Optimization of Electric Bus Charging and Discharging Schedules with Vehicle-to-Grid Technology

As electric vehicles are recognized for their potential to mitigate greenhouse gas emissions, their adoption has expanded beyond passenger cars to include commercial vehicles such as buses and trucks. Among these, electric buses are notable for their contribution to improving air quality in densely populated urban areas. However, the widespread deployment of electric buses and their associated charging infrastructure has introduced challenges in optimizing power grid stability and managing limited charging resources. Vehicle-to-Grid (V2G) technology, enabling bidirectional energy transfer between vehicles and the grid, has emerged as a promising solution. In this paper, we address a charging and discharging scheduling problem for an electric bus depot equipped with V2G technology. We propose a mixed integer linear programming model which optimizes charging and discharging schedules to achieve two objectives: maximizing net discharging during peak demand hours and minimizing overall operation costs. A hierarchical approach is employed to deal with the two objective functions. To enhance computational efficiency for large-scale instances, a heuristic algorithm based on the optimization model is also proposed. Computational experiments were conducted to demonstrate the advantages of the proposed optimization model and algorithm. The results indicate the potential of V2G technology to not only stabilize the power grid but also provide economic benefits to depot operators.