Inter-line dynamic voltage restorer control using a novel optimum energy consumption strategy

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 energy storage capacity limitation of DC link, it is necessary to minimize energy injection from DVR.The techniques of the supply voltage sag compensation in a distribution feeder are reviewed in this paper. Then a new device which is named Inter-line Dynamic Voltage Restorer (IDVR) is discussed. This device consists of two conventional DVRs which are installed in two different distribution feeders and the DC link capacitor. DVR which is installed in LV feeder operates in voltage sag compensation mode. A novel control technique minimizes the energy flow from DC link capacitor to this feeder. The DVR, which is installed in MV feeder, controls the voltage of DC link capacitor. The proposed device and its new control strategy have been modeled and simulated by PSCAD/EMTDC. The results verify the effectiveness of IDVR and the suggested control method.