Aggregation and Control of Electric Vehicles AC Charging for Grid Services Delivery

The mass electrification and penetration of converter-based renewable energy source (RES) challenges the conventional stability and operation of the power grid. Therefore, the power grid necessitates the support of flexible and controllable demand side units. This article presents a novel methodology and results for measuring, controlling, aggregating and modeling electric vehicle (EV) AC slow charging. The investigation quantifies the entire control loop to deliver a grid service with EVs. Over-the-air communication is measured to be from 0.37 to 10 seconds. Consequently, depending on the vehicle, it is possible to achieve subsecond grid service delivery. Additionally, the dynamic charging behaviors (ramp rates and delays) of EVs are mathematically modeled. Ramp rates are asymmetric and the longest delay is the initial start-charging delay. The article demonstrates the simulated power demand of 100 EVs, highlighting the significant uncertainties in the power ramp depending on vehicle types. The highly detailed data set provides for the first time solid ground for modeling the dynamic behavior of the AC charging process. Finally, the article investigates the conflicting requirements of the IEC 61851-1 standard editions. Of the four chargers tested, two do not comply with the IEC 61851-1:2019 which hampers the delivery of grid services from EVs.