Characteristic Of Very Fast Transient Overvoltages In GIS And Analysis Of Influencing Factors

With the development of power industry and the rise of voltage class, more and more gas insulated substations (GIS) are used in modern power systems. In recent years, more attention has been paid to very fast transient overvoltages(VFTO) which are induced by disconnector switching and have great influence on primary equipments and adjacent equipments in GIS. The modeling methods for each primary equipment in GIS are discussed and summarized in this thesis. A primary system model for Laxiwa 750kV GIS is built in EMTP. The VFTOs induced by disconnector switching as well as lightning overvoltages intrude into GIS are calculated. The lightning overvoltage values on each equipment, protective projects adopting metal oxide arrester (MOA) and the effects of ground resistance on lightning overvoltages are presented respectively. Besides, combining with two different voltage classes and configuration GIS computational model, some typical factors influencing VFTO are analyzed.