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Increasing Energy Efficiency in Electric Trains Operation: Driver Advisory Systems and Energy Storage
Mälardalen University, School of Business, Society and Engineering, Future Energy Center.ORCID iD: 0000-0001-8697-855x
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electric traction is the most efficient traction system in the railway transportation. However, due to the expensive infrastructure and high power demand from the grid, the share of electric trains in the railway transportation is still lower than other trains. Two of the possible solutions to increase the share of electric trains are: optimal train operation to minimize energy consumption, the use of batteries as the energy source for driving electric trains on non-electrified lines. This thesis aims to extend the knowledge in the field of energy optimal operation of electric trains and battery-driven electric trains.

Energy optimal operation of electric trains is supervised using a driver advisory system (DAS), which instructs the driver to operate the train in an energy-efficient manner. This thesis contributes to DAS technology under two topics: the increase of energy efficiency and the design of DAS.

This thesis presents a complete procedure of designing a DAS from the mathematical formulation to application on the train. The designed DAS is in the form of an Android application and is based on a dynamic programming approach. The computational performance of the approach is enhanced using heuristic state reducing rules based on the physical constraints of the system. The application of the DAS shows a potential reduction of 28% in energy consumption.

This thesis considers the detailed energy losses in the whole propulsion system using a regression model that is generated from validated physical models. The application of the regression model instead of a previous constant efficiency factor model results in 2.3% reduction in energy consumption of the optimum speed profiles.

Based on the solution for the normal electric trains, a solution is also offered for the optimal operation of battery-driven electric trains, in which the characteristics of the battery as one of the main components are considered using an electrical model. The solution presented in this thesis, is to combine the popular single mass point train model with an electrical circuit battery model.

Furthermore, this thesis evaluates the performance of the optimization approaches and validates the models against the measurements from actual drives of a real-life battery train. The results show a potential of around 30% reduction in the charge consumption of the battery.

The results of this thesis (algorithms and the Android application) are provided as open source for further research in the field of energy efficient train control.

Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2018.
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 275
Keywords [en]
Driver Advisory System, Catenary-free Operation, Electric Train, Electric Multiple Unit, Battery, Energy Efficiency, Energy Storage, Speed Profile Optimization
National Category
Energy Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-41136ISBN: 978-91-7485-409-1 (print)OAI: oai:DiVA.org:mdh-41136DiVA, id: diva2:1253814
Public defence
2018-11-16, Pi, Mälardalens högskola, Västerås, 13:00 (English)
Opponent
Supervisors
Projects
STREAM
Funder
VINNOVA, 2014-04319VINNOVA, 2012-01277Available from: 2018-10-08 Created: 2018-10-06 Last updated: 2018-10-16Bibliographically approved
List of papers
1. Optimal Control of an EMU Using Dynamic Programming and Tractive Effort as the Control Variable
Open this publication in new window or tab >>Optimal Control of an EMU Using Dynamic Programming and Tractive Effort as the Control Variable
2015 (English)In: Proceedings of the 56th SIMS, Linköping University Electronic Press, Linköpings universitet, 2015, p. 377-382Conference paper, Published paper (Refereed)
Abstract [en]

Problem of optimal train control with the aim of minimizing energy consumption is one of the old optimal control problems. During last decades different solutions have been suggested based on different optimization techniques, each including a certain number of constraints or different train configurations, one being the control on the tractive effort available from traction motor. The problem is previously solved using dynamic programming for trains with continuous tractive effort, in which velocity was assumed to be the control variable. The paper at hand presents a solution based on dynamic programming for solving the problem for trains with discrete tractive effort. In this approach, tractive effort is assumed to be the control variable. Moreover a short comparison is made between two approaches regarding accuracy and ease of application in a driver advisory system.

