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Ing. Pavel Hrzina, Ph.D.

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EQUILIBRIUM THERMODYNAMIC PROPERTIES AND ITS NEW RATING FOR LITHIUM-ION BATTERY

  • Department: Department of Electrotechnology
  • Annotation:
    Lithium battery diagnostics should comprehensively monitor battery status. To increase the level of diagnostics, it is necessary to expand with new parameters. The GITT method is used for the analysis of diffusion process. However, the method has drawbacks when applied to current electrode structures. They exhibit inconsistencies during their measurements and evaluation. Consequently, this work builts upon state-of-the-art and it proposes a new solution for determination of necessary relaxation time after a pulse to determine accurately a diffusion coefficient.

Quick Diagnostic Tool for Thin-Film Photovoltaic Power Plants Utilizing Dark Current Measurement

  • DOI: 10.1109/JPHOTOV.2022.3145096
  • Link: https://doi.org/10.1109/JPHOTOV.2022.3145096
  • Department: Department of Electrotechnology
  • Annotation:
    There exist many photovoltaic (PV) power plants which are based on thin-film technology. Unlike PV power plant with crystalline silicon technology, the diagnostic possibilities of thin-film PV modules are limited due to seasonal effects and problematic utilization of thermography. The main problem of degradation of these PV plants is the area degradation which affects even PV power plants with transformer inverters. Although there exist measurement methods based on I–V curve measurement, these methods require specific climatic conditions (clear sky, sufficient irradiance) and time. Here, we present the novel approach to diagnose thin-film modules affected with degradation which provides quick results with low-cost equipment.

SET OF PARAMETERIZATION TESTS FOR BMS SETUP ON KNOWN AND UNKNOWN LITHIUM BATTERIES

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: 43. Nekonvenční zdroje elektrické energie. Praha: Česká elektrotechnická společnost, 2022. p. 34-38. ISBN 978-80-02-02972-4.
  • Year: 2022
  • Department: Department of Electrotechnology
  • Annotation:
    BMS parameterization is one of the main factors influencing the life of the battery system. It is not always possible and recommended to rely on the manufacturer's data. By analysing the discharge and charging process, it is relatively easy to determine the correct BMS settings. The article addresses a comprehensive view of BMS settings on practical examples.

Teaching electrochemical resources and its implementation during the COVID-19 pandemic

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: Proceedings of 10th INTERNATIONAL WORKSHOP ON TEACHING IN PHOTOVOLTAICS. PRaha: České centrum Institution of Engineering and Technology, 2022. p. 85-86. ISBN 978-80-01-07014-7.
  • Year: 2022
  • Department: Department of Electrotechnology
  • Annotation:
    Currently, two basic courses focused on electrochemical sources are offered at the CTU in Prague, FEE. One in the bachelor's stage, this is a shared course with the basics of photovoltaics and one in the master's stage, this is a separate course with an hourly allowance of 2 + 2 (2 hours of lectures, and 2 hours of exercises) for 14 weeks. At the time of the greatest restrictions associated with the COVID-19 pandemic, it was necessary to adjust this concept so that students can also carry out practical measurements.

Teaching Photovoltaics for Children

  • Department: Department of Electrotechnology
  • Annotation:
    In recent years, there has been little interest from students in technical fields and the industrial sector thus suffers from a significant shortage. This shows the importance of motivating future students to study technical disciplines from an early age. Within the CTU in Prague, a very successful event is organized every year - the Children's University, where children spend a week at the university and get acquainted with the world of technology. One of the fields they come into contact with is photovoltaics. The form of teaching for children is described in the article.

Diagnostics of PID Early Stage in PV Systems

  • DOI: 10.3390/en14082155
  • Link: https://doi.org/10.3390/en14082155
  • Department: Department of Electrotechnology
  • Annotation:
    Potential induced degradation (PID) is a serious threat for the photovoltaic (PV) industry. The risk of PID may increase with increasing operating voltage of PV systems. Although PID tests are currently standard tests, the expansion of floating PV power plants and installation in humid climates show that PID-free modules are still sensitive to this type of degradation. Therefore, a method that can detect PID in the initial phase before standard tests reveal it, is necessary to increase the reliability of PV systems and maintain their lifetime. One possible tool for revealing early-stage PID manifestations is impedance spectroscopy and I-V dark curves measurements. Both IS and dark current measurement methods are sensitive to cell shunt resistance (RSH), which is strongly influenced by PID before significant power loss and can act as an early stage PID detection mechanism. The paper describes the differences of the common P-type PV module parameters both during the degradation process and also during the regeneration process when diagnosed by conventional and IS and dark current measurement methods.

PV Panel and PV Inverter Damages Caused by Combination of Edge Delamination, Water Penetration, and High String Voltage in Moderate Climate

  • DOI: 10.1109/JPHOTOV.2021.3050984
  • Link: https://doi.org/10.1109/JPHOTOV.2021.3050984
  • Department: Department of Electrotechnology
  • Annotation:
    There exist over 2 GW of photovoltaic (PV) systems in the Czech Republic, exposed to moderate continental climate. Although there exist many PV modules defects, thanks to the generallythe same production year 2009, only some ofthem are usual at systems installed in Czech Republic. This work shows delamination failures that are frequent in moderate climate conditions. Special account istaken into edge delamination defect and its possible propagation in modules of standard construction. Combined PV panel and PV inverter failure is caused by edge delamination with water penetration and high string voltage. The electric discharge channel is created between the string of solar panels and the grounded PV panel frames. The result of the discharge channel created because of edge delamination is inverter switch-OFF and few months later total destruction of the inverter because of protective relay damage. The number of combined PV panel and PV inverter failures is increasing substantially after ninth year of operation of PV panels in moderate climate. Additional sealing of the PV panel frames by transparent polysiloxane gel reduced the number of combined PV panel and PV inverter failures very substantially.

