The principle and influencing factors analysis of lightning arc root jumping on overhead ground wire based on field-circuit coupling

In the field of power grids, overhead ground wire (OGW) is primarily used to protect transmission lines from lightning strikes. Lightning arc root jumping causes multiple lightning strike points on the OGW, which may lead to simultaneous breakage of multiple strands, significantly increasing the risk of OGW breakage. Currently, research on the physical process of lightning arc root jumping after lightning strike to the OGW remains unexplored. Therefore, a field-circuit coupling simulation method is employed to analyze the principles and influencing factors of lightning arc root jumping, providing essential data support for future assessments of OGW breakage caused by lightning arc root jumping incidents. Firstly, the physical process of lightning arc root jumping is analyzed, focusing on the effects of the three action effects corresponding to the two main forces: wind force and electromagnetic force. Then, a lightning arc root jump model based on field-circuit coupling is proposed, building on existing chain model research. Finally, the occurrence conditions for lightning arc root jumping are determined through simulations, and influencing factors such as the amplitude of the lightning current pulse component, the magnitude of the sustained component, the interval between return strokes, wind speed, and air boundary layer thickness are quantitatively analyzed. The results indicate that the process of lightning arc root jumping is based on the sliding phenomenon of the roots. During the continuous process of lightning arc root sliding and jumping, the jumping distance is at least 0.2 m, which is more than twice the sliding distance. Multiple return strokes with a sustained component may induce arc root jumping when the lightning strike duration exceeds 0.12 seconds. When other conditions remain unchanged, the amplitude of the pulse component is roughly positively correlated with the jump distance, while the magnitude of the sustained component is negatively correlated with the jumping distance. The air boundary layer thickness is a significant factor affecting the jumping; arc roots only jumps when the boundary layer thickness is between 4 and 8 cm, and the jumping distance decreases as the boundary layer thickness increases. The simulation results and analysis conclusions on influencing factors of lightning arc root jumping obtained in this paper provide new insights into understanding the breakage mechanism of OGW caused by lightning strikes, and have important reference value for improving the transmission safety of power systems.