Place, publisher, year, edition, pages
Linköping University Electronic Press, Linköpings universitet: , 2015
Keywords
Optimal Control; Dynamic Programming; Electric Trains
National Category
Energy Systems Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-29921 (URN)10.3384/ecp15119377 (DOI)978-91-7685-900-1 (ISBN)
Conference
The 56th Conference on Simulation and Modelling (SIMS 56), October 07-09, 2015, Linköping, Sweden
Funder
VINNOVA, 2014-04319
Available from: 2015-12-13 Created: 2015-12-13 Last updated: 2018-10-06Bibliographically approved
2. Speed profile optimization of an electric train with on-board energy storage and continuous tractive effort
Open this publication in new window or tab >>Speed profile optimization of an electric train with on-board energy storage and continuous tractive effort
2016 (English)In: 2016 International Symposium on Power Electronics, Electrical Drives, Automation and Motion, SPEEDAM 2016, 2016Conference paper, Published paper (Refereed)
Abstract [en]

Electric traction system is the most energy efficient traction system in railways. Nevertheless, not all railway networks are electrified, which is due to high maintenance and setup cost of overhead lines. One solution to the problem is battery-driven trains, which can make the best use of the electric traction system while avoiding the high costs of the catenary system. Due to the high power consumption of electric trains, energy management of battery trains are crucial in order to get the best use of batteries. This paper suggests a general algorithm for speed profile optimization of an electric train with an on-board energy storage device, during catenary-free operation on a given line section. The approach is based on discrete dynamic programming, where the train model and the objective function are based on equations of motion rather than electrical equations. This makes the model compatible with all sorts of energy storage devices. Unlike previous approaches which consider trains with throttle levels for tractive effort, the new approach considers trains in which there are no throttles and tractive effort is controlled with a controller (smooth gliding handle with no discrete levels). Furthermore, unlike previous approaches, the control variable is the velocity change instead of the applied tractive effort. The accuracy and performance of the discretized approach is evaluated in comparison to the formal movement equations in a simulated experimented using train data from the Bombardier Electrostar series and track data from the UK.

Keywords
Digital storage; Dynamic programming; Electric batteries; Electric traction; Electric vehicles; Energy efficiency; Energy storage; Equations of motion; Overhead lines; Power electronics; Railroads Catenary free operation; Electric traction system; Electric trains; Electrical equations; High power consumption; Objective functions; On-board energy storage; Speed profile
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:mdh:diva-31549 (URN)10.1109/SPEEDAM.2016.7525913 (DOI)000387110600104 ()2-s2.0-84994182006 (Scopus ID)
Conference
2016 International Symposium on Power Electronics, Electrical Drives, Automation and Motion, SPEEDAM 2016; Capri; Italy; 22 June 2016 through 24 June 2016; Category numberCFP1648A-ART; Code 123134
Available from: 2016-05-11 Created: 2016-05-11 Last updated: 2018-10-06Bibliographically approved
3. Review of Application of Energy Storage Devices in Railway Transportation
Open this publication in new window or tab >>Review of Application of Energy Storage Devices in Railway Transportation
2017 (English)In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, p. 4561-4568Article in journal (Refereed) Published
Abstract [en]

Regenerative braking is one of the main reasons behind the high levels of energy efficiency achieved in railway electric traction systems. During regenerative braking, the traction motor acts as a generator and restores part of the kinetic energy into electrical energy. To use this energy, it should be either fed back to the power grid or stored on an energy storage system for later use. This paper reviews the application of energy storage devices used in railway systems for increasing the effectiveness of regenerative brakes. Three main storage devices are reviewed in this paper: batteries, supercapacitors and flywheels. Furthermore, two main challenges in application of energy storage systems are briefly discussed. 

Keywords
Energy Storage System, Railway, Battery, Supercapacitor, Flywheel
National Category
Environmental Engineering Energy Systems
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-34049 (URN)10.1016/j.egypro.2017.03.980 (DOI)000404967904101 ()2-s2.0-85020733634 (Scopus ID)
Conference
8th International Conference on Applied Energy, ICAE 2016; Beijing; China; 8 October 2016 through 11 October 2016
Projects
STREAM
Funder
VINNOVA, 2014-04319
Available from: 2016-12-09 Created: 2016-12-09 Last updated: 2018-10-06Bibliographically approved
4. Modeling of Losses in the Motor Converter Module of Electric Multiple Units for Dynamic Simulation Purposes
Open this publication in new window or tab >>Modeling of Losses in the Motor Converter Module of Electric Multiple Units for Dynamic Simulation Purposes
2017 (English)In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 2303-2309Article in journal (Refereed) Published
Abstract [en]

Simulation of power consumption in electric trains is categorized in two categories: electrical power simulation and mechanical power simulation. The mechanical power is calculated as speed times tractive effort and it gives an overall view on the total energy consumption of the train during different driving cycles. Detailed calculation of losses in different components in the propulsion system is however done using complex electrical models. In this paper, we introduce a nonlinear regression model generated from validated electrical equations for the calculation of the power loss in the motor converter module of electric trains. The function can be used instead of efficiency maps to evaluate the trains’ performance during the operation or dynamic simulations.

