用于改善VSG频率响应的模型预测控制方法

MPC Control Method for Improving VSG Frequency Response

针对虚拟同步发电机(virtual synchronous generator,VSG)控制策略存在二次调频能力不足的问题,提出一种基于模型预测控制(model predictive control,MPC)的VSG反馈控制方法。该方法首先通过转子运动方程和下垂控制方程建立了VSG的可优化模型,并对该模型进行离散化;再利用MPC得到转子角频率的运动轨迹,取最优的预测控制输入向量的第1项作为下一时刻控制器的反馈输入;然后通过构建的转子角频率增量与转矩增量间的反馈通道,对频率偏差进行实时预测补偿;同时通过分析反馈控制器参数对系统稳定性的影响,给出参数选取的基本原则;最后,基于MATLAB/Simulink构建的含所提反馈控制器的逆变器离/并网的仿真模型。与3种现有的方法进行仿真对比分析,结果表明所提出的方法能更有效地抑制频率越限,减少频率的恢复时间,验证了该方法的有效性和可行性。

To improve the existing virtual synchronous generator(VSG)control strategy,a model predictive control(MPC)based on feedback control method is proposed in this paper.In this method,the optimized model of VSG is firstly established by rotor motion equation and droop control equation,and the model is discretized.Then,the motion trajectory of rotor angular frequency is obtained by using MPC,and the first term of the optimal predictive control input vector is taken as the feedback input of the controller at the next time.Thirdly,a feedback channel between the rotor angular frequency increment and torque increment is constructed to compensate the frequency deviation in real time.At the same time,the influence of feedback controller parameters on system stability is analyzed,and the basic principle of parameter selection is given.Finally,the simulation model of the inverter with the feedback controller proposed in this paper based on the MATLAB/Simulink is compared with three existing methods.The results show that the method proposed in this paper can be adopted to more effectively restrain the frequency out-of-limit and reduce the frequency recovery time,which verifies the effectiveness and feasibility of this method.