Performance analysis of earthing system with different grid configurations in non-homogenous soil

Abstract The selection of earthing system configuration and design play the critical role in operational integrity stability and reliability of electrical power systems. This article presents comparative assessment of different earthing grid configurations to obtain the most suitable grid shape with minimum values of safety parameters. Four configurations of earthing grid (Square, rectangular, T-shape and L shape) were used in this analysis. Considered earthing grids are buried in two-layer soil structure. Equal coverage area of substation was considered for all adopted configurations of earthing system. E-EG and U-EG designs were used in the analysis and, it is observed that U-EG design gives better results in terms of safety parameters. Performance of earthing grid with various configurations, grid burial depth, and different soil models are analyzed. IEEE standard 80–2,000 and variable spacing method are adopted to design the earthing system and all safety requirements are strictly followed as per the prescribed standard. Effects of varying resistivity in two layer soil model on earthing system resistance are also evaluated for E-EG. Rectangular U-EG design exhibited consistent results in terms of GPR, touch voltage and step voltage that improve system safety and performance. Vertical earthing rods were located at the periphery of earthing grids.