A Detailed Comparison of System Topologies for Dynamic Voltage Restorers

In this paper, four different system topologies for dynamic voltage restorers (DVRs) are analyzed and tested, with particular focus on the methods used to acquire the necessary energy during a voltage sag. Comparisons are made between two topologies that can be realized with a minimum amount of energy storage, with energy taken from the grid during the voltage sag, and two topologies that take energy from stored energy devices during the voltage sag. Experimental tests using a 10-kVA DVR show that the no-energy storage concept is feasible, but an improved performance can be achieved for certain voltage sags using stored energy topologies. The results of this comparison rank the no-storage topology with a passive shunt converter on the load side first, followed by the stored energy topology with a constant dc-link voltage.