Influence of structural characteristics for overhead ground wire on arc root under lightning strike

When overhead ground wire (OGW) is struck by lightning, the damage or rupture accident occur. This is unacceptable for the stable operation of the power system. Therefore, the investigation on the lightning-induced damage mechanism of OGW is significant for the optimization of lightning protection measures. Combined with the structural characteristics of OGW, this paper evaluated the thermal ablation damage of OGW caused by lightning strike, which provided the data support for the damage mechanism research. Firstly, the magnetohydrodynamics (MHD) models based on OGW and plate structure were established. The current density distributions as well as the arc root radii of OGW and plate under lightning strikes were compared. The thermal ablation damage model of OGW was also established. The influence of arc root radius on thermal ablation damage evaluation of OGW under continuing component of lightning current was analyzed. The results show that the arc root radius of lightning striking OGW is reduced by at least 50% compared with that of lightning striking plate. When using arc root radius of OGW for modeling, the results of the thermal ablation damage model are consistent with the reported experimental results. The maximum error is 9.80%. While the arc root radius of plate is adopted, there is an obvious difference between the thermal ablation damage model and the experimental results. The maximum error exceeds 20%. Therefore, in the numerical modeling of thermal ablation damage of OGW, it is necessary to consider the influence of structural characteristics of OGW on arc root radius.