HYBRID DC CONVERTER FOR OFFSHORE WIND FARM

摘要

The present invention provides a hybrid offshore wind farm direct current converter, including: a diode rectifier, where an alternating current side of the diode rectifier is connected to a wind farm intranet, and a direct current side of the diode rectifier is connected to a high-voltage direct current (HVDC); and an auxiliary converter, where the auxiliary converter is separately connected to the wind farm intranet and the HVDC, where the auxiliary converter includes: a modular multilevel converter (MMC), where an alternating current side of the MMC is connected to the wind farm intranet via a transformer; a submodule string, where one end of the submodule string is connected to the MMC, and the other end is connected to an HVDC transmission line; and a filter circuit, where the other end of the submodule string is connected to the HVDC transmission line via the filter circuit. The present invention has the following beneficial effects: Compared with an MMC converter having a full voltage level, the present invention can significantly reduce quantities of submodules and IGBTs, thereby reducing system costs. A wind farm intranet voltage can be actively established in a wind farm start-up phase, start-up power of a wind farm can be provided, and a black-start of the wind farm can be implemented.