Method for Calculating the Ground Resistance of Grounding Grids Using FEM

Taking as given that ground resistance is independent of earth fault current, this paper presents a new way of calculating ground resistance of grounding grids using the finite-element method (FEM). Ground resistance is calculated by means of three consecutive tests, with an acceptable number of elements, and fast resolution. The results of the proposed method are compared with those measured experimentally or determined by other authors. Once ground resistance and earth fault current are known, grid potential and touch-and-step voltages are calculated. The main advantage of the method proposed here is that it permits us to analyze symmetrical and nonsymmetrical grids of any shape in uniform, two-layer, and multilayer soils. The method developed in this paper constitutes a fast-resolution industrial application, with acceptable results, for calculating the ground resistance of grounding grids of any shape.