Stability Analysis and Design of Islanded Microgrids Integrating Pinning-Based and Consensus-Based Distributed Secondary Control

In this article, the impact of pinning-based and consensus-based distributed secondary control on the stability of islanded microgrids is studied. A nonlinear model of the islanded microgrid is first established, incorporating the voltage-loop dynamics and communication delay. Using this model, the influence of the secondary control on the microgrid's dynamical behavior is explored, and in particular, the improved robustness and stability contributed by the voltage-increment-based secondary control is highlighted. Besides, the effects of the topology of communication networks and the selection of driver controllers on the system stability are revealed, and such effects are quantitatively measured by the algebraic connectivity and the conditional number. Moreover, small-signal models and the corresponding loop gains are derived for expediting the selection of suitable secondary control parameters. Furthermore, a design procedure of the distributed secondary control system is demonstrated. Finally, analytical findings are verified by cycle-by-cycle full-circuit simulations and laboratory experiments.