mitigate voltage fluctuation and flicker caused by Electrical Arc Furnace (EAF) in industrial distribution systems. A voltage fluctuation that results in flicker is caused by EAF power fluctuation. The Unified Power Quality Conditioner (UPQC) belongs to the group of FACTS devices based on power electronics converters, particularly equipped with component with turn-off capability (e.g. IGBT). They offer many compensation functions for power transmission systems and represent the most progressive way to increase power quality in the systems. The UPQC can be an effective means to suppress voltage fluctuation connected with the function of the EAF. Flicker has been compensated for mainly by using Static Var Compensators (SVC) whose capability to eliminate voltage subharmonics is limited by the frequency up to approximately 10 Hz at maximum. Recently, some studies and tests have been done to prove advantages of active filters (AF) over SVC in this field. The UPQC consists of the parallel and series AF. Therefore it offers more possibilities to solve instantaneous active and reactive power fluctuation than either the parallel or series AF alone. A model of a power system with an electric arc furnace was developed for a typical metallurgical plant. There is an important aspect of the suitability to keep the current SVC compensation. The advanced solution is to add SVC by less dimensioned UPQC for sparing investments and improving the system conditions together. The paper would like to emphasize that FACTS devices should have their position not only in large transmission system but for specific tasks also in local distribution systems.

Dynamic Loading Control using FACTS in Extraordinary States

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Proceedings of the 12th International Scientific Conference Electric Power Engineering 2011. Ostrava: Vysoká škola báňská - Technická univerzita Ostrava, 2011. pp. 1-4. ISBN 978-80-248-2393-5.
  • Rok: 2011
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper introduces the proposed methods to control transmission lines loading in ES extraordinary states given e.g. by high renewable sources production. The methods implement two basic modern approaches: evaluating transmission lines ampacity according to current weather conditions and using FACTS devices in transmission systems to reallocate the loading among more lines. The aim is to overcome the extraordinary states either by the installed and operated control devices or to obtain more time for the state to be solved by the dispatchers.

Effective Method of Synchronous Phasor Detection

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Large power system disturbances and their consequences represent a challenging problem for power system operation, its security and reliability. This fact has reinforced interest in the new generation of monitoring systems. Synchronized Phasor Measurement System has emerged as a powerful tool to improve power systems performance and reliability and e.g. fault localization possibility. Data measured by PMU (Phasor measurement unit) are source of progressive research and can be used for network state modeling including lot of variable parameters. The paper describes a PMU hardware solution developed at CTU in Prague and mainly an effective method of detecting synchronous phasors of voltages and currents for differently disturbed electrical quantities time behaviours.

Higher Harmonics Filters Parameters Diagnostics in Industrial Applications

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper analyses the solution possibilities of tuning, diagnostics and incorrect function discovering for higher harmonics filters in industrial applications. The paper principle topic is the possibility analysis of filters RLC elements parameters calculation during standard device operation. The method verification is carried out with a mathematical model as well as with a measurement in terms of a case study. The case study results from filters voltage and current measurement in a tube rolling mill in a metallurgical company.

Hybrid Power Filter for Industrial Network

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J., prof. Ing. Viktor Valouch, CSc.,
  • Publikace: Proceedings of the 12th International Scientific Conference Electric Power Engineering 2011. Ostrava: Vysoká škola báňská - Technická univerzita Ostrava, 2011. pp. 1-4. ISBN 978-80-248-2393-5.
  • Rok: 2011
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The new topology and control strategy of the Hybrid Power Filter (HPF) is presented. The topology is very effective to mitigate harmonic currents of a non-linear load, especially for high frequencies. Additionally, the functionality of this HPF is affected by changes of the grid inductance only negligibly. The behaviour and properties of the new HPF were compared with those for a usual option of the HPF and for a classic passive compensation by simulation done in the Matlab/Simulink environment. The voltage and current responses were also measured in the real industrial plant.

Impact of distributed sources on the currents in distribution networks

  • Autoři: Mareček, P., Šrom, J., Švec, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Sborník ČK CIRED 2011. Tábor: Český komitét CIRED, 2011. pp. 1-13. ISBN 978-80-905014-0-9.
  • Rok: 2011
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    In this paper is discuss impact of distributed sources connect to distributing networks on the short-circuit currents. The main problem is the change of proportion of short-circuits currents between the network and distributed sources and settings of protection system. It is mentioned the impact of size, character and location of distributed sources on current ratio when the disturbance happens. It also describes some ways to deal with these problems in operation and protection networks.

New Hybrid Power Filter for Power Quality Improvement in Industrial Network

  • DOI: 10.24084/repqj09.307
  • Odkaz: https://doi.org/10.24084/repqj09.307
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The new Hybrid Power Filter (HPF) with a split passive part whose impedance is divided into two individual parts tuned to 50 Hz and 250 Hz is presented. Its topology is very effective to mitigate harmonic currents of a non-linear load, especially for high frequencies. The value of the voltage of fundamental frequency at terminals of an electronic power converter is in the range of several percent of that voltage at the Point of Common Coupling (PCC) at the same time. The new HPF was compared with a usual HPF and a classic passive compensation by simulation done in the Matlab/Simulink environment. The voltage and current responses and their harmonic spectra were also measured in the real industrial plant under different conditions. The results obtained were in the line with those got by a theoretical analysis done in the frequency domain and confirm the priority of the new HPF above other HPF topologies.

