Planning of Energy Storage Systems in Unbalanced Microgrids

This paper proposes a planning technique aimed at optimally sizing and locating distributed storage devices in an unbalanced low voltage microgrid. The planning procedure is formulated in terms of a mixed, non linear, constrained optimization problem: the objective function to be minimized is the cost sustained for the energy provision and for the inclusion of the storage resources while the equality/inequality constraints guarantee the correct operation of the components and of the grid. The problem of unbalances is also dealt with by imposing a maximum unbalance factor value to all of the grid busbars' voltage. The results of numerical applications are shown to validate the proposal.