Abstract：This paper analyzes the power circuit topology and operating principle of five-level modular multilevel converter-unified power quality conditioner(MMC-UPQC), the mathematical model of dq0 coordinate system and EL model are established. In order to speed up the convergence of error storage function, the method of injecting damping is designed for passivity based controller in current inner loop to ensure the stability of MMC-UPQC. The desired current is obtained by PI controller in voltage outer loop, the static error is eliminated. Active and reactive power decoupling control is achieved through the proposed passivity based control, so the dynamic and static performance of system is ensured. Under the negative sequence double frequency coordinate transformation, inter-phase decoupling control is used to suppress circulating current and reduce the switch losses. The extraction of voltage and current compensation based on Park transformation is adopted, which has no need of phase lock loop, so the compensation precision is improved. At last, the simulation model of five-level is built in Matlab/Simulink. Simulation results show that accurately compensating unbalanced, harmonic voltage and reactive, harmonic current has verified the feasibility of passivity based control.
2017, Vol. 32 