Battery voltage - from cells to battery storage voltage systems

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: TZB-info: portál pro technická zařízení budov. 2020, 22(26.3.2020), ISSN 1801-4399.
  • Year: 2020
  • Department: Department of Electrotechnology
  • Annotation:
    Battery systems for different applications require specific voltages. Which quantities determine the voltage level in a given application and what options do individual battery technologies offer?

Cycles and battery life

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: TZB-info: portál pro technická zařízení budov. 2020, 22(1.9.2020), ISSN 1801-4399.
  • Year: 2020
  • Department: Department of Electrotechnology
  • Annotation:
    One of the important parameters that are monitored when choosing a battery is the so-called cyclic life. How is this parameter determined and what does it express?

Electricity storage in buildings: basic parameters and technologies

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: TZB-info: portál pro technická zařízení budov. 2020, 22(27.2.2020), ISSN 1801-4399.
  • Year: 2020
  • Department: Department of Electrotechnology
  • Annotation:
    What are the most common requirements for stationary batteries? What technologies are available and what can we expect from them?

Evaluation of Electrical Properties of Metalized Woven and Non-woven Polymer-Based Textiles

  • DOI: 10.1109/ISSE49702.2020.9120943
  • Link: https://doi.org/10.1109/ISSE49702.2020.9120943
  • Department: Department of Electrotechnology, Department of Telecommunications Engineering
  • Annotation:
    The smart textiles seem to be a very interesting possibility in many industrial fields e.g. medicine, automotive, textile industry etc. These types of textile are mainly based on metalized threads. It is necessary to know the physical characteristics of smart textiles before their use for a specific application. This article deals with the preparation and characterization of three types of textiles - copper-coated non-woven polyamide fabric and copper and nickel coated woven polyester fabric. Characterization was based on the measurement of textiles properties like the thickness of metallization, electrical resistance. The measurements of thickness metallization were done at micro-section by electron microscopy. The electrical resistance was evaluated for further usage of these fabrics as a heating system in smart textiles, where a low resistance of the heating part is desirable. The sheet resistance was measured in different directions to obtain information about the isotropic or anisotropic character of samples. The highest electrical resistance had woven copper-coated polyamide fabrics. The anisotropic character of samples was more obvious for woven polyester fabrics.

How to effectively eliminate risks when operating Li-Ion battery systems

  • Department: Department of Electrotechnology
  • Annotation:
    The development of mobile and stationary applications brings with an increase in the number of installations of battery systems. Battery systems are, in their physico-chemical nature, a storehouse of energy and it is therefore necessary to pay attention to them, especially from the point of view of safety, ie the elimination of accidental and uncontrollable leakage of energy. The article deals with the identification of these risks and subsequent recommendations for their elimination.

Impact of Defective Modules on the Characteristics of a Large-Scale Grid-Connected PV Power Plant

  • DOI: 10.4229/EUPVSEC20192019-5CV.4.42
  • Link: https://doi.org/10.4229/EUPVSEC20192019-5CV.4.42
  • Department: Department of Electrotechnology
  • Annotation:
    The effect of the connection of different, shaded or damaged module on the performance of the whole string or the photovoltaic (PV) panel connected to a single inverter is very often discussed. Although there exist the means for protecting the PV system against negative influence of connecting PV modules with different parameters into one system (diodes, power optimizers), the real impact is not examined anymore. The simulation tools presume the connection of the same module type with same parameters and the differences are discussed only theoretically. The simulations performed in the SPICE program rather indicate that with less damage, one different module should not have a significant effect on the power drop, even in the theoretical case that no bypass diode is included in the string. The results of simulation as well as the measurement on the real system with modules with different parameters are presented in this work.

Insight into the Flexibility of Households

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: Vytápění, větrání, instalace. 2019, 28 88-90. ISSN 1210-1389.
  • Year: 2019
  • Department: Department of Electrotechnology
  • Annotation:
    The article analyses the prospects for technically feasible ways of developing flexibility in the conditions of common Czech households, both housing units and family houses. It focuses mainly on the importance of the accumulation of energy from renewable energy sources (RES) and the manaagement of household consumption. It also mentions the psychological impact of remote control of energy consumption on the user. It addresses especially the technological, and not legislative, issues of the flexibility integration into the normal life of consumers.

New possibilities of teaching physics based on secondary school students’ projects

  • Authors: Krajčová, V., Ing. Pavel Hrzina, Ph.D.,
  • Publication: AIP Conference Proceedings. Melville, NY: AIP Publishing, 2019. ISSN 0094-243X. ISBN 978-0-7354-1897-4.
  • Year: 2019
  • DOI: 10.1063/1.5124759
  • Link: https://doi.org/10.1063/1.5124759
  • Department: Department of Electrotechnology
  • Annotation:
    On the basis of the development in education, where the necessity of interconnection of teaching with practice or higher education institutions is increasingly emphasized, the subjects Student Project and High School Graduation Project were introduced within the framework of education at SSPS, Prague (Smíchov Secondary Industrial School). These courses lead students to work independently on a given topic with the support of a teacher, a university teacher or an expert from the industry. That is why the SSPS established close cooperation with the CTU FEL (Faculty of Electrical Engineering of the Czech Technical University in Prague), which led to the creation of several new teaching tools and aids in Physics. In this article we describe some examples of projects implemented at SSPS and will also pay attention to their contribution to development and improvement of physics laboratories at SSPS.