Place, publisher, year, edition, pages
Elsevier Ltd, 2017
National Category
Energy Engineering
Identifiers
urn:nbn:se:mdh:diva-38717 (URN)10.1016/j.egypro.2017.12.633 (DOI)000452901602070 ()2-s2.0-85041531667 (Scopus ID)
Available from: 2018-03-01 Created: 2018-03-01 Last updated: 2019-01-03Bibliographically approved
5. A driver advisory system with dynamic losses for passenger electric multiple units
Open this publication in new window or tab >>A driver advisory system with dynamic losses for passenger electric multiple units
Show others...
2017 (English)In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 85, p. 111-130Article in journal (Refereed) Published
Abstract [en]

Driver advisory systems, instructing the driver how to control the train in an energy efficient manner, is one the main tools for minimizing energy consumption in the railway sector. There are many driver advisory systems already available in the market, together with significant literature on the mathematical formulation of the problem. However, much less is published on the development of such mathematical formulations, their implementation in real systems, and on the empirical data from their deployment. Moreover, nearly all the designed driver advisory systems are designed as an additional hardware to be added in drivers’ cabin. This paper discusses the design of a mathematical formulation and optimization approach for such a system, together with its implementation into an Android-based prototype, the results from on-board practical experiments, and experiences from the implementation. The system is based on a more realistic train model where energy calculations take into account dynamic losses in different components of the propulsion system, contrary to previous approaches. The experimental evaluation shows a significant increase in accuracy, as compared to a previous approach. Tests on a double-track section of the Mälaren line in Sweden demonstrates a significant potential for energy saving.

Place, publisher, year, edition, pages
Elsevier Ltd, 2017
Keywords
Driver advisory system, Electric multiple unit, Energy efficiency, Driver training, Electric losses, Electric railroads, Electric traction, Energy conservation, Energy utilization, Propulsion, Railroad transportation, Rapid transit, Advisory systems, Double-track section, Energy calculation, Experimental evaluation, Mathematical formulation, Minimizing energy, Optimization approach, control system, electric vehicle, energy use, optimization, railway transport, train, Sweden
National Category
Energy Engineering
Identifiers
urn:nbn:se:mdh:diva-37410 (URN)10.1016/j.trc.2017.09.010 (DOI)000423006600006 ()2-s2.0-85034098198 (Scopus ID)
Available from: 2017-12-07 Created: 2017-12-07 Last updated: 2018-10-06Bibliographically approved
6. Speed Profile Optimization of Catenary-free Electric Trains with Lithium-ion Batteries
Open this publication in new window or tab >>Speed Profile Optimization of Catenary-free Electric Trains with Lithium-ion Batteries
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Catenary-free operated electric trains, as one of the recent technologies in railwaytransportation, has opened a new field of research: speed profile optimization and energy optimaloperation of catenary-free operated electric trains. A well-formulated solution for this problem shouldconsider the characteristics of the energy storage device using a validated model and method. This paper,discusses the consideration of the battery behavior in the problem of speed profile optimization ofcatenary-free operated electric trains. We combine the single mass point train model with an electricalbattery model and apply a dynamic programming approach to minimize the charge taken from thebattery during the catenary-free operation. The models and the method are validated and evaluatedagainst experimental data gathered from the test runs of an actual battery driven train tested in Essex,UK. The results show a significant potential in energy saving. Moreover, we show that the optimumspeed profiles generated using our approach consume less charge from the battery compared to theprevious approaches.

Keywords
Electric Trains, Catenary-free Operation, Speed Profile Optimization, Energy Efficiency
National Category
Energy Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-41132 (URN)
Funder
VINNOVA, 2014-04319VINNOVA, 2012-01277
Available from: 2018-10-04 Created: 2018-10-04 Last updated: 2018-10-15Bibliographically approved

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Ghaviha, Nima

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Citation style
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  • ieee
  • modern-language-association-8th-edition
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  • en-GB
  • en-US
  • fi-FI
  • nn-NO
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More languages
Output format
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