A Comprehensive Discrete-Event Model for Optimal Allocation and Scheduling of Electric Bus Charging

The transition to electric mobility is essential to meet global climate targets, but it poses critical challenges to the stability of the power grid due to the high, concentrated demand from electric vehicles. This paper proposes a discrete-event optimisation model for the allocation and scheduling of electric vehicle charging, focusing on electric buses, which are characterised by large battery capacities and predictable schedules. The developed mixed-integer linear model introduces a detailed battery representation that captures nonlinear charging behaviour and incorporates key constraints such as power limits, time windows, charging station availability, time of use electricity tariff, and provides multiobjective optimisation for makespan and energy cost minimisation. Compared to traditional discrete-time approaches, the proposed formulation significantly reduces problem size while maintaining modeling accuracy. The proposed framework is validated using a real case study provided by Iveco S.p.A. company, involving a fleet of maximum fifty electric buses. The robustness of the model with respect to key parameters, together with the uncertainty analysis performed on simulated scenarios and the scalability analysis with an increasing number of electric buses, demonstrates the good performance of the proposed approach under different operational conditions.