The control and analysis of zero sequence components in DVR system

The magnitudes and phases of the compensating voltages in a dynamic voltage restorer (DVR) system depend on the voltage sag in the phases affected by the fault and on the influence of the zero sequence components. If the delta connection of the transformer is used, the zero sequence components do not appear on the load side. But nowadays, wye connected transformers with grounded neutral are usually used. Therefore the zero-sequence components occur during faults. The zero-sequence components result in the high insulation costs and the asymmetry of the phases and magnitudes of the terminal voltages. This paper proposes a method that can mitigate the zero-sequence under the unbalance faults causing voltage sags and phase angle jumps. Moreover, the energy optimizing method is considered in this paper.