The influence of motor loads on the voltage restoration capability of the dynamic voltage restorer

The performance of voltage sag mitigation devices such as the dynamic voltage restorer (DVR) has been analyzed in highly simplified electrical environment consisting of simple line and load models. The negative influences of dynamic motor loads on the existing voltage disturbance, such as post-fault sags, additional during-fault phase-angle deviations, during-fault and post-fault voltage fluctuations have often been overlooked. Hence the potential system-level interactions that may arise among common industrial loads and custom power devices have been neglected. In this paper, such motor load effects are included in the study of voltage sag magnitude and phase-angle jump mitigation abilities of the DVR model developed. First, the influence of induction motor operations on the during-fault and post-fault waveforms are discussed. After which, the ability of the DVR to dynamically respond to the various types of voltage sag conditions at the terminals of a dynamic motor load and restore the sagging voltage to its pre-fault conditions is presented