Microgrid/Macrogrid Energy Exchange: A Novel Market Structure and Stochastic Scheduling

This paper explores the stochastic scheduling of microgrids where energy exchange with the macrogrid must be coordinated ahead of time. In particular, a market structure is proposed in which microgrid operators make day-ahead energy exchange commitments. Microgrids are fined for deviating too far from commitments and a maximum difference between commitments in subsequent hours is enforced. These constraints are included to reduce the burden placed on the macrogrid by distributed generation. Under this market structure, a scheduling problem is formulated for a microgrid system consisting of microturbines, a photovoltaic array, a battery bank, and a bi-directional connection to the macrogrid. Chance-constrained optimization is used to minimize operational cost and ensure the energy exchange commitments are met. The problem is transformed into a mixed integer linear program, and is solved to show that these commitments can be satisfied with a high level of certainty and to illustrate inherent tradeoffs between microgrid performance and level of regulation.