Joint Optimization of Transportation-Energy Systems Through Electric Vehicle Charging Pricing in the Morning Commute

We investigate how electric vehicles (EV) market share and EV charging pricing would impact the joint transportation and grid system during the morning commute. Using a simplified network consisting of a single corridor, we analytically derive time-varying flow patterns for both EV and internal combustion engine vehicle (ICV) groups, as a result of travelers’ departure time choices upon travel time, schedule delay and EV charging fee at an arbitrary morning time. For cities with a small or moderate portion of electricity generated from solar, one primary cost for the grid system during the morning commute is power generation ramping in addition to energy cost. By imposing a single charging price change during the morning commute period, we solve for the optimal charging price change time and magnitude to minimize joint system cost. We show that a price increase during morning commute is always preferred. There is a trade-off between transportation and grid costs with respect to when/how grid and transportation infrastructure are utilized by vehicles, particularly electric vehicles. Increasing EV peak charge would increase the grid ramping cost, as more EVs would depart home earlier. However, the same EV peak charge would reduce the transportation cost when the charge is mild or EV penetration is relatively low. When the energy generation ramping is considerable, there always exists an optimal EV peak charge balancing transportation cost and grid cost. We mathematically show the benefits of replacing ICVs with EVs in reducing transportation cost on top of emission/energy reductions, which can be achieved by imposing optimal EV charging prices alone. In addition, we would impose a higher peak charging price during winter for high latitude areas, or areas on the western end of a time zone, as such a price would reduce transportation cost without burdening the grid.