Note on Circuit Simulations of Large PV Power Plants

  • Department: Department of Electrotechnology
  • Annotation:
    With effect from the end of 2018, the Energy Regulatory Office's (ERÚ) interpretative opinion allows the replacement of photovoltaic (PV) system components. These components also include PV modules. Due to the development of PV modules, it is not to be expected that modules with corresponding parameters will always be available. Thus, the question of the possibility of replacing a part of the modules in the string with modules with other parameters opens. This work deals with the issue of how such an exchange on a PV power plant will manifest itself.

PID EFFECT, DIAGNOSTICS AND CONSEQUENCES

  • Department: Department of Electrotechnology
  • Annotation:
    PID stands for "Potential Induced Degradation", a phenomenon first described in the 1970s. Furthermore, the PID was forgotten and module manufacturers, together with photovoltaic power plant owners, started to deal with it again in the new millennium, when it started to show up strongly in larger power plants. The impact of the PID on the power plant can be very significant, due to the fact that modules can lose up to 70 % of their original performance in real conditions due to PID. In addition, some modules run faster and the power plant becomes financially loss-making. The reach of the PID module increases over time and can cause high energy losses and ultimately total module failure. There are several types of PID. Some are reversible, others are not, and for some, the principle of their origin is relatively well known, while in others it is only speculated. However, they have one thing in common, namely that the basic condition for creating a PID is a high voltage difference in the string, so it is also sometimes called High-Voltage stress. PV systems using crystalline silicon are mostly PID shunting (PID-s), where local short-circuits are generated and thus a significant reduction in performance. Thin-film modules may also suffer from a PID effect. As a rule, thin-film modules are not reversible degradation due to electrochemical corrosion of the TCO layer (transparent conductive oxide).

Snails in the procedure

  • Department: Department of Electrotechnology
  • Annotation:
    This paper deals with a more detailed analysis of the mechanism of origin and propagation of a photovoltaic module defect known as the "snail trails" (SC).

When will the use of photovoltaic modules with batteries pay off for municipality?

  • Department: Department of Electrotechnology
  • Annotation:
    The question asked does not have a simple answer, it depends very much on many factors. In terms of assessing the suitability of the solution for the municipality, it is necessary to always include in the economic evaluation also the so-called "opportunity cost", the cost of lost opportunity. The management of each municipality has to decide how important it is to realize the project for its residents, rather than counting only the return of the solution in terms of costs incurred. The following article will attempt to analyze technical options, the decision whether to install batteries or photovoltaics will not be done for you today.

Capacity Detection of Internal Short Circuit

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Journal of Energy Storage. 2018, 2018(15), 345-349. ISSN 2352-152X.
  • Year: 2018
  • DOI: 10.1016/j.est.2017.12.006
  • Link: https://doi.org/10.1016/j.est.2017.12.006
  • Department: Department of Electrotechnology
  • Annotation:
    The most critical defect in electrochemical cells is connected with internal short circuit (ISCr) occurrence. It may cause a thermal runaway which can even lead to explosion of the cell. Although the causes are well know (manufacturing defect, overcharging, overdischarging),the timely detection of ISCr is very difficult. This work focuses on the detection of an internal short circuit while the cell is being charged using the time dependence of the capacity evaluation

Current limits and future development of accumulators

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: XXVIII. konference Radiokomunikace - Sborník přednášek. Pardubice: Unit s.r.o., 2018. p. 267-273. ISBN 978-80-87942-45-1.
  • Year: 2018
  • Department: Department of Electrotechnology
  • Annotation:
    This article summarizes the current state of the BESS (Battery Energy Storage Systems) field. Particular attention is paid to the reasons for increasingly frequent replacement of lead-acid batteries by lithium accumulators. Further attention is paid to the main differences in the operation of lead and lithium batteries in terms of recommended operating temperature, load and differences in discharging characteristics. A separate part is devoted to various types of lithium cells and their use. Finally, an estimate of the future development of BESS is discussed.

Diffusion diagnostics of electrochemical cell

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Journal of Energy Storage. 2018,(20), 492-496. ISSN 2352-152X.
  • Year: 2018
  • DOI: 10.1016/j.est.2018.10.022
  • Link: https://doi.org/10.1016/j.est.2018.10.022
  • Department: Department of Electrotechnology
  • Annotation:
    Currently, there is a number of impulse methods for evaluation of cells and batteries internal resistance. This work deals with the analysis and following calculation of diffusion process of cell. The study of the diffusion process is made after the end of the discharge/charging pulse when the electrochemical cells returns to equilibrium state.

Household flexibility - yes or no?

  • Department: Department of Electrotechnology
  • Annotation:
    The article analyzes the perspectives of technically realistic possibilities of gaining flexibility in conditions of common Czech households. It was first published this spring at the conference "Alternative Energy and Energy 2018" in Kroměříž. Since the publication of the original article, there have been several changes in the possibilities of gaining flexibility, so you are getting II. Supplemented Edition "Looking at Household Flexibility". We will focus on the importance of energy storage from RES and household consumption management. We also mention the psychological impact of remote power control on users. We will not address the legislative, but only technological, issues of the implementation of flexibility in the normal life of consumers, or so-called Prosumer (see the glossary at the end of the article).

