All nodes voltage regulation and line loss minimization in loop distribution systems using UPFC

Voltage regulation and line loss minimization in distribution lines are challenging problems, particularly when it is not economic to upgrade the entire feeder system. This paper presents a new method for achieving line loss minimization and all nodes voltage regulation in the loop distribution systems, simultaneously. First, loop system line loss minimum conditions are presented. Then, load voltage regulation is applied under line loss minimum conditions. Reference voltage of the controlled node is determined based on the assumption that this voltage can subsequently improve all node voltages to be within permissible range. Reference angle of the controlled node voltage is the main factor that can be used to minimize total line loss during load voltage control. In order to achieve these two objectives, simultaneously, the UPFC, a FACTS device, is used. Also, the proposed control scheme of the UPFC to regulate all node voltages under line loss minimization is presented. The effectiveness of the proposed control scheme has been verified experimentally.