Enhanced Multi-Level Electro-Geometric Model for Assessing Lightning Performance of Transmission Lines Under Non-Vertical Strokes

Abstract

In this paper, a procedure developed for evaluating lightning flashover rates caused by non-vertical strokes on transmission lines (TLs) is presented. To achieve this, a multi-level electro-geometric model (MEGM) is developed to determine the termination point of impact (TPI) of each lightning stroke on TLs in the presence of shield wires (SWs). The proposed method can detect strokes on each phase conductor and SWs separately. Then, a Monte Carlo  simulation is performed using an electromagnetic transient program (ATP/EMTP) and MATLAB to estimate the  lightning flashover rates. The outage rates are calculated for a test system through the proposed and conventional EGM models, and the results show that the lightning outage rate is not the same for different models. The difference in the estimated outage rate has a direct effect on the technical and economic protection strategy of power utilities. However, the results show that the outage rate calculated by the proposed EGM model is lower than that calculated by the conventional model and hence the proposed model predicts lower investment costs to implement the protection scheme for the power networks.