The current-controlled grid-connected inverter with LCL filter is widely utilized in the distributed power generation systems at remote places with weak grids. Oscillations in weak grids have raised the stability issue in grid-tied inverter systems, and the quality of the injected power into the grid is highly affected by the variations of grid-side inductance. In this study, a multi-loop control has been applied in the LCL-type grid-connected inverter based on capacitor current feedback control method. Computational delays in the control unit can remarkably influence the damping capability of this method. The accuracy of the modeling has been increased by considering the computational delays of the capacitor current active damping inner loop as well as the grid current outer loop. The impact of the computational delay is eliminated by the proposed approach, and the performance of the control system has been remarkably enhanced. The harmonic attenuation of the grid voltage has been improved by utilizing virtual series and parallel impedances, which leads to strong stability-robustness and high harmonic-rejection-ability even in severe variations of the grid-side inductance. Simulation results verify the credibility of the proposed approach, and the quality of the injected power is proved to be improved in a weak and harmonically distorted grid.

具有LCL滤波器的电流控制并网逆变器被广泛用于电网较弱的偏远地区的分布式发电系统中。弱电网中的振荡引起了并网逆变器系统的稳定性问题，并且注入到电网中的电能的质量在很大程度上受到电网侧电感变化的影响。在这项研究中，基于电容器电流反馈控制方法，在LCL型并网逆变器中应用了多回路控制。控制单元中的计算延迟会显着影响此方法的阻尼能力。通过考虑电容器电流有源阻尼内环路以及电网电流外环路的计算延迟，可以提高建模的准确性。所提出的方法消除了计算延迟的影响，并且控制系统的性能得到了显着提高。通过利用虚拟的串联和并联阻抗，改善了电网电压的谐波衰减，即使在电网侧电感发生严重变化的情况下，也可以实现强大的稳定性，鲁棒性和高谐波抑制能力。仿真结果验证了该方法的可靠性，并证明了在弱且谐波畸变的电网中注入功率的质量得到了改善。即使在电网侧电感发生严重变化的情况下，也具有很强的稳定性，鲁棒性和高谐波抑制能力。仿真结果验证了该方法的可靠性，并证明了在弱且谐波畸变的电网中注入功率的质量得到了改善。即使在电网侧电感发生严重变化的情况下，也具有很强的稳定性，鲁棒性和高谐波抑制能力。仿真结果验证了该方法的可靠性，并证明了在弱且谐波畸变的电网中注入功率的质量得到了改善。