Analysis of switching surge characteristics of 345kV GIS and their affections assessments

345kV gas-insulated switchgear (GIS) has been widely used in large power plants and substations. Since the buses of the GIS are the merging points of the power lines, with the large capacitance between its inner buses and casing interacting with the inductance of the main transformer, switching operations may generate large voltage and current surges and following-up residual voltages which will adversely affect the internal components of the GIS such as the potential transformer. This paper first applies the Electromagnetic Transients Program/Alternative Transients Program (EMTP / ATP) to construct the model of GIS and then analyzes the voltage and current surges caused by switching operations. The analysis includes both common and special switching operations, as well as synchronous and asynchronous three-phase switching operations. Finally, suggestions are made for future improvement strategies based on the analysis and evaluation on the effects of the switching surges of the GIS.