Spatial and temporal online charging/discharging coordination for mobile PEVs

Coordinated charging is an effective charging plan for PEVs to improve the overall system energy utilization and prevent the overload of an electric power grid. On the other hand, PEVs, which have energy storage and controllable loads, can be discharged to help the grid to smooth the fluctuations, for example, introduced by distributed generators (DGs). Either to prevent overloading or to regulate the power grid, most existing charging/discharging plans focus on temporal charging/discharging coordination for parked vehicles. However, for moving vehicles, spatial coordination can also bring benefits to the grid. For spatial coordination, the range anxiety problem should be carefully handled, since PEVs cannot reach some charging stations due to the limited battery levels. In this article, by exploiting both spatial and temporal coordinations, we introduce an online PEV charging/discharging strategy considering range anxieties. To collect real-time information for the proposed online strategy, a heterogeneous wireless infrastructure is proposed by integrating cellular networks with vehicular ad-hoc networks (VANETs). Challenging issues are discussed in terms of modeling PEV mobility, network selection for real-time information delivery, balancing the trade-off between the grid power utilization and drivers' preferences, and modeling business revenues for charging/discharging. Case studies demonstrate that joint spatial and temporal charging coordination can effectively improve power utilization and avoid overloading the power grid.