Simulation on lightning overvoltage of ±800kV converter station

The insulation coordination of the UHVDC converter station is important for the security and economic of UHVDC system. In this paper we have built the Zhexi station and it´s 2kM line in segment´s mode, EMTP/PSCAD has been used to analysis the equipment´s lightning overvoltage. To analysis the most serious situation, the selection of AC field´s operation mode has been discussed in detail, measures to limit the lightning overvoltage have been introduced. To get the equipments´ maximum overvoltage, the polarity of station´s working voltage has been studied. Calculation shows that, with the same polarity of lightning and station´s working voltage, the equipments´ phase to ground voltage reaches to the maximum, while when the lightning´s polarity is opposite to the station´s, the equipments´ two ends voltage reach to the maximum.