  The need for larger-scale fast-charging electric vehicle (EV) hubs is on the
rise due to the growth in EV adoption. Another area of power infrastructure
growth is the proliferation of independently operated stand-alone battery
storage systems (BSS), which is fueled by improvements and cost reductions in
battery technology. Many possible uses of the stand-alone BSS are being
explored including participation in the energy and ancillary markets, load
balancing for renewable generations, and supporting large-scale load-consuming
entities like hospitals. In this paper, we study a novel usage of the
stand-alone BSS whereby in addition to participating in the electricity reserve
market, it allows an EV hub to use a part of its storage capacity, when
profitable. The hub uses the BSS storage capacity for arbitrage consequently
reducing its operating cost. We formulate this joint operation as a
bi-objective optimization model. We then reformulate it into a second-order
cone Nash bargaining problem, the solution of which guarantees fairness to both
the hub and the BSS. A sample numerical case study is formulated using actual
prices of electricity and simulated data for the reserve market and EV charging
demand. The Nash bargaining solution shows that both participants can benefit
from the joint operation.
