模块化多电平有源电力滤波器误差反馈模型预测控制策略

Modular Multilevel Active Power Filter Error Feedback Model Predictive Control Strategy

有源电力滤波器(active power filter, APF)应用在高电压大容量场合需要采用模块化多电平换流器(modular multilevel converter, MMC)结构,然而,由于系统阻抗等参数与实际参数存在偏差,导致传统模型预测控制(model predictive control, MPC)输出预测值失去最优性,最终影响MMC-APF补偿效果。为此,针对MMC-APF提出一种误差反馈模型预测控制策略,通过结合MPC与电压排序算法将每个控制周期开关状态计算量从C2NN次降低至N+1次,并分别设计输出补偿谐波控制、环流抑制以及子模块电容能量均衡控制的评价函数,同时引入误差反馈对预测值进行修正,降低了预测值与输出值之间的稳态跟踪误差,从而提高了网侧电流谐波补偿效果,并实现对环流的有效抑制以及子模块电容能量均衡。在Matlab/Simulink仿真平台进行了验证,仿真实验结果表明:采用所提控制策略,MMC-APF能够将网侧电流谐波含量由27.6%降至0.2%,证明了所提控制策略的正确性及有效性。

The application of an active power filter(APF)at high voltage and large capacity requires the use of a modular multilevel converter structure(MMC).However,owing to the deviation of the system impedance and other parameters from the actual parameters,the predicted output value of the traditional model predictive control(MPC)loses its optimality,which ultimately affects the compensation effect of the MMC-APF.Therefore,this paper proposes an error feedback model predictive control strategy for MMC-APF.Combining the MPC and voltage sorting algorithms,the calculation amount of the switching state in each control period is reduced fromC2 N N times to N+1 times,and the evaluation functions of the output compensation harmonic control,circulating current suppression,and submodule capacity energy balance control are designed.Simultaneously,error feedback is introduced to correct the predicted value.The steady-state tracking error between the predicted and output values is reduced to improve the harmonic compensation effect of the current at the network side,as well as realize effective suppression of the circulation and capacitive energy balance of the submodules.The simulation results show that MMC-APF can reduce the current harmonic content from 27.6%to 0.2%using the proposed control strategy,proving the correctness and effectiveness of the proposed control strategy.