Analysis of Transformerless Voltage Quality Regulator with Load Current Feed-Forward and Dual-Loop Control

The transformerless voltage quality regulator is a new power electronic equipment designed to mitigate the voltage disturbance. Performance of the voltage quality regulator in improving the quality of power supply is examined. In order to improve the performance, a combined load current feed-forward and dual-loop(outer voltage loop and inner filter inductor current loop) control scheme is proposed in this paper. This paper analyzes the control scheme that with and without load current feed forward in detail. This paper also adopts the phase shift control to deal with DC link voltage pumping-up phenomenon when source voltage is long duration overvoltage. Through comparative analysis, the proposed scheme is verified to be better than traditional dual-loop control methods. At last, the validity and effectiveness of the proposed control scheme are verified by the computer simulation and laboratory experimental results.