Analysis of Active Damping Stability for LCL Grid-Tied Inverter in a Multiloop Current Control Strategy

This work shows the stability analysis of capacitor current feedback active damping for grid-tied inverters with LCL filter in a multiloop current control strategy. The inverter-side current is controlled by Gao's based sliding mode reaching law. The resulting outer loop is formed by a CL filter which has a resonance peak. To damp this resonance, capacitor current feedback is used in the reference of the inner loop current. Jury's stability criteria are used to define a region of stability for the active damping gain for different values of the sampling over the natural frequency. Modelica simulations were carried out to verify the behavior of the model. Also, experiments were performed in a real prototype to validate de theoretical stability analysis provided.