Reliability and survivability of electric power systems (EPS) depend on transient stability assessment (TSA). One of the most effective way to TSA is time-domain simulation. However, large-scale EPS mathematical model contains a stiff nonlinear system of high-order differential equations. Such system cannot be solved analytically. At the same time, numerical methods are imperfectly applied for such system due to limitation conditions. To make it appropriate, the EPS mathematical model is simplified and additional limitations are used. These simplifications and limitations reduce reliability of simulation results. Consequently, their validation is needed. The most reliable approach to provide it is to compare the simulation results with the field data. However, in practice, there are not enough data for such validation. This paper proposes an alternative approach for validationthe application of a reference model instead of field data. A hardware-software system HRTSim was used as a reference model. This power system simulator has all the necessary properties and capabilities to obtain reliable information required for comprehensive validation of transient stability calculations in EPSs. Main disturbances leading to instability in EPSs are investigated to conduct the validation (processes in cases of faults, single-phase auto-reclosing operation and power system interconnection). Fragments of corresponding experimental studies illustrate the efficiency of the proposed approach. Obtained results confirmed the possibility of the developed approach to identify the causes of numerical calculation errors and to determine disturbances calculated with the significant error. In addition, experimental studies have revealed that numerical calculations error depends on disturbances intensity.
Abstract. The objective of this work is to determine the influence of highfrequency link (HFL) on functioning of phase comparison protection (PCP) through the usage of detailed models that take into account specific features of the PCP and processes in HFL. The article describes the case of the most common variant of the high frequency signal transmission by using a scheme 'phase-to-ground'. To verify suggested solution the developed mathematical model of HFL has been studied. Presented simulation results confirm the effectiveness of the proposed approach for solving the problem.
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.
This paper is aimed at determining the effect of a variable number of Type 4 wind turbines in the total generation of the corresponding electric power system on the parameters of an asynchronous regime of such a system. Processes occurring in an electric power system were simulated using an all-mode real-time simulation complex of electric power systems constituting a multi-processor software and hardware system. A model of an electric power system was developed, which, in addition to conventional power sources, included a wind-operated power plant combining a variable number of Type 4 wind turbines. The automatic control system of the simulated wind-operated power plant comprised a control loop (in terms of active power and voltage) equipped with an additional regulator of virtual inertia. An analysis of changes in the parameters of the asynchronous regime using a virtual inertia algorithm showed that the time of its advancement along the protected line was reduced maximally by 0.1 s. However, the time of the first cycle of asynchronous motion between two generators in the post-emergency regime increased by 2 times. Thus, for a wind-operated plant with a capacity of 100 MW, the time of asynchronous motion was 0.36 sec and 0.74 sec without using and when using a virtual inertia algorithm, respectively. It was experimentally confirmed that an increase in the power of a wind-operated power plant leads to a decrease in both the time of advancement of the asynchronous regime and the time, during which conventional generators transit from the synchronous regime. The latter was evidenced by the effect of Type 4 wind turbines on the value of total inertia, which ranged from 8.746 to 5.478 s. A study of the virtual inertia algorithm confirmed its impact on the electromechanical transient processes in power systems. The most favourable effect was noted at a virtual inertia value of 2 s and a wind-operated power plant capacity of 100 MW.
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