IMPEDANCE SPECTROSCOPY OF CDTE PV MODULES – COMPARATIVE STUDY

  • Department: Department of Electrotechnology
  • Annotation:
    One of interesting technology of photovoltaic modules which can be used within an industrial scale is CdTe. These modules are indeed problematic due to Cd content, but still represent interesting alternative to standard crystalline photovoltaic modules, mainly thanks to their significantly higher energy yield. Often discussed problems connected with thin-film modules are their stability, variability of production generations and also the degradation. One of possible method which can reveal early state of degradation connected with shunts is described in this article.

New Curricula for Teaching PV on the Bachelor Level at the CTU in Prague, FEE

  • Department: Department of Electrotechnology
  • Annotation:
    At the Czech Technical University in Prague, Faculty of Electrical Engineering, courses dealing with PV system technology form a part of both the bachelor and master study programme in Electrical Engineering and Information Technology. The courses were modified to fit better to present trends in photovoltaics. Synopsis of individual courses (both lectures and exercises) are discussed in details.

Simulation and Measurement of Bypass Diodes Functionality within Laboratory Exercises

  • Department: Department of Electrotechnology
  • Annotation:
    Bypass diodes are an integral part of the most of current silicon PV modules and help ensure troublefree operation of the module under different light conditions. The main function of the bypass diode is well known and is often simply explained as a protection of the module against power loss at partial shading. This article describes how to present this partial truth to students and how to help them, by using standard simulation tools and laboratory exercises, to study and understand the behavior of this part of the PV Module.

Study of the Current Value Influence on the Internal Resistance Value

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Proceedings of Advanced Batteries Accumulators and Fuel Cells – 19th ABAF. Brno: Brno University of Technology, 2018. p. 176-179. ISBN 978-80-214-5651-8.
  • Year: 2018
  • Department: Department of Electrotechnology
  • Annotation:
    Lithium-ion batteries are a complex energy storage device that is characterized by a complex degradation behavior that affects both its capacity and internal resistance. There are currently a number of impulse methods for evaluating the internal resistance of cells and batteries. This work deals with the analysis of the chosen method for calculating the internal resistance of the cell in dependence on the different C-Rates of the current.

Thermal Cycle Testing of Printed Circuit Board Vias (Barrel Plates)

  • Department: Department of Electrotechnology
  • Annotation:
    Printed circuit board (PCB) reliability is a very important factor from the point of total quality of output products. The ambient environment has influence on the reliability of PCBs and various issues can appear during its lifetime, even if the PCB properly passes the quality control before and after its assembly. This article deals with reliability test-monitoring of resistance behavior of the printed circuit board vias (barrel plates) during thermal stress (shock test). Appropriate printed circuit boards have been designed for this purpose. PCB sample was double-sided, vias were connected serially and PCB design allowed the use of four wire measurement method for measuring of all vias at once. The temperature sensor Pt100 was attached onto the PCB for better temperature monitoring of PCB during shock test. The shock test cycle took 20 minutes, the temperature of hot zone was set to 160 degrees C and the temperature of cool zone was -60 degrees C. The experiments help in understanding the barrel plate behavior during thermal stress, when the thermal expansion of composite substrate (glass-epoxy laminate) cause force (Young's modules), which stretches the barrel plate from the middle outwards. The identification of faulty vias is not easy during ambient temperature, it is easier when a measurement is conducted during thermal cycling or when the PCB is heated.

What is hidden in batteries?

  • Department: Department of Electrotechnology
  • Annotation:
    The article was presented as a presentation of the CTU FEE, namely, the laboratory for the diagnostics of electrochemical sources.

Capacity Detection of Internal Short Circuit

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Proceedings of Advanced Batteries Accumulators and Fuel Cells – 18th ABAF. Brno: Brno University of Technology, 2017. p. 1-191. ISBN 978-80-214-5529-0.
  • Year: 2017
  • Department: Department of Electrotechnology
  • Annotation:
    Internal short circuit (ISCr) detection in the electrochemical cell is very difficult. The internal short circuit may cause a thermal runaway. This thermal runaway (TR) can even cause an explosion of the cell. That is why it is very important to timely detect internal short circuit. The cause of the internal short circuits is a manufacturing defect, overcharge or overdischarge. There are several methods of analysis. This work focuses on the detection of an internal short circuit while the cell is being charged. This work then focused on calculating ISCr from the capacity of battery.

Capacity Detection of Internal Short Circuit for Charge

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: ECS Transactions. 2017, 81(1), 209-215. ISSN 1938-6737.
  • Year: 2017
  • DOI: 10.1149/08101.0209ecst
  • Link: https://doi.org/10.1149/08101.0209ecst
  • Department: Department of Electrotechnology
  • Annotation:
    Internal short circuit (ISCr) detection in the electrochemical cell is very difficult. The internal short circuit may cause a thermal runaway. This thermal runaway (TR) can even cause an explosion of the cell. That is why it is very important to timely detect internal short circuit. The cause of the internal short circuits is a manufacturing defect, overcharge or overdischarge. There are several methods of analysis. This work focuses on the detection of an internal short circuit while the cell is being charged. This work then focused on calculating ISCr from capacity of battery.