Synchrofázorová měření a systémy WAMS (Wide Area Monitoring System)

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Návrh a rozvoj elektroenergetických sítí. Praha: Czech Technical University in Prague, 2011. p. 130-182. ISBN 978-80-01-04939-6.
  • Rok: 2011
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Kapitola popisuje synchrofázorová měření, jejich základní prinicpy a problémy spojené s přesností měření. Rovněž jsou popsány základní možnosti využití (stabilita, oscilace, estimace parametrů vedení, spínání oblastí). Rovněž je popsána architektura systému WAMS včetně sběru dat, jejich zpracování a výměny s dalšími systémy.

Telekomunikační sítě pro elektroenergetické systémy

  • Pracoviště: Katedra elektroenergetiky, Katedra telekomunikační techniky
  • Anotace:
    Kapitola popisuje telekomunikační sítě a jejich klíčové vlastnosti pro použití v elektroenergetice. Jsou ukázány vhodné telekomunikační struktury a topologie pro Smart grids. Rovněž jsou popsány příslučné standardy.

Teorie řízení výkonových toků v soustavách

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Švec, J.
  • Publikace: Monitorování, řízení a chránění elektrizačních soustav. Praha: Czech Technical University in Prague, 2011. p. 16-39. ISBN 978-80-01-04940-2.
  • Rok: 2011
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Kapitola popisuje vlastnosti činných a jalových toků v přenosových sítích a ukazuje možnosti jejich řízení pomocí pasivních a aktivních zařízení. Rovněž je provedena diskuze sériové kompenzace a šuntování a jejich charakteristiky a vliv na napěťovou hladinu.

Transmission Overhead Lines Audible Noise of Typical EHV Line Configurations Operated in the Czech Republic

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Rosenkranz, J., Švec, J., Tlustý, J., Krejčí, P., Santarius, P.
  • Publikace: International Conference on Large Electric Systems. Haifa: Cigré Israel, 2011. pp. 1-6.
  • Rok: 2011
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper shows calculated and analysed audible noise levels generated by overhead lines of different configurations utilized in the Czech Republic. The surface electrical gradient influencing the line audible noise of conductor wires can be checked by operational voltage and construction parameters, i.e. conductor wires diameter, their surface roughness, conductor wires number in the bundle, symmetrical and nonsymmetrical bundle configuration, phase-to-phase distances in the 3-phase system, phase rotating on the tower, phase conductors height above the ground, mutual distance of parallel 3-phase systems on a double powerline common tower, or separate parallel powerlines distance. The analyses result in important knowledge for configuration design, operation and also for the overhead line trace choice.

Dynamic Equivalents in Power System Stability Assessment

  • Autoři: Mareček, P., Ing. Miroslav Müller, Ph.D., doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Sýkora, T., Tlustý, J.
  • Publikace: Proceedings of the 11th International Scientific Conference Electric Power Engineering 2010. Brno: Brno University of Technology, 2010. pp. 135-138. ISBN 978-80-214-4094-4.
  • Rok: 2010
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper is concerned with transformation of dynamic behaviour of the meshed power system to the cooperation dynamic of two regulated generators working to the equivalent connection. The transformation preserves dominant dynamic features of the original system and the resulting layout enables monitoring of faults representation to the value of its equivalent connection and their impact to the function of regulations and protection equipments. The paper show possible solution to the problem of connecting distributed generations to the existing electrical system. In this paper we have processed advanced model and tools consisted in formulation of the equivalent system in order to study the dynamic behaviour of the system. The results from steady state conditions and short-circuit calculations are the basic information for the formation of the simplified dynamic equivalent.

Eliminace negativního vlivu metody přizemnění postižené fáze při zemních spojeních v systémech vn

  • Autoři: Cimbolinec, I., Sýkora, T., Švec, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Sborník konference CIRED 2010 Tábor. Praha: CIRED, 2010. pp. 1-14. ISBN 978-80-254-8519-4.
  • Rok: 2010
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zabývá negativními důsledky uvedené metody, které se projeví při kovových zemních spojeních a zemních spojeních s nízkým přechodovým odporem poruchy. V další části příspěvku je navrženo řešení, které umožňuje významně eliminovat negativní vlivy metody "Přizemnění postižené fáze".

HV Lines Current Unbalances Reduction Possibilities by Phase Conductors Configuration Changes

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Sborník konference ELEN 2010. Praha: ČVUT FEL, Katedra elektroenergetiky, 2010. pp. 1-7. ISBN 978-80-254-8089-2.
  • Rok: 2010
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper describes current unbalances elimination possibilities on double cross-border powerline 400 kV and presents particular phase conductors configuration changes and their influences on phase current unbalances, ground wires currents, ground currents and total losses on powerlines. The aim is to show a very strong influence of suitable phase configuration version choice on the final unbalance as well as significant differences in results for different towers choice for compensation measures realization. There are mentioned basic computational procedures for determining current flows and power losses on the powerline if considering specific conditions on the line being solved without knowing other transmission system parts state. There are also notified different reasons of differences between current values calculated and those measured in real substation outputs.

