A supervisory hierarchical fuzzy controller for dynamic voltage restorer (DVR)

Dynamic voltage restorer (DVR) is a static Var compensator that plays an important role in voltage sag/swell compensation, especially during faults. This paper proposes a novel fuzzy logic based control structure to improve DVR performance. The proposed structure consists of two layers, namely, the lower or main layer and the upper or supervisor layer. The upper layer supervises and rectifies the main, when required. The numerical results show the superiority of the proposed control structure in comparison with the cases in which, classical methods (i.e. PI) or conventional fuzzy controller is employed.