基于双二阶滤波器的LCL型并网逆变器延时补偿方法OA北大核心CSTPCD

To attenuate the LCL filter resonance peak,capacitor-current-feedback active damping is widely used in an LCL-type grid-connected inverter.Because of the adverse effect introduced by the digital control delay,the performance of capacitor-current-feedback active damping significantly deteriorates.The negative damping region appears from s/6f to s/2f.This weakens the stability and robustness of the grid-connected inverter against the grid impedance variation.A biquad filter is adopted to insert into the capacitor-current-feedback path to compensate for the phase-lag resulting from the digital control delay.The positive damping region can be expanded to s/3f,thus achieving high robustness against grid impedance variation.The proper discrete method is chosen and the system stability after compensation is analyzed.Also,a detailed close-loop parameter design procedure is presented to obtain better control performance.Finally,experimental results are provided to verify the effectiveness of the proposed method and the feasibility of the parameter design procedure.