Pole-to-Ground DC Fault Protection of MMC-MTDC Systems
Luo Yongjie1, Xu Luona2, Xiong Xiaofu1, Li Yaohua2
1. State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing 400044 China; 2. Key Laboratory of Power Electronics and Electric Drive Institute of Electrical Engineering Chinese Academy of Sciences Beijing 100190 China
Abstract DC fault protection is a key issue of modular multilevel converter (MMC) based multi-terminal high voltage direct current (MTDC) transmission systems. Most of the existing literatures focus on the pole-to-pole DC short circuit fault. But the pole-to-ground fault also threatens the system security in some conditions. The fault characteristics of the half-bridge MMC-MTDC system is analyzed, adopting with AC and DC grounding modes, respectively. The grounding resistance is also discussed in this paper. Then, based on the capability of the fault current clearance of the full-bridge MMC, this paper proposed a pole-to-ground DC fault protection strategy to restore power transmission quickly. This method can avoid cutting off the AC and DC systems. The theory analysis and the proposed strategy are demonstrated by the PSCAD/EMTDC simulation.
Luo Yongjie,Xu Luona,Xiong Xiaofu等. Pole-to-Ground DC Fault Protection of MMC-MTDC Systems[J]. Transactions of China Electrotechnical Society, 2017, 32(增刊1): 98-106.
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