Moderní prostředky pro eliminaci kolísání napětí v elektrické síti

  • Autoři: Tlustý, J., Sýkora, T., Švec, J., doc. Ing. Zdeněk Müller, Ph.D., Mareček, P.
  • Publikace: Sborník konference CIRED 2010 Tábor. Praha: CIRED, 2010. ISBN 978-80-254-8519-4.
  • Rok: 2010
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Z hlediska budoucího rozvoje provozu distribučních soustav lze očekávat zvyšující se nároky na kvalitu dodávané elektrické energie. V příspěvku je věnována pozornost zejména problematice kolísání napětí a flickeru. Rušení, které způsobuje flicker, je poměrně rychlé, a proto nelze použít klasické možnosti filtrace pasivními prvky, ale je třeba použít zařízení, které je schopno okamžitě reagovat na změny aktivních elektrických veličin. Aktivní filtry a zařízení FACTS jsou schopny na tyto rychlé změny okamžitě reagovat. Pokud se vlivem provozu objevuje v síti kolísání napětí, je třeba provést kompenzaci jalového výkonu a napětí. Jednou z možností je využití moderního zařízení UPQC (Unified Power Quality Conditioner).

Moderní spotřebiče a kvalita odebírané elektrické energie

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J.
  • Publikace: Sborník konference ELEN 2010. Praha: ČVUT FEL, Katedra elektroenergetiky, 2010. pp. 1-7. ISBN 978-80-254-8089-2.
  • Rok: 2010
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek se zabývá problematikou kvality elektrické energie, kterou mohou významnou měrou ovlivnit elektrické spotřebiče obsahující výkonové polovodičové součástky na napěťové úrovni nn. Mezi tyto spotřebiče patří: spínané zdroje u PC, UPS kompaktní a indukční zářivky. V bodě připojení (bod PCC) je měřeno množství předané elektrické energie a také kvalitativní parametry a to zejména: změna napětí, napěťové poklesy, přerušení napětí, vyšší harmonické, flicker, útlum signálu HDO aj. Povolené limity jednotlivých parametrů jsou definovány v pravidlech provozování distribučních soustav. Článek prezentuje měření proudu a napětí při zapnutí a během provozu. Dále je zde uvedeno měření harmonického spektra napětí a proudu, které má negativní vliv na elektrickou síť. Jediné zařízení během provozu nezpůsobuje problémy, ale když je použito dané zařízení ve vysokém počtu, můžou vytvářet problémy v elektrické síti.

Phasor Measurement Units in Power System Monitoring

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Large power system disturbances and their consequences represent a challenging problem for the power industry and especially for system operators who are responsible for the network operation, its security and reliability. This fact has reinforced interest in the new generation of monitoring systems with the aim to gain a precise and maximum knowledge about those disturbances and their impact. Most of these severe events with impact on the entire system typically occur in or near the transmission system (TS) and are therefore best monitored at TS level. This puts great demands on the equipments and in general restricts the use of the data since it becomes property of the TSO. Synchronized Phasor Measurement System has emerged as a powerful tool to improve power systems performance and reliability and fault localization possibility. An example of fault event that occurred in TS and was registered by Phasor Measurement Units installed in the distribution system will be shown.

Stability Control of Renewable Energy Sources in Distribution Systems

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Deregulation in the power market has encouraged the move towards distributed generation, where many smaller generating plants located close to major loads are penetrating into interconnected power systems. When the penetration level increases, several other problems will need to be faced and solved. Stability problems may arise, new planning tools will be needed, dispatching of energy sources with typical random production will be necessary, protection systems must be integrated and revised. In order to simulate power system dynamics programmable opened software in Matlab - DynaSolv was developed. The paper describes various principles of penetration synchronous machine type DGS into distribution network. This study provides possible complex analysis view on DGS stability issues, which can answer the possibility of connection.

Transmission Lines Loading Control Using FACTS Systems

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Proceedings of the 11th International Scientific Conference Electric Power Engineering 2010. Brno: Brno University of Technology, 2010. p. 75-82. ISBN 978-80-214-4094-4.
  • Rok: 2010
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper introduces the most common FACTS devices used in ES and their operational capabilities mainly with the aim to control current and power flows on ES lines. It is focused especially on series compensation and active power flow control. There are compared control abilities of TCSC and PST devices with respect to line current control. The line current carrying capacity is considered as variable influenced by climatic quantities and the conductor temperature can then be controlled dynamically.

Vybrané problémy připojování a provozu OZE v distribučních soustavách

  • Autoři: Tlustý, J., Švec, J., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T.
  • Publikace: Sborník konference CIRED 2010 Tábor. Praha: CIRED, 2010. pp. 1-8. ISBN 978-80-254-8519-4.
  • Rok: 2010
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek se věnuje podmínkám připojování obnovitelných a rozptýlených zdrojů elektrické energie do distribučních soustav. Pozornost je věnována zejména specifickým faktorům ovlivňujícím napěťové poměry v soustavě s OZE. Cílem je poukázat na různě významný vliv činného a jalového výkonu zdrojů, zatížení soustav, zkratového výkonu apod. na napěťové změny vyvolané připojení OZE do DS. Snahou je zdůraznit nutnost při výpočtech respektovat konkrétní podmínky a parametry v oblasti připojení zdrojů, pokud chceme dosáhnout věrohodných výsledků výpočtů.

Advanced Power System Models for Transient stability analysis

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Deregulation in the power market has encouraged the move towards distributed generation, where many smaller generating plants located close to major loads, as opposed to a few large centrally located power stations, are penetrating into interconnected power systems. Nowadays, generating electricity using decentralized generators of relatively small scale is attracting a great interest from electric energy researchers. Such kind of generation is known as Distributed Generation Systems (DGS).

