Research on Improved Circulation Suppression Strategy of MMC Based on Quasi-PR Controller

Modular Multilevel Converter (MMC) has the advantages of strong scalability, high output voltage level, and low output current harmonics. It is widely used in DC transmission, offshore wind power grid connection, and AC/DC hybrid power distribution network. However, the circulation causes bridge arm current distortion and converter station loss. This paper designs circulation suppression strategy based on quasi-PR controller, which can effectively suppress the double, quadruple, and six-frequency circulation component by setting four quasi-PR controllers. The PSCAD simulation model verified the circulation suppression strategy based on the quasi-PR controller studied in this paper can effectively improve the performance of MMC.