Computer Methods for the Design and Assessment of the Lightning Performance on Transmission Lines

Abstract

Available methods for the calculation of the lightning performance of transmission lines are mentioned. To date, statistical methods based on Monte Carlo manipulations of lightning and system data together with the Dynamic Travelling Wave Method of Computation of potentials stressing insulation, appear to be the most sophisticated and indeed provided the most realistic simulations with high accuracy of results. To illustrate the above, a comprehensive computer program based on the two techniques for the calculation of the lightning performance of unshielded transmission lines is described. The program is a major improvement over existing calculation methods as it models the presence of weak-link structures, corona wavefront distortion, change in structure insulation characteristics following flashovers, dynamic representation of resistance of earth connections, lightning arresters, multiple flashover assessment of transition from impulse flashover to power arc formation as well as the use of the electrogeometric method for determining the number of strokes to line. The validity of the program is verified by the successful prediction of the lightning outage rates and types of several operating unshielded woodpole lines.