Impact of unit commitment on the optimal operation of hybrid microgrids

This paper presents an energy management system to minimize the total combined operational and emission costs of a hybrid microgrid by optimal scheduling of the operating time of distributed generators and power exchange between the battery storage system and the utility grid. The impacts of unit commitment on the optimal operation of the hybrid microgrid are evaluated by formulating and solving the optimization problem using mixed integer quadratic programming technique. Both grid-connected and isolated modes on the hybrid microgrid, which comprises of a combination of distributed generators, renewable energy resources, storage batteries, and a variety of loads, are investigated. Realistic constraints and battery degradation are also factored into the optimization. The results show comprehensively that incorporation of the unit commitment into the optimization problem typically reduces the total operational and emission costs for both isolated and grid-connected modes. In addition, it helps to increase the penetration of renewable energy resources with microgrid.