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.
[1] 徐政, 薛英林, 张哲任. 大容量架空线柔性直流输电关键技术及前景展望[J]. 中国电机工程学报, 2014, 34(29): 5051-5062. Xu Zheng, Xue Yinglin, Zhang Zheren. VSC-HVDC technology suitable for bulk power overhead line transmission[J]. Proceedings of the CSEE, 2014, 34(29): 5051-5062. [2] Li Rui, Fletcher J E, Xu Lie, et al. A hybrid modular multilevel converter with novel three-level cells for DC fault blocking capability[J]. IEEE Transactions on Power Delivery, 2015, 30(4): 2017-2026. [3] Marquardt R. Modular multilevel converter: an universal concept for HVDC-networks and extended DC-bus-applications[C]//International Power Electronics Conference(IPEC), Sapporo, Japan: IEEE, 2010: 502- 507. [4] 彭浩, 邓焰, 王莹, 等. 模块化多电平换流器模型及稳态特性研究[J]. 电工技术学报, 2015, 30(12): 120-127. Peng Hao, Deng Yan, Wang Ying, et al. Research about the model and steady-state performance for modular multilevel converter[J]. Transactions of China Electrotechnical Society, 2015, 30(12): 120- 127. [5] Chaudhuri N, Chaudhuri B. Adaptive droop control for effective power sharing in multi-terminal DC (MTDC) grids[J]. IEEE Transactions on Power Systems, 2013, 28(1): 21-29. [6] Beerten J, Cole S, Belmans R. Modeling of multi- terminal VSC HVDC systems with distributed DC voltage control[J]. IEEE Transactions on Power Systems, 2013, 29(1): 34-42. [7] Wang Y, Marquardt R. Future HVDC-grids employing modular multilevel converters and hybrid DC- breakers[C]//European Conference on Power Elec- tronics and Applications(EPE), Lille, France, 2013: 1-8. [8] 梁营玉, 张涛, 刘建政, 等. 不平衡电网电压下模块化多电平换流器的环流抑制策略[J]. 电工技术学报, 2016, 31(9): 120-128. Liang Yingyu, Zhang Tao, Liu Jianzheng, et al. A circulating suppressing mehtod for modular multilevel converter under unbalanced grid voltage[J]. Transac- tions of China Electrotechnical Society, 2016, 31(9): 120-128. [9] 廖武, 黄守道, 黄晟, 等. 基于模块化多电平换流器的直流输电系统网侧不平衡故障穿越研究[J]. 电工技术学报, 2015, 30(12): 197-203. Liao Wu, Huang Shoudao, Huang Sheng, et al. Unbalanced grid fault ride-through control method of HVDC power transmission based on modular multilevel converters[J]. Transactions of China Electrotechnical Society, 2015, 30(12): 197-203. [10] Tang Lianxiang, Ooi B T. Locating and isolating DC faults in multi-terminal DC systems[J]. IEEE Transac- tions on Power Delivery, 2007, 22(3): 1877-1884. [11] 赵成勇, 许建中, 李探. 全桥型MMC-MTDC直流故障穿越能力分析[J]. 中国科学: 技术科学, 2013, 43(1): 106-114. Zhao Chengyong, Xu Jianzhong, Li Tan. DC faults ride-through capability analysis of full-bridge MMC- MTDC system[J]. Science China: Technological Sciences, 2013, 43(1): 106-114. [12] 王姗姗, 周孝信, 汤广福, 等. 模块化多电平换流器HVDC直流双极短路子模块过电流分析[J]. 中国电机工程学报, 2011, 31(1): 1-7. Wang Shanshan, Zhou Xiaoxin, Tang Guangfu, et al. Analysis of submodule overcurrent caused by DC pole-to-pole fault in modular multilevel converter HVDC system[J]. Proceedings of the CSEE, 2011, 31(1): 1-7. [13] 罗永捷, 李耀华, 李子欣, 等. 全桥型MMC-HVDC直流短路故障穿越控制保护策略[J]. 中国电机工程学报, 2016, 36(7): 1933-1943. Luo Yongjie, Li Yaohua, Li Zixin, et al. DC short-circuit fault ride-through control strategy of full-bridge MMC-HVDC systems[J]. Proceedings of the CSEE, 2016, 36(7): 1933-1943. [14] 赵成勇, 陈晓芳, 曹春刚, 等. 模块化多电平换流器HVDC直流侧故障控制保护策略[J]. 电力系统自动化, 2011, 35(23): 82-87. Zhao Chengyong, Chen Xiaofang, Cao Chungang, et al. Control and protection strategies for MMC-HVDC under DC faults[J]. Automation of Electric Power Systems, 2011, 35(23): 82-87. [15] Adam G P, Davidson I E. Robust and generic control of full-bridge modular multilevel converter high- voltage DC transmission systems[J]. IEEE Transactions on Power Delivery, 2015, 30(6): 1877-1884. [16] 徐政, 屠卿瑞, 管敏渊, 等. 柔性直流输电系统[M]. 北京: 机械工业出版社, 2012. [17] Ahmed N, Ängquist L, Mahmood S, et al. Efficient modeling of an MMC-based multiterminal DC system employing hybrid HVDC breakers[J]. IEEE Transac- tions on Power Delivery, 2015, 30(4): 1792-1801. [18] 罗永捷, 李耀华, 王平, 等. 多端柔性直流输电系统直流电压自适应下垂控制策略研究[J]. 中国电机工程学报, 2016, 36(10): 2588-2599. Luo Yongjie, Li Yaohua, Wang Ping, et al. DC voltage adaptive droop control of multi-terminal HVDC systems[J]. Proceedings of the CSEE, 2016, 36(10): 2588-2599.
2017, Vol. 32 
