Design of shunt-connected dynamic voltage restorers

This paper deals with the design and analysis of dynamic voltage restorers (DVR) based on shunt-connected inverters and grid decoupling reactors. The primary task of these devices is to keep the voltage level sufficiently high during voltage dips and outages. A shunt-connected, four-wire capacitor midpoint type converter topology acting as a voltage source is considered. In order to limit the current between two parallel voltage sources with unequal voltages, the AC grid is decoupled by an additional line inductor. The proposed topologies and driving algorithms of the DVR are verified by simulations in an advanced software package, namely PSCAD/EMTDC.