Analysis and Calculation of Multi-Phase Lightning Trip-Out in 220 kV Double-Circuit Transmission Lines

The multi-phase lightning trip-out of multi-circuit transmission line is very easy to occur after the lightning strikes the tower directly, which seriously threatens the safe operation of the power grid. Based on the actual electrical parameters of a 220 kV double-circuit transmission line on the same tower, a simulation model is built by using ATP-EMTP. This paper analyzes the situation of multi-phase trip-out caused by lightning strike under different operating conditions, and studies the lightning strike resistance level of transmission line under different grounding resistance and differential insulator configuration. The results show that the line operating voltage and phase angle have an effect on the tripping phase sequence. The unbalanced insulation configuration of multi-circuit lines and the reduction of grounding resistance of towers can effectively improve the lightning resistance level of lines and reduce the probability of multi-circuit and multi-phase trip-out. The research provides a reference for the lightning strike back analysis and differential lightning protection of the muti-circuit transmission line.