Optimal Energy Management of Unbalanced Three-Phase Grid-Connected Microgrids

This paper presents a non-linear optimization problem based on nodal current injections to solve the optimal energy management of unbalanced, three-phase, grid-connected microgrids. The focus is on the modelling of small synchronous machines under unbalanced operation. Inverter-interfaced distributed energy resources, i.e., renewable sources and energy storage systems, are also considered and described. The proposed formulation minimizes the cost of the energy consumed by the microgrid while satisfying active and reactive power balances, the devices operational constraints, as well as current and voltage operational limits. The proposed model is tested using the IEEE 123 node test feeder and compared to commonly used formulations. Simulation results show the impact of unbalanced models on the energy management of three-phase microgrids.