Fractional‐Order Sequence Impedance Modelling and Stability Assessment of Grid‐Connected Virtual Synchronous Generators

ABSTRACT In this study, a sequence impedance model for a virtual synchronous machine (VSG) grid‐connected inverter that incorporates fractional‐order characteristics of real inductive and capacitive components was developed, utilising the harmonic linearisation method. The model's accuracy was validated through simulation. The impact of altering the sequence of the inductor and capacitor on the impedance characteristics was further examined, system's stability was assessed using the generalised Nyquist criterion. The outcomes of hardware‐in‐the‐loop studies indicate that the fractional‐order features of the components influence the stability of the VSG grid‐connected system. In the interim, the parameter‐optimised fractional‐order model exhibited superior stability compared to the integer‐order model.