New staggered time-of-use tariffs to mitigate the impact of electric vehicle charging demand on distribution networks

The peak demand of the power grid determines the maximum capacity required for the network infrastructure. Even short-term high peaks can significantly increase the required capacity and hence increase the grid operational costs, wholesale market prices and retail prices. To reduce the peak demand, time-of-use (TOU) tariffs were introduced, encouraging customers to shift their electricity consumption to the off-peak periods. However, conventional TOU tariffs may exacerbate the grid peak demand due to increasing electric vehicle (EV) charging demand in the near future. To address the challenge, this paper proposes innovative TOU tariffs with staggered pricing segments and presents critical analysis based on a distribution network in Australia. The results indicate that the proposed staggered TOU tariffs offer significant advantages by spreading the EV charging demand over the off-peak periods. At 100 % EV penetration, if 50 % of the customers charge their EVs using a staggered TOU tariff then the peak-to-valley power difference in the daily average load profile can be reduced by 20.0 %, and the sum of standard deviation for transformer utilization can be decreased to less than 16.6 %. For 100 % TOU adoption rate, the proposed staggered TOU tariffs can meet the EV charging demand without causing overloading of the network transformers.