The effect of longitudinally varying soil conductivity on the aerial mode wave-propagation parameters of overhead power lines

This contribution is the second part of a two-paper set concerning the effect of longitudinally varying soil conductivity on the propagation parameters of overhead lines. In this paper, an analysis is developed for the evaluation of the wave parameters characterizing the aerial modes of a three-phase overhead line running above an inhomogeneous soil whose conductivity varies along the line length. The global line section is broken down into a number of homogeneous uniform cells, the length and conductivity assigned to each cell, as well as the total number of cells, being randomly generated. Simulation experiments for low, mid, and high frequencies, clearly show that random conductivity fluctuations give rise to absolutely negligible variations of the wave-propagation parameters being analyzed-thus reinforcing the idea that the standard average-soil-conductivity-approach can be safely employed without significant errors incurred. Perturbation technique theoretical results are also derived for explaining the outcome of the simulation experiments.