New concepts of dynamic voltage restoration for three-phase distribution systems

In three-phase AC power distribution systems, a dynamic voltage restorer (DVR) can be used to protect sensitive power customers from voltage disturbance. The outputs of the DVR relates to the disturbance level of supply voltages, the required restoration level of load voltages, and the limitation of energy exchange between the DVR and the transmission line. In this paper, the influences of these factors on the DVR outputs are analyzed in detail. A generalized DVR with multiple voltage source inverters that are connected to a common DC energy storage device and inserted into the different sensitive load branches respectively is presented. It has the potential to reduce the rating of DVR and its DC energy storage device, and the adverse effects of the DVR fault will be limited. The analysis results and the feasibility of the generalized DVR are verified by digital simulation