Abstract:

 In order to alleviate the contradiction between power transmission corridors and power transmission capacity in Peral River Delta Area, a number of triple-circuit power transmission lines have been built. Compared with normal double-circuit transmission line, the tower of triple-circuit transmission line is much higher so that it is more likely to be struck by lightning. This paper introduces the calculation method of lightning performance of shielding failure and back flashover by settling a 500 kV triple-circuit transmission lines in Guangdong as an example. The result shows that for 500 kV and above transmission lines, the operating voltage will affect the lightning performance of shielding failure and back flashover. Due to the higher tower of triple-circuit transmission line, the insulation configuration can be different according to the height of cross arm in each layer. When considering the mutual shielding effect of lines, shielding failure rates of all lines at different layers will all decrease. In addition, the shielding failure rates will decrease with the decrease of shielding angles and fielding angles.

Key words: back flashover, shielding failure, operating voltage, insulation configuration, shielding angle, fielding angle