Voltage sag compensation with energy optimized dynamic voltage restorer

The compensation capability of a dynamic voltage restorer (DVR) depends primarily on the maximum voltage injection ability and the amount of stored energy available within the restorer. A new phase advance compensation (PAC) strategy for the DVR is proposed in order to enhance the voltage restoration property of the device. The scheme requires only an optimum amount of energy injection from the DVR to correct a given voltage sag. Supply voltage amplitude and phase detection scheme as well as phase advance determination scheme are also included. The resulting DVR design is shown to be superior in terms of lower storage energy need compared to the conventional in-phase boosting method. The analytical results are validated by laboratory tests carried out on a prototype of the restorer. The efficacy of the proposed method is illustrated.