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

Abstract

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.