Impulse Diagnostical Test of Batterries

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Journal of Energy Storage. 2017, 2017(14), 405-409. ISSN 2352-152X.
  • Year: 2017
  • DOI: 10.1016/j.est.2017.03.015
  • Link: https://doi.org/10.1016/j.est.2017.03.015
  • Department: Department of Electrotechnology
  • Annotation:
    Currently there exists a number of impulse methods for cells’ and batteries’ internal resistance evaluation. This work deals with the analysis of such methods and brings their optimization to calculate cell’s internal resistance. Further, this work is focused on the definition of the new parameter for electrochemical cells’ state evaluation – the diffusion process, namely charging diffusion process.

Internal short circuit is being charged

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: 38. NEKONVEKČNÍ ZDROJE ELEKTRICKÉ ENERGIE. Praha: Česká elektrotechnická společnost, 2017. p. 98-102. ISBN 978-80-02-02725-6.
  • Year: 2017
  • Department: Department of Electrotechnology
  • Annotation:
    Internal short circuit (ISCr) detection in the electrochemical cell is very difficult. The internal short circuit may cause a thermal runaway. This thermal runaway (TR) can even cause an explosion of the cell. That is why it is very important to timely detect internal short circuit. The cause of the internal short circuits is a manufacturing defect, overcharge or overdischarge. There are several methods of analysis. This work focuses on the detection of an internal short circuit while the cell is being charged.

Modeling, Operation and Results of Photovoltaic System with Optimizers in 2016

  • Department: Department of Electrotechnology
  • Annotation:
    This article discusses the experience of the PV plant based on optimizers and analyzes annual PVP production. Subsequently, the production is compared with the SAM NEREL simulation software and the simulation output made in the PVGIS system.

NOTE ON COLE-COLE DIAGRAMS OF PHOTOVOLTAIC MODULES EVALUATION

  • Department: Department of Electrotechnology
  • Annotation:
    There exist many method used for photovoltaic (PV) modules and systems diagnostics. One of the less conventional is impedance analysis of PV cells or modules which gives additional information about measured cell, module respectively. Due to high amount of possible sources of uncertainties and low repeatability when performed under samples irradiation, the evaluation of obtained results is relatively complicated. In this paper, the comparison of conventional methods and impedance analysis and its possible evaluation and limits are presented.

Photocurrent Spectroscopy of Perovskite Layers and Solar Cells: A Sensitive Probe of Material Degradation

  • DOI: 10.1021/acs.jpclett.6b02854
  • Link: https://doi.org/10.1021/acs.jpclett.6b02854
  • Department: Department of Electrotechnology
  • Annotation:
    Optical absorptance spectroscopy of polycrystalline CH3NH3PbI3 films usually indicates the presence of a PbI2 phase, either as a preparation residue or due to film degradation, but gives no insight on how this may affect electrical properties. Here, we apply photocurrent spectroscopy to both perovskite solar cells and coplanar-contacted layers at various stages of degradation. In both cases, we find that the presence of a PbI2 phase restricts charge-carrier transport, suggesting that PbI2 encapsulates CH3NH3PbI3 grains. We also find that PbI2 injects holes into the CH3NH3PbI3 grains, increasing the apparent photosensitivity of PbI2.

Electromobiles Infrastructure Evolution

  • Authors: Ing. Pavel Hrzina, Ph.D., Cetl, T.
  • Publication: 37. Nekonvenční zdroje elektrické energie. Praha: Česká elektrotechnická společnost, 2016. pp. 6-9. ISBN 978-80-02-02653-2.
  • Year: 2016
  • Department: Department of Electrotechnology
  • Annotation:
    With the development of electromobility begs the question how to integrate a network of charging stations into the existing infrastructure. One frequently discussed option is also renewable energy utilization. In the following text, the possibilities of using these resources and along with that also the feasibility of rapid development of electromobility in the Czech Republic are discussed.

IMPEDANCE SPECTROSCOPY AND ITS POSSIBLE USE FOR DEFFECTS DETECTION

  • Department: Department of Electrotechnology
  • Annotation:
    A common problem to be solved during the operation of photovoltaic (PV) power plants is early detection of PV modules defects. Usual methods are based on both measurement of electric parameters and visualization of possible defects (thermography). The common electric measurement usually doesn’t show the initial damage like less serious cracks inside the module. For these purposes is necessary to use some advanced visualization method like electroluminescence. But this requires either special equipment or the dark chamber. In this text is presented a new approach to revealing the hidden defects using impedance spectroscopy. The results of measurement are presented as well as comparison between the individual methods.

Impulse Diagnostic Test of Battery and Load Influence

  • DOI: 10.1149/07401.0009ecst
  • Link: https://doi.org/10.1149/07401.0009ecst
  • Department: Department of Electrotechnology
  • Annotation:
    For power source diagnostics and lifetime prediction, it is necessary to define the major processes which influence the source’s behaviour in the most significant way. The first process is connected with the internal resistance (Ri) of electrochemical source (ES) which influence the voltage decrease of source’s voltage course. The second substantial process in electrochemical conversion is the diffusion process. This process dominates when the pulsed load is applied where it influences the source’s capacity and can be evaluated using the impulse measurement methods, where internal resistance and diffusion process are evaluated simultaneously.

Impulse Diagnostic Test of Battery and Load Influence

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Proceedings of Advanced Batteries Accumulators and Fuel Cells – 17th ABAF. Brno: Brno University of Technology, 2016. ISBN 978-80-214-5384-5.
  • Year: 2016
  • Department: Department of Electrotechnology
  • Annotation:
    For power source diagnostics and lifetime prediction, it is necessary to define the major processes which influence the source’s behaviour in the most significant way. The first process is connected with the internal resistance of electrochemical source (ES) which influence the voltage decrease of source’s voltage course. The second substantial process in electrochemical conversion is the diffusion process, which is the slowest process in electrochemical conversion thus it determines its overall rate. In the work, the descripiton of diffusion process and its extraction from impulse characteristics is described.

