说明：  提出了一种基于电网电流反馈内环和重复控制外环的双闭环控制策略。利用数字控制固有的一拍延时特性，设计了控制系统内环，实现LCL 滤波器的稳定控制；根据内环闭环传递函数特性，设计了相应陷波器、二阶滤波器以及超前环节作为控制系统外环；同时，引入了给定前馈和电网电压前馈控制环节来抑制电网电压对系统的影响，以增强系统的动态性能。理论分析和实验结果表明，该方法使LCL 型并网逆变器具有稳态精度高、动态性能好以及抗干扰能力强的优点。
(the repetitive dual closed-loop control strategy based on grid current feedback was proposed in this paper. The LCL filter was stable due to effective utilization of inherent one-beat delay of digital control. Based on the inner closed-loop transfer function, the corresponding notch filter, the second-order filter and lead-link were designed as a compensator of epetitive control. The gird voltage and current reference feed-forward control suppressed grid disturbance and increased dynamic tracking performances. Theoretical analysis and experimental results show that, the proposed method has the advantages of high steady accuracy, fast dynamic response and strong robustness.)