Research and Development of Flexible Loop Closing Controller Based on D-UPFC

Closed loop power supply can greatly improve the power supply reliability of distribution network and is an effective guarantee for the safe and stable operation of distribution network. Due to the different voltages in the two areas, a large impulse current will be generated during ring closing, resulting in ring closing failure, or the transfer capacity of the line cannot be detected and controlled after successful ring closing. Therefore, the current distribution network adopts open-loop operation and power outage. This paper presents a D-UPFC type flexible loop closing controller, which realizes flexible loop closing by adjusting the pressure difference at both ends of the substation through series transformer side comprehensive compensation. After loop closing, it controls the transmission current of the line and realizes the power flow control of the line. The feasibility of this scheme is verified by simulation through a specific experimental example. The research results show that the D-UPFC flexible loop closing controller can realize the flexible loop closing, avoid power failure and power transfer, and realize power flow control, which improves the transparency of distribution operation and the reliability of power supply quality.