Increasing Extinguishing Efficiency of Low and Medium Pressure Water Mist of Fire Extinguishing Equipment by Electric Field Generated by High Voltage DC

  • Authors: Lukáš, P., Koller, J., Dvořák, O., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Požární ochrana 2016 - Sborník přednášek XXV. ročníku mezinárodní konference. Ostrava: Sdružení požárního a bezpečnostního inženýrství, 2016. pp. 232-235. ISSN 1803-1803. ISBN 978-80-7385-177-4.
  • Year: 2016
  • Department: Department of Electrotechnology
  • Annotation:
    This paper describes experiments applied to extinguishing the flame test vessel with n-heptane. It was considered possible to increase extinguishing efficiency of low pressure and moderate water DC HV charged mist. Results of experiments confirmed the effect of voltage and take into account also configurations of electrodes, the size of the volume water flow, water pressure and the type of fog head. Higher extinguishing effect electrically charged water mist to extinguish showed a shorter time, a smaller volume of water consumed to extinguish the fire and extinguishing a higher percentage of successful attempts. Benefit: Faster and efficient fire fighting with less risk of injury and less consequential damages in a protected space.

Study of Shunt Distributions in Thin Film Multijunction Solar Cells

  • Department: Department of Electrotechnology
  • Annotation:
    The thin film technology of photovoltaic modules is perspective from the low cost point of view and with the respect of special, for example flexible modules. However, within a range of allowed temperature it is hard to prepare a high quality semiconductor material. On the other hand the technology can easily adopt a complex multi-layer structure, particularly a tandem structure, in which the cell with the narrower band gap is covered by the one with the wider band gap. For the characteristics and diagnostics of tandem cells it is necessary to distinguish the contributions of the component sub-cells to the total performance. One of the tasks is the determination of the component contributions to the total voltage, which is strongly influenced by the amount and spatial distribution of shunts in each sub-cell. We show that the total voltage is not a simple sum of component voltages. The experimental results are presented in this paper.

Teaching of PV Energy Storage at the Department of Electrotechnology

  • Department: Department of Electrotechnology
  • Annotation:
    The support of renewable energy sources (RES) in European Union, especially in neighbouring Germany, means gradual revolution in energetics. Recently applied approach, where, easily said, for every produced kW coming from RES, the power from conventional source in the net was reserved, is no more sustainable. For this reason, the educational institutions must respond sufficiently flexibly for the increased demand on experts in the area of energy storage, because this is the combination of energy storage and RES (especially photovoltaics) which is in our opinion the solution of current problems. In the article, the application of PV and energy storage connection is described.

A Simple Method of Evaluating Thermograms of Photovoltaic Modules

  • Department: Department of Electrotechnology
  • Annotation:
    A common problem to be solved during the operation of photovoltaic (PV) power plants is early detection of faults in PV systems. For this purpose was developed many diagnostic methods which can be applied directly at the PV system without the need of its disassembling. A very popular tool is especially the analysis of temperature distribution on the PV module - thermography, which is also a good tool for checking electrical connections (fire hazard). The problem is that there is virtually no quantification of obtained thermograms. This work provides guidance on how to reliably perform such quantification without the need of any other special device using.

Batteries for START/STOP Systems

  • Authors: Ing. Pavel Hrzina, Ph.D., Cetl, T.
  • Publication: Energetika. 2015, 65(8-9), 466-469. ISSN 0375-8842.
  • Year: 2015
  • Department: Department of Electrotechnology
  • Annotation:
    In the work, the possibilities of solving the problems of increased claims on starting accumulators in the vehicles are described.

Decentralized System of Traction Batteries Charging with an Atypical Strain for Solar-Powered Boat

  • Authors: Ing. Pavel Hrzina, Ph.D., Vyhnánek, J., Makeš, P.
  • Publication: Sympozium Energeticky efektivní budovy 2015. Praha: Společnost pro techniku prostředí, 2015. pp. 111-115. 1. vydání. ISBN 978-80-02-02615-0.
  • Year: 2015
  • Department: Department of Electrotechnology
  • Annotation:
    The article deals with the optimization of electrical energy production from the sun in the conditions of the moving object, namely solar powered boat. It describes both the optimization design process of the PV modules itself and the design of the charging system with high resistance to the total failure.

Electromobility the Current State in 2015

  • Authors: Cetl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: 36. Nekonvenční zdroje elektrické energie. Praha: Česká elektrotechnická společnost, 2015. pp. 13-17. ISBN 978-80-02-02593-1.
  • Year: 2015
  • Department: Department of Electrotechnology
  • Annotation:
    Electromobility is currently being more and more discussed topic. The most problematic component is still accumulator which represents the power of the entire vehicle. The paper summarizes the basic types of currently used accumulators. There are also their properties and possible future developments discussed.

Keeps the alkaline cells abreast with the times?

  • Authors: Reichl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: 36. Nekonvenční zdroje elektrické energie. Praha: Česká elektrotechnická společnost, 2015. pp. 118-122. ISBN 978-80-02-02593-1.
  • Year: 2015
  • Department: Department of Electrotechnology
  • Annotation:
    There exist many applications that still use conventional primary cells. Manufacturers are trying to meet the diverse requirements in terms of performance profiles of individual appliances. On the market, it is possible meet with cells intended for different applications. The paper deals with the evaluation of the characteristics of different cell groups with an emphasis on assessing the relevance of this classification.

