Impact of electric vehicle fast charging on power system voltage stability

• Development of a static load model for an EV dc fast charger.
• EV having a combination of constant power and negative exponential characteristics.
• The parameters of the model depend on the parasitic resistances of the charger.
• EV load consumes more power at lower system voltages.
• EV load affects system voltage stability more compared to P, I, Z, load models.

The electric vehicle (EV) brings a sustainable future for the next generation of automobiles. Market penetration of EV has been increasing drastically in the recent past. However, EV integration into power grids adds more challenges for power system engineers worldwide. It is essential to evaluate potential grid impacts due to EV integration to guarantee consistent grid operation. Even though a number of power system impact studies have been performed covering several aspects of the problem, the impact on voltage stability has remained almost unattended. The lack of accurate load models to represent EV load for system stability studies is found to be a major gap. Hence, a static load model is developed in this study as an essential base for realistic stability studies. A specific EV load behavior which has not yet been revealed in the literature is identified during the study. Subsequently, the influence of EV load on power system voltage stability is evaluated under different scenarios. The study has discovered that integration of EV fast charging stations may significantly reduce the steady state voltage stability of the power grid.