Simulation method and system for VFTO generated by opening and closing of GIS disconnecting switch

The invention discloses a method and a system for simulating VFTO (Very Fast Transient Overvoltage) generated by opening and closing of a GIS (Gas Insulated Switchgear) disconnecting switch, which belong to the technical field of GIS disconnecting switches and comprise the following steps of: adding a physical field to a model based on a pre-established geometric model of the disconnecting switch in the GIS; setting boundary conditions of a physical field to obtain a model with set simulation parameters; performing mesh generation on the model with the set simulation parameters to obtain a plurality of generation units; and performing physical field calculation on each subdivision unit, and completing simulation of generating VFTO by opening and closing the GIS isolation switch. Simulation calculation is carried out on the electromagnetic field distribution condition when the isolation switch in the GIS generates VFTO based on a finite element three-dimensional electromagnetic field modeling method, VFTO wave