Study on the Lightning Withstand Performance of Back Striking for the ±1100kV UHVDC Large Crossing Overhead Transmission Line

Large crossing overhead transmission lines are usually erected on the ultra-high towers with long span, and its lightning withstand performance should be paid more attention to. Considering the propagation process of lightning current along the high tower, an improved simulation model of back striking was established by using the electromagnetic transient program, and then the lightning withstand performance of back striking under different conditions for the ± 1100kV UHVDC large crossing line were studied. The results show that comparing with the conventional transmission line for the ±1100kV UHVDC project, the large crossing section has a much lower lightning withstand level of back striking (LWLBS); The LWLBS for the large crossing line with high tower is not significantly affected by the footing resistance, while enhancing the insulation level can effectively improve the LWLBS. Furthermore, the LWLBS increases with the increase of the distance between striking point and the tower when lightning strikes the large crossing overhead ground wire.