A Novel Approach to Dynamic Voltage Restorer

The Dynamic Voltage Restorer (DVR) is one of the most common custom power devices use for the protection of sensitive loads against voltage sag and swell.The main functions of the DVR are the injection of voltage to power line and maintain the pre-sag voltage condition in the load side. Different control strategies are available depending upon the compensation technique. In this paper, emergency control in distribution systems is discussed by using the proposed multifunctional DVR control strategy. Also, the multiloop controllers using the Posicast and P+Resonant controllers is proposed in order to improve the transient response and eliminate the steady-state error in DVR response, respectively. The proposed algorithm is applied to some disturbances in load voltage caused by induction motors starting, and sudden change in load on load side.The innovation here is that the DVR acts as virtual impedance with the main aim of protecting the point of common coupling (PCC) voltage during downstream fault without any problem in real power injection into the DVR. The simulation was carried usingMATLAB/SIMULINK and the results of the simulation show the capability of the DVR to control the emergency of the distribution systems.