Electric Vehicles in an Alpine Distribution Grid: Impact Assessment and Mitigation through Smart Charging

The increasing uptake of electric vehicles (EVs) foreseen threatens the stability of both medium (MV) and low-voltage (LV) distribution networks. Specifically, MV/LV transformers will experience high loading periods due to the residential EV chargers drawing power in the early evening or public chargers being used during the day and night, depending on the parking regulations. In this work, we present the future impact of EV charging on the distribution grid of the city of Trento, Italy. Firstly, a detailed power grid model was developed and validated using the measured data collected in the primary substations; then the analysis of the impact of different EV mass penetration scenarios on the MV/LV transformers was performed via power flow simulations. The results show that for EV penetration levels lower than 50%, the transformers are not heavily impacted until 2050, but if the number of EVs increases to "rapid" penetration scenarios, the violation frequency in urban transformers increases by 13.5% compared to the previous one, and additional undervoltage events could be experienced at the LV side. Finally, we evaluated the effect of a centralised smart EV charging strategy, including Vehicle-to-grid (V2G) capabilities, and the results show that it minimises the transformer overloading frequency values.