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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]

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]

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]

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Currently, an issue of relay protection (RP) settings determination that ensures its correct operation in electric power systems (EPSs) has not been resolved completely. The main reason for this is the lack of methods and tools for adequate consideration of transients during a fault existence for RP settings calculation. In this study, a novel approach for RP settings determination is presented. Its main feature is the application of detailed mathematical models reproducing simultaneously processes in the entire set of elements in the RP scheme, including instrumental transformers, and in large-scale EPS mathematical model as a whole. This key feature can be achieved via the hybrid power system simulator -- hybrid real-time power system simulator -- implementing a methodically accurate analogue--digital solution of the EPS mathematical model. The numerical transformer differential protection (NTDP) based on this approach was set up via the standard dual-slope tripping characteristic. Also, a novel approach to the formation of the tripping characteristic is proposed. The key feature of this approach is applying a flexible curve that enveloping all fault characteristics Idiff = f(Irest) of those modes in which the NTDP should not trip. [ABSTRACT FROM AUTHOR]

Summary: Reliability and efficiency of electric power systems (EPS) operation depend on the adequacy of information about quasi‐state and transient processes in EPS used for their research, design, and operation. A value of short‐circuit currents (SCC), especially their maximum values, is one of the important information used for different tasks. The difficulty of obtaining this information is the need to use a large‐scale EPS mathematical model for SCC calculation. The total mathematical model of any large‐scale EPS is a stiff and nonlinear system of differential equations of high order. Such system cannot be solved analytically. Satisfactory solution is also impossible by using the numerical approach that leads to the need for applying simplifications and limitations reducing the adequacy of simulation results. Therefore, each solution should be validated. The comparison of simulation results with the field data is the most reliable way of validation. However, the acceptable amount of field data cannot be obtained in the foreseeable future in view of the obvious variety of EPS modes, especially emergency ones. An alternative way of validation is suggested in the paper: the using of an adequate reference model instead of field data. The experimental sample of hybrid real‐time power system simulator having the necessary properties and capabilities is used as the reference model. The indicated possibility of SCC calculation validation is proved by the experimental studies shown in the paper. [ABSTRACT FROM AUTHOR]

Nowadays in the world a lot of attention is paid to the integration of renewable energy sources, especially wind power plants, into existing electric power systems. However, the modern simulation tools usage based on numerical integration for studying and assessment of renewables impact on transient processes in EPS is always associated with different simplifications and limitations. In this regard, the authors suggest the Hybrid Real-Time Power System Simulator (HRTSim) usage for comprehensive and accurate simulation of large-scale EPS with RES. The results of the synthesis of the wind turbine mathematical model as a part of the specialized module for the HRTSim are presented in the paper. The developed means are intended to solve the issue of this hardware-software simulator upgrade for comprehensive and adequate modelling of wind power generation facilities. [ABSTRACT FROM AUTHOR]

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]

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]

• Novel approach for relays tuning using detailed mathematical model. • Hybrid Real-Time Power System Simulator is used as a source of necessary data. • Proposed approach allows to adapt protection settings to practical conditions. The correct operation of relay protection (RP) devices largely determines the security of electric power systems (EPS). The key point that in turn determines the behavior of protection in various emergency modes is a determination of their settings. The existing methodologies and tools often do not allow to provide RP settings adequate to the practical conditions of their functioning. This statement is confirmed by the statistics of faults in EPSs. The main reason for this issue is the inability to reliably reproduce transients in EPS via the software programs used in practice to calculate the RP settings. The Hybrid Real-Time Power System Simulator (HRTSim), developed by the authors, allows to reliably reproduce the entire range of normal and emergency modes and processes in EPS of any scale, topology and configuration by using detailed three-phase models of all power system components. Taking into account this possibility and features of the HRTSim, the task of detailed modeling of RP devices, including instrument current and voltage transformers, becomes relevant. The implemented special tools for RP modeling and the HRTSim in general allow to develop a new methodology for RP tuning. At the same time, the typical elements – relays – can be identified for each type of RP that determine their operation algorithm. This paper presents an analysis of the main relays of the most modern microprocessor-based RP devices and proposed principles of their tuning. The developed approach allows to adapt the RP settings to the practical conditions of their functioning in EPSs and to minimize the probability of RP maloperation. [ABSTRACT FROM AUTHOR]