  High penetration of distributed energy resources (DERs) is transforming the
paradigm in power system operation. The ability to provide electricity to
customers while the main grid is disrupted has introduced the concept of
microgrids with many challenges and opportunities. Emergency control of
dangerous transients caused by the transition between the grid-connected and
island modes in microgrids is one of the main challenges in this context. To
address this challenge, this paper proposes a comprehensive optimization and
real-time control framework for maintaining frequency stability of
multi-microgrid networks under an islanding event and for achieving optimal
load shedding and network topology control with AC power flow constraints. The
paper also develops a strong mixed-integer second-order cone programming
(MISOCP)-based reformulation and a cutting plane algorithm for scalable
computation. We believe this is the first time in the literature that such a
framework for multi-microgrid network control is proposed, and its
effectiveness is demonstrated with extensive numerical experiments.
