Stability analysis of time-delay perturbed microgrids via a critical eigenvalue tracking method

The time delay among neighboring microgrids is inevitable. Besides, the perturbations in the microgrid control process may make the time-delay stability more complicated. In order to consider the stability issues, this paper builds the time-delay dynamic model of microgrids with eigenvalue tracking method. To address the effect of communication delays and perturbations on the frequency stability of the microgrid, an effective frequency domain method called eigenvalue tracking is used. This method accurately determines the stable delay margin and the critical eigenvalue on the imaginary axis of the interconnected time-delay microgrids. It demonstrates that the method is easier to use to obtain accurate delay margins than the Lyapunov stability principle. Finally, a three-zone delayed power system and a multi-zone power system with AC-DC interconnection are used as examples to illustrate the feasibility and superiority of the method.