Distributed Generation Stability Analysis in Central Bohemia Distribution Networks

  • Autoři: Tlustý, J., Salzman, C., Salzman, D., Soibelzon, H. L., Sýkora, T., Švec, J., Ing. Jan Špetlík, Ph.D., doc. Ing. Zdeněk Müller, Ph.D., Mgaya, E., Kasembe, A.
  • Publikace: 20th International Conference and Exhibition on Electricity Distribution. Stevenage: IET Publishing Group, 2009. pp. 1-4. ISBN 978-1-84919-125-8.
  • Rok: 2009
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The presented study describes various principles of penetration of synchronous machine-type DGS into the distribution network. The study was aimed at a possible operation area of the connected sources with regard to the stable operation in steady-state conditions and stable operation after clearing the fault. This study, however, provides a possible complex analysis view on DGS stability issues, which can answer the possibility of a connection. From this point of view, the following results are obtained.

Dynamic Equivalents in Power System Stability Analysis

  • Autoři: Diallo, O., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Electric Power Engineering 2009. Ostrava: VŠB, 2009. p. 357-361. ISBN 978-80-248-1947-1.
  • Rok: 2009
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper shows a possible solution to the problem of connecting distributed generations to the existing electrical system. In this paper we have processed an advanced model and tools consisted in formulation of the equivalent system in order to study the dynamic behaviour of the system. The results from steady state conditions and short-circuit calculations are the basic information for the formation of the simplified dynamic equivalent. The paper is concerned with transformation of dynamic behavior of the meshed power system to the cooperation dynamic of two regulated generators working to the equivalent connection. The transformation preserves dominant dynamic features of the original system and the resulting layout enables monitoring of faults representation to the value of its equivalent connection and their impact to the function of regulations and protection equipments.

Moderní prostředky pro eliminaci rušivých vlivů v elektrických světelných obvodech

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Kurz osvětlovací techniky XXVII. Ostrava: VŠB - Technická univerzita Ostrava, 2009. pp. 308-313. ISBN 978-80-248-2087-3.
  • Rok: 2009
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek se zabývá možnostmi eliminace rušení vyššími harmonickými, které se v elektrických sítích mohou začít více vyskytovat z důvodu používání méně kvalitních světelných zdrojů. Článek reaguje i na aktualizaci norem a vyhlášek, které úzce souvisí s dodávkou a kvalitou elektrické energie. Díky nařízení EU, kdy došlo k zákazu výroby klasických žárovek od 100 W a vyšších, budou tyto světelné zdroje nahrazovány kompaktními zářivkami, které obsahují elektronické předřadníky. V elektronických předřadnících používají polovodičové součástky a na trhu se objevují i méně kvalitní světelné zdroje, které jsou i zdrojem rušení. Do budoucna je třeba řešit eliminaci tohoto rušení, což si vyžádá nemalé investiční náklady.

Některé názory na pravděpodobný rozvoj slunečních elektráren v ČR

  • Autoři: Willmann, B., doc. Ing. Zdeněk Müller, Ph.D., Švec, J.
  • Publikace: EE - Odborný časopis pre elektrotechniku a energetiku. 2009, 15(6), 37-40. ISSN 1335-2547.
  • Rok: 2009
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Podmínky rozvoje slunečních elektráren (SLE) v konkurenčních podmínkách trhu s elektřinou. Charakteristika vývoje instalovaného výkonu SLE z pohledu jejich umístění a vlivu na elektrizační soustavu. Pravděpodobné roční využití instalovaného výkonu SLE, podmínky v síti a pravděpodobný směr rozvoje ve směru Smart grid. Některé dopady využití SLE na cenu elektřiny a charakter toků v síti nn a také vn.

Použitelnost metody "přizemnění postižené fáze (shuntingu)" při zemních spojeních v kompenzovaných sítích vn

  • Autoři: Cimbolinec, I., Sýkora, T., Švec, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Sborník konference ČK CIRED 2009. Tábor: Český komitét CIRED, 2009. pp. 1-11. ISBN 978-80-254-5635-4.
  • Rok: 2009
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Tento příspěvek v úvodu stručně porovnává známé principy provozování kompenzovaných sítí vn, v dalším se pak podrobně zabývá využitím metody přizemnění postižené fáze - shuntingu, kdy na základě teoretického rozboru a následného praktického měření v kompenzované síti vysokého napětí definuje oblast bezpečné aplikace této metody.

Power Flow Control in ES using FACTS Systems

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Proceedings of the 5th International Scientific Symposium on Electric Power Engineering ELEKTROENERGETIKA 2009. Košice: TU Košice, FEI, 2009. p. 427-433. ISBN 978-80-553-0401-4.
  • Rok: 2009
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with principles of controlling active and reactive power in electrical systems. There are briefly explained the basic methods and equipments of passive and active compensation and control devices. The paper shows the differences between classical and modern devices using power electronics. Two case studies show the influences of shunt and series compensation on possibilities of controlling voltage, active and reactive power. Also different operational capabilities of several FACTS devices are compared.

The Monitoring of Power System Events on Transmission and Distribution Level by the use of Phasor Measurement Units (PMU)

  • Autoři: Tlustý, J., Kasembe, A., doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Sýkora, T., Popelka, A., Mgaya, E., Diallo, O.
  • Publikace: 20th International Conference and Exhibition on Electricity Distribution. Stevenage: IET Publishing Group, 2009. pp. 1-4. ISBN 978-1-84919-125-8.
  • Rok: 2009
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Large power system disturbances and their consequences,represent a challenging problem for the power industry and especially for the network system operators, the ones who are responsible for the network operation at large, its security and reliability. This fact has reinforced interest in the new generation of monitoring systems with the aim to gain if possible a precise and maximum knowledge about those disturbances and their impact. Most of these severe events with impact on the entire system typically occur in or near the transmission network and are therefore best monitored at transmission system level. This puts great demands on the equipments and in general restricts the use of the data since it becomes property of the transmission system operator. Synchronized Phasor Measurement System has emerged asa powerful tool to improve power systems performance and reliability and fault localization possibility.

