Load Leveling Utilizing Electric Vehicles and their Used Batteries

The increase of electric vehicles (EVs) has led to some challenging problems and opportunities, especially related to electricity issues. The uncontrolled charging and discharging of EVs can reduce the quality of electricity grid due to frequency and voltage instabilities. However, the optimized utilization of EVs also offers high potential for ancillary service including frequency control and storage. The adoption of EVs and used EV batteries is expected to be able to improve the total economic performance of EVs as well as reduce the environmental impact. In this chapter, the utilization of EVs, together with their used batteries, to support the electricity (load leveling) in a small-scale energy management system (EMS) is analyzed and demonstrated. The demonstration bed consists of five EVs, five used EV batteries, and photovoltaic (PV) panels. The EMS forecasts the load of the office building and the possibly generated power from PV panels. In addition, it also calculates the potential of EVs which are available for joining the load leveling program. EMS will control all the charging and discharging behaviors of connected EVs and used EV batteries, therefore the grid load can be maintained to be lower than the calculated peak-cut threshold. It is found that the utilization of EVs to support small-scale EMS through direct contract is feasible, and hence applicable. At the end of the chapter, some suggestions earned from demonstration test are also listed for further consideration.