**3. EV involvement in energy management system**

Europe owns the assets and it belongs to certain stakeholders, but has a regulation to guarantee its independence. On the other hand, ISO is fully unbundled operator having no assets

In Japan, community energy management system (CEMS) has been proposed and demon‐ strated. The main purpose of CEMS is realizing a resilient and smart community, especially related to efficiency in energy utilization and minimization of CO2 emission. The concept of CEMS comes from the demand to optimize the energy services, maximize the potential economy, and minimize the environmental impacts. CEMS coordinates and monitors all the energy supply and demand throughout the community, hence improving the comfort, security, and safety of the whole community members. In CEMS, the streams of energy and information are flowing simultaneously covering supply, demand, storage, and distribution. As a system, CEMS must be robust and secured because it deals with individual information

**Figure 1** shows the basic concept of CEMS. CEMS has an important role of monitoring and controlling all the energy involved in the community. It becomes the core of efficient, secured, and optimized energy utilization throughout the community. CEMS is able to communicate with other entities inside and outside its authority. Inside the community, CEMS communi‐ cates intensively with its lower EMSs such as home energy management system (HEMS), building energy management system (BEMS), and factory energy management system (FEMS). In addition, it also may communicate directly with EVs distributed in the community which are not controlled under certain EMS. CEMS is also able to communicate with other

although still belongs to certain stakeholders.

128 Modeling and Simulation for Electric Vehicle Applications

and its authentication.

**Figure 1.** Basic concept of CEMS.

EVs can be applied to support the grid electricity, mainly providing energy storage and ancillary services, due to the above-mentioned characteristics. As energy storage, EVs can be charged when the electricity price is relatively low because of surplus electricity in supply side, including RE and excess power, and lower demand (such as during night time). Furthermore, the ancillary services which can be performed by EVs to support the grid electricity mainly cover frequency regulation (up and down regulations), electricity storage, and spinning (synchronous) reserve. Compared to other energy storages or generators, EVs have a very advantageous characteristic which is its ability to charge and discharge instantaneously their electricity once they received the command from the operator or EMS. The above-mentioned ancillary services are required to preserve the balance between supply and demand of electricity, therefore the electricity can be appropriately reliable.

To participate in the ancillary services, the EV owners are requested to have any service contract with the operator or EMS. Possible utilization contract schemes of EVs to support the grid electricity or any electricity-related system are shown in **Figure 2**. In general, the partici‐ pation of EVs in the electricity market could be conducted through two types of participation contracts, they are direct and aggregator-based contracts. To facilitate a communication between EVs and operators, a real time data collection is conducted by vehicle information system (VIS) in a certain time interval from EVs covering battery state of charge (SOC), position (GPS data), and predicted arrival time. VIS might be owned and managed directly by EMS, aggregator or it is independent as service operator which provides EV information services to EMS and aggregator.

**Figure 2.** Possible contract schemes of EV in EMS: (a) direct contract and (b) aggregator-based contract.

In a direct contract, the EV owners have the service contract directly with the energy service providers (EMS). In this contract scheme, both the electricity and information are transferred privately and directly between EVs and energy service provider. Therefore, this type of con‐ tract is considered applicable for a relatively small-scale EMS, including BEMS and FEMS, and in where EVs are parked and connected to the chargers for relatively long time, for ex‐ ample during working hours. The main advantage of this type of contract scheme is the abil‐ ity to optimize the profit for the involving entities (EV owners and EMS). Furthermore, controls for both charging and discharging are more simple and faster as EVs are directly and fully under control of EMS. The report in this chapter describes mainly on this type of contract scheme.

On the contrary, in an aggregator-based contract scheme, EV owners have service contracts with the aggregators which are providing and managing electricity services. Therefore, there is no direct contract between EV owners and EMS or other electricity-related entities. The information including EV position (GPS), battery condition (SOC), and estimated arrival time is basically coordinated by aggregator via VIS. Based on these data, the aggregator calculates the available number of EVs as well as the total capacity of the battery which is potential for power services. Furthermore, the aggregator can offer and negotiate for electricity services with other electricity-related entities including aggregators, EMS, and/or electricity utilities. It is assumed that this kind of contract scheme is suitable to be adopted for comparatively largescale EMS or electricity utilities. The participating EVs are not only located in certain single place, but they might be distributed in different places as long as both electricity connection and communication are available and possible to perform ancillary services. The electricity absorbed from and discharged to the grid can be transferred through power wheeling service utilizing the available distribution and transmission lines. Aggregator acts as service operator, hence they offer some possible ancillary services to the EV owners. On the contrary, the EV owners have the right to select the offered ancillary service programs and receive the service fee from the aggregator.

Load leveling has a strong correlation with the management of both electricity demand and supply. The main objective is to lower the total grid load (electricity purchased from grid) during peak-load hours and avoid the electricity usage higher than the contracted power capacity by shifting the load from peak to off-peak-load hours. In this study, load leveling is conducted by employing both peak-shift and peak-cut. The former is defined as dislocating the electricity load during peak-load time to off-peak-load time. It can be performed by utilizing the stationary battery or other power storage devices which can absorb and store the electricity during off-peak-load time and discharge it during peak-load time. The latter is described as the effort to reduce the electricity which is purchased from the grid. In real practice, this can be conducted by generating its own energy supply especially during peakload hours, such as RE, or by purchasing the electricity from other entities including the connected EVs. In the case that additional power supply is purchased from EVs, EVs are considered as energy storage and carrier which are storing and transporting the electricity from and to different times and places. Therefore, the economic performance of EVs can be improved by participating in this kind of ancillary services.
