Transient behaviour of grounding systems in multilayer soil under lightning strikes

In this article, transient behaviour of grounding systems buried in multilayer soil structure is analysed under the influence of lightning discharge. Vertical grounding rods, horizontal conductors and grounding grids are considered in the analysis. The computation of transient behaviour is performed in the frequency domain and obtained in time domain using inverse Fourier transform (IFT). The presented method is a hybrid approach based on PEEC technique that represents an equivalent circuit of grounding system buried in multilayer soil structure. Inductive, capacitive and conductive effects of grounding electrodes due to current leaking into the soil are also considered in the analysis. A procedure is adopted that simplifies the computation process of Sommerfeld method using small number of sample points over the grid. Also impulse impedance for horizontal grounding electrode, vertical rod and grounding grid is evaluated in two-layer soil structures. Simulated results are validated with the experimental and theoretical results reported in the literature and good agreements are found. Proposed method will help to improve the modelling of simple as well as complex grounding system buried in multilayer soil structure.