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

Vepsäläinen, Jari; Kivekäs, Klaus; Lajunen, Antti; Otto, Kevin

doi:10.1016/j.trd.2018.06.004

Cited by 67 publications

(35 citation statements)

References 36 publications

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“…In addition to the high initial investment, the life cycle costs (LCC) depend on the selected charging strategy (e.g., overnight vs. opportunity charging) and the selected battery capacity that is defined by the charging strategy [2]. However, the energy consumption rate (ECR) varies because of uncertainties in weather and driving behavior [3]. Variation in ECR may cause delays in the charging schedules, which are hard to predict, because such delays have not been an issue with diesel buses.…”

Section: Introductionmentioning

confidence: 99%

Energy Uncertainty Analysis of Electric Buses

et al. 2018

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Uncertainty in operation factors, such as the weather and driving behavior, makes it difficult to accurately predict the energy consumption of electric buses. As the consumption varies, the dimensioning of the battery capacity and charging systems is challenging and requires a dedicated decision-making process. To investigate the impact of uncertainty, six electric buses were measured in three routes with an Internet of Things (IoT) system from February 2016 to December 2017 in southern Finland in real operation conditions. The measurement results were thoroughly analyzed and the operation factors that caused variation in the energy consumption and internal resistance of the battery were studied in detail. The average energy consumption was 0.78 kWh/km and the consumption varied by more than 1 kWh/km between trips. Furthermore, consumption was 15% lower on a suburban route than on city routes. The energy consumption was mostly influenced by the ambient temperature, driving behavior, and route characteristics. The internal resistance varied mainly as a result of changes in the battery temperature and charging current. The energy consumption was predicted with above 75% accuracy with a linear model. The operation factors were correlated and a novel second-order normalization method was introduced to improve the interpretation of the results. The presented models and analyses can be integrated to powertrain and charging system design, as well as schedule planning.

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Section: Introductionmentioning

confidence: 99%

Energy Uncertainty Analysis of Electric Buses

et al. 2018

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“…In reality, there is variation in the energy demand that is caused by uncertainty of environmental conditions, such as ambient temperature and road-grade, in addition to driving style, traffic and auxiliary power usage variations [20]. These uncertainties are unpredictable in the planning phase of operation and charging schedules.…”

Section: Discussionmentioning

confidence: 99%

Cost-Benefit Analysis of Electric Bus Fleet with Various Operation Intervals

Vepsäläinen

Baldi

Lajunen

et al. 2018

2018 21st International Conference on Intelligent Transportation Systems (ITSC)

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Electric buses are particularly suitable for city and suburban routes due to zero local exhaust and noise emissions. The operation schedule interval defines the charging power, bus fleet size and total cost of ownership of a bus. We propose a novel cost-benefit method for the scheduling of an electric city bus fleet on a single route. Three different charging infrastructure scenarios were considered. In the first scenario, only one charging station was used. The second scenario considered two charging stations that were located at the same terminus. In the third scenario, two charging stations were located at opposite terminuses. The costs and utilization rates of the buses were analyzed with operation intervals up to 40 minutes. The first scenario with a single charging station had the lowest costs for the entire bus fleet system when the utilization rate was considered. Furthermore, the results show that certain schedule intervals are more cost-beneficial in terms of vehicle specific life-cycle costs than others. In the future, the proposed method is expanded to aid the design of bus network scheduling under energy demand uncertainty.

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“…In the case of these lines, electric buses with a length of 18 m and a capacity C of battery equal to 240 kWh and an energy consumption u c equal to 1.8 kWh/km are going to be used. In the literature, the mentioned consumption often amounts to 1.3-1.5 kWh/km, however, buses with a length of 12 m are most frequently used in the research [3,11,23,24]. Additionally, it should be noted that all three lines are quite long and their routes lead through areas with high traffic density.…”

Section: Methodology Of Researchmentioning

confidence: 99%

Impact of Electric Bus Charging on Distribution Substation and Local Grid in Warsaw

et al. 2020

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Electric buses are increasingly appearing on the streets of cities around the world. Thus, it is necessary to consider the impact of their charging on the distribution system operation, especially near the charging point. This article presents the problems that may arise while new charging points are connected. Research was carried out on the existing charging point at Spartańska Street in Warsaw, which allowed to obtain daily bus charging profiles and voltage curves. The authors then proposed an exemplary model of a bus terminus with the designed infrastructure for charging buses, based on the assumptions of the public transport operator in Warsaw. The comparison of these two solutions was made and based on it, a methodology of calculating daily demand for any terminus was prepared. In addition, no problems with the power quality were found during the research. This allows us to state that the introduction of electric buses into the fleet of passenger carriers will have a minor impact on the operation of the power system in Warsaw.

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

Cited by 67 publications

References 36 publications

Energy Uncertainty Analysis of Electric Buses

Energy Uncertainty Analysis of Electric Buses

Cost-Benefit Analysis of Electric Bus Fleet with Various Operation Intervals

Impact of Electric Bus Charging on Distribution Substation and Local Grid in Warsaw

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