Time-harmonic analysis of grounding system in horizontally stratified multilayer medium

This paper extends an electromagnetic model for time-harmonic analysis of grounding system in horizontally stratified multilayer medium which consists of air and arbitrary number of soil layers. Complete electromagnetic coupling between grounding system segments is taken into account. The model is based on applying the finite element technique to an integral equation formulation. Through an effective approximation of the attenuation and phase shift effects the computation of Sommerfeld integrals has been avoided, which considerably shortens the computational time. The treatment of non-horizontal segments of grounding grid conductors has been resolved by approximating the segment with five current point sources distributed along the segment length. An algorithm for scalar electric potential computation in any soil layers is presented and compared to published results. The effects of approximating a complex heterogeneous earth structure with a homogeneous earth is also analyzed and discussed.

► Electromagnetic model for time-harmonic grounding system analysis is developed.
► Conductors can be located in air or in horizontally stratified multilayer earth.
► Electromagnetic model is based on fixed image method and finite element technique.
► Attenuation–retardation effect is taken into account without Sommerfeld integrals.
► Computational model is robust, general and highly accurate in short execution time.