Cluster-Type Photovoltaic Inverter Resonance Suppression Method Based on Adaptive Notch.

Due to the non-negligible impedance of the long-distance transmission line, the string-type photovoltaic inverter cluster system will resonate with the impedance of the grid in the weak grid. Aiming at this problem, a resonance suppression method based on adaptive notch is proposed. The method firstly designs the traditional notch transfer function as a biquad function, and introduces the adjustment coefficients m1 and m2 to obtain different notch depths and bandwidths. QPR (Quasi-Proportional Resonant) controller is adopted, and the grid impedance observation module is introduced, the impedance of each inverter side and QPR controller parameters are adjusted in real time and the calculated resonance frequency is fed back to the notch frequency. The resonance peak is eliminated, and the system resonance is effectively suppressed. Finally, the correctness and effectiveness of the proposed method are verified by Matlab/Simulink simulation.