Voltage droop charging of electric vehicles in a residential distribution feeder

Abstract

Uncoordinated charging of electric vehicles may cause significant voltage deviations in some residential distribution grids. Grid voltage stabilizing load models, such as developed for distributed energy resources, can be applied to electric vehicle chargers as well. A fleet of 10 electric vehicles is considered, modeled according to current Flemish mobility behavior. For this fleet, different voltage droop load models for the chargers are discussed in terms of charging duration increase, grid losses and grid voltages. Load flow simulations are performed for a real and highly loaded residential grid in Belgium. In the worst case, the average charging rate is reduced to 0.847 pu of the nominal charging rate (4 kW). Accordingly, regardless of charging coordination, deviation from power set points will occur, thereby mitigating the impact on the grid. Furthermore, electric vehicle chargers equipped with voltage droop load models present robust, fault-tolerant behavior at times the coordination of the vehicles is hampered.