Distributed Hybrid Power-Sharing Control Strategy within Islanded Microgrids

The stable operation of an islanded microgrid powered by multiple distributed energy sources (DESs) depends on the control of the voltage magnitude, the frequency and the power-sharing among the DESs. Uncontrolled power-sharing among sources can lead to voltage and frequency stability issues characterized by poorly damped oscillations. To achieve efficient power-sharing, a level-one control strategy is required. This paper proposes a communication-less hybrid control strategy to implement power-sharing regardless of the inverter output impedance. In this strategy, the power-sharing control is achieved with the inverters in both grid-forming and grid-following control modes - in particular, for the sources interfaced with rotating machines. Simulation results show that the instantaneous power-sharing is correctly carried out while maintaining the RMS voltage at the required value. Furthermore, the voltage drops remain within the 10% admissible range.