Observed Induced Overvoltage on the Test Overhead Distribution Line Initiated by Natural Lightning Activities

The lightning-induced overvoltage (LIV) observed on a test overhead distribution line system located in a newly built rocket-triggered lightning experiment site in Zhanjiang (China) is studied. Twenty-four natural lightning return-stroke events were recorded during two consecutive thunderstorms. Two waveform types were initially classified based on whether the initial slow-evolving negative peak occurs before the first positive peak, which is considered a response to the lightning leader development process. The LIVs have an amplitude of the first-positive peak from 124.9 V to 1397.1 V and a 10-90% rise time from 117.2 μs to 991.2 μs. The rise time and the half-peak-width time of the initial negative peak are several times longer than that of the first positive peak, while the amplitude is much smaller. The typical characteristics of the recorded LIV pulses are largely consistent with those of the classical rocket-triggered lightning or nearby natural lightning observations, while there is a significant difference in the rise time and amplitude of the first positive peak. With a comprehensive comparison with computational simulations for scene reproduction and linear coefficient fitting analysis of our previous experimental observations, the slower rising edge is found to be related to the high-frequency characteristics of the discharge velocity of the lightning channel, as well as the lightning electromagnetic radiation propagation, the novel line-terminal configuration first adopted in this study and the LIV sensor response. The study provides an important guide for research and practical techniques of lightning strike monitoring, localization, and pulse identification in real operation, inspiring the comprehensive explanation of multiple influences to improve the plausibility of the engineering LIV database.