A Novel Minimal Energy Consumption Strategy for the Inter-line Dynamic Voltage Restorer

To restore the load voltage, Dynamic Voltage Restorer (DVR), which is installed between the supply and a sensitive load, should inject voltage and active power from DVR to the distribution system during voltage sag. Due to the limit of energy storage capacity of DC link, it is necessary the minimize energy injection from DVR. In this paper the techniques of the supply voltage sag compensation in a distribution feeder are presented. In addition, a concept of inter-line dynamic voltage restorer (IDVR) that two DVRs in two different voltage distribution system are connected to a common DC link capacitor is proposed. One of these two DVR (low voltage) operates in voltage sag compensation mode and a novel control technique uses to inject minimum energy from DC link capacitor to low voltage distribution system. The other DVRs (medium voltage) controls the voltage of DC link capacitor so that energy flows from medium voltage distribution system to the DC link capacitor. Simulation results carried out by PSCAD/EMTDC, verify the efficiency of the proposed method.