Study on Optimized Grid Voltage Feedforward Approach with QPR-Based Active Damping

The grid-connected power converter based on LCL topology could effectively restrain the line current harmonic of high-frequency switching, but the third-order structure usually produces resonance, which would lead to system instability. Through grid current feedback along with active damping, the resonance peak in LCL topology can be actively suppressed without adding additional sensors. Due to the reduction of feedback state quantity, the system is prone to oscillation when the grid voltage contains harmonic components, which reduces the anti-interference ability of the power converter. The optimized grid voltage full feedforward approach based on QPR controller with active damping is proposed to decline THD value of grid-connected current under the fluctuation of line voltage, and the experimental results validate the feasibility and correctness, in which the system reaches the unity power factor with well transient performance.