Direct Lightning Overvoltage and Flashover Risk in Complex Distribution Line Network Considering Electromagnetic Coupling From Lightning Channel

Abstract

There are few studies on the characteristics of lightning overvoltage and flashover distribution in complex distribution line networks, considering both direct lightning surge injection and the lightning electromagnetic coupling pulse (LEMP) effect during direct lightning strikes. This article adopts a hybrid computational approach to analyze this issue, with an actual distribution line network modeled for a case study. The overvoltage waveforms and flashover pole counts under different lightning conditions, including the effects of LEMP, lightning strike points, lightning current characteristics, and the inhomogeneity of grounding resistance, are investigated. The results indicate that insulator overvoltage is highly sensitive to the LEMP effect, particularly when lightning strikes the poles. Increased pole density leads to greater overvoltage dispersion compared to sparse configurations. As the amplitude of the lightning current increases, the amplitude of the overvoltage on the insulator also increases, but the distribution of overvoltage remains essentially constant, which is significantly influenced by the complexity of the topology. The impact of uneven grounding conditions in distribution networks on overvoltage and flashover primarily depends on the grounding performance of the lightning-struck pole. The sensitivity of the LEMP effect to the lightning strike attachment point, the grounding resistance, and the line topology, as well as the comparison with that of the simple line configuration, were further summarized.