Generalized droop-based control for an islanded microgrid

This paper demonstrates a hierarchical control approach, comprising primary and secondary controllers, for islanded microgrids. At the primary level, each Distributed Generation (DG) unit adopts a generalized communication-less droop-based primary controller, which allows the connected DGs to autonomously share the total microgrid load in proportion to their capacities. Furthermore, the droop controllers apply an advanced scheme, based on the DGs' line impedances, to decouple the active- and reactive-powers of each DG for enhanced performance. Moreover, a decentralized communication-based secondary controller is implemented to restore the deviated microgrid's voltage magnitude and frequency, due to droop-controls, to their nominal values. A test microgrid is implemented in PSCAD/EMTDC to verify the presented hierarchical control scheme. The simulation results show that the presented controllers successfully achieve the control objectives while maintaining stable system operation under various disturbances.