Direct Lightning Performance of Distribution Lines With Shield Wire Considering LEMP Effect

Abstract

In medium-voltage distribution lines, lightning outages associated with indirect strokes are less frequent when surge arresters are installed at close intervals. In this case, the lightning performance is mainly determined by the line response due to direct strikes, usually assessed disregarding the effect of the lightning electromagnetic pulse (LEMP). This paper examines the influence of such an electromagnetic effect on the voltages across the line insulators caused by direct lightnings. The presence of both surge arresters and a shield wire is considered. By means of adequate modeling and numerical calculations, we show that the flashover rate due to the direct strikes is increased by the LEMP. The obtained results indicate that in the statistical assessment of the direct lightning performance of lines equipped by surge arresters and shield wires, the LEMP effect is not negligible and its accurate evaluation is hence required.