Probabilistic evaluation of lightning performance of overhead transmission lines, considering non-vertical strokes

This paper represents a developed procedure for the evaluation of flashover rates caused by both lightning vertical and non-vertical strokes on transmission lines, using a Monte Carlo method. The main goal of this paper is to increase the accuracy flashover rates through the accurate modelling of network components, such as footing impedance, the transmission tower and chain of insulators, and also simulation of lightning non-vertical strokes. Modelling network components, statistical parameters related to lightning and a problem-solving algorithm are described. Parametric studies using this procedure can also be performed to determine the sensitivity of the flashover rate with respect to some parameters of the return stroke and the transmission line. Simulation results obtained using MATLAB and the ATP/EMTP show that considering the lightning non-vertical instead of vertical strokes leads to a better evaluation of the lightning performance of transmission lines.