Time-Domain Analysis of Overhead Line in presence of Stratified Earth

The presence of the ground affects the propagation on overhead lines through a magnetically induced earth return current. Numerous researches have been conducted to study this influence by considering a homogeneous earth. In the current paper, the transient response of Multi-conductor transmission Lines (MTL) considering a lossy stratified earth is presented. Based on the finite difference time-domain (FDTD) and an improvement of the convolution integral arising from time-domain modeling of frequency-dependent conductors' parameters through the Vector Fitting (VF) algorithm, a novel numerical procedure for solution of a system of telegraph equations is presented. Many simulations are introduced to highlight the effect of soil stratification on the response of the line for a given excitation. The efficiency of an equivalent model, using an equivalent single-conductor, of a multiple conductor system is also established in this work.