A CONVERTER STATION

摘要

A converter station for connecting an AC system to a bipolar HVDC transmission line has a DC neutral arrangement provided with first DC breakers enabling breaking of a first current path from the neutral bus (11 1 ) of one pole (104) of said transmission line to the neutral bus (1 12) of the other pole (105) at bipolar operation of the station for isolation of a faulty section and changing to monopolar operation/metallic return thereof. The DC neutral arrangement has in said first current path at least two first DC breakers (133, 136 and 134, 137) connected in series and adapted to act as a backup for each other would the other thereof fail to break said first current path upon a control to isolate a faulty section by changing from bipolar to monopolar operation.