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The provision of system support services by converter-interfaced generation (CIG), which were previously assigned to the conventional synchronous generation, is a challenging task extremely necessary for the stable operation and control of modern power systems. The most promising solution in this direction is the application of grid-forming control strategies for the CIG. This paper proposes a CIG' control system based on a freely configurable structure of a virtual synchronous generator (FC-VSG). In this control system, different levels of the inverter control are implemented in parallel, and in order to improve the transient performance and damping properties of CIG, the inertial and governor response are coupled at the inner control level, a voltage regulator is added at the outer control level, as well as the combined use of a virtual damper winding and power system stabilizer is applied. Such solutions made it possible not only to mimic the behavior of a conventional rotating machines, but also to significantly improve the transients' dynamics. To show the effectiveness of the proposed control system, time-domain simulations and experimental case studies have been performed. In addition, the qualitative and quantitative assessment of the dynamic response of the FC-VSG in comparison with both the conventional voltage-controlled VSG structure and the dynamics of a practical synchronous machine have been carried out. [ABSTRACT FROM AUTHOR]

The penetration of renewable-based converter-interfaced generation and flexible alternating current transmission systems significantly changes properties and dynamic characteristics of modern electric power systems, which leads to the need to take measures to ensure security of their operation. These measures may consist in using the capabilities of new penetrated units or in adapting conventional means. Such adaptation consists in reconfiguration of control systems, development of new systems or approaches to settings determination, which include tuning of automatic voltage regulators with power system stabilizers of conventional synchronous generation. This paper proposes a new approach to tuning of automatic voltage regulators, based on the use of the most complete and reliable information about processes in modern power systems. This approach allows to get settings that are most adequate to practical conditions of operation as part of power systems. For this purpose, the hybrid real-time power system simulator and concept of hybrid modeling are used, and within this paper, and the hybrid modeling tools necessary for the tuning process have been developed. The result of the study is a comprehensive assessment of the reliability of the simulation results obtained using the developed tools, which allows to conclude about the possibility of their application. [ABSTRACT FROM AUTHOR]

In case of sharp disturbances in the electric power system (EPS), emerging transients may be accompanied by a loss of synchronism. This incident may lead to cascade-fault severe consequences for the whole EPS. One of such consequences may be the occurrence of an active power overgeneration in one part of the electric power system. In this regard, it is necessary to apply actions to implement targeted effects on transients in EPS. The most technologically and economically advantageous is the use of fast turbine valving control (FTVC). The task of this automation is to maintain the dynamic and static stability of overgenerated area. However, the effectiveness of FTVC is mainly dependent on its control action (CA). Tuning the parameters of FTVC is not a trivial task, because it is necessary to take into account the processes and their mutual influence in the equipment not only directly involved in the FTVC but also in the EPS as a whole. The article shows the results of FTVC action with various CA configuration. The use of complete and reliable mathematical models of equipment not only directly involved in FTVC but also EPS, as well as a tool capable of working with similar types of models, allowed the optimization of FTVC CA parameters. [ABSTRACT FROM AUTHOR]

Penetration of renewable energy sources (RES) significantly changes operating modes of electric power systems (EPS) and has an unpredictable effect on operation of relay protection devices (RP). That is a reason, why the existing methods for calculating RP' settings need to be updated. The authors carry out research and studies focused on development of new methods and means for RP setting up. The feature of the author's approach is application of detailed mathematical models, reproducing processes simultaneously in the whole RP' scheme, including primary transducers, and hybrid real-time simulator (HRTSim), implementing methodically accurate analog–digital (hybrid) solution of EPS model. Within the framework of the problem solution, a mathematical model of measuring part of digital protective relay was synthesized and its research was carried out in MATLAB. It is revealed that numerical methods for solving differential equations are badly applied for solving even simple mathematical models of RP, which is manifested in the obvious distortion of the simulation results. Using hybrid approach, a software–hardware mean was created and its test was carried out that showed no distortion of the output simulated signal. In addition, the operation of numerical transformer differential protection was studied via this mean. [ABSTRACT FROM AUTHOR]

The reliability and efficiency of electric power system (EPS) operation depends on the adequacy of the information about processes in the EPS. The complexity of obtaining this information lies in the need to use large-scale EPS mathematical model for calculations. Within the framework of numerical integration, a satisfactory solution of such model is hardly to be ensured; consequently, the simplifications and limitations are applied. In this regard, every obtained solution should be validated. The most reliable way of validation is to compare simulation results with field data. However, it is not always possible to receive the necessary amount of field data. The paper proposes an alternative approach for validation: the adequate reference model (RM) usage instead of field data. The prototype of hybrid real-time power system simulator having the necessary properties and capabilities is used as the RM in this paper. The adequacy of proposed approach is illustrated by the fragments of the experimental studies. [ABSTRACT FROM AUTHOR]

In the frame of the constantly increasing in electric power systems (EPSs) complexity, the challenge of ensuring adequacy of relay protection (RP) devices operation becomes more and more urgent. The authors propose to use the detailed mathematical models of the combination «instrument transformers (IT)—RP» with modern EPS simulators as the solution. It is very important to adequately simulate IT, in particular, the magnetic core magnetization process, because IT largely determines the shape of the RP-controlled signal and affects on its operation. However, in practice simplified models are currently used due to the lack of an accurate mathematical description of the IT core magnetization characteristics. Such models do not reflect all processes in the magnetic core. The aim of this work is to develop a hysteresis mathematical model, which will have a high accuracy in reproducing the magnetization processes of transformer core. The main research method is mathematical modeling of the ferromagnetic material magnetization processes in the MathCAD software. The article presents main development principles of the mathematical model with magnetic hysteresis memory based on the Preisach theory, which reproduces with high accuracy both the major and minor hysteresis loops. [ABSTRACT FROM AUTHOR]

The trend in semiconductor developments has made the high-voltage direct current (HVDC) technologies based on voltage source converters feasible. This type of convertor has a number of potential advantages compared with "classic" HVDC, but deep analysis should be carried out before its integration in electric power system. In this paper, the results of realization of the VSC HVDC model based on a concept of hybrid simulation of electric power system are presented. Hybrid concept combines three approaches of simulation: analog, digital and physical, combination of which allows to achieve a maximum efficiency. The obtained simulation results have confirmed an adequacy of the model and possibility to integrate it to the hybrid real-time simulator for carrying out various researches and analyses of the operation of large electric power system, including HVDC technologies, in real time without any decompositions and limitations. [ABSTRACT FROM AUTHOR]