耦合量前馈的并网逆变器解耦控制

Decoupling Control Based on Coupling Feedforward for Grid Connected Inverter

传统的基于同步旋转坐标系的LCL型并网逆变器电流双闭环控制策略,在建立逆变器模型时,直接忽略了d轴和q轴之间的耦合关系。这样会造成系统模型的不准确,影响控制效果,为此提出了一种基于耦合量前馈的解耦策略。在各轴加入其他轴的耦合分量,耦合分量的大小和本轴被控对象实际产生的耦合量大小相等、方向相反。通过这种耦合量前馈补偿的策略最终消除了d、q轴之间的耦合关系,提高了系统控制模型和控制性能的精确性。为了进一步提高系统的控制性能,提出了一种基于频率特性的新型控制器参数设计方法。该方法可以准确计算出内外环控制器的参数,解决了传统控制器参数设计过程中需要反复试凑的问题。MATLAB仿真结果表明,所提出的控制策略取得了良好的解耦效果,并网电流的总谐波失真较小,实现了高功率因素并网。

For LCL grid connected inverter,in traditional current double closed loop control strategy based on synchronous rotating coordinate system,the coupling between d axis and q axis is ignored when the inverter model is established. This will cause the system model being inaccurate, and influence the control effects. Thus, a decoupling control strategy based on feedforward coupling is proposed. The coupling components are added in other axes, the amount of coupling component is equal to the actual coupling component of the controlled object,while the direction is reverse. By this coupling feedforward compensation strategy,the coupling relation between d and q axis is eliminated, so the precision and performance of the system control model are improved. In order to further improve the control performance of the system, a new design method for parameters of controller based on frequency characteristics is put forward. The method can accurately calculate the parameters of the inner and outer loop controllers, and avoid the trouble of repeated process of test and try in traditional design method for controller. The simulation results in MATLAB show that the proposed control strategy reaches good decoupling effect, and the total harmonic distortion （ THD） of grid connected current is smaller,and the grid connected with high power factor can be implemented.