A hierarchical framework for generation scheduling of microgrids

The uncertainty and intermittency of renewable energy sources pose a challenge to generation scheduling of microgrids. This paper presents a hierarchical framework to handle the uncertainty and realize an economic generation schedule of microgrids. The lower level combines a battery energy-storage system (BESS) with renewable energy sources, targeting maximal utilization of renewable power and minimal deviation from the schedule, to provide an optimal generation plan in the day-ahead market. The upper level minimizes the total cost of the microgrid by the genetic algorithm (GA) to yield an economic generation plan of dispatchable distributed generators (DGs) based on the lower level. Two stages of such hierarchical scheduling before and in the day gradually reduce the uncertainty, and lead the overall schedule to evolve toward a stable and economic one. The method is tested on a 14-bus microgrid system. The simulation indicates that the wind turbine and photovoltaic are gradually stabilized by BESS Besides, the operation is scheduled economically, and cheap DGs are always arranged in priority.