Estimation of Required EVs Battery Capacity for Leveling Demand Energy Considering Parking Durations Tomoya Imanishi 1 & Hiroaki Nishi 1 Received: 22 May 2015 /Revised: 16 May 2016 /Accepted: 13 July 2016 # Springer Science+Business Media New York 2016 Abstract Vehicle-to-grid (V2G) is a key technology that is receiving significant attention as a method for achieving an efficient energy management system (EMS) by connecting electric vehicles (EVs) to an electric power grid. In this study, a fuzzy control method and an optimization control method were proposed as effective control methods for reducing the installation battery capacity and the electric charge in one day by leveling the electric load. As the result, the required battery capacity was 429 kWh for IEVBS model, and 480 kWh for MEVBS model using optimization control method. The con- trol method could save at most $17.98 of an electric bill and achieve power leveling. Keywords Energy management . Batteries . Smart grid . Electric vehicles 1 Introduction Recently, the reduction in the available energy resources has become a serious problem. Therefore, power fluctuation con- trol, demand response, and autonomous distributed control of energy are in high demand. Under these circumstances, it is necessary to use natural energy sources such as photovoltaic or wind power to supply electricity to the power grid [1]. However, if these generators are introduced in large quantities, it is difficult for power grids to maintain demand and supply balance because the electric power generation of natural ener- gy sources is unstable. In order to deal with these problems, it is indispensable to provide a technique for adjusting power demand by controlling a battery appropriately. Given this background, energy management systems (EMS) have been studied widely. In a related study about power supply and demand adjust- ment, the following three control methods have mainly been studied. The first is power generator control, the second is demand side (power consumer’ s house) control, and the third is battery control. In this study, we lay emphasis on battery control because it has the ability to adjust electric power, par- ticularly long-term leveling, which is difficult for demand control or super capacitor-based leveling. Because of the cost of battery introduction, control methods that maintain the de- mand and supply power and suppress its introduction volumes are needed [1]. Therefore, vehicle-to-grid (V2G) systems are attracting considerable attention because the batteries imple- mented in the vehicles can be substituted for power storage installed in the power grid [2]. According to statistics, vehicles are parked approximately 95 % of the time, and if plugged into a power grid, the batteries existing in the vehicles could serve an important function in terms of power storage [ 3]. Furthermore, it is expected that in-vehicle batteries can absorb voltage fluctuations, frequency fluctuation, and short-term power fluctuations, such as a sudden power peak, because they have large capacities and have superior responsiveness [4–9]. From an economic point of view, introducing the V2G technology would have a positive effect. However, it is im- portant to employ a battery control method in order to sup- press sudden power fluctuations [10]. The battery control method can be classified into the fol- lowing three time scales: a short-term, middle-term, and long- term power control [4]. The short-term power control is used * Tomoya Imanishi imanishi@west.sd.keio.ac.jp * Hiroaki Nishi west@sd.keio.ac.jp 1 Graduate School of Science and Technology, Keio University, Yokohama, Japan Int. J. ITS Res. DOI 10.1007/s13177-016-0129-8