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The most important hydrogen energy storage technologies, developed between 1974 and 2022, now enable the quality operation of global power grids that integrate alternative energy facilities (wind power, solar power, geothermal power, etc.). With the continuous large-scale penetration of converter-interfaced generation (CIG), based on the combined use of renewable energy sources (RES) and hydrogen energy storage systems (ESS), into practical power systems, the dynamic characteristics of the latter change significantly. New challenges with the power system control and stability arise due to the specific CIG properties. A positive-sequence time-domain simulation is frequently used to solve them. However, the known simplifications and limitations are inevitably applied in case of such simulation. These become critical for the CIG with RES and hydrogen ESS models due to their fast dynamics. Therefore, the validation of such simulation results becomes relevant. This paper proposes a novel validation approach based on the use of a benchmark tool Hybrid Real-Time Power System Simulator (HRTSim) instead of field measurements. A major feature of the proposed approach is the possibility of a guaranteed validation of the benchmark tool using any state of the modeled power system. A hybrid implementation of a detailed three-phase model of CIG is also developed for the HRTSim, which provides an adequate simulation of the full range of dynamic processes. The results of validation of a positive-sequence simulation of a practical power system with CIG, which includes both RES and hydrogen ESS, using the developed approach presented in this paper have allowed to identify the causes of calculation errors, as well as factors affecting them. [ABSTRACT FROM AUTHOR]

• Enhanced current-controlled virtual synchronous generator with feedforward controller is proposed. • Feedforward controller affects mainly the low-frequency roots without worsening VSG inertial response. • Enhanced CC-VSG ensures stable operation in a wide range of grid strength conditions. Novel grid-forming control strategies based on the virtual synchronous generator (VSG) algorithm are becoming a key technology for power converters in modern hybrid power systems. This paper considers an alternative current-controlled VSG structure (CC-VSG). However, this structure is complex third-order system and is characterized by the lack of damping torque when the grid strength changes. Therefore, in this paper an enhancement of the CC-VSG damping properties via a feedforward controller is proposed. The analysis of the closed-loop transfer function demonstrates the reduction of the model order to the second order due to the proposed controller. By analyzing the state-space model, the predominant impact of the gain of the developed controller on the low-frequency roots is proved. As a result, it is concluded that the enhanced CC-VSG structure is efficient, stable and can be flexibly tuned to obtain any desired dynamic response under different grid strength conditions and load variation. [ABSTRACT FROM AUTHOR]

Currently, there is a large-scale penetration of renewable energy sources (RES) in power systems around the world, most of which are based on the power converter technology. The result of such penetration is the emergence of frequency and voltage regulation problems in power systems with RESs. An effective way to solve the mentioned problems is the use of energy storage systems (ESS), among which hydrogen ESSs are promising. However, the quality of such solution mainly depends on the approach to the power converters control. One of the most effective is a grid-forming power converter control strategy. Within this strategy, many scientific groups have proposed the concept of a virtual synchronous generator (VSG). However, the existing VSG models use a series structure with a stiff direction of signals, which completely mimics conventional synchronous generators. In this regard, the fundamental problems inherent in such a structure arise, e.g., a coupling between active and reactive power control. This paper describes a freely configurable VSG model (FC-VSG), in which the structural control blocks can be transferred from one level to another, and the levels themselves can be installed not only in series, but also in parallel. The case studies carried out made it possible to identify the configuration of the FC-VSG, which excludes the fundamental problems inherent in the conventional VSG structures. At the same time, the most efficient and reliable frequency and voltage regulation is provided, which has been proved by qualitative and quantitative comparison, including with the conventional VSG structure. [ABSTRACT FROM AUTHOR]

The dominant trend of the modern energy is the use of generating plants based on renewable energy sources, among which the most common is a wind power plant based on doubly fed induction generator (Type 3 WT). The large-scale introduction of Type 3 WT into the modern power systems significantly changes their dynamic properties. There are problems with ensuring the basic condition of the reliability and the survivability of power systems – the stability. The study and solution of the indicated problems is possible only with the help of the mathematical modeling of a large-scale power systems which is currently being carried out with the help of widespread purely numerical software tools of calculations of modes and processes, which are characterized by various simplifications and limitations. For the properties and capabilities of software tools for studying stability issues, mathematical models of Type 3 WT, the so-called generic models, which also have simplifications and limitations, are adapted. In this article, the reliability of stability calculations of a real power system with Type 3 WT using software tools was evaluated, which allows to identify the influence of the applied simplifications and restrictions with a purely numerical approach on the quality of solving problems of assessing the stability of power systems with Type 3 WT. Also, the studies made it possible to identify the areas of the application of generic models of Type 3 WT as a part of the model of the real dimension power system, at which the greatest and least errors arise, as well as their causes. Such a comprehensive assessment becomes feasible due to the alternative approach proposed in the article, based on the use of a detail benchmark tool model instead of the full-scale data to compare the results of modeling. [ABSTRACT FROM AUTHOR]

This study aims to propose an alternative hybrid approach to model renewable energy sources (RESs), which provide the most reliable results in comparison with the existing simulating tools. Within the framework of this approach, a specialized hybrid processor for modeling converter-interfaced generation (CIG) is developed. This study describes its structure and validation in the test system by comparing the results with commercial modeling tools, and also presents experimental studies of its operation as parts of the practical power system. The results obtained confirm the adequacy of the developed tools. [ABSTRACT FROM AUTHOR]

