A finite element method for calculating the electromagnetic fields generated by substation grounding systems

This paper develops a basic idea which allows low frequency electromagnetic fields generated by cylindrical conductors, with very small radii compared with their length, to be calculated. The proposed method can be applied to both power overhead conductors and those buried in a conducting environment. The paper presents a direct application for this concept which consists in calculating the electromagnetic fields created by a substation grounding system following an accidental short circuit or a lightning stroke. The finite element method (FEM) with several formulations is used. Currents in the cylindrical conductors which make up the earth network grid are taken into account without volume meshing; simple line discretization of these is carried out. Electromagnetic fields generated by leakage currents and currents induced underground are taken into account. Furthermore, open boundaries of both air and earth environments are processed by introducing a spatial transformation. This application for an earth network enables to show the advantages of FEM processing compared with the method traditionally used in antenna theory for this kind of problem