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Banebranchen Session 2012 May 9th - 2012
1
High Performance Railway Power
Introduction to Autotransformer system (AT)
Banebranchen – Session infrastructure May 9th 2012
Tommy O. Jensen/Atkins Danmark
Banebranchen Session 2012 May 9th - 2012
2
Agenda
Historical
AT system ”reinvented”
Principle of operation
AT supply system
AT system at HSL-railways
AT system in SwedenAT system in Sweden
AT system in Norway
Advantages/drawbacks of AT
Suitable for use in Denmark?
Banebranchen Session 2012 May 9th - 2012
3
Introduction of AC-systems
Historical
1900 AC locomotives are introduced Ganzdevelops the first AC locomotive (3 kV)
1905 Many AC systems open in the eastern US, among others New York – New Haven (11 kV)
Valtellina 3 kV – 15
Hz, Italien1902
Haven (11 kV)
1910 Auto transformer supply tends to become a standard on densely traficated lines in USA
(e.g. AT-systems +11/-22 kV – 25 Hz)
1915 The Iron Ore line Kiruna-Narvik
was electrified (15 kV – 15 Hz with
80 kV supply)
New Haven-system 11/22 kV–25 Hz
CG1- loco at 4.600 kW
New York 1934
Banebranchen Session 2012 May 9th - 2012
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Increased demands for power necessitates new solutions for
train power systems
AT system ”reinvented”
1972 Japan, Sanyo Shinkansen
(25/25 kV – 60 Hz)
1981 France, TGV Paris-Lyon
(25/25 kV – 50 Hz)(25/25 kV – 50 Hz)
1987 Hungary, simplified AT system
(25/25 kV – 50 Hz)
1995 Sweden, Kiruna – Svappavaara
(15/15 kV – 16,7 Hz)
Suitable for busy conventional railways, heavy haul and high speed lines.
Substations are expensive and technical complicated installations.
Banebranchen Session 2012 May 9th - 2012
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Operation for Auto Transformer
Principle of operation for an Auto Transformer
250 A
500 Ae1+e2 e2
Ampere winding balance: I1• N1 = I2 • N2 (”the ideal transformer”)Power for autotransformator: SAT = U1 • I1 = U2 • I2Common winding = reduced weight, smaller volume, reduced losses
Lower price compared to normal two winding transformer.
Option for low leak reactance, particularly important in a train power system
Draw back – no galvanic separation (easier "path" for short circuit currents)
Banebranchen Session 2012 May 9th - 2012
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Terminology for AT systems
Normally used terms:
� Auto transformer only has one coil with three terminations
� Primary and secondary side have no galvanic separation *)
� ”Plus conductor” is connected to contact wire and positive feeder (PL)
� ”Minus conductor” is only connected to negative feeder (NL)
� Midpoint termination – ideally 0 V – is connected to track / return circuit
� Angel between ”plus” and ”minus” conductors is 180°
� Normal designations are 2x25 kV or +25/-25 kV
*) Power supply (transformer) from the high voltage grid, e.g. 220 kV,
will normally be galvanic separated from the train power system.
Banebranchen Session 2012 May 9th - 2012
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AC supply system
Direct supply running rail (RR) or
Direct supply with return conductor (RC)
Return conductorRC
Banebranchen Session 2012 May 9th - 2012
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AC supply systems
Booster transformer with return conductor (BT-RC)
Banebranchen Session 2012 May 9th - 2012
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AC supply systems
Auto transformer with full range voltage supply (AT-2U)
Train power transformer with two secondary coils
Banebranchen Session 2012 May 9th - 2012
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AC supply systems
Auto transformer with contact wire voltage supply (AT-1U)
Train power transformer equipped with one secondary coil
Some times named ”AT-Light”
Banebranchen Session 2012 May 9th - 2012
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AC supply systems
Earth currents with direct supply (RR)
Earth currents with direct supply
with return conductor (RC)
Banebranchen Session 2012 May 9th - 2012
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AC supply systemsEarth currents with BT system
Earth currents with AT system
Banebranchen Session 2012 May 9th - 2012
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AC supply systems
Why choose a complicated AT system?
Source:Comparison of BT and ATsystem, EMC-symposium York 1-2. July 2004.Prof. György Varju, Budapest University
Because supply
conditions will
improve
significantly!
