Abstract: To confirm the lightning insulation level of the equipment in DC yard and the cable in converter station, a electromagnetic transient simulation model is built for flexible DC transmission project, which consists of a 1~2 km long DC transmission line in the entrance segment and a converter station. The lightning stroke current is calculated based on the electrical and structural parameters of tower-insulator-conductor. The lightning current wave is simulated by applying dual-exponential function. The tower gap flashover criterion is determined according to intersection method. The lightning invasion wave overvoltage caused by main equipment and cable in DC yard is calculated with the overhead transmission line suffering lightning. The insulation level is determined through simulation for the main equipment and cable in DC yard. In addition, the simulation shows that the DC reactor plays a certain role in controlling lightning invasion overvoltage.

Key words: flexible DC transmission, overvoltage, electrical geometry model, lightning invasion wave, cable, intersection method, converter station, DC yard