Shanxi Key Laboratory of Mining Electrical Equipment and Intelligent Control, Taiyuan University of Technology, Taiyuan, 030024, China; Taiyuan University of Science & Technology, Taiyuan, 030024, China.
Shanxi Key Laboratory of Mining Electrical Equipment and Intelligent Control, Taiyuan University of Technology, Taiyuan, 030024, China.
ISA Trans. 2018 Mar;74:194-208. doi: 10.1016/j.isatra.2018.01.029. Epub 2018 Feb 3.
Grid-connected inverters with LCL filters need high steady-state control accuracy, fast dynamic response performance, and strong robustness to guarantee the power quality. However, there are many problems in traditional control strategies that restrict improvements to control system performance, such as poor dynamic performance of traditional single-repetitive control, large ripples, low steady-state accuracy of inverter current feedback based repetitive dual-loop control or grid-current feedback based single-loop proportional-integral control. In this paper, a novel dual closed-loop repetitive control strategy based on grid current feedback is proposed for single-phase grid-connected inverters with LCL filters. The proportional-integral inner loop is stabilized by using an inherent one-beat delay achieved by digital controller. Based on the inner loop system, a detailed design scheme of a repetitive controller is presented, through which direct control of the grid current is realized, the reference is tracked perfectly to a zero phase shift, and high-attenuation gain is achieved in the high frequency range. In particular, the gird-voltage feed forward control and current reference feedforward control are adopted to suppress grid-voltage disturbance and increase dynamic tracking performance. Finally, the simulation and experimental results show that the proposed method has the advantages of high steady-state accuracy, fast dynamic response, and anti-disturbance ability.
具有 LCL 滤波器的并网逆变器需要高稳态控制精度、快速动态响应性能和强鲁棒性，以保证电能质量。然而，传统控制策略存在许多问题，限制了对控制系统性能的改进，例如传统单重复制控制的动态性能差、电流反馈重复双环控制的纹波大、基于电网电流反馈的单环比例积分控制的稳态精度低。本文针对具有 LCL 滤波器的单相并网逆变器，提出了一种基于电网电流反馈的新型双闭环重复控制策略。数字控制器固有的一拍延迟稳定了比例积分内环。基于内环系统，提出了重复控制器的详细设计方案，通过该方案实现了对电网电流的直接控制，完美跟踪参考值，实现了在高频范围内的高衰减增益。特别是，采用电网电压前馈控制和电流参考前馈控制来抑制电网电压干扰，提高动态跟踪性能。最后，仿真和实验结果表明，所提出的方法具有稳态精度高、动态响应快和抗干扰能力强的优点。
