SMART CHARGING: Large-scale experimentation in partnership with RTE

The French transmission system operator, RTE, has carried out several prospective studies on the subject of intelligent recharging of electric vehicles, which it wished to complete in partnership with the CEA by conducting a large-scale experiment.

The experiment is testing a program for the intelligent management and control of electric vehicle recharging that has been developed and tested since 2010 by the CEA teams at INES, called "ICPM" for INES ChargePoint Manager. This program controls the consumption of a group of vehicles according to an external setpoint without affecting the comfort of the user or the life of the batteries. For this experiment, the CEA is also using the information system, developed by the same teams, which makes it possible to

- Collect all the data needed for intelligent management; data from the vehicles, the electricity network, the charging stations, or even data from solar production forecasts and the solar power plant.

- Communicate with the charging stations via 3G connection and thus follow the status of each charging station in real time but also act on them, for example by restarting a charging session remotely.

- Provide statistics per charging station, per user, or per charging point.

- Controlling charging by detecting user badges and allocating charging power according to the user's preferences as entered on a web interface.

The experiment runs from autumn 2021 to summer 2022. It consists of linking the consumption of a fraction of the charging infrastructure at the CEA Cadarache centre, i.e. 24 charging points spread over 5 zones, to the production of a fraction of the Mégasol photovoltaic solar power plant located in the immediate surroundings of the centre. The key to the success of this experiment lies in the participation of a large number of volunteers who allow the CEA to modulate the charge of their electric vehicles according to the photovoltaic production.

The processing of part of the data over a period of 244 days from October 2021 to May 2022 has made it possible to draw some conclusions from the Smart Charging system put in place. Over this period, 1,362 charges took place with more than 24.4 MWh transferred to the vehicles of around 100 users who volunteered to participate and around 30 service vehicles whose users did not volunteer. 42 different models of electric vehicles use these facilities at the centre.

The study compares the rate of self-generation with and without piloting for these test days. It shows:

• That the supervision system developed effectively maximises the gain in self-generation. The rate of self-generation with control is equal to or higher than the rate of self-generation without control, with the vast majority of days when it is higher.
   
• That it allows the self-generation rate to be increased by up to 60 percentage points, without harming the user. In fact, by shifting certain loads by a few hours, the solar production is used optimally and is then sufficient to fully recharge the connected vehicles.
   
• The self-generation rate without piloting, as well as the self-generation rate with piloting, are high on sunny days. The region where the Cadarache centre is located enjoys high sunshine almost all year round. The supervision system is even more advantageous on cloudy days, when the time delay in recharging allows less power to be drawn from the electricity grid and thus favours solar production.
   
• User involvement is essential. Indeed, we have observed that non-voluntary users can drastically reduce the rate of self-generation on a given day, especially on days with less sunshine. Without their active participation, the loads tend to start when they arrive on site, i.e. around 8am when solar production is still low.
   
• Piloting can increase the occupancy rate of the stations as the charging of some vehicles is more extended in time. This can therefore lead to greater saturation of the stations in certain geographical areas of the centre. However, the main problem of station occupancy is due to the fact that the vehicle remains plugged in at the end of charging.

In a growing context of the use of electric vehicles, this study confirms that the combining of solar production and intelligent recharging management is a real opportunity.

RTE plans to extend the scope of the experiments by including other types of flexible electrical consumption (such as heating, air conditioning, water heaters, storage systems, etc.). The results of the experiments will also be used to estimate the consumption of electric vehicles on a larger scale (region and then country) and to analyse the impact of this consumption on the network.