Abstract：When LCC-MMC type hybrid DC distribution system has a pole-to-pole fault, the effective fault transient information is rare, and the fault feature quantity is not obvious, which make it difficult to reliably distinguish the fault boundary. Based on this, this paper proposes a protection scheme for pole-to-pole faults in LCC-MMC type hybrid DC distribution system. After CDSM-MMC and DAB dc transformer are blocked, combined with the typical characteristics that LCC provides the steady-state fault current, the ratio of the positive currents at two ends of line is used to identify the internal and external faults. Based on the series fault circuits, the relationship among the positive steady-state fault currents at both ends of the line and the positive steady-state fault current injected by LCC is deduced and the fault distance is obtained, which can accurately locate the fault positions and solve the problem of fuzzy fault boundary. The LCC-MMC type hybrid DC distribution system model is built in the PSCAD/EMTDC simulation platform. The simulation analyses show that the protection scheme can reliably distinguish fault boundaries, locate the fault position accurately and better satisfy the requirements of DC system for protection reliability and selectivity.
贾科, 冯涛, 陈淼, 王聪博, 毕天姝. LCC-MMC型混合直流配电系统线路保护方案[J]. 电工技术学报, 2021, 36(3): 656-665.
Jia Ke, Feng Tao, Chen Miao, Wang Congbo, Bi Tianshu. Line Protection Scheme for Hybrid LCC-MMC Type DC Distribution System. Transactions of China Electrotechnical Society, 2021, 36(3): 656-665.
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2021, Vol. 36 
