Ground impedance assessment employing earth measurements, numerical simulations, and analytical techniques

This work aims to perform an analysis of different numerical and analytical prediction techniques for obtaining the impedance of grounding systems in power substations according to the Fall-of-Potential Method. A test field with 4 grounding meshes of different geometric configurations was implemented and used to evaluate the quality of the results obtained in this study. Two analytical models found in the technical literature (ABNT Standard and Laurent´s equation) and four different methods of numerical simulation (TLM - transmission line method, FEM -finite elements method, PM - potential method, CEEE computing platform) were used to evaluate the phenomenon and estimate the grounding resistance for the 4 meshes of the test field. The numerical results are compared to results obtained in a series of measurement tests which employed megger and two types of surge generators, in order to provide an overall understanding of this problem.