Research On Lightning Over-voltage Of500kV GIS Substation

500kV substation is a pivot point of power system,which have momentous status.Compared with traditional substation, GIS substation have higher reliability, need lessmaintenance and smaller floor area, and is immune to electromagnetic interference. GISsubstation, which thus have great advantages, have been uesd more and more in powersystem. lightning accident of500kV substation is an important reason for the power pausein a large area.And most of the electric equipments in substations does not have resumeability, which would cause serious consequences. So the research of the lightningovervoltage of500kV GIS substation is especially necessary.Study on lightning overvoltage of substation need to establish an accurate simulationmodel, including lightning model, towers and transmission lines model, insulator stringflashover process of insulators model, and other substation equipment model. Parametersof the model directly affects the accuracy of the results. overvoltage response ofelectrical equipment in the substation casued by lightning impulse affected byuncontrollable and controllable factors,the uncontrollable factors include lightning currentand waveform, lightning point and so on,controllable factors include operation mode ofsubstation, insulators, parameters of the tower, the impulse grounding resistance of tower,electrical distance, the reactor branch, elevation and other environmental factors. Thecontrollable factors can be improved at design and operation.This paper takes a real500kV GIS substation as sample, merges the substation andthe lines near the substation to a whole net, and uses of electromagnetic transient programATP to calculation the lightning overvoltage of substation system,and analyzes response ofdifferent lightning source, and gets the characteristics of lightning protection for GISsubstation. The controllable factors have been considered separately.The conclusions can bereferred for the design and operation of500kV GIS substation.