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Shadow price based co-ordination methods of microgrids and battery swapping stations

Wang, Yang, Lai, Kexing, Chen, Fengyun, Li, Zhengming, Hu, Chunhua
Applied energy 2019 v.253 pp. 113510
algorithms, batteries, cost effectiveness, electric vehicles, equations, infrastructure, linear programming, market share, models, operating costs, prices, transportation
The growing market share of electric vehicles embodies the remarkable progress of transportation electrification. Battery swapping station serves as a critical infrastructure for efficient electric vehicles refueling. To coordinate the scheduling of a battery swapping station and a microgrid managed by non-cooperative entities, we develop two shadow price-based coordination methods, namely peer-to-peer method and leader-follower method. The context is of great importance for mitigating potential barriers of integration of battery swapping stations and microgrids. The peer-to-peer method only requires the exchange of individual shadow price and power trading requests between two entities. This mechanism is the first-of-its-kind solution that allows for co-ordination between two systems without releasing proprietary information. An iterative heuristic algorithm is developed to obtain outcomes of the co-ordination mechanism. For the leader-follower method, microgrid entity gets access to proprietary information of battery swapping station that is managed by an independent entity. A bi-level optimization model is developed to model the gameplay between two non-corporative entities, which is solved by a modified nested column-and-constraint generation algorithm. For both methods, we use an AC optimal power flow model to optimize operation of microgrid while battery swapping station operation is determined by a mixed-integer linear programming model. This work is also the first-of-its-kind study that incorporates AC power flow equations into relevant research. We demonstrate the effectiveness of both methods using an integrated system comprising a standard IEEE 33-bus system and a battery swapping station serving multiple private electric sedans or public electric buses. Nearly 10% of total operational cost saving can be attained if the proposed methods are applied for coordinating two systems, compared to implementing a baseline method.