Study On Dynamic Equivalent Methods Applied To Electromagnetic Transient Simulation Based On PSS/E

As the development of China AC-DC large-scale power systems, more and more large-capacity direct current transmission lines locate in the same power system. Errors may occur when using electromechanical transient simulation program to analyze the asymmetric fault in the AC-DC large scale power systems. Electromagnetic transient simulation method is necessary in this case. Electromagnetic transient simulation on the large-scale power system directly is very difficult, so this paper focuses on the physical equivalence of the dynamic equivalent method by using power system simulation software PSS / E. This method can be used in Electromagnetic transient simulation analysis, including the following three points.1. A comparison is made between the dynamic equivalence method applicable to the existing electromechanical transient simulation and the physical equivalence of the dynamic equivalent method applicable to electromagnetic transient simulation in this paper. The difference of application is found out between electromechanical transient simulation and electromagnetic transient simulation. This paper has a thorough research on the dynamic equivalent method applicable to electromagnetic transient simulation, stratifies the system according to voltage level. The short-circuit capacity, the result of power flow and the capacity and active power of generators remain the same after the equivalence. Steps and the program of the physical equivalence of the dynamic equivalent method are given with formula in details.2. An equivalent is made of Zhejiang power grid 500kV buses with the physical equivalence of the dynamic equivalent method. Formulas are optimized in accordance with the practical problems encountered in the calculation. The experience in the process of equivalence is summarized to lay the foundation for IPLAN programming applied to the electromagnetic transient simulation of the dynamic equivalent method. The result of 500kV buses dynamic simulation analysis shows the feasibility and effectiveness of this plan.3. The experience of equivalence of Zhejiang power grid 500kV buses in 2008 is summarized. The physical equivalence of the dynamic equivalent is programmed with IPLAN in PSS/E. This program stratifies the system according to voltage level, remains the 500kV grid and equals the low voltage level direct to standard structure which is applicable to electromagnetic transient simulation. The equivalence of Zhejiang power grid with this program is made and the dynamic characters of the system before and after the equivalence are compared. The result shows the equivalence is effective to apply to projects applications.