Joint operation of a fast-charging EV hub with a stand-alone independent battery storage system under fairness considerations

The need for large-scale fast-charging hubs for electric vehicles (EVs) is on the rise due to the growth in their adoption. Another growth area for power infrastructure is the independently operated stand-alone battery storage systems (BSS). This is fueled by the improvements in battery technology and the associated cost reductions. Many possible uses of the stand-alone BSS are being explored in the literature. These include participating in the energy and ancillary electricity markets, load balancing for renewable generation, and supporting supply continuity for large-scale load-consuming entities like hospitals. Our study presents a novel business case for a stand-alone BSS, which, in addition to capacity bidding in the electricity reserve markets, also allows EV hubs to use a part of its storage capacity. Hubs buy power from day-ahead and real-time electricity markets while also using the BSS storage capacity for arbitrage. We formulate this joint cooperative operation as a bi-objective optimization model. The model is reformulated into a second-order cone Nash bargaining problem, the solution of which guarantees fairness in cooperation for both the hub and the BSS. A sample numerical case study is formulated using actual prices of electricity from the ERCOT market, and simulated data for the electricity reserve market and EV charging demand. The Nash bargaining solution shows that both the BSS and the hub can fairly distribute among themselves the added benefit of joint operation.