Study On Overvoltage Of 500kV Series Compensator

With the development of huge electric power grid in China, more and more series compensation devices are applied in thr grid. Series compensation capacitors compensate part of inductance of the transmission line, reducing the electrical distance of the transmission lines, it can greatly improve the stability limit, but also bring the problem of system short-circuit current enlargement. Overvoltage will happen between the capacitors when large short-circuit current through the capacitors, and the compensation equipments will operate in a dicky environment which will directly impact on the safe operation of equipments.Overvoltage protection for series compensation directly related to the investment of series compensation and the safe operation of equipments, it is a vital part of engineering design.500kV Jianshui Series Compensation is an important part for power transmission from west to east in China Southern Power Grid. This paper prevents over voltage protection design for 500kV Jianshui Series Compensation, some main technical specifications parameters are also given in this paper. The main contents are as follow,(1) Initially determining the overvoltage protection for Jianshui Series Compensation based on comprehensive analysis of various series compensation overvoltage protection and control strategies.(2) Generation mechanism of low frequency oscillation component in secondary arc current when single phase grounding fault happens on series compensation line is analyzed. After analyzing the influence of serier compensation capacitor on Secondary Arc Current and Transient Recovery Voltage of Circuit Breaker, secondary arc current and transient recovery voltage of circuit breaker are calculated by EMTP.(3) The maximum current and energy of Metal Oxide Varistor (MOV) are calculated when short-circuit faults happened outside the series compensated line, Over Current Setting and High Energy Setting of MOV are given based on the calculated maximum current and energy. Finally, the thermal capacity of MOV is given.(4) The electric paremeters of damping circuit are given based the design request for damping circuit.