Electric Bus charging scheduling optimization utilizing spatio-temporal modeling

Transportation electrification presents a promising solution to diversifying transportation fuels and reducing the negative impacts of petroleum-based transportation on the environment. Electrification of transportation networks by adopting zero emission battery electric buses (BEBs) offers an opportunity to mitigate such environmental problems.

Recent advancements in long-range BEB technologies and development of associated charging infrastructure has made electrification of public transit system a reality in many cities around the world, and would offer a lower cost per mile operation as compared to diesel and compressed natural gas buses despite utility demand charges.

Researchers at the University of Utah have developed a model to schedule the spatio-temporal charging flexibility of BEBs in the power distribution system considering transit system operation constraints. The model captures the flexibility offered in times and locations by the BEBs in the transit system to minimize power distribution system cost. The coordinated scheduling of BEBs considers the power flow constraints to ensure delivering reliable power to BEBs and other loads in power distribution systems. The spatio-temporal BEB charging scheduling model is implemented on the IEEE 33-bus power distribution system that supplies the electrified transit system designed based on bus transit routes of Park City, UT, USA. The simulation results indicate that uncoordinated BEB charging scheme may result in violation of the power distribution system voltage limit in a few nodes, abrupt variation in line currents, and increased active energy loss. The simulation results reflect the cost effectiveness of the proposed optimal BEB charging model from the power DSO and transit system operator view points. The proposed model significantly reduces the operation cost of the power DSO as well as the energy and demand charge of transit system operation. Further, the coordinated scheduling of BEBs considers transit route limitations to utilize specific charging stations such that transit system constraints are not violated. Future works include modeling the arrival time uncertainty of buses in transit networks and developing a stochastic BEB scheduling model.

Proof of Concept

• Captures the flexibility offered in times and locations by the BEBs
• Minimize power distribution system cost
• Considers power flow constraints to ensure reliable power delivery to BEBs

Spatio-Temporal Electric Bus Charging Optimization With Transit Network Constraints

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 56, NO. 5, SEPTEMBER/OCTOBER 2020

Dean Gallagher
(801) 585-0396
dean.gallagher@utah.edu