Research on Lightning Performance of Quadruple Circuit Transmission Line with Dual Voltage 500/220-kV on the Same Tower

The lightning performance on four 500/220-kV segments of quadruple circuit lines on the same tower of Nanyan line is analyzed by traveling wave method and electric geometry method in this paper. The results indicate that double-circuit 220-kV transmission line protect double-circuit 500-kV transmission line because of different insulation protection, the lightning-understanding level of 220-kV line is corresponding to the usual single lines, and the level of double circuit 500-kV line is higher. Also the back flashover tripout rate of transmission line increases with the increase of the height of tower and the ground resistance. The shielding failure calculation results show that the protect angle of 500-kV transmission line is negative, and the insulation level is high, the shielding failure mainly occur on 220 kV transmission lines. And the shielding failure tripout rate increases with the increase of protect angle of shielding line and the obliquity of ground.