Protection Against Lightning-Induced Voltages: Transient Model for Points of Discontinuity on Multiconductor Overhead Line

Induced voltages on overhead distribution lines owing to lightning return strokes cause insulators flashovers and consequently, line outages. Basically, shield wires and surge arresters form the lightning protection system for overhead lines to improve the performance of distribution systems against return strokes. The effectiveness of the lightning protection system depends essentially on the grounding system on which shield wire and surge arrester are installed. This article presents a numerical approach to consider the transient models at the points of discontinuity where the lightning protection system exists on multiconductor overhead line. The finite-difference time-domain method is applied to Agrawal coupling model to solve numerically the electromagnetic wave propagation along the line, whereas the Newton–Raphson method is exclusively used for the points of discontinuity. The results obtained considering the transient model as well as a dc model are compared to clarify the influence of the line discontinuity model on the propagating electromagnetic waves. The computational stability of the proposed method is confirmed for different cases of lightning waveforms, distances between points of discontinuity, and stroke locations with line discontinuities.