Study of Grounding System Transients in Two-Layer Soil Structure during Lightning Events

This article explores the response of earthing electrodes embedded in two-layer soils when exposed to lightning, focusing on factors like soil ionization, resistivity, and permittivity. The research investigates the performance of vertical rods, horizontal conductors, and grounding grids within two-layer soil structure. Transmission line modeling (TLM) is employed, incorporating the nonlinear conductance phenomenon to model grounding systems effectively. The developed model takes into account frequency-dependent soil parameters to study the transient behavior of these systems. Soil ionization is modeled by considering nonlinear conductance as a time-dependent function, along with the presence of residual resistivity. The grounding models are tested against lightning current impulses of varying magnitudes and rise times to assess GPR, transient behavior, and grounding impulse impedance. To enhance the accuracy of the study, both apparent and effective diameters of the grounding electrodes are considered. The results obtained from the model are validated by comparing them with other developed model that showing good agreement. The impulse impedances of vertically and horizontally buried grounding electrodes in two layer soil structure with different electrical characteristics under a 5 kA peak impulse are evaluated. Peak voltages at the current injection point are also calculated for horizontal electrodes, considering variations in length and soil electrical properties