Impact of uncoordinated electric vehicle charging on the distribution grid

摘要

Charging electric vehicles (EVs) represents an extra and increasing load for the power system. And the higher the charging power is, the more likely it is that serious problems will arise. In addition to home charging, in Hungary - the area of interest in this paper - Level 2 chargers in the streets are currently installed with a maximum charging power of 22 kW. Since the local market share of EVs is low at present and expected to remain relatively low in the years to come, it is essential to see where the limits of the low-voltage distribution grid are in terms of taking the extra EV charging load. This paper presents extensive simulation results taking various EV charging characteristics, arrival statistics, household load variation, and other assumptions into consideration to determine how EV charging will affect the low voltage grid. The stochastic simulations were conducted in DIgSILENT Power Factory augmented with a Python code. Simulation results indicate that an already moderately loaded grid is capable of accommodating EVs at a penetration level of approximately 20%, which can be considered a high value.