Vliv větrných elektráren na provoz elektroenergetické soustavy ČR

  • Autoři: Willmann, B., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: EE - Odborný časopis pre elektrotechniku a energetiku. 2009, 15(2), 32-35. ISSN 1335-2547.
  • Rok: 2009
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek informuje o problémech souvisejících s růstem instalovaného výkonu větrných elektráren ve srovnání s maximem a strukturou zdrojů. Dotýká se problému vztahu technických možností přenosových soustav a volného obchodu s elektřinou. Pojednává o vlivu proudů vyvolaných silným provozem VTE na přenosové soustavy v sousedních státech.

Analysis Of The Power System Stability Using Simplified Dynamic Equivalents

  • Autoři: Mgaya, E., Doležal, J., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J., Hong Thai, L.
  • Publikace: Control of Power Systems 2008. Bratislava: Slovak University of Technology, 2008. pp. 1-8. ISBN 978-80-227-2883-6.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper solves the problem of connecting distributed generations (DGs) to the distribution networks. It solves the problem of steady-state and dynamic behaviors. In order to study the dynamic behavior of the system we have processed advanced model and tools consisted in formulation of the equivalent system. The results from steady state conditions and short-circuit calculations are the basic information for the formation of the simplified dynamic equivalent. The paper is concerned with transformation of dynamic behavior of the meshed power system to the cooperation dynamic of two regulated generators working to the equivalent connection. The transformation preserves dominant dynamic features of the original system and the resulting layout enables monitoring of faults representation to the value of its equivalent connection and their impact to the function of regulations and protection equipments.

Evaluation of Reliability in Electric Power System

  • Autoři: Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D., Hong Thai, L., Tlustý, J.
  • Publikace: Proceedings of the 9th International Scientific Conference Electric Power Engineering 2008. Brno: Brno University of Technology, 2008. pp. 269-271. ISBN 978-80-214-3650-3.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper presents a method for calculation and evaluation of reliability in electric power systems by using the theory of probability and the theory of reliability. In this paper methods for determining reliability according to loss of load probability (LOLP) have discussed two. One case study was carried out for verification of these methods.

Hodnocení flickeru v průmyslových sítích

  • Autoři: Tlustý, J., Sýkora, T., Švec, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Kurz osvětlovací techniky XXVI. Ostrava: VŠB - Technická univerzita Ostrava, 2008. pp. 301-305. ISBN 978-80-248-1851-1.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Flicker jakožto kolísání světelného toku patří k jedněm z nejvíce diskutovaných typů energetických rušení. Jeho dopady na jednotlivce z řad zákazníků do značné míry závisí na subjektivním posouzení, proto i jeho šíření a eliminace vyvolávají rozdílné reakce a názory mezi laiky i provozovateli soustav a průmyslových zařízení. Způsob šíření flickeru v síti vychází z principu napěťového a proudového děliče, z čehož plynou známá pravidla o přenášení hodnot flickeru mezi napěťovými hladinami.

Hodnocení míry flickeru v průmyslových sítích

  • Autoři: Tlustý, J., Sýkora, T., Švec, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Sborník konference CIRED 2008. Praha: CIRED, 2008. pp. 1-7. ISBN 978-80-254-2790-3.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Tento příspěvek se věnuje otázce šíření energetických rušení v průmyslových sítích, která jsou obvykle vyvolána průmyslovými odběrateli přenášena k dalším komerčním i domácím odběratelům, kteří mají často vysoké nároky na kvalitu dodávané elektrické energie. Z hlediska světelných zdrojů přítomných u odběratelů všech typů je hlavním kritériem úroveň flickeru, tedy kolísání světelného toku vyvolané změnami napěťové úrovně. Problematika šíření flickeru je aplikována na distribuční síť 110 kV oblasti Podbrezová na Slovensku. Železárny Podbrezová provozují 50 MW obloukovou pec jako hlavní zátěž ve výrobě. Tato oblouková pec je napájena vedením 110 kV ze vzdálené rozvodny Medzibrod, která disponuje pro daný vývod dvěmi transformátory 220/110 kV, které mohou být na straně 110 kV provozovány odděleně i společně.

Šíření flickeru od obloukové pece v průmyslových sítích

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se věnuje otázce šíření energetických rušení v průmyslových sítích, která jsou obvykle vyvolána průmyslovými odběrateli a přenášena k dalším komerčním i domácím odběratelům, kteří mají často vysoké nároky na kvalitu dodávané elektrické energie. Z hlediska světelných zdrojů přítomných u odběratelů všech typů je hlavním kritériem úroveň flickeru, tedy kolísání světelného toku vyvolané změnami napěťové úrovně.

System stability analysis and dynamic equivalents

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper shows a new method for the simulation of system operation in the context of connection of new sources or change the parameters of existing resources. The models demonstrates opportunities to develop the system and its architecture. The presented models can be used for stable and economic management.

Technologie vnitrozemských větrných elektráren a jejich vliv na elektrickou síť a životní prostředí

  • Autoři: Sýkora, T., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J.
  • Publikace: Sborník konference ELEN 2008. Praha: ČVUT FEL, Katedra elektroenergetiky, 2008. pp. 1-13. ISBN 978-80-254-2293-9.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zabývá problematikou výroby elektrické energie z větru. Je zde uveden výběr turbín podle velikosti výkonu a dále je zde uveden technologický popis větrné elektrárny. Dále je v článku uveden výběr lokality pro stavbu elektrárny a zhodnocení vlivu elektrárny na elektrickou síť a životní prostředí.

