Distributed Fixed-time Control for Islanded AC Microgrids Based on Grid-forming Converters with Time Delay

With the continuous construction of new power systems, it is characterized by a high proportion of renewable energy and high-power electronic products. The grid-forming converters have the advantage of flexibility and controllability, which can provide voltage and frequency support for the new power system with low rotational inertia and weak damping. A model of an islanded AC microgrid (MG) with time-delay based on grid-connected converters is established. Utilizing Artstein transformations, the model is subsequently transformed into a model without any delays. Then, considering the problem of communication link disturbance and information delay, a distributed fixed-time controller (DFTC) for the islanded AC MG based on the grid-forming converters is proposed. The proposed strategy can guarantee that the frequency and voltage are restored to its rated value and accurate power allocation is gained within a fixed time. Furthermore, the fixed-time stability of the proposed method is analyzed using the Lyapunov stability principle and the fixed-time theorem. Finally, the effectiveness and excellent performances of the DFTC strategy are verified by MATLAB/Simulink simulation.