Analysis of Grounding Systems

Abstract

A general methodology for the analysis of electrical grounding systems is presented. Earth is represented as a two layer semiinfinite region. An equivalent circuit model of the earth embedded electrodes and conductive soil is developed via numerical lution of Laplace equations. The equivalent circuit model, together with the electric power system network, represents a large scale network which is solved via the modified nodal analysis method. The procedure enables accurate analysis of complicated grounding systems and computation of touch, step and transfer voltages. Effects of tower footing resistance, counterpoised wires, types of system faults (phase to ground, line to line, etc.) can be analyzed. Practical grounding systems can be easily analyzed because model reduction techniques can be incorporated in the analysis method. The methodology is demonstrated with the study of a nontrivial grounding system analysis problem.