What are the control challenges and strategies for microgrids?

Microgrids must operate reliably in both grid-connected and islanded modes with potentially high renewable penetration. Control challenges include: frequency/voltage regulation with low inertia, power sharing among inverter-based sources (droop control, virtual synchronous generator), seamless mode transition, and protection coordination for bi-directional flows. Hierarchical control uses: primary (local droop), secondary (frequency/voltage restoration), and tertiary (economic optimization). Energy storage provides fast response and synthetic inertia. Islanding detection must avoid nuisance trips.