Integrated Utility-Transit Model for Optimal Configuration of Battery Electric Bus Systems

The electrification of transportation sector represents a promising approach to reduce transit-related greenhouse gas emissions. However, both transportation and power utility sectors retain various challenges in facilitating the seamless integration of battery electric bus (BEB) fleet systems. Among those challenges, the lack of appropriate simulation tools to model, design, and optimize BEB fleet systems is the most salient. Accordingly, this paper proposes a new mathematical formulation to model BEB fleet systems. The model considers the operational requirements of public bus transit systems and the energy consumption characteristics of BEBs. The proposed transit model is then integrated with the power distribution system model to develop an integrated utility-transit problem formulation for the optimal design of BEB systems. The formulated optimization problem aims at determining the optimal configuration parameters of BEB fleet systems that include the bus battery capacity, chargers rated power, and the total number of installed chargers in the charging station. The developed utility-transit model is formulated as a mixed integer nonlinear programming problem (MINLP) and is solved using the Basic Open-Source Nonlinear Mixed INteger Programming (BONMIN) optimization solver. Real-world transit system data are used to validate the efficacy of the proposed integrated utility-transit model. The simulation results indicate that consideration of both power distribution and transit networks operation requirements significantly impact the choice of the BEBs configuration.