Statistical analysis of lightning transients in grounding grids

An statistical description of safety aspects of grounding grids is presented in this paper. The methodology is based on the Monte Carlo simulation of the grounding grid response to the probabilistic distribution of the injected current. Frequency domain method of moments (MoM) solution of the governing electric field integral equation (EFIE) is used to simulate the grounding grid performance. The mapping of frequency domain data to the corresponding data and vice versa are achieved through using the fast Fourier transform (FFT) and inverse FFT (IFFT) techniques. The proposed simulation methodology is used to obtain the probability by which the safety limits of a given grounding grid are violated. For the current simulation we considered the maximum value of ground surface electric field and scalar potential or namely the ground potential rise (GPR) as representatives of safety indices.