An Improved Method for Probabilistic Evaluation of lightning-related failures of Overhead Transmission Lines with Considering Non-Vertical Strokes

lightning strokes cause non-predicted supply interruptions in power networks because of a failure of the insulation. This paper represents an improved procedure for the evaluation of flashover rates, overvoltages and risk of failure of insulation caused by both lightning vertical and non-vertical strokes on transmission lines using a Monte Carlo method. The main goal of this paper is increase the accuracy lightningrelated failures through an accurate modelling of network components such as footing impedance, transmission tower and the chain of insulators and also simulation lightning nonvertical strokes. Modelling network components, statistical parameters related to lightning and problem-solving algorithm is 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 nonvertical strokes Instead of vertical strokes leads to better evaluation for lightning-related failures of transmission line

Keywords:

Transmission line , lightning performance , Monte Carlo method , flashover , lightning strokes