基于模型预测控制的MMC-HVDC系统控制策略研究

为提高基于模块化多电平换流器的直流输电系统(MMC-HVDC)电流内环的动态响应速度，提出了一种MMC-HVDC系统的模型预测控制(Model predictive control, MPC)方法。该方法通过预测模型、反馈校正和滚动优化得到最优的电压控制量，克服了传统双闭环控制PI参数整定困难和动态响应慢的问题。针对外环PI控制器参数对系统参数敏感的问题，对PI控制器参数进行了自适应调整，根据控制器的输入偏差和输出的大小来调整PI参数，提高了控制器的鲁棒性。针对子模块电容的均压问题，采用了基于排序法的最近电平调制(NLM)均压调制算法，有效地实现了子模块电容电压的平衡。最后，通过Matlab/Simulink平台搭建了5电平的MMC-HVDC系统仿真模型。仿真结果表明了该控制策略的有效性和可行性。

Study of control strategy for MMC-HVDC system based on model predictive control

In order to improve the dynamic response speed of the inner loop of the HVDC transmission system based on modular multilevel converter (MMC-HVDC), a model predictive control method (MPC) for MMC-HVDC system is proposed. In this method, the optimal control voltage is obtained by predicting model, feedback correction and rolling optimization. MPC overcomes the problem of PI parameter tuning difficulties and slow dynamic response of traditional double closed loop control. In view of the outer loop PI controller parameters on the system sensitivity problem, the parameters of PI controller are adjusted adaptively. The robustness of the controller is improved by adjusting the PI parameters according to the input error and the output of the controller. In order to realize the voltage balance between sub module capacitor, the NLM voltage balance modulation algorithm based on the ranking method is adopted to realize the capacitor voltage balance between the sub modules. At last, the simulation model of 5 levels MMC-HVDC system is built on Matlab/Simulink platform. The simulation results show the effectiveness and feasibility of the proposed control strategy. This work is supported by Fundamental Research Funds for the Central Universities (No. 2682014CX028).