Performance improvement of the dynamic voltage restorer with closed-loop load voltage and current-mode control

The performance of a dynamic voltage restorer (DVR) in improving the quality of power supply is examined. It is shown that the existing open-loop control strategy used in the DVR to regulate load voltage can produce poorly damped response due to the presence of the switching harmonic filter in the restorer. Damping is shown to be improved if the proposed multiloop controller is used. Furthermore, the new control scheme permits a closer tracking of the reference load voltage under varied load conditions. The analysis of the proposed method is then validated by simulation studies and laboratory experimental tests which show the efficacy of the new control scheme.