Introduction  The transient enclosure voltage (TEV) will threaten the personal safety of the staff and the normal operation of the secondary equipment, and may cause the discharge between the flanges of the GIS enclosure. In order to analyze the spark discharge fault between the flanges of the GIS enclosure when operating the disconnecting switch in a 500 kV substation, a TEV simulation calculation model based on the transmission line theory was proposed, and the suppression measures of the discharge between the flanges caused by TEV were discussed.

  Method  In order to simulate the TEV more accurately, an improved dynamic arc model was constructed using the Cassie-Mayr theory, and the VFTO generation circuit was combined with the TEV calculation circuit, and the VFTO generated by disconnecting switch operation was directly added to the GIS enclosure potential calculation model.

  Result  The simulation results show that, in the worst case, the maximum voltage difference between flanges exceeds the surface flashover voltage of insulating barriers between flanges, which is enough to cause discharge between flanges. Reducing the residual charge on the island side of the disconnecting switch and reducing the inductance of the grounding wire can reduce the amplitude of TEV to varying degrees, but cannot completely suppress the potential difference between the flanges. The use of shorting connectors for bridging can effectively suppress the voltage difference between the flanges and avoid the resulting discharge phenomenon, but it is necessary to verify the selection of the shorting pieces and cancel the original three-phase shorting row to avoid circulation.

  Conclusion  Verified by on-site engineering transformation, the conclusions obtained in this paper are correct and effective, and have great reference significance for preventing such discharge phenomena.