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.

[1]  S. J. Schwarz,et al.  Analytical Expressions for the Resistance of Grounding Systems [includes discussion] , 1954, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[2]  D. Mukhedkar,et al.  Computer Aided Design of a Toroidal Ground Electrode in a Two-Layer Soil , 1987, IEEE Transactions on Power Delivery.

[3]  D. Mukhedkar,et al.  Evaluation of the effect of vertical faults on the voltage distribution around HVDC electrodes using a supercomputer , 1990 .

[4]  V. Gerez,et al.  Evaluation of ground resistance of a grounding grid of any , 1991, IEEE Power Engineering Review.

[5]  H. B. Dwight.  Calculation of Resistances to Ground , 1936, Transactions of the American Institute of Electrical Engineers.

[6]  F. Dawalibi,et al.  Optimum design of substation grounding in a two layer earth structure: Part IIߞComparison between theoretical and experimental results , 1975, IEEE Transactions on Power Apparatus and Systems.

[7]  Jung-Hoon Kim,et al.  Efficient ground grid designs in layered soils , 1998 .

[8]  S. L. Goyal,et al.  Scale Model Studies of Grounding Grids in Non-Uniform Soils , 1987, IEEE Transactions on Power Delivery.

[9]  J. G. Sverak.  Simplified Analysis of Electrical Gradients Above a Ground Grid, Part I: How Good Is the Present IEEE Method? (A Special Report for WG78.1) , 1984, IEEE Power Engineering Review.

[10]  F. Dawalibi,et al.  Optimum design of substation grounding in a two layer earth structure part: IIIߞStudy of grounding grids performance and new electrodes configuration , 1975, IEEE Transactions on Power Apparatus and Systems.

[11]  F. Dawalibi,et al.  Optimum design of substation grounding in a two layer earth structure: Part IߞAnalytical study , 1975, IEEE Transactions on Power Apparatus and Systems.

[12]  H. B. Dwight.  Calculation of resistances to ground , 1936, Electrical Engineering.

[13]  J. Sverak,et al.  Simplified Analysis of Electrical Gradients Above a Ground Grid-I How Good Is The Present IEEE Method? (A Special Report For WG 78.1) , 1984, IEEE Transactions on Power Apparatus and Systems.

[14]  H. R. Seedher,et al.  Finite Expressions for Computation of Potential in Two Layer Soil , 1987, IEEE Power Engineering Review.