A novel high-power AC/AC modular multilevel converter in Y configuration and its control strategy

A novel high-power direct AC/AC modular multilevel converter topology in Y configuration, which is called Y-MMC, suitable for low frequency power transmission and distribution applications is proposed in this paper. The detailed topology and operation principles are addressed in this paper and the dynamic mathematical model of the Y-MMC system in dq coordinates is deduced. Corresponding control scheme is thoroughly discussed, including the inner loop current control, the outer loop power control and the reactive power distribution among branches. The validity of the Y-MMC topology and the control scheme are verified by computer simulation results.