Study on the lightning overvoltage protection of a 500 kV unified power flow controller station

摘要

The unified power flow controller (UPFC) is the third generation of flexible AC transmission systems. It can control the power flow and voltage of the power system quickly and flexibly that has an advantage in compensating the AC transmission system in real time. The world's first 500 kV UPFC project is under construction in Jiangsu Province of China. On the paralleled converter side, it is connected to the 500 kV Mudu substation by using a gas insulated transmission line, and the series converter side is connected to the 500 kV Meili substation through a 500 kV double-circuit overhead transmission line. In order to optimise insulation design of the UPFC system and ensure the safety operation of the power system, it is essential to analyse the characteristics of lightning overvoltage. Considering the invaded path of lightning surges in the UPFC system, a detailed model was established by using Electro-Magnetic Transient Program/Alternative Transients Program in this study. The lightning overvoltage level at key nodes of the UPFC system was presented. The check calculation for the configuration and protection level of ZnO arresters were also carried out. The obtained results can provide a reference for insulation coordination design of the 500 kV UPFC project.