**2. EV User Behavior Scenario and V2H Charging Strategy**

The availability of EV to be used for V2H services depends on EV user behaviors, which are unpredictable to a large extent. However, some typical user behaviors can be identified on the basis of factors describing the way of EV exploitation, i.e.,:


In this paper, the following scenario of EV exploitation is assumed. The EV is used in urban and non-urban areas for commuting. The vehicle is mainly charged on a private property. The most probable choice is charging in the user's private garage in the evening, less probable is charging in the workplace during the day.

Currently the typical charging solutions may include: AC on-board charger (rectifier), or off-board DC charger, or on-board motor converter (also used for motor propulsion, braking energy regeneration and battery charging). In a further consideration, only the controlled AC charging, with the use of motor inverter, will be dealt with.

The control strategy applied defines charging and control parameters [29] and requires infrastructure. A vehicle used for commuting is parked most of the day and can be connected to the electric installation. Hence, it is justified to extend the charging control strategy in order to use the EV battery as energy storage for the EV user needs.

The control of the charging process can be based on the tariff signal and the power limit value set by the distribution system operator (DSO). This strategy is beneficial for both the EV user and the network operator. The EV user reduces energy costs and the DSO receives network management opportunities (such as network load control).

The utilization of energy storage devices by end-users has been known for a long time and reported in the literature [30–33]. The typical application concerns a peak-shaving. When a distinction is made in tariffs between peak and off-peak hours, it is profitable for an end-users to reduce the peak demand. The EV battery is charged during off-peak hours, when energy is cheaper, and it is discharged during peak load periods. For EV users the reduction of peak power demand means decreasing demand charges. It should be noted that the peak demand occurs usually in the evening time period, so, according to the described scenario, while the EV is parked and its battery is available for ancillary service.

Another useful application of energy storage in LV installations is the supply of loads during dips and short interruptions. Its purpose is lowering the costs of losses incurred by end-users due to such disturbances in the network.

According to authors the infrastructure for the V2H services requires both the EV motor inverter and the building installation equipped with a home energy management system (HEMS) (Figure 1). HEMS is responsible for the calculation of the starting and ending time of charging or discharging processes. It is based on the following parameters:


The vehicle should be connected to the AC power network via dedicated EVSE (Electric Vehicle Suppling Equipment) i.e., socket outlet, connecting cable and wallbox. Communication between EV and EVSE must be bi-directional.

**Figure 1.** Vehicle-to-home (V2H) charging scheme.

### **3. Description of EV Simulation Model**

### *3.1. Asumptions*

During driving, the EV motor inverter provides power to its motor or is used for regenerative braking. While an EV is parked, the motor inverter is connected to 3-phase LV home installation and is used to charge the batteries or for the V2H services such as energy storage operation or uninterruptable power supply (UPS). This functionality requires an appropriate control system and procedures to run depending on the function being performed: drive, energy storage or UPS (when the installation is disconnected from the network). The controller is located on-board the vehicle. Its operation modes and settings should include all limitations regarding all the cooperating devices: battery, vehicle engine, electric loads and the supplying feeder.

During driving the EV driver controls the power fed to the EV motor within the limits of its rated power (using accelerator and brake pedals).

While EV is parked and connected to the home installation, the battery can be charged or discharged according to the user's decision or predefined profile. The amount of power drawn from or returned to the customer installation is limited by EV motor rated power, technical parameters of home installation and should be managed by the HEMS. Additionally, it should be noted that every EV is equipped with the on-board battery management systems (BMS). It is responsible for battery protection, monitoring and controlling its state. The HEMS cannot and should not have priority over BMS so it cannot jeopardize the battery safety. However, HEMS has access to the additional information (the energy tariffs, current energy consumption at home or other EV user preferences). That data can be used to effectively manage services like the peak shaving or planning the charging schedule.

The UPS option requires fully autonomous operation of the controller in order to balance an active and reactive power in the user's home installation (islanded operation). The amount of power drawn from or returned to the customer installation is limited by EV motor rated power and technical parameters of the home installation.

The objective of the presented model is to create a simulation tool to examine and evaluate the EV capability for V2H services. In particular, the model can be used to:

