Economic power transaction using coalitional game strategy in micro-grids

Due to the uncontrollability of renewable energy resources, micro-grids (MGs) often have to exchange excessive or insufficient power with the utility grid in traditional non-cooperative mode. In contrast, power transaction considering direct energy trading between MGs has been considered as a promising method to improve economic efficiency. Specifically, MGs with complementary power surplus or shortage have an incentive to cooperate with each other and perform direct trading due to lower costs and power losses. In this study, the authors focus on comprehensive economic power transaction of the multiple MGs network with multi-agent system. A three-stage algorithm based on coalitional game strategy is proposed consisting of request exchange stage, merge-and-split stage and cooperative transaction stage. The developed algorithm enables MGs to form coalitions, where each MG can exchange power directly by paying a transmission fee. With local power transaction, MGs can minimise their expenditures comprising the generation costs, transmission costs, power losses and load shedding compensation; hence, ensure the cost efficiency of the whole MGs network. Moreover, the implementation of load shedding is discussed and its benefit is demonstrated. Simulation results show that the proposed cooperative scheme significantly reduces the total cost of MGs compared with the non-cooperative method.