T型三电平并网逆变器有限集模型预测控制快速寻优方法

Finite Control Set Model Predictive Control Method with Fast Optimization Based on T-Type Three-Level Grid-Connected Inverter

三电平变流器控制系统采用有限集模型预测控制(FCS-MPC),滚动优化需要遍历所有开关状态,针对其导致处理器运算量增加、处理时间长的问题,提出一种T型三电平并网逆变器优化计算量的FCS-MPC方法。通过构建基于电压预测的单目标代价函数,避免设计权重系数问题,减化单次寻优的步骤;根据直流母线电位分布选择冗余小矢量,实现中点电位平衡,使每个控制周期的预测次数减小至3次,提高寻优效率。有限控制集在预测过程中将所包含矢量的加权误差二次方最小作为依据划分,并利用矢量角补偿系统延迟,提高预测精度,使并网电流质量得到改善。搭建基于RT-Lab的功率硬件在环仿真系统和物理装置验证所提控制策略,实验结果验证了所提理论分析的正确性和控制策略的有效性。

Rolling optimization of Finite Control Set model predictive control(Finite Control Set-MPC,FCS-MPC)needs to traverse all the switch states in the three-level converter control system,which will cause the problems of increased processor calculation and long processing time.For this reason,this paper proposes a FCS-MPC method with optimized calculation amount of T-type three-level grid-connected inverter.By constructing a single objective cost function based on voltage prediction,the design of weighting factor is avoided and the steps of single optimization are reduced.For improving the efficiency of optimization,the redundant small vector is selected according to the DC bus potential distribution to balance the neutral-point potential and reduce the number of predictions per control cycle to 3 times.The finite control set is divided according to the minimum weighted error square of the included vectors in the prediction process,and the vector angle is used to compensate the system delay,thereby improving the prediction accuracy and the grid-connected current quality.A power hardware-in-the-loop simulation system based on RT-Lab and a physical device are established to verify the proposed control strategy.The results show that the proposed theoretical analysis is correct and the control strategy is effective.