The Hydro Power Plant Dynamics Simulation

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Sborník konference ELEN 2008. Praha: ČVUT FEL, Katedra elektroenergetiky, 2008. pp. 1-7. ISBN 978-80-254-2293-9.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with the hydro power plant modeling. The developed solution is useful for transient pipe flow study. The main part of the paper focuses on the comparison of basic solution philosophies. The first kind of solution is an evaluation using signal-based solution. This model is suitable for hydro power plant control systems, the drawback of this solution is very simplified pipe flow model. The second used model is based on the finite elements method. Finally, the third discussed solution is a direct formulation and solving partial differential equations. Main advantages and drawbacks of these methods are explained.

The Impact of Connecting Distributed Generation to the Distribution System

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper deals with the general problem of utilization of renewable energy sources for the generation of electric energy. Recent advances in renewable energy power generation technologies, i.e. wind and photovoltaic (PV) technologies, have led to increased interest in the application of these generation devices as distributed generation (DG) units. This paper presents the results of an investigation about the possible improvement in system voltage profile and reduction of system losses by the addition of wind power DG (wind-DG) to a distribution system. Simulation results are given for a case study and show that properly sized wind DGs placed at carefully selected sites near key distribution substations could be very effective in improving distribution system voltage profile and reducing power losses, and hence improve the effective capacity of the system.

The Power System Stability Analysis Using Simplified Dynamic Equivalents

  • Autoři: Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Sborník konference ELEN 2008. Praha: ČVUT FEL, Katedra elektroenergetiky, 2008. pp. 1-7. ISBN 978-80-254-2293-9.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper solves the problem of connecting distributed generations (DGs) to the distribution networks. It solves the problem of steady-state and dynamic behaviors. In order to study the dynamic behavior of the system we have processed advanced model and tools consisted in formulation of the equivalent system. The results from steady state conditions and short-circuit calculations are the basic information for the formation of the simplified dynamic equivalent. The paper is concerned with transformation of dynamic behavior of the meshed power system to the cooperation dynamic of two regulated generators working to the equivalent connection. The transformation preserves dominant dynamic features of the original system and the resulting layout enables monitoring of faults representation to the value of its equivalent connection and their impact to the function of regulations and protection equipments.

Use of Simplified Dynamic Equivalent for the Power System Stability Analysis

  • Autoři: Mgaya, E., Tlustý, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Power and Energy Systems - AfricaPES 2008. Calgary: IASTED / Acta Press, 2008. pp. 64-69. ISBN 978-0-88986-761-1.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    This paper intends to solve the problem of connecting distributed generations to the existing electrical system. In this paper we have processed advanced model and tools consisted in formulation of the equivalent system in order to study the dynamic behaviour of the system. The results from steady state conditions and short-circuit calculations are the basic information for the formation of the simplified dynamic equivalent. The paper is concerned with transformation of dynamic behavior of the meshed power system to the cooperation dynamic of two regulated generators working to the equivalent connection. The transformation preserves dominant dynamic features of the original system and the resulting layout enables monitoring of faults representation to the value of its equivalent connection and their impact to the function of regulations and protection equipments.

Vliv změn v energetickém prostředí na spolehlivost sítí

  • Autoři: Willmann, B., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J.
  • Publikace: Sborník konference ELEN 2008. Praha: ČVUT FEL, Katedra elektroenergetiky, 2008. pp. 1-6. ISBN 978-80-254-2293-9.
  • Rok: 2008
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek se věnuje strukturálním změnám v elektroenergetickém odvětví v Evropě i v USA. Komentuje problémy vztahu tržního prostředí a potřeb výstavby nových přenosových tras. V této souvislosti diskutuje rozsáhlé výpadky v elektrizačních soustavách a jejich důsledky. Upozorňuje rovněž na časté změny podnikatelského prostředí v přenosu a distribuci elektřiny. V závěru prezentuje možnosti výpočtu zatížení sítí na základě znalosti odebrané energie a charakteru odběru.

Analysis of the Impact of Distributed Generation Sources in Islanded Operation

  • Autoři: Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: EEUG Meeting 2007. Leon: Universidad de Leon, 2007. pp. 15-22.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper aims at analyzing the impacts that distributed generators might have on the dynamic stability of the power distribution networks. A distribution network connected with distributed generators can potentially support unintentional system island. When there is general use of DG to support the existing network, under the new rules and satisfaction of technical conditions, it is possible that islanded operation will offer an alternative to reinforcement. Without the network support role of DG, it is unlikely that islanding will take place. The paper describes different methods which are used to detect an island in case of its formation and its operation using ATP. To provide for islanded operation of DG requires investment in voltage and frequency control, which is done by controlling the load connected to the island.

Analýza stability energetických systémů s větrnými a vodními elektrárnami

  • Autoři: Qin, C., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Sborník ČK CIRED 2007. Praha: CIRED, 2007. pp. 1-12. ISBN 978-80-254-0304-4.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zaměřuje na tvorbu matematického modelu soustrojí větrné elektrárny. Model je implementován do prostředí MATLAB, kde je provedena jeho validace a zpracována analýza stability jak pro konvenční větrné elektrárny, tak pro energetické systémy s větrnými a vodními elektrárnami. Rovněž jsou uvedeny případové studie takových hybridních systémů v čínské provincii Xinjiang.

