이중 변환 UPS의 병렬 운전 시 외란 저감 성능 향상을 위한 정지 좌표계 상의 전향 보상 기법

Abstract

Generally, a proportional-resonant controller is used to eliminate steady-state errors during the voltage–current control of a double-conversion uninterruptible power supply (UPS) in a stationary reference frame.Additionally, the feed-forward control compensating for the load current, which can be considered a disturbanceof the voltage controller, can be used to improve the disturbance rejection performance. However, during theparallel operation of UPSs, circulating current can occur between UPS modules when performing bothfeed-forward control and droop control because feed-forward control reduces the circulating current impedance.This study proposes a feed-forward compensation technique that considers the impedance of circulating current.An additional feed-forward compensation technique is developed to enhance the disturbance rejectionperformance. The validity of the proposed feed-forward compensation technique is verified by the experiment results of the parallel operation of a 500 W double-conversion UPS module.