Method of Reducing Losses of PV Power Plants Based on CIGS Technology with Transformerless Inverters

  • Department: Department of Electrotechnology
  • Annotation:
    The problematics of thin film PV modules degradation connected with transformerless inverters operation is relatively well known. But, there exists also the problem connected with immediate power loss, caused also by high-frequency currents, which can occur when the used inverter doesn’t have sufficient filter. In the case of new installations, these problems are solved and no more occur, but there is a large couple of already existing PV systems, where changing of all inverters is not cost effective or worse, restricted by law (loss of license and advantageous feed-in tariff). Such problems can be partially solved using additional filter with suitable characteristic. In this paper, the description and verification of such a filter is presented.

PID effect on photovoltaic power plants

  • Department: Department of Electrotechnology
  • Annotation:
    In recent years, the owners of large solar parks pay his attention to the term Potential Induced Degradation (PID). It is one of the most important influences that cause considerable loss of performance of the entire photovoltaic (PV) system. The article describes the types of PID and possible mechanisms of their formation. Particularly the effect on the crystaliline silicon modules and possible solution are described.

From Basic Knowledge to Diagnostics

  • Department: Department of Electrotechnology
  • Annotation:
    There is described the educational system of Photovoltaics at FEE CTU in Prague in the article. The connection with praxis and interfaculty study programm Inteligent Buildings is also discussed.

Students' projects at the Department of Electrotechnology CTU FEE Prague

The Acumulators of Cars Start/Stop Systems

  • Authors: Cetl, T., Ing. Pavel Hrzina, Ph.D.,
  • Publication: 35. Nekonvenční zdroje elektrické energie. Praha: Česká elektrotechnická společnost, 2014. pp. 8-12. ISBN 978-80-02-02528-3.
  • Year: 2014
  • Department: Department of Electrotechnology
  • Annotation:
    The requirement to emissions reducting from the cars according to EURO 5 and EURO 6 norms is solved by the automotive companies with the START/STOP system. The frequent engine starting means a substantial increasing requirements on car battery. The paper deals with a solving of this problem.

The Interaction of Electrical Field with Flames

  • Authors: Dvořák, O., Staněk, Z., Koller, J., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Sborník příspěvků z konference Požární ochrana 2014. Ostrava: Sdružení požárního a bezpečnostního inženýrství, 2014. pp. 55-59. ISSN 1803-1803. ISBN 978-80-7385-148-4.
  • Year: 2014

Thermography in photovoltaics

  • Department: Department of Electrotechnology
  • Annotation:
    The article summarizes the basic properties of the PV modules from the viewpoint of thermal manifestations of defects. It outlines a new evaluation method of taken thermograms.

Using Measurement of AC Parameters for CIGS PV Modules Degradation Studying

  • DOI: 10.1109/MIEL.2014.6842150
  • Link: https://doi.org/10.1109/MIEL.2014.6842150
  • Department: Department of Electrotechnology
  • Annotation:
    In the paper is described Time Domain Reflectometry method which can be used for differentiation of PV modules with same static plate values. Different AC parameters can cause dissimilar behavior in alternating fields leading to premature degradation.

Diagnostics of Photovoltaic Modules by Using AC Measurement Methods

  • Department: Department of Electrotechnology
  • Annotation:
    The presentation summarizes the basic methods used for the diagnostics of PV modules. Attention is paid to the analysis of alternate methods and achieved unique results in the measurement of PV modules.

Diagnostics of PV Modules Using Time Domain Reflectometry

  • Department: Department of Electrotechnology
  • Annotation:
    In the article are described possibilities of using TDR method for distinction of various generation of the same PV module type.

Economic and Technological Trends in Photovoltaics

  • Department: Department of Electrotechnology
  • Annotation:
    The article describes the current and future prospects of the photovoltaic installation in the Czech Republic and Europe.

Diagnostics of Photovoltaic Modules

  • Department: Department of Electrotechnology
  • Annotation:
    The article summarizes the diagnostic methods used in photovoltaics. Special emphasis is placed on explaining the difficulties related to their incorrect application and possible consequences.

Laboratory Exercises in Teaching Solar Systems at the Department of Electrotechnology CTU FEE Prague

  • Department: Department of Electrotechnology
  • Annotation:
    There are almost 2 GW installed capacity of photovoltaic sources in Czech Republic. This situation requires more specialists in the field of photovoltaics, diagnostics especially. At the Department of Electrotechnology are many subjects focused on this problematic. With the growth of photovoltaics were these subjects enhanced by other diagnostic method and grater allowance of lessons allowed coming deeper into problematic. This article contains description of laboratory exercises and equipment used in the education.

Photovoltaic Modules Diagnostics

  • Department: Department of Electrotechnology
  • Annotation:
    The article summarizes the basic methods of diagnostics of PV modules. In addition to describing the consequences at an incorrect procedure for their application are listed. It is also one part devoted to performance guarantee and its relationship to modules aging .

Possibilities of Using Photovoltaics in Automobiles

  • Department: Department of Electrotechnology
  • Annotation:
    The paper describes the basic properties of various photovoltaic modules with emphasis on automobile using possibilities and mobile applications.

