Abstract
To study the system stability of three-phase grid-connected inverter with LCL filter, an impedance modeling method is established in this paper. This model built in the dq-frame considers the phase locked loop, the current control loop and what's more, the decoupling control method. Based on it, the output impedance model with active damping strategy is established. The accuracy of the model is verified by frequency scanning. After that, the Generalized Nyquist Criterion is applied to analyze the influence of controller parameters and the control strategy on the system stability. It is theoretically proved that decoupling control method can improve the system stability and the resonance peak can be restrained after adding active damping strategy. The validity of the model and the theoretical analysis are verified by simulations and experimental results, illustrating that the model proposed in this paper can be well used to analyze the three-phase LCL-type grid-connected inverter with decoupling control method and active damping strategy.
Published Version
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