Mmc Loss Reduction Control Strategy Considering Capacitor Voltage Ripple Suppression

suppressing the capacitor voltage ripple of submodule to reduce the demand of modular multilevel converter (MMC) on submodule capacitor is the key issue to realize the lowcost, lightweight and compact design of MMC. However, the existing capacitor voltage ripple suppression method is mainly achieved by injecting a second harmonic circulating current, which leads to a significant increase in MMC losses, reduces the operation efficiency and reliability of converter. In order to solve the above problems, the characteristics of MMC capacitor voltage ripple under the optimal second harmonic circulating current injection and the loss increment caused by capacitor voltage ripple suppression are analyzed. Then, a MMC loss reduction control strategy considering capacitor voltage ripple suppression is proposed, which meets the optimization objectives and constraints of capacitor voltage ripple and converter losses, and eliminates the converter loss increment under capacitor voltage ripple suppression by optimizing control arm current, while ensuring that the effect of capacitor voltage ripple suppression is not significantly affected, thus improve the economy and reliability of system operation. Finally, a simulation of MMC with carrier phase shift PWM (CPS-PWM) in MATLAB/Simulink is carried out to verify the correctness of converter loss characteristics and the effectiveness of the proposed control strategy.