Determination of Breakdown Voltage Characteristics of 1'100 kV Disconnector for Modeling of VFTO in Gas-Insulated Switchgear

This paper presents a method for determination of breakdown voltage characteristics (BDV) of a gas-insulated switchgear (GIS) disconnector. The method is applicable for modeling very fast transient overvoltages that are generated during the disconnector opening and closing operations. The method is based on full-scale measurements, as typically performed during the disconnector development and/or type tests. The method is first presented in a simplified, illustrative setting, and then applied for the full-scale measurement results obtained for an 1'100 kV disconnector design. The BDV determined is then applied for two 1'100 kV test setups as recently reported for the Wuhan (China) station. Selected test cases are simulated, analyzed, and validated with the use of the multispark modeling approach, with two BDV characteristics implemented: the nonlinear BDV obtained with the method presented here applied for the measurement results on the example 1'100 kV disconnector, and the linear BDV reported in the literature for the 1'100 kV disconnector used in the Wuhan GIS station.