Sizing of energy storage system for microgrids

This paper presents a new method for optimal sizing of an energy storage system (ESS) in a microgrid (MG) for storing electrical/renewable energy at the time of surplus and for re-dispatching. The unit commitment problem with spinning reserve for MG is considered in this new method. The total cost function, which includes the cost of ESS, cost of output power and cost of spinning reserve, is introduced. The effectiveness of the approach is validated by a case study where the optimal ESS rating for MG is determined. The quantitative results show that the ESS with an optimal size is not only storing renewable energy and re-dispatching it appropriately, but also saving the the total cost for MG. The main method is formulated as a mixed nonlinear integer problem (MNIP), which is solved in AMPL (A Modeling Language for Mathematical Programming).