An Auxiliary DC Circuit Breaker Utilizing an Augmented MMC

• Published in: IEEE transactions on power delivery Vol. 34; no. 2; pp. 561 - 571
• Main Authors: Li, Shuai, Xu, Jianzhong, Lu, Yu, Zhao, Chengyong, Zhang, Jiyuan, Jiang, Chongxue, Qiu, Shuming
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Breaking; Circuit breakers; Circuit faults; Computer simulation; Converters; DC circuit breaker; DC grid; DC short-circuit fault; Economic analysis; Electric bridges; Electric power transmission; Equivalent circuits; Fault currents; HVDC transmission; Insulated gate bipolar transistors; Model testing; Modular multilevel converter (MMC); over-voltage; Switches; Transmission lines
• ISSN: 0885-8977; 1937-4208
• DOI: 10.1109/TPWRD.2019.2892445

With the development of HVdc transmission technology, the isolation of dc faults is becoming increasingly important. As the most effective solution, hybrid HVdc circuit breaker (CB) is not mature enough, which has restricted its engineering application. Accordingly, this paper proposes an auxiliary dc CB scheme suitable for HVdc grid. In this scheme, the traditional half-bridge modular multilevel converter (MMC) is partially innovated to have the ability of auxiliary breaking operation. With the effect of the MMC auxiliary breaking (MAB) operation at both ends of the fault line, the dc fault current can be easily interrupted and isolated by low-cost CB unit installed in the dc transmission line. The equivalent circuit under MAB process is analyzed, and the fault isolation sequences are designed. Furthermore, the economic comparative analysis among three schemes is performed. Finally, a four-terminal bipolar HVdc grid test model is built in PSCAD/EMTDC; in addition, an MMC prototype with proposed scheme is also developed. The simulation and experimental results validate the effectiveness of the proposed scheme.