A Novel Dual-DC-Port Dynamic Voltage Restorer With Reduced-Rating Integrated DC–DC Converter for Wide-Range Voltage Sag Compensation

A novel dual-dc-port dynamic voltage restorer (DDP-DVR) is proposed. One low-voltage dc port is directly connected to the energy storage, while the other high-voltage dc port is connected to the intermediate dc bus. An integrated dc–dc converter is interfaced with these two dc ports which is aimed at providing a high-dc-link voltage and maintaining the voltage injection capability even if the energy-storage voltage is lower than the peak value of the injected ac-line voltage. Compared with the traditional DVR that uses the dc–dc converter for all voltage sag compensation, the proposed DDP-DVR can compensate shallow voltage sags without using the dc–dc converter, and for deep voltage sags, only partial active power needs to be processed by the dc–dc converter. Therefore, the power rating of the dc–dc converter can be reduced significantly. Meanwhile, much lower power losses can be achieved by the proposed DDP-DVR due to reduced power conversion stages. The operation principles, modulation strategies, and characteristics of the proposed DDP-DVR are analyzed in detail and verified with experimental results.