A Connectively Stable and Robust DAPI Control Scheme for Islanded Networks of Microgrids

The transition towards clean energy and the introduction of Distributed Energy Resources (DERs) are giving rise to the emergence of Microgrids (MGs) and Networks of MGs (NMGs). MGs and NMGs can operate autonomously in islanded mode. However, they face challenges in terms of secondary level frequency and voltage regulation, due to the variable nature of Renewable Energy Sources (RES) and loads. Distributed-Averaging Proportional-Integral (DAPI) control has been proposed in the literature for distributed frequency and voltage control of droop-controlled DERs, but it is not robust to operational or structural perturbations. To address this, we propose a robust DAPI frequency and voltage control scheme that ensures robustness using the concept of connective stability, along with the invariant ellipsoid technique for disturbance rejection. Simulation of an NMG model in MATLAB\textsuperscript{\textregistered}/Simulink\textsuperscript{\textregistered} consisting of 3 MGs and 5 DERs validates the effectiveness of the proposed method, and demonstrates that it can successfully mitigate the effects of major disturbances such as cyberattacks.