Study of the impact of electric vehicles fleets in HV electric power grids based on an uncontrolled charging strategy

Abstract

This paper addresses the impact of the integration of plug-in electric vehicles (PEV) in a high-voltage (HV) electric grid located in the metropolitan area of the city of Morelia, Mexico. A penetration scenario of 10.5%, which corresponds to 31316 vehicles, is considered by allocating electric vehicles to substations. A time domain modelling of an electric vehicle (EV) and an AC Level-2 charger is implemented in a PSS/E-based simulation platform. Furthermore, an uncontrolled charging strategy is implemented in this paper, which is based on the assumption that EVs owners are free to connect and charge their vehicles whenever they want. Power flow solutions are reported in terms of nodal voltages, power losses and loading impacts in the 115 kV sub-transmission system, substation transformers and transmission system. Results show that the load due to the EVs can help to the nodal voltages regulation in the grid during certain times of the day. However, a large number of EVs can significantly increase the losses and exceed the capacity of the transformers depending on the load curve of each substation.