Advanced dynamic voltage restorer to improve power quality in microgrid

A dynamic voltage restorer (DVR) based on photovoltaic (PV) generation/battery units is proposed to improve voltage quality in a microgrid. The restorer is connected with the grid by a rectifier, which is in series with the point of common coupling (PCC). Using energy management system (EMS), the proposed apparatus could be operated under dynamic voltage restorer mode, uninterrupted power supply mode and micro-source mode, and be switched smoothly among them. The dynamic voltage restorer could handle voltage sag or surge, and thus to improve the power quality in microgrid. The uninterrupted power supply could enhance the power supply reliability. And the micro-source could reduce the energy absorbed from utility grid so as to achieve energy conservation and emission reduction. The simulation and experimentation show the validity of the proposed DVR.