Analysis of the Frequency Response of a Grounding System Using the Finite Element Method

Abstract

This paper analyzed the frequency response of a simple grounding system, consisting of a rod, through computational simulations. A finite-element-based software for solving the electromagnetic problem governed by differential equations was used. In the simulations, the grounding system was submitted to currents with different frequencies with a spectrum from 60 Hz to 1 MHz. From the relation between the frequency and the calculated impedance, transfer functions that model the behavior of the grounding system were obtained. For the estimation of the function parameters, methods of optimization and curve-fitting methods were used. In addition, since both the resistivity and the electric permittivity attributed to the soil should be considered the simulated response, a sensitivity analysis was performed with different resistivity and permittivity values. Obtaining analytical expressions for the description of the ground response provides a tool for the evaluation of the grounding response to signals in the frequency or time domain. Considering the results obtained in the simulations, it is possible to evaluate how the parameters resistivity and electric permittivity of the soil influence the analytical expression that characterizes a grounding system. Thus, it is planned to compare in a future work the results obtained in the simulation with field experiments.