AC Voltage Compensation and DC Voltage Balance on Cascaded H-bridge Converter for Dynamic Voltage Restorer

For sensitive loads in distribution network, voltage sag is a major power quality (PQ) problem, and the dynamic voltage restorer (DVR) is an effective device to solve this problem. This paper introduces a high-voltage direct-connected DVR based on a cascaded H-bridge multilevel converter. The dq-axis decoupling control scheme is developed for DVR AC voltage compensation, and carrier phase shifted pulse width modulation (CPSPWM) with voltage offset injection algorithm is applied for DC capacitor voltage balance of the multilevel converter. Finally, the proposed DVR is modeled and simulated by MATLAB/SIMULINK, and the feasibility of the proposed method is verified.