Numerical analysis of lightning by finite element method

Lightning is a fractal phenomenon with its light (flash) and its sound (thunder), caused by ionization of electrical positive and negative charges by atmospheric processes. It is an electrical discharge that occurs in a big electrode separation with high current and high voltage. Lightning discharges might have direct and indirect effects on electrical circuits as well as all living creatures. Since the lightning might be very destructive, it is very important to understand the phenomena. In this study an electrostatic model is presented to determine the field distribution on transmission line tower during the preliminary breakdown phase of lightning. The model includes thundercloud (cumulonimbus), lightning leader and transmission line tower. Finite Element Method (FEM) is applied by software called COMSOL to calculate electric field and current density distribution simultaneously in several models. Lightning leader is first modelled with a fixed stepped leader that approaches to a transmission line tower vertically. By linking the COMSOL with MATLAB, the model is expanded to have a leader that approaches to the tower with a random path to create more realistic solution. As the results of numerical analysis of this study, it is possible to get informative data about preliminary lightning breakdown. Therefore, the effects of lightning can be analysed; development pattern of lightning can be observed, striking position of lightning can be analyzed and transient electromagnetic behaviour can be investigated. Numerical electrostatic lightning model is a good tool for risk assessment and protection. Keywords: Lightning discharge, preliminary breakdown, finite element method.