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| Improved nearest level modulation strategy for modular multilevel converters |
| Zhou Yang1, HU Peng-fei1, JIANG Dao-zhuo1, ZHANG Ke-bo2 |
| 1. College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China;2. State Grid Ningbo Yinzhou Power Supply Company, Ningbo 315100, China |
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Abstract In order to solve the fluctuations of DC voltages and circulating currents of modular multilevel converters by using traditional nearest level modulation (NLM), an improved NLM method for the modular multilevel converter was proposed. In the proposed method, full consideration to capacitance voltage of the sub-module was given and capacitance voltage balancing strategy of optimization was used. Instead of each module voltage, the module average voltage was used because the voltage of each module is approximately equal. Through the analysis of the circulating current’s generation mechanism, mathematical model was established. According to the mathematical model, in view of the impact of the sub-modules’ voltage fluctuations, the control strategy of NLM has been proposed, which is, feeding back actual capacitance voltage to curb circulating current. In this way, the improved NLM both eliminates the errors between actual arm voltage and reference voltage and inhibits the fluctuations of DC voltages and circulating currents. By the simulation in PSCAD/EMTDC, the results show that the improved NLM can suppress the fluctuation of DC voltage and circulating currents both in steady and dynamic state, which means that the system has a high reliability.
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Published: 01 August 2015
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| Fund: 浙江省重点科技创新团队资助项目(2010R50004) |
模块化多电平换流器改进最近电平调制策略
针对传统最近电平调制策略(NLM)在模块化多电平换流器（MMC）中造成的直流侧电压波动和二倍频环流等问题,提出改进最近电平的调制策略.充分考虑子模块电容电压的波动,采用优化的电容电压均衡策略.由于每个桥臂中各子模块的电压近似相等,用子模块平均电压代替每个子模块电压,通过分析系统的二倍频环流产生机理,建立数学模型,根据数学模型提出改进最近电平调制策略的控制策略.针对子模块电压波动带来的影响,改进的策略采取反馈实际电容电压,消除了实际桥臂电压与参考电压间的误差,抑制了直流侧电压波动和二倍频环流.通过PSCAD/EMTDC软件对系统进行仿真,结果表明,在系统稳态和动态运行情况下,提出的改进策略均能够有效抑制直流电压波动和二倍频环流,系统输出电流的毛刺显著减小,具有较高的稳定性.
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| ［1］ LESNICAR A, MARQUARDT R. An innovative modular multilevel converter topology suitable for a wide power range ［C］∥Power Tech Conference Proceedings.Bologna, Italy: IEEE, 2003.
［2］ GLINKA M. Prototype of multiphase modular multilevel converter with 2 MW power rating and 17-level-output-voltage ［C］∥Power Electronics Specialists Conference.Aachen, Germany: PESC 04. 2004 IEEE 35th Annual, 2004, (4): 2572-2576.
［3］ 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.
［4］ HARNEFORS L, ANTONOPOULOS A, NORRGA S, et al. Dynamic analysis of modular multilevel converters ［J］. IEEE Transactions on Industrial Electronics,2012, 60(7): 2526-2537.
［5］ 郭捷,江道灼,周月宾,等.交直流侧电流分别可控的模块化多电平换流器控制方法［J］.电力系统自动化. 2011, 35(7): 42-47.
GUO Jie, JIANG Dao-zhuo, ZHOU Yue-bin, et al. AC and DC Current hybrid control strategy for modular multilevel converter ［J］. Automation of Electric Power Systems,2011, 35(7): 42-47.
［6］ 管敏渊,徐政,屠卿瑞,等.模块化多电平换流器型直流输电的调制策略［J］.电力系统自动化.2010, 34(2): 48-52.
GUAN Min-yuan, XU Zheng, TU Qing-rui, et al. Nearest level modulation for modular multilevel converters in HVDC transmission ［J］. Automation of Electric Power Systems, 2010, 34(2): 48-52.
［7］ 胡鹏飞,江道灼,郭捷,等.基于晶闸管换向的混合型多电平换流器［J］.电力系统自动化,2012, 36(21): 102-107.
HU Peng-fei, JIANG Dao-zhuo, GUO Jie, et al. Hybrid multilevel converters based on thyristor alternate-arms ［J］. Automation of Electric Power Systems, 2012, 36(21): 102-107.
［8］ HAGIWARA M, AKAGI H. Control and experiment of pulse width modulated modular multilevel converters ［J］. IEEE Transactions on Power Electronics, 2009, 24(7): 1737-1746.
［9］ ILVES K, ANTONOPOULOS A, HARNEFORS L, et al. Capacitor voltage ripple shaping in modular multilevel converters allowing for operating region extension［C］∥ 37th Annual Conference on IEEE Industrial Electronics Society. Melbourne, VIC: IEEE, 2011: 4403-4408.
［10］ HU Peng-fei, JIANG Dao-zhuo, ZHOU Yue-bin, et al. Study of the proportional resonant control based modular multilevel converter ［C］∥ 3rd International Conference on Digital Manufacturing and Automation. GuiLin: IEEE, 2012: 810-813.
［11］ 屠卿瑞,徐政,管敏渊,等.模块化多电平换流器环流抑制控制器设计［J］.电力系统自动化,2010,34(18)： 57-61.
TU Qing-rui,XU Zheng,GUAN Min-yuan,et al.Design of circulating current suppressing controllers for modular multilever converter ［J］.Automation of Electric Power Systems,2010,34(18)： 57-61.
［12］ ANGQUIST L, ANTONOPOULOS A, SIEMASZKO D, et al. Open-Loop control of modular multilevel converters using estimation of stored energy ［J］. IEEE Transactions on Industry Applications, 2011, 47(6): 2516-2524.
［13］ 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 Shan-shan, ZHOU Xiao-xin, TANG Guang-fu, 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.
［14］ MINYUAN G, ZHENG X. 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.
［15］ 李强,贺之渊,汤广福,等.新型模块化多电平换流器空间矢量脉宽调制方法［J］.电力系统自动化.2010, 34(22): 75-79.
LI Qiang, HE Zhi-yuan, TANG Guang-fu, et al. A Space-vector PWM method for a new type of modular multilevel converter ［J ］. Automation of Electric Power Systems, 2010, 34(22): 75-79.
［16］ TU Qing-rui, XU Zheng, XU Lie. Reduced switching frequency modulation and circulating current suppression for modular multilevel converters ［J］. IEEE Transactions on Power Delivery, 2011, 26(3): 2009-2017.
［17］ 周月宾,江道灼,胡鹏飞,等.利用均压策略消除MMC死区影响的方法［J］.浙江大学学报:工学版, 2014, 48(4): 561-567.
ZHOU Yue-bin, JIANG Dao-zhuo, HU Peng-fei, et al. Method through voltage balancing strategy for eliminating dead time effect of MMC ［J］. Journal of Zhejiang University ：Engineering Science, 2014, 48(4): 561-567.
［18］ ZHOU Yue-bin, JIANG Dao-zhuo, GUO Jie, et al. Analysis and control of modular multilevel converters under unbalanced conditions ［J］. IEEE Transactions on Power Delivery, 2013, 28(4):1986-1995. |
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