基于反馈线性化的MMC直接功率控制策略研究  

Feedback Linearization-Based Direct Power Control for the Modular Multilevel Converter

作　　者：金昱[1] 肖迁[2] 王建赜[1] 贾宏杰[2] 谢冰 纪延超[1] Jin Yu;Xiao Qian;Wang Jianze;Jia Hongjie;Xie Bing;Ji Yanchao(School of Electrical Engineering and Automation,Harbin Institute of Technology,Harbin 150006,China;Key Laboratory of Smart Grid of Ministry of Education,Tianjin University,Tianjin 300072,China;Electrical Power Research Institute of State Grid Liaoning Electric Power Co.,Ltd.,Shenyang 110006,China)

机构地区：[1]哈尔滨工业大学电气工程及自动化学院,哈尔滨150006 [2]天津大学智能电网教育部重点实验室,天津300072 [3]国网辽宁省电力有限公司电力科学研究院,沈阳110006

出　　处：《天津大学学报（自然科学与工程技术版）》2021年第12期1230-1240,共11页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(52107121);中国博士后科学基金资助项目(2020M680880);国家自然科学基金国际合作资助项目(52061635103,EP/T021969/1).

摘　　要：模块化多电平变换器(MMC)通常采用级联结构的线性控制方法,针对其功率跟踪精度差、动态响应慢等问题,本文提出一种基于反馈线性化的直接功率控制方法.首先,以换流器交、直流回路的控制信号为输入,以其输出功率及环流为输出,建立多输入多输出(MIMO)的控制模型,并利用反馈线性化技术,将所建立的非线性模型线性化;其次,基于线性化变换后新系统中交、直流回路控制目标的特性,设计各回路的线性控制器,进而提出相应的直接功率控制方法,并根据线性化方程求解MMC换流器的最终控制信号;最后,考虑到线性化变换后系统变量无法被完全观测的问题,建立无法观测变量的特征方程,利用稳定性分析理论,对所提控制方法的零动态稳定性进行讨论.所提方法利用反馈线性化手段解决了MMC非线性功率模型下的控制难题,可同时实现MMC的功率控制和环流控制,并提高MMC换流器对功率参考的跟踪精度与动态响应速度.实验结果表明:在稳态运行工况下,所提方法的有功及无功功率跟踪精度更高,误差更小;在有功功率阶跃运行工况下,所提方法有功功率动态响应速度更快,无功功率的波动更小;在无功功率阶跃运行工况下,所提方法无功功率动态响应速度更快,有功功率的波动更小.该方法可有效控制MMC换流器的有功和无功功率,具有更高的功率跟踪精度和更快的动态响应.The cascaded linear control structure is usually adopted in the modular multilevel converter(MMC).This paper proposes a direct power control method based on feedback linearization,in order to improve the power tracking accuracy and dynamic responses of MMC.First,the control signals in the AC and DC paths are taken as the input variables while the AC output power and the circulating currents are taken as the output variables.The multiple-input multiple-output(MIMO)nonlinear model of MMC is established and linearized based on the feedback linearization technique.Then,the linear controllers in the AC and DC paths can be designed according to the control targets of the new linearized system,and the direct power control method is proposed.With the feedback linearization equations,the final control signals of the MMC can be derived.Finally,because some variables cannot be observed,the characteristic equations of these variables are established,and the zero-dynamics stability of the proposed control method is discussed on the basis of stability analysis theory.The experiments are conducted to verify the proposed method.With the proposed method,higher tracking accuracy and smaller tracking errors of the active and reactive power can be observed in the steady-state operation condition;faster active power dynamic responses and smaller reactive power fluctuations can be observed in the active power step operation condition;faster reactive power dynamic responses and smaller active power fluctuations can be observed in the reactive power step operation condition.These results indicate that this method can effectively control the active and reactive power of the MMC and has a higher power tracking accuracy and faster dynamic response.

关 键 词：模块化多电平变换器 并网换流器 直接功率控制 非线性系统 反馈线性化 

分 类 号：TM464[电气工程—电器]