Effects of Lightning Current Waveform on the Fast-Front Overvoltages and Critical Currents Causing Insulation Flashover to a 150 kV Overhead Transmission Line

Abstract

This work investigates with the aid of ATP- EMTP simulations the effects of lightning current waveform on the computed fast-front overvoltages and critical currents causing insulation flashover to a typical 150 kV overhead transmission line. First return-strokes of negative and positive downward lightning flashes are considered for shielding failure flashover and backflashover cases. The CIGRE current waveform is employed in simulations; recorded lightning current waveforms are used as well. The front time, maximum steepness, and time to half value are varied taking into account their statistical distributions. It is shown that the representation of lightning current affects considerably the waveform of the arising fast-front overvoltages and consequently the minimum currents causing flashover. The effects of waveform parameters are quantified and discussed for the 150 kV line under study.