Hierarchical droop controlled frequency optimization and energy management of a grid-connected microgrid

This paper proposes a frequency security based Energy Management System (EMS) for a hierarchically controlled grid-connected microgrid. The centralized hierarchical EMS is based on precise energy scheduling of droop controlled inverter interfaced Distributed Energy Resources (DERs). A Latin Hypercube Sampling based methodology is applied to model the uncertainties caused by Renewable Energy Sources (RESs), load deviations, and DERs. Simulations are performed on a microgrid in a grid-connected mode. The results verify the effectiveness of considering droop controlled inverter interfaced DERs in preserving the frequency in a hierarchical energy management system. Using this approach, unpredicted changes in the power output of RESs are controlled and microgrid frequency security is satisfied.