Evaluation of Lightning Flashover Risk of HV Overhead Transmission Lines

Based on the idea of risk evaluation proposed by IEC standard 62305-2, an evaluation method of lightning flashover risk of HV overhead transmission lines is proposed in this paper. The method consists of three important parts: statistics of lightning parameters along the transmission line corridor, computation of lightning flashover performance of each tower as well as the whole line, and definition of lightning flashover risk grade. The method is expounded with an example of lightning shielding failure flashover risk evaluation of a 500 kV transmission line. The evaluation results show that the evaluated risk grades of the line have a good agreement with the operation of the line, and the shielding failure flashover risks of the line have big temporal and spatial differences. The reasons for the worse grade of lightning flashover performance of towers are obtained simultaneously through the method, which would increase the technology-economy rate for the improvement of lightning performance of transmission lines. Evaluation of lightning flashover risk provides a good strategy for power supply companies to master and improve the lightning performance of HV overhead transmission lines.