Very fast transient overvoltage research and simulation in GIS of 750kV substation

Gas insulated switchgear (GIS) has been widely used due to its advantages of small footprint, reliable operation, and long maintenance cycle. Isolating switches and circuit breakers are important components of GIS. When closing the circuit, a very fast transient overvoltage (VFTO) will be generated inside the device and spread to other connected equipment, seriously affecting the insulation safety of the equipment. To solve this problem, the overvoltage situation on 750kV GIS equipment under different operating modes was studied. The results indicate that during routine operation of GIS internal isolation switches, high-frequency rapid transient overvoltages are generated. The magnitude of overvoltage is related to the structural dimensions, equipment layout, internal equipment parameters, and external equipment characteristics of GIS substations. Revealed the VFTO characteristics in the GIS of 750kV substations, providing theoretical support for the design of ultra-high and extra high voltage GIS structures and parameters.