Calculation of surface electric field on UHV transmission lines under lightning stroke

Abstract

Lightning is the major cause of interruptions in power transmission lines. Ultra-high voltage (UHV) AC transmission line has been put into operation in China. Due to the large tower height up to 90m and the high operation voltage up to 1000kV, the shielding failure probability increase obviously. Nowadays the leader progression model is an advanced method to evaluate the shielding failure probability of transmission lines. The surface electric field is the key issue for lightning failure analyzing, because the upward leader inception mainly depends on the surface electric field. In this paper, the lightning leader model is introduced. A charge simulation method based piecewise linear function is adopted to analyze the surface electric field on phase conductors and ground wires. The influence factors, such as operation voltage, lightning peak current, lightning down leader position, protection angle, on surface electric field were analyzed.