Direct Lightning Surge Analysis of Distribution Lines Considering LEMPs From Lightning Channel and Struck Pole in EMT Simulation

Abstract

Direct lightning strikes mainly determine the lightning performance of medium-voltage distribution lines with surge arresters installed at close intervals. Recent studies have shown that in such lines, the effect of a lightning electromagnetic pulse (LEMP) on insulator voltages has a large impact on lightning performance assessment. In this article, we propose an analysis method that can consider the effect of LEMPs radiated from the lightning channel and the struck pole in electromagnetic transient (EMT) analysis. In the proposed method, first, the LEMPs are calculated using potential formulae that are extended to include the presence of the struck pole. Second, the insulator voltages induced by the LEMPs and generated by currents flowing into the struck pole, earth electrode, and shield wire are calculated using a field-to-line coupling formula interfaced with the EMT analysis. The proposed method is validated by comparison with three-dimensional finite-difference time-domain analysis. The proposed method is potentially a powerful tool for statistically assessing the lightning performance of distribution lines while considering LEMP effects.