A sliding mode based controller for no inertia islanded microgrids

The papers presents a new concept for controlling voltage and frequency in islanded microgrids composed by a Battery Energy Storage System (BESS) and Photo-Voltaic (PV) Units. The proposed approach is totally decentralized as each source is equipped with a purely local controller and no communication infrastructure is needed. Moreover, a centralized secondary control is not required as the developed local controllers are able to nullify both frequency and voltage errors. Finally, the physical constraints related to BESS power and State Of Charge (SOC) limits are accounted and some theoretical hints are provided to justify why the frequency can be used as a triggering signal for the controllers to switch among the different operation modes even in absence of synchronous machines directly connected to the grid.