基金项目:国家自然科学基金(51667007)；中国南方电网有限责任公司重点科技项目(GZKJQQ00000417)。Project Supported by National Natural Science Fund (51667007); The key science and technology projects of China Southern Power Grid Co., Ltd. (GZKJQQ00000417). 0 引言
Under the unbalanced load condition, the AC side current, the internal circulation and the sub-module capacitor voltage must be considered for the comprehensive compensation of the static synchronous compensator based on modular multi-level converter (MMC-STATCOM). Firstly,the working principle of the comprehensive compensation in modular multilevel converter based MMC-STATCOM is analyzed; Then, in allusion to existing control methods control the ac current and circulating current by separating each component, a STATCOM unbalanced compensation control method based on MMC bridge current is proposed, can simultaneously control the internal and external characteristics of MMC-STATCOM without a dedicated inner circulating current controller, and the quasi-PR controller is used to realize the static tracking of the upper and lower MMC bridge current, which makes the overall control structure simple; Finally, simulation platform of MMC-STATCOM is built in PSCAD /EMTDC, the simulation results show that the proposed method can realize the comprehensive compensation of STATCOM, and also can restrain the internal circulation of MMC effectively.