LCL Grid-Connected Inverter Resonance Feedforward-Active Damping Hybrid Control Strategy for Mitigating Weak Grid Resonance and Harmonic Currents

In weak grid inverter grid-connected systems, the presence of grid impedance and voltage harmonic disturbances can cause distortion in the grid-connected current. While traditional voltage full-feedforward methods reduce steady-state error, they compromise current quality and may even threaten system instability. To address these issues, an improved grid voltage feedforward approach is proposed. This involves incorporating resonant feedforward into the feedforward channel to counteract grid impedance effects while preserving the system’s open-loop gain, increasing system margin, and enhancing stability. Additionally, the Proportional–Integral (PI) controller is modified to an active damping method using quasi-proportional resonant and harmonic compensation controllers. This enhances harmonic suppression while reducing sensor usage. Finally, the effectiveness of the proposed control strategy was validated through simulation experiments and a hardware-in-the-loop simulation platform based on RT-LAB.