Research on fast transient overvoltage suppression measures in 750kV GIS

Abstract The isolation switch in gas-insulated switchgear (GIS) will generate rapid transient overvoltage VFTO during opening and closing, which will cause great harm to the GIS itself and adjacent equipment. In order to solve the problem of rapid transient overvoltage in GIS, the electromagnetic transient program (ATP-EMTP) was used to simulate and calculate two measures to suppress rapid transient overvoltage: installing a zinc oxide arrester (MOA) and installing a closing resistor. The research results indicate that firstly, the zinc oxide arrester (MOA) installed only on the transformer side can, to some extent, limit overvoltage, but the main suppression effect is reflected in the equipment near the MOA, and the suppression effect is relatively small for electrical equipment far away from the MOA such as isolation switches, CTs, etc. Secondly, after installing a 500Ω closing resistor, the VFTO level of GIS internal and external equipment, such as transformers, CTs, and other electrical devices, was effectively suppressed, with amplitudes below 1000kV and wavefront steepness reduced.