Development and validation of energy demand uncertainty model for electric city buses

Authors

Jari Vepsäläinen
Klaus Kivekäs
Kevin Otto
Antti Lajunen
Kari Tammi

Document Type

Journal Article

Publication Date

2018

Subject Area

mode - bus, economics - operating costs, planning - methods

Keywords

Electric vehicle, Energy demand, Uncertainty, Modelling, Simulation

Abstract

The prediction of electric city bus energy demand is crucial in order to estimate operating costs and to size components such as the battery and charging systems. Unfortunately, there are unpredictable dynamic factors that can cause variation in the energy demand, particularly concerning driver choices and traffic levels. The impact of these factors on energy demand has been difficult to study since fast computing sufficiently accurate dynamic simulation models have been missing, properly quantified in terms of relevant inputs which contribute to energy demand. The objective is to develop and validate a novel electric city bus model for computing the energy demand, to study the nature and impact of various input factors. The developed equation-based model predicted real-world electric city bus energy consumption within 0.1% error. The most crucial unmeasurable input factors were the driven bus route, the number of stops, the elevation profile, the traffic level and the driving style. This understanding can be used to specify routes and stops for a given electric bus battery capacity. Worst-case scenarios are also necessary for electric bus sizing analysis. The best- and worst-case levels of the crucial factors were identified and with them synthetic best- and worst-case speed profiles were generated to demonstrate their effect to the energy demand. While the measured nominal consumption was 0.70 kWh/km, the computed range of variation was between 0.19 kWh/km and 1.34 kWh/km. For design sizing purposes, an electric city bus can have a broad range of possible energy consumption rates due to mission condition variations.

Rights

Permission to publish the abstract has been given by Elsevier, copyright remains with them.

Comments

Transportation Research Part D Home Page:

http://www.sciencedirect.com/science/journal/13619209

Recommended Citation

Vepsäläinen, J., Kivekäs, K., Otto, K., Lajunen, A., Tammi, K. (2018). Development and validation of energy demand uncertainty model for electric city buses. Transportation Research Part D: Transport and Environment, Vol. 63, pp. 347-361.