A High Efficiency Quasi-Single-Stage Unified Power Quality Conditioner Integrating Distributed Generation

A novel quasi-single-stage unified power quality conditioner integrating distributed generation (UPQC-DG) is proposed in this paper. With the help of quasi-single-stage architecture, the low-voltage distributed generation, e.g., PV modules or energy storages, can directly supply active power to the ac grid or ac load within single power conversion stage. Therefore, in comparison with traditional two-stage UPQC-DG, the power conversion stages are reduced and the overall conversion efficiency is enhanced. A modified SVPWM strategy aiming at realizing most active power transferred within single power conversion stage is discussed. Besides, the power flow through the quasi-single-stage UPQC-DG is analyzed in detail to understand the system operation and design the power converters properly. Experimental results with a 3kVA prototype are provided to verify the feasibility and effectiveness of the presented quasi-single-stage UPQC-DG.