Predicting Electric Fields Distribution in Lightning Protection Systems with Heterogeneous Grounding Under Negative Impulse Voltage

This research investigates the effect of geological discontinuities on the electric breakdown distributions near vertical and horizontal lightning conductors (VLC and HLC) in various ground conditions. To investigate this effect, numerical simulations were carried out using COMSOL Multiphysics, a state-of-the-art finite element analysis software. The simulations took into consideration detailed models of the conductor geometries, ground structures, and parameters of the lightning discharge for a variation of distance ratios (D/hc) between the conductor and earth discontinuity. Results show that for D/hc = 1.5, the electric field strength near the conductor and discontinuity interface is 20% lower than that obtained from the homogeneous model without a conductor. On the other hand, for D/hc ≥ 3.5, the electric breakdown strength has agreed well with the conductor less model, indicating negligible impact on discharge attraction. The equipotential lines and field intensities around the interface have shown non-uniform distributions, with maximum field strengths directly at the interface surface. Results have brought forth important practical implications in developing an efficient lightning protection system over different earth natures and emphasized the role of accurate numerical modeling approaches with consideration to boundary conditions.