Risk Analysis of Lightning Strike Tripping for Overhead Transmission Lines Considering the Coupling Effect of Wind Speed and Micro-Topography

Lightning shielding failure is a major cause of insulation flashover and unplanned outages of overhead transmission lines. Conventional electrogeometric models generally assume windless conditions, flat terrain, and fixed line geometry, and thus cannot adequately represent changes in the relative positions of conductors and ground wires under strong winds and complex micro-topography. This study develops an electrogeometric-model-based method for calculating shielding failure trip rates by jointly considering wind-induced conductor and ground-wire displacements and micro-topographic geometry. A 220 kV overhead transmission line is analyzed in MATLAB. The proposed model is compared with the procedural method and conventional EGM, and parameter sensitivity analysis is performed. Results show that the proposed model remains consistent with established calculation methods under the baseline condition. The coupled effects of wind speed, wind direction, annual thunderstorm days, and ground inclination angle are then investigated. As the wind direction approaches the line-normal direction, differential wind-induced displacement becomes more pronounced, increasing the wind-dependent shielding angle, conductor exposure distance, and shielding failure risk. Mountain-top and steep hillside sections exhibit higher risk, whereas deep, narrow valleys provide stronger terrain shielding. The method provides a quantitative basis for differentiated lightning-protection design under complex meteorological and terrain conditions.