Budapest University
Banebranchen Session 2012 May 9th - 2012
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AC supply systems
Why choose a complicated system?
Inductance in an overhead line AC
system is heavily dependent on the
geometric design CL (+25 kV)
PL (+25 kV) NL (-25 kV)
Reduced EMC impact on the surroundings
and reduced stray currents with balanced
impedances in PL and FL (reduced "leakage"
of currents)
geometric design
Inductance can be reduced by a
symmetric configuration and small
distances between conductors
CL (+25 kV)
RR (0 kV)
Banebranchen Session 2012 May 9th - 2012
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AC supply systems
Why choose a complicated system?
Principle of supply (normal operation)
Relative impedance
Acceptabel distance single track
Booster transformer (BT-RC) 100 % 20-30 km
Possible increased distance between substations
Significantly improved quality of voltage
Reduced losses
Better utilization of brake energy
Direct (RR-RC) ~ 65 % 30-40 km
Direct with supply feeder (RR-RC-FL) ~ 60 % 35-45 km
Auto transformer (AT) ~ 20-25 % 60-80 km
Banebranchen Session 2012 May 9th - 2012
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AT system at HSL-railway
French AT transformer 225 kV /2x27,5 kVNominal power 72 MVA (36-36 MVA) SNCF TGV
Banebranchen Session 2012 May 9th - 2012
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AT system at HSL-railway
Electric layout for AT supplySupply station, feeder cables, substation
Banebranchen Session 2012 May 9th - 2012
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AT system in Sweden
Supply system with distributed auto transformers (”AT-Light”)
Source:
BVS 1543.11601 KraftförsörjningsanläggningarAutotransformatorsystem – systembeskrivning,
Banebranchen Session 2012 May 9th - 2012
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AT system in Sweden
Supply system with distributed auto transformators (”AT-Light”)
Banverket AT system 2 x 15 kVAT-transformers 5 MVAUsed at Vännas – Umeå line
Banebranchen Session 2012 May 9th - 2012
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AT system in Sweden
Supply system with distributed auto transformators (”AT-Light”)
Banebranchen Session 2012 May 9th - 2012
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AT system in Norway
Supply system with distributed auto transformators (”AT-Light”)
15 kV samleskinne
returstrøm samleskinne
Omformerstasjon
1o km 1o km 1o km
Negativledning – NL -15 kV
Kontaktledning KL + 15 kV
Positivledning PL + 15 kV
Banebranchen Session 2012 May 9th - 2012
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AT system in Norway
Banebranchen Session 2012 May 9th - 2012
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AT system in Norway
Banebranchen Session 2012 May 9th - 2012
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Advantages / drawbacks AT-system
AT system compared to BT system
+ Very low voltage drop in overhead catenery system.+ Reduced losses in overhead catenary system = saved energy! + Auto Transformer every 10th km compared to Booster Transformer every 3rd km.+ Possible longer distance between substations.
- More conductors mounted in overhead catenary system.- More complicated switching equipment in train power system- Risk of locally higher earth current caused by higher power levels.
BT system employed on lines with parallel signaling and telecommunication cables in order to avoid electromagnetic disturbances. AT system can offers the same advantages.
AT system is widely used on high speed lines and railways with heavy freight traffic.AT system can be used on long single track lines to reduce numbers of substations.
Banebranchen Session 2012 May 9th - 2012
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AT system interestingin Denmark?
Electrification 2011
Existing network too expensive to rebuild.
Cost for Kystbanen estimated at 120 mio.kr!
Lines to be electrified in the future could prove interesting.
Banebranchen Session 2012 May 9th - 2012
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AT system interestingin Denmark?
Electrification till 2020
Lunderskov-Esbjerg
København - Ringsted
Ringsted – Rødby/FemernRingsted – Rødby/Femern
Note: Yellow substations not yet decided!
Banebranchen Session 2012 May 9th - 2012
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AT-system interestingin Danmark?
Probable development
after 2020
The rest of Sealand 2018-2022
Main lines in Jutland 2020-2025
Other local lines 2025-2035
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Thank you for your attention!Electric railway at Skærum Teglværk 1909
Electric railway at Ørestad 2012
Questions?