Modular Multilevel Converter Control Strategy Based on Arm Current Control Under Unbalanced Grid Condition

The existing control strategies of modular multilevel converter (MMC) balance the capacitor voltage on the premise that the active power of ac side is balanced with that of dc bus. Thus, the symmetrical ac-side current references and the unevenly distributed dc current references in three legs are obtained by coordinate transformation, precise calculation, and numerous filters under unbalanced gri...