Line-Interactive Single-Phase Dynamic Voltage Restorer With Novel Sag Detection Algorithm

This paper describes the development of a line-interactive single-phase dynamic voltage restorer (DVR) with a novel sag detection algorithm. The developed detection algorithm has a hybrid structure composed of an instantaneous detection part and the root-mean-square (rms) variation detection part. The source voltage passes through the instantaneous sag detection part. If instantaneous sag is detected, the rms variation detector-1 is selected to calculate the rms variation. The rms variation detector-2 is selected when the instantaneous sag occurs under the operation of the rms variation detector-1. The feasibility of proposed algorithm was verified through computer simulations and experimental works with a 3-kVA-rating prototype of line-interactive DVR. The line-interactive DVR with the proposed algorithm can compensate the input voltage sag or interruption within 2.0-ms delay. The developed DVR can be effectively utilized for the sensitive loads, such as a computer, communication device, and automation device.