Optimal scheduling of a storage device in a grid-connected microgrid using stochastic chance-constraint optimization

This paper is concerned with off-line optimal control of an energy storage device in a grid-connected microgrid with the objective of minimizing the user electricity cost. The electricity prices and the microgrid net electricity demand, i.e. the difference between load any renewable generation, are assumed to be subject to uncertainties with known probabilistic distributions. A stochastic chance constraint optimization problem is formulated and solved off-line to determine optimal charge/discharge scheduling of the storage device. The objective function of the optimization problem is the expected value of the electricity cost and its constraints are of both deterministic and probabilistic nature. Deterministic convex nonlinear optimization formulations are derived which are equivalent to the original stochastic optimization problem, for two cases of uncertainties with normal and uniform distributions. These equivalent problems can be effectively solved using standard optimization algorithms to obtain an exact solution. Simulation results demonstrate the effectiveness of the proposed energy storage control methodology.