On the Mitigation Effect of Surge Arresters on the Lightning Performance of Overhead Distribution Lines

For the accurate statistical assessment of the lightning performance of distribution lines one needs to take into account the presence of protection devices such as surge arresters and shielding wire/neutral groundings. Indeed, the presence of those devices can significantly modify the indirect lightning response of the overhead line and, therefore, the relevant lightning performance. In particular, this paper aims at investigating the impact of the presence of surge arresters on the indirect lightning performance of overhead distribution lines having realistic configuration. Specifically, reference is made to typical Italian distribution lines. The investigation is performed with the help of a statistical procedure developed by the authors – based on the Monte Carlo method and of the use of an accurate modelling/calculation tool for the induced surges – that has been recently compared with one proposed in the IEEE 1410 Std for the same purpose, and shown to be more complete and suitable for the problem of interest. The paper also aims at investigating the influence of the presence of surge arresters on the indirect lightning surges transferred through power transformers. Such an additional investigation is performed by means of a suitable high-frequency power transformer mode integrated with the lightning-induced computation tool.