Grounding Performance Analysis of the Substation Grounding Grids by Finite Element Method in Frequency Domain

Based on finite-element method (FEM) of 1-D conductor element coupled with 3-D soil element, we take into account the frequency dependent characteristic of the discretized elements to analyze the grounding performance of the substation grounding grids. Compared with A-V formulation of 3-D FEM, the proposed method can greatly save the CPU time, and the frequency can be considered during FEM modeling. In comparison with the method of moment (MoM) and the measured results, the presented method is proved to be correct and effective. Furthermore, we can calculate the H-field generated by the substation grounding grids with both currents in the underground conductors and leakage currents flowing in the soil. The results show slight difference between FEM and MoM, which can be explained by the fact that the leakage currents in the soil are not taken into account for MoM