Simulation model of lightning stroke to a transmission line considering the leader propagation randomicity

In recent years, with the increase of voltage grade of transmission line, the proportion of outages because of shielding failure also increases. Therefore, exactly evaluating lightning-withstanding level of transmission line is especially important for system service and stable operation. Considering the randomicity of leader propagation, a lightning stroke simulation model on lightning shielding performance of transmission line was presented, in which the simulation charge method had been applied. Simulation results of this model reflected the general rules of lightning stroke: with the direction of downward leader changing from close to the transmission line to far away from it, the lightning strike aim changed gradually from ground wire to conducting wire, finally the earth. Shielding failure probability and stroke distance to earth, which were calculated by the simulation model, were in accordance with the results of lightning simulation experiment and the stroke distance equation recommended by IEEE. So, the simulation model is reasonable.