Abstract—This paper introduces and evaluates an auxiliary control strategy for down stream fault current interruption in a radial distribution line by means of a dynamic voltage restorer (DVR). The proposed controller supplements the voltage-sag reduction control of the DVR. It does not require phase-locked loop and independently controls the magnitude and phase angle of the injected voltage for each phase. Fast least error squares digital filters are used to estimate the magnitude and phase of the measured voltages and effectively reduce the impacts of noise, harmonics, and disturbances on the estimated phas or parameters, and this enables effective fault current interrupting even under arcing fault conditions. The results of the simulation studies performed in the PSCAD/EMTDC software environment indicate that the proposed control scheme: 1)can limit the fault current to less than the nominal load current and restore the point of common coupling voltage within10ms;2)can interrupt the fault current in less than two cycles;3) limits the dc-link voltage ost and, thus, has no restrictions onthedurationoffaultcurrentinterruption;4)performs satisfactorily even under arcing fault conditions; and 5) can interrupt the fault current under low dc-link voltage conditions.
Index Terms—Digital filters, dynamic voltage restorer (DVR), fault current interrupting, multi loop control.