两电平并网逆变器模型预测电流控制策略研究

Research on Model Predictive Current Control Strategy of Two-Level Grid-Connected Inverter

对于并网逆变器传统的电流闭环控制存在PI参数调节对系统性能影响较大、设计复杂、追踪精度不高等问题,介绍了一种模型预测电流控制方法。该方法是在dq坐标系下建立电流预测模型,首先采样当前的并网电流值经旋转变换后预测下一时刻的并网电流,再构建价值函数选择最优电压矢量,当价值函数最小时,选择的电压矢量最优,最后将该电压矢量所对应开关状态作用于逆变器。对传统电流闭环控制和模型预测电流控制进行详细介绍,再通过Matlab/Simulink搭建仿真模型进行分析,结果显示两种控制都可以实现并网运行,畸变率满足要求,但是模型预测电流控制更为简单,追踪精度更高,响应更快,稳定性更好。

For the traditional current closed-loop control of grid-connected inverters,PI parameter adjustment has great influence on system performance,complex design and low tracking accuracy.A model predictive current control method is introduced.The method is to establish a current prediction model in the dq coordinate system.First,the current grid-connected current value is sampled and rotated to predict the grid-connected current at the next moment and then the value function is selected to select the optimal voltage vector.When the value function is minimum,the selected voltage vector is optimal and finally the switching state corresponding to the voltage vector is applied to the inverter.The traditional current closed-loop control and model predictive current control are introduced in detail and then the simulation model is built by Matlab/Simulink.The results show that both controls can be connected to the grid.The distortion rate meets the requirements,but the model predicts the current control is simpler which has higher tracking accuracy,faster response,and better stability.