An Analytical Approach to Assess the Influence of Shield Wires in Improving the Lightning Performance due to Indirect Strokes

The lightning performance of an overhead line due to indirect strokes is a measure of its ability to resist to surges produced by nearby lightning. The estimation of the lightning performance generally requires a huge number of calculations requiring computationally intensive simulations. In this paper, we present an approach that uses analytical expressions, leading to a very significant reduction of the required computer resources. By this analytical approach, we investigate the lightning performance under different line arrangements; the study is also devoted to assessing the improvement that can be obtained by addition of underbuilt shield wires to arrangements in which only upper shield wires are typically used: it is shown that such a measure can lead to significant enhancements in terms of lightning performance.