TRIPOLAR VSC-HVDC TRANSMISSION SYSTEM AND METHOD

摘要

A tripolar VSC-HVDC system and method, include a rectifier and an inverter formed by a three-phase six-bridge arms modular multilevel converter (MMC) respectively, and two converter valves are arranged on the DC side of the rectifier and inverter respectively. The midpoint of upper and lower converter valves of the rectifier and inverter are connected with a pole 3 DC line by a smoothing reactor. Triggering of the upper and lower converter valves is controlled to change the DC voltage polarity of the pole 3 periodically, and tripolar DC transmission is realized by modulating current orders of the three poles.

主权项

1. A tripolar VSC-HVDC system adopting three conductors to transmit DC power, the system comprising a rectifier and an inverter formed by a three phase six-bridge arms modular multilevel converter (MMC) respectively, midpoints of 1, 2, 3 phase units of the rectifier and inverter are connected with a secondary side of a converter transformer, and two converter valves of fully controlled semiconductor devices are arranged between poles 1 and 2 on the DC side of the rectifier and inverter respectively, anodes of the rectifier and inverter are connected with a pole 1 DC line by a smoothing reactor, cathodes of the rectifier and inverter are connected with a pole 2 DC line by a smoothing reactor, and connecting points of the upper and lower converter valves of the rectifier and inverter are connected with a pole 3 DC line by a smoothing reactor.