Finite element modeling of the Grounding System in consideration of soil nonlinear characteristic

The aim of this paper is to calculate the response of grounding system under high-magnitude fault current accurately. In this work, A FEM model is presented to solve the problem in frequency domain. The ionized phenomenon in the soil around the grounding electrode is taken into account by setting the resistivity of every soil element varying with the electric field intensity. Open boundaries of earth are processed by introducing a spatial transformation which translates the semi-infinite space into the finite space. The suggested modeling is validated by comparison of the calculated results, which are laid out for grounding rod and grounding grid, with experimental and simulation results found in literatures.