基于扰动补偿的LCL型并网逆变器无差拍预测电流控制策略

Deadbeat Predictive Current Control Strategy Based on Disturbance Compensation for Grid Connected Inverter With LCL Filter

在对电感–电容–电感(inductive-capacitive-inductive,LCL)型并网逆变器进行模型预测电流控制时,数字延时会引入控制误差,同时,被控对象模型精确程度也会影响预测控制性能。为降低数字延迟影响和预测控制对系统模型变化的敏感度,最终提高LCL型并网逆变器在弱电网并网环境下的运行性能,该文提出一种基于扰动补偿的LCL型并网逆变器无差拍预测电流控制策略。通过采用基于线性插值法的改进型无差拍预测控制策略,降低数字延时带来的控制误差;在弱电网阻抗辨识基础上,设计内模扰动观测器,通过构造李雅普诺夫函数,选择满足系统稳定的自适应增益,以抑制模型失配及测量噪声等扰动量对预测控制性能的影响,并提高逆变器在弱电网环境下运行适应性。最后通过仿真和实验,验证所提策略有效性。

In the model predictive current control of grid connected inverter with an inductive-capacitive-inductive(LCL)filter,the digital delay will introduce control error,and the accuracy of the plant model may also affect the predictive control performance.In order to reduce the impact of digital delay and the sensitivity of predictive control to system model changes,and enhance the output performance of grid connected inverter with LCL filter in the weak grid,a deadbeat predictive current control strategy based on disturbance compensation is proposed.The improved deadbeat predictive control strategy based on linear interpolation is adopted to reduce the control error caused by digital delay.Based on the impedance identification of weak grid,the internal model disturbance observer is designed.The adaptive gain satisfying the stability of the system is selected by constructing Lyapunov function,so as to suppress the influence of disturbance such as model mismatch and measurement noise on the predictive control performance,and thus improve the adaptability of the inverter in weak grid.Finally,theory analysis,simulation,and experimental results are presented to illustrate the effectiveness of the proposed control techniques.