Comparative Study of AC / DC Side Loop-Closing Strategy Based on Back-to-Back VSC-HVDC Flexible Loop-Closing Device in Distribution Network

With the development of social industry and the advancement of smart grid, users' requirements for power quality and power supply reliability are getting higher and higher. Therefore, it is of great significance to transfer the load of distribution network without stopping power supply. In this paper, the back-to-back VSC-HVDC flexible loop-closing device with flexible control function is adopted to meet the demand of non-stop power load transfer under extreme conditions, and propose a scheme for loop-closing adjustment from the AC side and DC side respectively. Firstly, the structure and working principle of the closed-loop device are analyzed. Secondly, the control strategy is determined according to the requirements of the loop-closing. Finally, the simulation analysis of 10kV distribution network system in PSCAD/EMTDC environment further verifies the feasibility of the proposed loop-closing scheme and the effectiveness of the control strategy, and compares the advantages and disadvantages of the two schemes.