Model-Reference Adaptive Damping: Enhancing the Resilience of Grid-Forming Inverters Under Uncertain Grid Conditions

Uncertainties can present significant challenges for the resilient operation of grid-forming (GFM) inverters, particularly affecting virtual synchronous generators (VSGs) due to their inherent oscillatory behavior and vulnerability to grid contingencies and variations in grid strength. This study introduces a resilient damping method, termed model-reference adaptive damping (MRAD), designed for VSGs to effectively address these grid uncertainties. The approach dynamically shapes the VSG response by utilizing a reference model that represents the desired dynamic behavior. The influence of grid impedance on the VSG's dynamic response is examined through eigenvalue analysis, and the adaptive law for the proposed MRAD is formulated based on Lyapunov stability theory. In addition, a robust modification of the MRAD is introduced to enhance its performance under conditions of high adaptation rates. Frequency-domain analysis is performed to further validate the dynamic shaping of the VSG response across varying grid strengths. Finally, simulation results and real-time experiments confirm the effectiveness of the proposed method in dynamically shaping the VSG response under uncertain grid conditions and diverse disturbances.