Ecodesign of external power supply

  • Authors: Ing. Pavel Hrzina, Ph.D., Kudláček, I., Žák, P.
  • Publication: Sborník konference ELEN 2010. Praha: ČVUT FEL, Katedra elektroenergetiky, 2010. pp. 1-5. ISBN 978-80-254-8089-2.
  • Year: 2010
  • Department: Department of Electrotechnology
  • Annotation:
    Last year, the entry into force of Commission Regulation (EC) No 278/2009 implementing Directive 2005/32/EC of the European Parliament and of the Council and laying down the ecodesign requirements for no-load condition electric power consumption and average active efficiency of external power supplies. External power supplies represent significant volumes of sales and trade. Their energy efficiency has not been the main criterion of their design. It is stated that losses due to power conversion and no-load consumption amounts to 17 TWh, which converted to CO2 emissions amounts to 6.8 Mt of emissions per year. Given the size of these losses appear to be useful not only to formulate the basic requirements for the design of electric power sources, but also to formulate the requirements of the overall structure in terms of LCA and product's future recycling. But, it is also necessary to ensure the required reliability of power supplies.

Power Passive Components Measurement.

  • Department: Department of Electrotechnology
  • Annotation:
    This article discusses the measurement of parameters of coils and capacitors used in switching power supply (SMPS - Switch Mode Power Supply) small and medium power. To identify the basic physical parameters of passive components, such as resistance, inductance and capacity in engineering practice mostly used by digital RLC meters. This article is given an alternative way to identify these parameters. This method also allows for analysis of other properties of coils and capacitors.

EMC of Magnetotherapeutic Devices

  • Authors: Kuba, J., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Sborník konference ELEN 2008. Praha: ČVUT FEL, Katedra elektroenergetiky, 2008. ISBN 978-80-254-2293-9.
  • Year: 2008
  • Department: Department of Electrotechnology
  • Annotation:
    The EMC measuring methods that are usable for magnetotherapeutic devices are described. These devices used a low frequency pulse magnetic field as therapeutic medium.

Power MOSFETs Bias Voltage Temperature Stabilization

  • DOI: 10.1049/ic:20080213
  • Link: https://doi.org/10.1049/ic:20080213
  • Department: Department of Electrotechnology
  • Annotation:
    The article describes a development of system that automatically stabilizes operating point of the MOSFETs used in Radio Frequency Power Amplifier (RFPA) with output power approx 500 W. This device uses a micro controller based system for measurement of power MOSFETs temperature and generating output bias voltage.

Measurement of Magnetic Field of Electromagnetics of Magnetotherapeutic Devices

  • Authors: Kuba, J., Ing. Pavel Hrzina, Ph.D.,
  • Publication: Diagnostika '07. Plzeň: Západočeská univerzita v Plzni, 2007. pp. 38-41. ISBN 978-80-7043-557-1.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    A design and performing of controlled measuring device for measurement of level, distribution and orientation of the induction of pulse magnetic field near (in 3D) the electromagnets (applicators) of the magnetotherapeutic devices are described in this paper. Measured results at three types of applicators are presented and discussed from therapeutic effect point of view.

Design of RF SMPS Power Circuits With Technological Restrictions Consideration

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: Advanced Engineering Design AED 2006. Praha: České vysoké učení technické v Praze, 2006. ISBN 80-86059-44-8.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    This article deals with problems concerning design of Switch Mode Power Source which works within frequency range from 300 kHz to 1 MHz. The described source was realized as SMPS with planar core. The relations between winding options and magnetic core parameters were studied. Round cross-sectional and a rectangular cross-sectional wires are compared in this article. Some recommendations for design improvements of these SMPSs are presented.

Pulse Source for Power Supply of Magnetotherapeutic Devices

  • Authors: Ing. Pavel Hrzina, Ph.D., Kuba, J.
  • Publication: Applied Electronics 2006. Plzeň: ZČU Plzeň, 2006. pp. 63-66. ISBN 978-80-7043-442-0.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    A special by microprocessor controlled source designed and made for power supply of electromagnets used in magnetotherapy, is written in this paper.

Parameters of the Magnetic Core and Parasitic Structure in RF SMPS Circuit

  • Authors: Ing. Pavel Hrzina, Ph.D., Žáček, J.
  • Publication: EPE2005 DRESDEN 11th European Conference on Power Electronics and Applications. Brussels: EPE Association, 2005. pp. 1-6. ISBN 90-75815-08-5.
  • Year: 2005
  • Department: Department of Electrotechnology
  • Annotation:
    The article describes the system for measurement of parasitic parameters of designed SMPS (Switched Mode Power Supply) structures operating at frequencies of hudreds of kHz. The method uses a comparison between simulation results and practical measurement. For simulation the most popular circuit simulators as PSPICE, PSIM, SIMULINK can be applied.

System for Education in the Field of Switching Power Sources

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: 7th International Seminar on Power Semiconductor. Praha: Ediční středisko ČVUT, 2004. pp. 219-222. ISBN 80-01-03046-6.
  • Year: 2004

System for Verification of Theoretical Conclusions for Design of Switching Source

  • Authors: Ing. Pavel Hrzina, Ph.D.,
  • Publication: Workshop 2004. Praha: České vysoké učení technické v Praze, 2004. pp. 704-705. ISBN 80-01-02945-X.
  • Year: 2004

Diagnostics of Large Area Solar Cell Homogenity by Local Irradiation

Over-Voltage Protection for Universal Laboratory Power Supply

  • Authors: Ing. Pavel Hrzina, Ph.D., Zubák, V.
  • Publication: Poster 2003. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2003. p. E19. ISSN 0277-786X. ISBN 0-8194-5368-4.
  • Year: 2003

Responsible person Ing. Mgr. Radovan Suk