Autonomous Control of Electric Vehicles Using Voltage Droop

The surge of electric vehicles (EVs) in Denmark challenges the country’s residential low-voltage (LV) distribution system. Especially, it increases the demand for home EV charging significantly and overload the LV grid possibly. This study analyses the impact of EV charging integration on Denmark's residential distribution networks. A residential grid comprising 67 households powered by a 630 kVA transformer is studied using DiGSILENT PowerFactory. With the assumption of simultaneous charging of all EVs, the transformer can be heavily loaded up to 147.2%. Thus, a voltage-droop based autonomous control approach is adopted, where the EV charging power is dynamically adjusted based on the point-of-connection voltage of each charger instead of fixed rated power. This strategy eliminates overloading of the transformer and cables, ensuring they operate within a pre-set limit of 80%. Voltage drops are mitigated within the acceptable safety range of ±10% from normal voltage. These results highlight the effectiveness of the droop control strategy in managing EV charging power. At last, it exemplifies the benefits of intelligent EV charging systems in Horizon 2020 EU Projects like SERENE and SUSTENANCE. The findings underscore the necessity to integrate smart control mechanisms, consider reinforcing grids, and promote active consumer participation to meet the rising demand for a low-carbon future.