Voltage stability analysis of distribution systems in presence of electric vehicle charging stations with coordinated charging scheme

Recent advancements in the electric vehicle (EV) battery technologies and the promotion of EVs through government policies has seen a drastic rise in the number of EVs on the road. This leads to a change in the load profile of distribution systems by altering the peak demand intervals from what is being forecast without the consideration of EVs. This necessitates a quantitative approach for determining the load profile in a scenario where the number of EVs are high. This paper addresses the planning and operation problem from the perspective of grid stability by determining the load profile of electric vehicle charging stations (EVCS) and subsequently quantifying the impact of EVCS on the voltage profile of the distribution system. A coordinated charging strategy is used to determine the load profile of EVCS constrained by both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) rulesets. voltage sensitivity factor (VSF) and Voltage Stability Index (VSI) were used to quantify the impact of the EVCS load profile on the distribution system. This work proposes a novel algorithm to determine the voltage stability indices given the refuel and travel patterns of EVs of a region. Simulations and analysis were performed on IEEE 69 and 118 bus distribution systems.