Ing. Lavr Vetoshkin, Ph.D.

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.

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.

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.

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.

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.

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.

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.

This paper describes an alternative method of correction of the influence of wind speed within thermographic measurements of power system components. Instead of measurements of wind speed measured temperature of a resistor fed by known electrical power is used. The paper gives theoretical background of the method and measurement's results.