Studyon Energy-savingStrategies for Dynamic Voltage Restorer

Traditional voltage injection methodsforDVR are in-phase strategy whichinjects voltage inphasewiththesag voltage andmissing voltage technique whichcompensates forthe difference between thesagandpre-sag voltages. Since acertain component ofinjected voltage isin-phase withtheloadcurrent, DVR hastoprovide someamountofenergy tothegrid. ThispaperuseDQ analyzing methodbasedoninstantaneous reactive powertheories todetect andobtain theparameters of sourcesidevoltage forbalanced faults ofthree-phase three-wire system. Throughcircumgyrating thephasor andinjecting voltage withanappropriate advance phaserelative tosourceside voltage, theminimumenergyinjection canbeachieved. Forunbalanced faults, fictitious three-phase voltages whichcomefromasingle- phasesource canbeconstructed mathematically, sounbalanced faults canbedealt witheasily ina balanced way.Simulation results arepresented todemonstrate thevalidity oftheproposed method. IndexTermsvoltage sag,in-phase strategy, missing voltage technique, circumgyrate phasor, energy-saving