Energy-optimal speed control for connected electric buses considering passenger load

Electric buses (EBs) have gained increasing popularity in public transportation services due to zero-emission and less noise. However, range limitations have substantially hindered the mass adoption of EBs. How to reduce energy consumption is a pressing challenge for bus operations and businesses. This paper develops a whole trip energy-optimal speed control model for connected electric buses passing multiple signalized intersections considering the passenger load, with the help of advanced connected technology. First, the energy consumption related to speed, acceleration and statical features is investigated based on longitudinal dynamics. Then, the energy-optimal speed control model is developed that comprehensively considers passenger load, stop-free passage through multiple signalized intersections and constraints such as travel speed, acceleration, arrival time at stations and intersections. The model is simplified and recast into a mixed-integer linear programing (MILP) with high computational efficiency. Finally, numerical experiments show that the model could reduce energy consumption by approximately 40% compared to the greedy strategy. Sensitive analysis indicates that the model's performance is robust to vehicle mass and forecast error in passenger load.