One of the problems associated with the integration of renewable energy sources is reducing the total inertia of the electric power system. By substituting the traditional synchronous generators to wind turbines connected to a network via power electronics devices the system the inertia constant is sharply reduced. In addition, the inertia of the system changes over time due to the wind turbine power change. Systems with lower inertia in the serious faults incident loses its stability easier. The question of the reduction of energy system inertia influence on the out-of-step mode parameters is not answered yet. Authors created a grid test model using software-hardware hybrid simulation tool HRTSim. The several experiments to determine the influence of type 4 wind turbine on the parameters of the out-of-step mode is realized. The oscillograms confirming the influence of the wind turbine on the parameters of the out-of-step mode are obtained. Problems of the influence of changes in the inertia of the power system during the integration of type 4 wind turbines on the parameters of the out-of-step mode are considered. The international experience in this field is analysed. The results of the analysis confirmed the insufficient study of this field and the almost complete lack of information about this in the grid codes of foreign countries. The experiments confirmed the theoretical expectation: the higher inertia induction stroke starts later, and the frequency slip is decreased. [ABSTRACT FROM AUTHOR]

Currently, the world is widely introducing renewable energy sources including solar power plants (SPP). In order to predict their work, it is necessary to adequately simulate the processes occurring in solar panels, not only in standard conditions, but also in conditions of partial shading. At present, the effect of partial shadowing is considered from the point of view of changes in the luminous flux, however, for a more adequate and comprehensive simulation, it is also necessary to take into account the temperature change in the shaded areas of SPP, especially considering the area of powerful SPP, the temperature of individual sections of which can radically differ, which is undoubtedly will lead to a change in the output characteristics of the SPP. Failure to take this factor into account, when modeling high-power SPP leads to results that do not correspond to real data. [ABSTRACT FROM AUTHOR]

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Currently, the number of distributed generation (DG) objects in the world is growing mainly due to renewable energy sources (RES). However, the integration of a large volume of DG based on RES into existing electric power systems (EPS) is associated with a number of significant problems. For a comprehensive study and solution of these problems, it is necessary to carry out detailed simulation of real EPS, which is not always feasible with the help of existing tools. Therefore, the article proposes the use of an alternative solution – the Hybrid Real-Time Power System Simulator (HRTSim). To confirm the properties and capabilities of the HRTSim, the simulation results of a test scheme obtained using the HRTSim and the widely used digital hardware-software complex RTDS were compared. The results of a comprehensive comparison in both complexes confirmed the adequacy of information about the processes in equipment and EPS as a whole, obtained by the HRTSim. Thus, it is proved that further use the HRTSim as a tool for detailed and adequate simulation of real EPS with DG will provide complete and reliable information about normal and abnormal quasi-steady-state and transient processes, which is necessary for reliable and efficient design, research and subsequent operation of EPS with DG. [ABSTRACT FROM AUTHOR]

Electric power systems are becoming more complex. This is due to the widespread use of renewable energy sources (RES) and FACTS devices. At the same time, protection devices for equipment and automation of power systems are becoming subject to influence from new devices. The article pays attention to the study of such influence from the side of RES and FACTS devices on the operation of one of the most important automation systems ensuring the stable operation of the power system - out-of-step protection (OSP). At the first stage of the project, the main reasons for the difficulty of setting up resistance control devices of OSP in networks with FACTS devices and RES were identified, which are related to the fact that the parameters of these devices vary depending on the operation mode, therefore, the zone of the OSP resistance relay should also be changed. Based on the analysis, a new approach to the study of the functioning of OSP in power systems with FACTS devices and RES has been developed. The performed experimental studies confirm the theoretical research. [ABSTRACT FROM AUTHOR]

The rapid growth of renewable energy capacity, in particular photovoltaic systems, is creating challenges associated with changing the rate of transient processes in the power system. This is due to the approach PV systems are connected to the grid using power converters and the absence of a rotating mass in the PV power plant. One of the most pressing challenge is the participation of PV stations in the process of frequency control in power systems, including in emergency modes. Simultaneously with PV power plants, it is efficient to use energy storage systems, including hydrogen ones. This is due to the fact that it is possible to obtain hydrogen for such energy storage systems using excess energy from PV power plants. The article proposes to solve the problem of frequency regulation in the power system by using an algorithm that allows to control the frequency in the power system using a synthetic inertia block of PV station, including at different levels of insolation and temperature of PV panels. The robustness of the proposed algorithm allows it to be used at different levels of power generated by the PV station, as well as in emergency modes. [ABSTRACT FROM AUTHOR]

• The synthesis of the modern VSG models into generic structures is performed. • The comprehensive assessment of the generic VSG structures is carried out. • The most reliable VSG structure for grid-connected operation is highlighted. The large-scale penetration of renewable energy sources has a significant impact on the steady-state operation and emergency control of modern electric power systems (EPS). Moreover, as a rule, the mentioned impact is negative. Therefore, the challenge associated with the development of a 'comprehensive' control strategy for renewables becomes extremely relevant. Such a strategy should ensure the same reliable operation of EPSs, as in the case of conventional synchronous generation. Among the existing directions, the concept of a virtual synchronous generator (VSG) is the most preferable. Within this paper, the synthesis and combination of the state-of-the-art concepts of VSG into generic structures has been performed. For the obtained structures, a comprehensive assessment and an experimental comparison were performed. On the basis of the results obtained, the benefits and drawbacks of the generic structures are highlighted, and a conclusion is made about the VSG structure, demonstrating the most effective and reliable operation. [ABSTRACT FROM AUTHOR]