Design of complex grounding system in uniform or non-uniform soil structure: development of grounding design software

Abstract

Current practice for grounding system design is mainly guided by IEEE 80-2000 standard. This practice is an iterative process of changing design variables until safety requirements for step and touch voltages and maximum ground grid resistance are met. It uses rectangular or square shape mesh arrangements. However, most of earthing systems in buildings, telecom towers are very complicated and not pure square or rectangular. Furthermore, IEEE process only allows to design grounding systems under uniform soil approximations. Since there are significant variations in the soil resistivity present at actual sites, multilayer soil model approach has been found to be much more accurate than the uniform soil model. This paper presents a mathematical model to analyze both simple and complicated grounding systems under uniform or non-uniform (multi-layered) soil structures. A grounding design software package was developed using MATLAB App Designer, and its core algorithm and the key features are introduced. In order to check the validity of the results, they have been compared with the results taken from ETAP- Power system analysis software.