A control strategy for dynamic voltage restorer with harmonic compensation function

To ensure dynamic response performance of dynamic voltage restorer (DVR) and make it enable to compensate voltage harmonics from load in the steady state, a single-phase space vector pulse width modulation (SVPWM) based hybrid control strategy composed of double closed-loop proportional integral (PI) control and multiple proportional resonant (PR) control is proposed. Applying SVPWM to H-bridge inverter unit of DVR, on the basis of leading in single-phase coordinate rotating transformation the basis principle of single-phase SVPWM is analyzed and its implementation is given. The double closed-loop PI controller in single-phase fundamental synchronous coordinate environment can ensure the compensation effect of voltage sag by DVR, and multiple PR controller with harmonic voltage-loop for the compensation to specified order of harmonic is added to replace the PI controller in multiple rotating synchronous coordinate environment, thus the astatic compensation to harmonic voltage in specified order is implemented. The effectiveness and feasibility of the proposed control strategy are verified by results from theoretical analysis and experiments.