Abstract:

The overvoltage of lightning intruding wave is the important basis for determining equipment insulation level in DC transmission system converter station. This paper built the simulation calculation model of lightning intruding wave for ±160 kV Nan’ao three-terminal flexible DC transmission system at DC side, with using PSCAD/EMTDC software. Then, the maximum shielding failure current of DC transmission line was calculated by electrical geometry model （EGM） and the intersection method was used as the criterion for air gap flashover. Finally, the voltage stresses of pole bus equipment and connection cable were calculated for the convertor station after DC transmission line suffering from the lightning shielding failure and counterattack, and the equipment’s insulation level for lightning impulse was checked. The results show that the insulation margin of the equipment meets the requirements.

Key words: flexible DC transmission, lightning intruding wave, overvoltage, electrical geometry model