Research the effect of UHV GIS disconnector contact shape on the multi-restrike

The multi-restrike during UHV GIS disconnector operation produces the very fast transient overvoltage (VFTO). In order to study the effect of contact shape on the multi-restrike process, this paper calculates the electric field of the disconnector gas cell based on the finite element method, and the contact gap breakdown voltage under different distance with different contact shape according to streamer breakdown criterion. Obtain the breakdown voltage characteristics between the contact gap using the least square method, building the multi-restrike simulation model of disconnector operation adopting ATP/EMTP software. Simulation results show that: under a certain operating speed, the breakdown voltage and the amplitude of high frequency transient oscillation pulse caused by breakdown are positively correlated; when operation phase angle in a power frequency cycle, the distribution of the maximum VFTO amplitude in the process of multi-restrike is approximately normal distribution. The value of contact fillet radius has certain influence on the VFTO amplitude.