Lightning Surge Analysis of Transmission Line Towers With a Hybrid FDTD-PEEC Method

This paper addresses lightning surges on the transmission systems with a new hybrid method, using a 1D FDTD model for the transmission line and a PEEC model for the tower and lightning channel. Compared with other circuit-based models, mutual coupling between the lightning channel and other parts in the system can be fully considered. This hybrid method has been validated numerically and experimentally, and good agreements are observed. This method then is applied to analyze the lightning surges on a 500 kV double-circuit transmission line system. It is found that the lightning channel has a significant impact on the surge response of the tower struck. Ignoring the coupling from the channel to the tower will weaken the hazard of lightning strikes. However, the influence of its coupling to the transmission line is not critical. The choice of interfacing points between these two models is then suggested. Furthermore, the influence of the tower footing is inves tigated. It is found that the insulator voltage is made of inductive and resistive components. The inductive component becomes dominant in the case of high soil conductivity and low grounding resistance. The voltage generally increases with decreasing soil conductivity and tends to decay slowly with time.