Energy Management System with Stability Constraints for Stand-alone Autonomous Microgrid

This paper presents an energy management system (EMS) for a stand-alone droop-controlled microgrid, which adjusts generator outputs to minimize fuel consumption and also ensures stable operation. It has previously been shown that droop gains have a significant effect on stability in such microgrids. Approximate relationships between these parameters and stability margins are therefore identified, using qualitative analysis and small-signal techniques. This allows them to be selected to ensure stability. Optimized generator outputs are then implemented in real-time by the EMS, through adjustments to droop characteristics within this constraint. Experimental results from a laboratory-sized microgrid confirm the EMS function.