A flexible HVDC system and fault control method Multiport

The present invention relates to a multi-terminal HVDC flexible system comprises at least three flexible HVDC converter stations, each flexible HVDC converter station comprises a converter valve, respectively, two flat wave reactor, at least one set of transmission cable, and At least two DC cutting device, between the various flexible HVDC converter station via a transmission cable is connected to the DC breaking device number of positive transmission cable, negative cable in the number of and consistent with each DC disconnects respectively the positive transmission cable, negative cable in one correspondence; the positive converter valve, the latter connected to the negative and smoothing reactors are, respectively, by the DC cutting device group corresponds to the positive transmission cable, negative transmission cable is connected. The present invention also relates to a method of controlling fault flexible HVDC system of the present invention is based on the design of multi-terminal, a DC cutting device can effectively cut all kinds of faults, which greatly improves the multi-terminal HVDC flexible system reliability.