Distributed optimization for the trade-off between state-of-charge balancing and strategic battery usage in a networked BESS

Battery energy storage systems (BESSs) are critical components of microgrids. In this paper, we consider the dynamics of discharging batteries and propose a model for making a trade-off between balancing the state-of-charge (SoC) of battery units in a networked BESS and strategic usage of these battery units. To realize such a trade-off, we formulate an optimization problem that takes the total discharging power requirement and the limitations on individual battery units into account. The dynamics of SoC rely on the solution to the optimization problem. Furthermore, we reformulate the optimization problem in a distributed manner, employing estimators for certain global variables, and analyze the gap between the optimum with global information and the optimum with estimation in the steady state. Our simulation results verify that the trade-off between SoC balancing and strategic usage of battery units can be adjusted by tuning the weighting parameters in the optimization problems.