Fast Calculation of the Impedence Using Tensor-Based FEM for Evaluating Very Fast Transient Overvoltage in GIS

To solve the VFTO in GIS, it is necessary to perform the earth and GIS interconnection system, and then calculate the impedance to earth. The GIS interconnection system is rarely considered in current studies. To solve the problem of large computation time and meshes, a semi-analytical method is used to decompose the region into two sub-regions and calculate the sub-regions by finite element method and analytical solution method respectively, while introducing tensor calculation in the finite element part greatly reduces the computation time. The results are calculated in case of single-phase and three-phase, meanwhile, the frequency domain results for the overall system were analyzed. The approach proposed in this paper can be used to solve the problem of GIS impedance to ground, and has a large improvement in computational performance.