Analýza stability soustavy s rozptýlenými zdroji

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    V poslední době stále roste význam rozptýlených zdrojů a jejich podíl na výrobě elektřiny. Tato skupina zahrnuje zejména asynchronní generátory ve větrných elektrárnách, nicméně v části z nich jsou instalovány generátory synchronní. Článek obsahuje studii popisující různé principy začleňování rozptýlených zdrojů se synchronními generátory do distribuční soustavy s ohledem na minimalizaci jejich negativních vlivů. Studie je zaměřena na možné oblasti provozu připojených zdrojů s ohledem na stabilní provoz v ustáleném stavu a ve stavu po odstranění poruchy. Studie poskytuje komplexní pohled na problematiku stability rozptýlených zdrojů, která úzce souvisí s možností připojitelnosti těchto zdrojů.

Dynamic Behavior of the Distributed Generation Sources in Island Mode

  • Autoři: Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J.
  • Publikace: Proceedings of the 8th International Scientific Conference Electric Power Engineering 2007. Ostrava: VŠB - Technická univerzita Ostrava, 2007. pp. 179-185. ISBN 978-80-248-1391-2.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper aims at analyzing the impacts that distributed generators might have on the dynamic stability of the power distribution networks. A distribution network connected with distributed generators (DG) can potentially support unintentional system island. Existence of islands has negative impact to the performance of the system as well as the risk to safety and equipment hence need to be quickly detected and eliminated. Generally, island can be detected either by frequency function or by sensitive under- and over- voltage functions of the protective devices. After the detection of island, then some of the load can be disconnected automatically by the use of automatic balance so as to maintain the synchronism of the distributed generation connected to the island.

Dynamické vlastnosti vodních elektráren

  • Autoři: Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T.
  • Publikace: IVth International Scientific Symposium ELEKTROENERGETIKA 2007 - Proceedings. Košice: Technická univerzita v Košiciach, 2007. p. 499-504. ISBN 978-80-553-0400-7.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zabývá problematikou modelování vodních elektráren v transientních stavech. Model přivaděče byl vyvinut použitím přímého řešení parciálních diferenciálních rovnic. Hlavní část článku se soustřeďuje na srovnání modelovacích přístupů. Jsou popsány hlavní výhody a nedostatky jednotlivých metod.

Některé faktory ovlivňující tvar diagramu zatížení transformátorů 110/22 kV a přesnost určení velikosti ročních ztrát

  • Autoři: doc. Dr. Ing. Jan Kyncl, Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Tlustý, J., Willmann, B.
  • Publikace: IVth International Scientific Symposium ELEKTROENERGETIKA 2007 - Proceedings. Košice: Technická univerzita v Košiciach, 2007. p. 247-252. ISBN 978-80-553-0400-7.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    V předloženém příspěvku jsou rozvedeny příčiny, které vedou k odchylkám při určování velikosti ztrát naprázdno a nakrátko v transformaci 110/22 kV. Dále se příspěvek zabývá formou získání podkladů pro určení ročního maxima na jednotlivých transformátorech z různých pramenů u provozovatelů distribuční soustavy. Analyzuje problémy, které takové objemy ročních údajů z měření přenášených na dispečink mohou doprovázet při zpracování výchozích dat. Ukazuje na rozdíly, které může vyvolat změna tvaru diagramu ročního průchozího toku přes tento druh transformace a rizika použití obvyklého vzorce pro určení doby plných ztrát pro obvyklý průběh zatížení v soustavě. Zabývá se také vlivem některých vybraných případů na přesnost určení ztrát.

Problematika záložního napájení světelných obvodů v administrativních centrech

  • Autoři: Mgaya, E., Sýkora, T., Švec, J., Tlustý, J., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Sborník přednášek konference "Světlo 2007". Ostrava: Česká společnost pro osvětlování, 2007. pp. 143-148. ISBN 978-80-248-1579-4.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek se zabývá problematikou záložního napájení světelných obvodů v administrativních centrech. V úvodu je uveden nejčastější způsob záložního napájení světelných obvodů. Hlavní část článku je věnována problematice napájení světelných obvodů přes záložní systém, který je tvořen jednotkou UPS. V článku je uveden praktický případ nevhodného zapojení záložního systému UPS do světelného obvodu a jsou zde uvedena nápravná doporučení, aby bylo docíleno bezproblémového provozu s cílem, který zajistí maximální využití životnosti světelných zdrojů.

Problémy připojování zdrojů do distribuční soustavy z hlediska kvality dodávané elektrické energie

  • Autoři: Tlustý, J., Sýkora, T., Švec, J., doc. Ing. Zdeněk Müller, Ph.D., Mgaya, E.
  • Publikace: Sborník ČK CIRED 2007. Praha: CIRED, 2007. pp. 1-10. ISBN 978-80-254-0304-4.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zaměřuje na problematiku výroby elektrické energie z obnovitelných zdrojů energie a energetického rušení v elektrizační soustavě. Je probírána problematika posuzování výroben z hlediska připojení k distribuční síti a zpětných vlivů na ni. Je provedena analýza vlivu jednotlivých typů generátorů včetně přídavných zařízení výkonové elektroniky na kvalitu dodávané elektrické energie. Výsledky výpočtů jsou porovnány s podmínkami pro připojení výroben elektrické energie k distribuční síti.

