Abstract：Modular multilevel converter(MMC) is a potential topology for the medium or high voltage and high power applications due to the modular structure, high efficiency, low distortion and high reliability. In this paper, a four order large signal model is built with the state variables of the summation of all the capacitor voltages, the difference between the total voltages of the upper arm and lower arm, the circulating current and the output current. Based on the model, the steady-state performance can be evaluated and the accurate steady-state expressions of the circulating current, the arm current and the average capacitor voltage can be obtained. It can be inferred that the circulating current is mainly composed of the DC component and the second harmonic. For the upper capacitor voltages and the lower capacitor voltages, the even harmonics are with the same phase and the odd harmonics are with the inverse phase. Furthermore, the DC bias of the capacitor voltage is a little different from the rated value. At last, a three-phase 48 sub-modules platform is built to verify the accuracy of the four order model and the steady-state expressions. The simulation and experimental results are highly matched with the theoretical expressions.
彭浩,邓焰,王莹,王昆,何湘宁,赵荣祥. 模块化多电平变换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,Wang Kun,He Xiangning,Zhao Rongxiang. Research about the Model and Steady-state Performance for Modular Multilevel Converter. Transactions of China Electrotechnical Society, 2015, 30(12): 120-127.
[1] Flourentzou N, Agelidis V G, Demetriades G D. VSC-Based HVDC Power Transmission Systems: An Overview[J]. IEEE Transactions on Power Electronics, 2009, 24(3): 592-602. [2] Friedrich K. Modern HVDC PLUS application of VSC in Modular Multilevel Converter topology[C]. 2010 IEEE International Symposium on Industrial Electronics (ISIE), Bari, 2010: 3807-3810. [3] 雷鸣, 李耀华, 葛琼璇等. 一种新型单桥臂电感模块化多电平变流器及其控制方法[J]. 电工技术学报, 2014, 29(2): 231-238. Lei Ming, Li Yaohua, Ge Qiongxuan, et al. A New Modular Multilevel Converter with Single Arm Inductor and Its Control Strategies[J]. Transactions of China Electrotechnical Society, 2014, 29(2): 231-238. [4] 武健, 刘瑜超, 徐殿国. 基于模块多电平变换器的并联有源滤波器控制策略研究[J]. 电工技术学报, 2013, (12): 52-59. Wu Jian, Liu Yuchao, Xu Dianguo. Control Strategy of Shunt Active Power Filter Based on Modular Multilevel Converter[J]. Transactions of China Electrotechnical Society, 2013, (12): 52-59. [5] 杨晓峰, 范文宝, 王晓鹏等. 基于模块组合多电平变换器的STATCOM及其控制[J]. 电工技术学报, 2011, 26(8): 7-13. Yang Xiaofeng, Fan Wenbao, Wang Xiaopeng, et al. Static synchronous compensator based on modular multilevel converter based STATCOM and Its control[J]. Transactions of China Electrotechnical Society, 2011, 26(8): 7-13. [6] 管敏渊, 徐政. 模块化多电平换流器型直流输电的建模与控制[J]. 电力系统自动化, 2010, (19): 64-68. Guan Minyuan, Xu Zheng. Modeling and control of modular multilevel converter in HVDC transmission [J]. Automation of Electric Power Systems, 2010, (19): 64-68. [7] 管敏渊, 徐政. 向无源网络供电的MMC型直流输电系统建模与控制[J]. 电工技术学报, 2013, (02): 255-263. Guan Minyuan, Xu Zheng. Modeling and control of modular multilevel converter based VSC-HVDC system connected to passive networks[J]. Transactions of China Electrotechnical Society, 2013, (02): 255- 263. [8] Guan M Y, Xu Z. Modeling and Control of a Modular Multilevel Converter-Based HVDC System Under Unbalanced Grid Conditions[J]. IEEE Transactions on Power Electronics, 2012, 27(12): 4858-4867. [9] 王奎, 郑泽东, 李永东. 新型模块化多电平变换器电容电压波动规律及抑制方法[J]. 电工技术学报, 2011, 26(5): 8-14. Wang Kui, Zheng Zedong, Li Yongdong. Voltage Ripple Principle and Restrain Method of Floating Capacitors in a New Modular Multilevel Converter[J]. Transactions of China Electrotechnical Society, 2011, 26(5): 8-14. [10] Yalong L, Wang F. Arm inductance selection principle for modular multilevel converters with circulating current suppressing control[C]. Applied Power Elec- tronics Conference and Exposition (APEC), 2013: 1321-1325. [11] 王姗姗, 周孝信, 汤广福等. 模块化多电平HVDC输电系统子模块电容值的选取和计算[J]. 电网技术, 2011, (01): 26-32. Wang Shanshan, Zhou Xiaoxin, Tang Guangfu, et al. Selection and calculation for sub-module capacitance in modular multi-level converter HVDC power trans- mission system[J]. Power System Technology, 2011, (01): 26-32. [12] Wang K, Li Y, Zheng Z, et al. Voltage balancing and fluctuation-suppression methods of floating capa- citors in a new modular multilevel converter[J]. IEEE Transactions on Industrial Electronics, 2013, 60(5): 1943-1954. [13] Vasiladiotis M, Cherix N, Rufer A. Accurate capacitor voltage ripple estimation and current control considerations for grid-connected modular multilevel converters[J]. IEEE Transactions on Power Electronics, 2014, 29(9): 4568-4579. [14] Zhang Y S, Adam G P, Lim T C, et al. Mathematical analysis and experiment validation of modular multilevel converters[J]. Journal of Power Electronics, 2012, 12(1): 33-39. [15] 周月宾, 江道灼, 郭捷等. 模块化多电平换流器子模块电容电压波动与内部环流分析[J]. 中国电机工程学报, 2012, (24): 8-14. Zhou Yuebin, Jiang Daozhuo, Guo Jie, et al. Analysis of sub-module capacitor voltage ripples and circula- ting currents in modular multilevel converters[J]. Proceedings of the CSEE, 2012, (24): 8-14. [16] Song Q, Liu W, Li X, et al. A Steady-State Analysis Method for a Modular Multilevel Converter[J]. IEEE Transactions on Power Electronics, 2013, 28(8): 3702-3713. [17] Ilves K, Antonopoulos A, Norrga S, et al. Steady- State Analysis of Interaction Between Harmonic Components of Arm and Line Quantities of Modular Multilevel Converters[J]. IEEE Transactions on Power Electronics, 2012, 27(1): 57-68.
2015, Vol. 30 
