A FINITE-ELEMENT METHOD FOR CALCULATING THE ELECTROMAGNETIC-FIELDS GENERATED BY SUBSTATION GROUNDING SYSTEMS

This paper develops a basic idea which allows low frequency electromag netic fields generated by cylindrical conductors, with very small radi i compared with their lengths, to be calculated. The proposed method c an be applied to both overhead conductors and those buried in a conduc ting environment. The paper presents a direct application for this con cept which consists in calculating electromagnetic fields created by a substation grounding system following an accidental short circuit or a stroke of lightning. The Finite Element Method (FEM) with several fo rmulations will be used. Currents in the cylindrical conductors which make up the earth network grid are taken into account without volume m eshing; simple line discretization of these will be carried out. Elect romagnetic fields generated by leakage currents and currents induced u nderground are taken into account. Furthermore, open boundaries of bot h air and earth environments are processed by introducing a spatial tr ansformation. This application for an earth network enables us to show the advantages of FEM processing compared with the method traditional ly used in antenna theory for this kind of problem.