Loadability Improvement of Unbalanced Hybrid AC-DC Microgrids Using a Supervisory Control Scheme for Interlinking Converters

This paper proposes a supervisory control scheme for hybrid AC-DC microgrids to enhance the system loadability under unbalanced loading conditions by implementing a new power routing mechanism for AC/DC converters. The system is studied on grid-connected mode and the supervisory control strategy is aimed to maximize the system loadability at the point of common coupling (PCC). The supervisory control receives the measurements from the PCC and calculates active and reactive power mismatches for all three phases. Afterward these mismatches are assigned to all three-phase interlinking converters (ICs) to keep the power balance at the PCC. Balancing the three-phase loadings at the PCC not only enhances the system loadability index, but also decreases voltage deviations and energy losses in the microgrid. Numerical results obtained by implementing the proposed method on the modified IEEE 13 bus system show the validity of the proposed control strategy.