The Energy Management Using SCADA in Medium Industrial Distribution System

  • Autoři: Sýkora, T., Hong Thai, L., Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D., Švec, J., Tlustý, J., Sendra, J.B., Stehlík, J.
  • Publikace: Sborník konference Energomatika 2007. Praha: Wirelesscom, 2007. pp. 1-23. ISBN 978-80-239-9076-8.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    A case study has been done to oversee the use of SCADA system for the energy management in an industrial distribution system. The SCADA system comprises of software which is able to communicate with metering and controlling devices as well as to create tables and graphs of all stored historical data. The equipments in the system communicate via XML in the Ethernet environment. The information from the system can be used by the operators, servicemen and the top management. All the information is being stored and is accessible in common office applications.

The Hydro Power Plant Dynamic Response

  • Autoři: doc. Ing. Zdeněk Müller, Ph.D., Doležal, J., Mgaya, E., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: EEUG Meeting 2007. Leon: Universidad de Leon, 2007. pp. 23-31.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The paper deals with the hydro power plant modeling. The developed solution in ATP is useful for transient pipe flow study. The main part of the paper focuses on the comparison of basic solution philosophies. The first kind of solution is an evaluation using signal-based solution. This model is suitable for hydro power plant control systems, the drawback of this solution is very simplified pipe flow model. The second used model is based on the finite elements method. Finally, the third discussed solution is a direct formulation and solving partial differential equations. Main advantages and drawbacks of these methods are explained.

The Impact of Distributed Generation to the Distribution Network

  • Autoři: Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: Poster 2007. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2007. pp. 1-6.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The need to provide acceptable power quality and reliability will create a very favorable climate for the entry of distributed generators and innovative operating practices. Integration of Distributed generators into an existing network can result in several benefits. These benefits include line loss reduction, reduced environmental impacts, peak shaving, increased overall energy efficiency, relieved transmission and distribution congestion, voltage support, and deferred investments to upgrade existing generation, transmission, and distribution systems. This paper indicates also the negative impacts of connecting wind power plants to the distribution network.

The Turbine Regulator Structure Influence on Island System Stability

  • Autoři: Švec, J., Sýkora, T., doc. Ing. Zdeněk Müller, Ph.D.,
  • Publikace: IVth International Scientific Symposium ELEKTROENERGETIKA 2007 - Proceedings. Košice: Technická univerzita v Košiciach, 2007. p. 703-710. ISBN 978-80-553-0400-7.
  • Rok: 2007
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    The large power plants behaviour is important for the frequency collapse preventing after the system emergency state origin. The power plants control systems mustn't cause other failure spreading and must contribute to the island system frequency stabilisation. The particular legislative requirements are defined in the Grid code. The analysis of turbine controller structure influence on the stability maintaining is carried out in the paper. Three basic types are used in the power plant unit model: 1. Proportional speed controller; 2. Island operation controller; 3. Island operation controller with the integration part which ensures the automatic island system frequency return to the rated value. Selected processes show that some legislative requirement can endanger the regulation process stability as well as improper operator interventions to the control system.

Optimalizace napájecích systémů osvětlovacích soustav tunelů

  • Autoři: Doležal, J., Mgaya, E., doc. Ing. Zdeněk Müller, Ph.D., Sýkora, T., Švec, J., Tlustý, J.
  • Publikace: Kurz osvětlovací techniky XXIV. Ostrava: VŠB - Technická univerzita Ostrava, 2006. pp. 275-283. ISBN 80-248-1178-2.
  • Rok: 2006
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zabývá problémy spojenými s napájením dlouhých silničních tunelů. Na základě laboratorních měření, matematického aparátu a počítačových simulací jsou vy-vozeny závěry týkající se možnosti vzniku ferorezonance v napájecích obvodech.

Problematika kolísání napětí v distribučních sítích

  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Příspěvek se zabývá návrhem linearizovaného modelu distribuční soustavy a elektrické obloukové pece s linkovým kondicionérem ve frekvenční oblasti. Tento model umožňuje analýzu základních vlastností harmo-nických napětí a proudů odebíraných nelineární zátěží. Model je dále využit k nalezení optimálního způsobu řízení kondicionéru a parametrů řídícího algoritmu. Analýza ukazuje, že nejefektivnější je využití univerzál-ních kondicionérů kvality energie. Linkové kondicionéry jsou tvořeny dvěma aktivními filtry (sériový a paralel-ní). Paralelní část tohoto zařízení kompenzuje celkový neaktivní výkon odebíraný pecí a udržuje hodnotu napětí v stejnosměrném meziobvodu na konstantní úrovni, sériová část kompenzuje napěťové poměry v napájecí síti.

Vybrané problémy racionalizace spotřeby elektřiny v rozvodu elektřiny

  • Autoři: Göhler, M., doc. Ing. Zdeněk Müller, Ph.D., Tlustý, J., Willmann, B., Zetka, J.
  • Publikace: ELEN 2006 (Elektroenergetika). Praha: České vysoké učení technické v Praze, 2006. pp. 1-12. ISBN 80-239-7650-8.
  • Rok: 2006
  • Pracoviště: Katedra elektroenergetiky
  • Anotace:
    Článek se zabývá problematikou ztrát energie v elektrizační soustavě. Porovnává významné provozní parametry sítě na různých napěťových hladinách a v různých časových obdobích dne. Podrobněji je zpracována problematika nesymetrie. Jednotlivé situace jsou zdokumentovány konkrétními případy z praxe a statisticky zpracovány.

Za stránku zodpovídá: Ing. Mgr. Radovan Suk