Optimal Power Flow in three-phase islanded microgrids with inverter interfaced units

In this paper, the solution of the Optimal Power Flow (OPF) problem for three phase islanded microgrids is studied, the OPF being one of the core functions of the tertiary regulation level for an AC islanded microgrid with a hierarchical control architecture. The study also aims at evaluating the contextual adjustment of the droop parameters used for primary voltage and frequency regulation of inverter interfaced units. The work proposes a mathematical method for the OPF solution also considering the droop parameters as variables. The output of the OPF provides an iso-frequential operating point for all the generation units and a set of droop parameters for primary regulation. In this way, secondary regulation can be neglected in the considered hierarchical control structure. Finally, the application section provides the solution of the OPF problem over networks of different sizes and a stability analysis of the microgrid system using the optimized droop parameters, thus giving rise to the optimized management of the system with a new hierarchical control architecture