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Optimal Control of an EMU Using Dynamic Programming and Tractive Effort as the Control Variable
Mälardalen University, School of Business, Society and Engineering, Future Energy Center.ORCID iD: 0000-0001-8697-855X
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.ORCID iD: 0000-0003-1597-6738
Mälardalen University, School of Business, Society and Engineering, Future Energy Center.ORCID iD: 0000-0003-4589-7045
Mälardalen University, School of Business, Society and Engineering, Future Energy Center.ORCID iD: 0000-0002-7233-6916
2015 (English)In: Proceedings of the 56th SIMS, Linköping University Electronic Press, Linköpings universitet, 2015, 377-382 p.Conference 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. 377-382 p.
Keyword [en]
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: urn:nbn:se:mdh:diva-29921DOI: 10.3384/ecp15119377ISBN: 978-91-7685-900-1 (print)OAI: oai:DiVA.org:mdh-29921DiVA: diva2:882038
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: 2017-03-22Bibliographically approved
In thesis
1. Energy Optimal Operation of Electric Trains: Development of a Driver Advisory System
Open this publication in new window or tab >>Energy Optimal Operation of Electric Trains: Development of a Driver Advisory System
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The electric traction system used in trains is the most energy efficient traction system in the transportation sector. Moreover, it has the least NOx and CO2 emissions in comparison to other transportation systems (e.g. busses, passenger cars, airplanes, etc.). On the other hand, they are extremely expensive, mainly due to high installation and maintenance cost of the catenary system, including e.g. overhead lines and substations. Consequently, the share of electrified lines is only slightly higher than non-electrified lines. For instance in Europe, 60% of the railway networks are electrified, and the percentage is much lower in other continents. Battery driven trains are a new generation of electric trains that can overcome such high costs while keeping CO2 emissions and energy consumption low.At the moment, there are only two battery driven electric trains developed and both of the trains are passenger electric multiple units (EMUs). An EMU is an electric train with a traction system in more than one wagon, in contrast to loco-haul electric trains which have a traction system in one wagon only. Energy management during the operation of battery driven trains is a crucial task, as energy optimal operation of trains considering the optimal use of batteries can increase both the operating time and the lifetime of batteries. Energy efficient train operation is realized using driver advisory systems (DAS) that instructs drivers on how to drive trains for minimum energy consumption. The aim of this research is to propose an algorithm for speed profile optimization of both EMUs and battery driven EMUs. The desired algorithm should be suitable as a core component for an online DAS with short response time.Several approaches are proposed in the literature for speed profile optimization of electric trains, and a few of these have been proposed for speed profile optimization of battery driven electric trains. The trains modeled in almost all of the approaches are trains using a notch system for controlling tractive effort. The proposed solution in this research project is to use discrete dynamic programming (DP) to find the optimum speed profile. The application of DP is studied for speed profile optimization of EMUs with a notch system as well as EMUs with a smooth gliding handle for controlling tractive effort. The problem is solved for both normal EMUs and battery driven EMUs.The results of this research show that DP can provide accurate results in a reasonably short time. Moreover, the proposed algorithm can be used as a base for a DAS with fast response time (real-time).

Abstract [sv]

Elektriska traktionssystem i tåg är det mest energieffektiva alternativet inom transportsektorn, och dessutom har det lägst NOx- och CO2-utsläpp i jämförelse med andra transportsystem (exempelvis bussar, personbilar, flygplan, etc.). Å andra sidan är de relativt dyra, främst på grund av höga installations- och underhållskostnader för kontaktledningssystem, inklusive t.ex. luftledningar och transformatorstationer. Följaktligen är andelen elektrifierade linjer något högre än andelen icke-elektrifierade linjer. I Europa är endast 60 % av järnvägsnäten elektrifierade, och andelen är till och med mycket lägre i andra världsdelar. Batteridrivna tåg representerar en ny generation av eltåg som kan nå rimliga kostnader samtidigt med låga CO2-utsläpp och låg energiförbrukning.För närvarande finns det bara två batteridrivna elektriska tåg utvecklade och båda tågen är passagerartåg med elektriska multipla enheter (EMUs). En EMU är ett elektriskt tåg med drivsystem i mer än en vagn, i motsats till lokomotiveltåg som har framdrivningssystemet centrerat till en enda vagn. Energihantering under driften av batteridrivna tåg är en viktig uppgift, och vid en energioptimal drift av tåget tillsammans med en optimerad användning av batterier ökar både driftstiden och livscykeln för batterierna. Energioptimal drift tillämpas i tågdrift med hjälp av ett system som kallas förarrådgivning (eng. Driver Advisory Support, DAS). DAS är ett system som instruerar tågföraren om hur man kör tåget med minimal energiförbrukning.Syftet med denna forskning är att föreslå en algoritm för hastighetsprofilsoptimering av både vanliga EMU:er samt motsvarande batteridrivna. Den önskade algoritmen skall vara lämpad att användas som en bas för ett online-DAS med kort svarstid.Olika metoder föreslås i litteraturen för hastighetsprofilsoptimering av eltåg, och några även för hastighetsprofilsoptimering av batteridrivna elektriska tåg. De tågmodeller som används har oftast ett så kallat “notch”-system för kontrollering av dragkraft. Den föreslagna lösningen i detta forskningsprojekt är att använda diskret dynamisk programmering (DP) för att hitta den optimala hastighetsprofilen. Tillämpning av DP studeras för hastighetsprofilsoptimering av EMU:er både med ”notch”-system samt EMU:er med ett kontinuerligt glidhandtag för styrning av dragkraft. Problemet löses för både normala EMU:er och batteridrivna EMU:er.Resultaten av denna forskning visar att DP kan ge korrekta resultat inom rimlig tid. Vidare kan den föreslagna algoritmen användas som en bas för en DAS med snabb svarstid (realtid).

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2016
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 237
National Category
Environmental Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-31494 (URN)978-91-7485-267-7 (ISBN)
Presentation
2016-06-14, Paros, Mälardalens högskola, Västerås, 09:00 (English)
Opponent
Supervisors
Projects
STREAM
Funder
VINNOVA
Available from: 2016-05-03 Created: 2016-05-02 Last updated: 2016-05-18Bibliographically approved

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Publisher's full texthttp://www.ep.liu.se/ecp/119/038/ecp15119038.pdf

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