Phase-angle compensation control of LCL-type grid-connected inverter based on impendance analysis

In a weak grid system, grid impedance variations will increase harmonic current of the grid-connected inverter, even system stability will be significantly influenced. This paper establishes the impedance model, the impedance stability criterion is used to analyze the stability of weak grid system with LCL inverter under traditional current control. A phase angle compensation control strategy with capacitor current feedback is proposed, then the phase angle of output impedance of the system is increased, it will improve the stability of grid-connected inverter under weak grid. The simulation results show that the proposed method can effectively solve the instability caused by high grid impedance, the system has good steady-state performance and rapid dynamic response. © 2020, Editorial Board of Acta Energiae Solaris Sinica. All right reserved.