Download Autotransformer system

Banebranchen Session 2012
May 9th - 2012
High Performance Railway Power
Introduction to Autotransformer system (AT)
Banebranchen – Session infrastructure May 9th 2012
Tommy O. Jensen/Atkins Danmark
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Banebranchen Session 2012
May 9th - 2012
Agenda
Historical
AT system ”reinvented”
Principle of operation
AT supply system
AT system at HSL-railways
AT system in Sweden
AT system in Norway
Advantages/drawbacks of AT
Suitable for use in Denmark?
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Banebranchen Session 2012
May 9th - 2012
Historical
Valtellina 3 kV – 15
Hz, Italien1902
Introduction of AC-systems
1900
1905
1910
1915
AC locomotives are introduced Ganz
develops the first AC locomotive (3 kV)
Many AC systems open in the eastern
US, among others New York – New
Haven (11 kV)
Auto transformer supply tends to
become a standard on densely
traficated lines in USA
(e.g. AT-systems +11/-22 kV – 25 Hz)
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
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Banebranchen Session 2012
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AT system ”reinvented”
Increased demands for power necessitates new solutions for
train power systems
1972 Japan, Sanyo Shinkansen
(25/25 kV – 60 Hz)
1981 France, TGV Paris-Lyon
(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.
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Banebranchen Session 2012
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Operation for Auto Transformer
Principle of operation for an Auto Transformer
250 A
e1+e2
e2
500 A
Ampere winding balance: I1• N1 = I2 • N2 (”the ideal transformer”)
Power for autotransformator: SAT = U1 • I1 = U2 • I2
Common 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)
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Banebranchen Session 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.
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Banebranchen Session 2012
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AC supply system
Direct supply running rail (RR) or
Direct supply with return conductor (RC)
Return conductor
RC
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Banebranchen Session 2012
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AC supply systems
Booster transformer with return conductor (BT-RC)
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Banebranchen Session 2012
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AC supply systems
Auto transformer with full range voltage supply (AT-2U)
Train power transformer with two secondary coils
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Banebranchen Session 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”
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Banebranchen Session 2012
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AC supply systems
Earth currents with direct supply (RR)
Earth currents with direct supply
with return conductor (RC)
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Banebranchen Session 2012
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AC supply systems
Earth currents with BT system
Earth currents with AT system
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Banebranchen Session 2012
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AC supply systems
Why choose a complicated AT system?
Source:
Comparison of BT and AT
system, EMC-symposium
York 1-2. July 2004.
Prof. György Varju,
Budapest University
Because supply
conditions will
improve
significantly!
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Banebranchen Session 2012
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AC supply systems
Why choose a complicated system?
NL (-25 kV)
Inductance in an overhead line AC
system is heavily dependent on the
geometric design
PL (+25 kV)
CL (+25 kV)
Inductance can be reduced by a
symmetric configuration and small
distances between conductors
Reduced EMC impact on the surroundings
and reduced stray currents with balanced
impedances in PL and FL (reduced "leakage"
of currents)
RR (0 kV)
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Banebranchen Session 2012
May 9th - 2012
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
Direct (RR-RC)
~ 65 %
30-40 km
Direct with supply feeder (RR-RC-FL)
~ 60 %
35-45 km
~ 20-25 %
60-80 km
Auto transformer (AT)
Possible increased distance between substations
Significantly improved quality of voltage
Reduced losses
Better utilization of brake energy
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Banebranchen Session 2012
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AT system at HSL-railway
French AT transformer 225 kV /2x27,5 kV
Nominal power 72 MVA (36-36 MVA) SNCF TGV
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Banebranchen Session 2012
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AT system at HSL-railway
Electric layout for AT supply
Supply station, feeder cables, substation
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Banebranchen Session 2012
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AT system in Sweden
Supply system with distributed auto transformers (”AT-Light”)
Source:
BVS 1543.11601 Kraftförsörjningsanläggningar
Autotransformatorsystem – systembeskrivning,
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Banebranchen Session 2012
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AT system in Sweden
Supply system with distributed auto transformators (”AT-Light”)
Banverket AT system 2 x 15 kV
AT-transformers 5 MVA
Used at Vännas – Umeå line
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Banebranchen Session 2012
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AT system in Sweden
Supply system with distributed auto transformators (”AT-Light”)
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Banebranchen Session 2012
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AT system in Norway
Supply system with distributed auto transformators (”AT-Light”)
Omformerstasjon
15 kV samleskinne
returstrøm samleskinne
1o km
1o km
1o km
Negativledning – NL -15 kV
Positivledning PL + 15 kV
Kontaktledning KL + 15 kV
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Banebranchen Session 2012
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AT system in Norway
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Banebranchen Session 2012
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AT system in Norway
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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.
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Banebranchen Session 2012
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AT system interesting
in 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.
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Banebranchen Session 2012
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AT system interesting
in Denmark?
Electrification till 2020
Lunderskov-Esbjerg
København - Ringsted
Ringsted – Rødby/Femern
Note: Yellow substations not yet decided!
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Banebranchen Session 2012
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AT-system interesting
in 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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Banebranchen Session 2012
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Thank you for your attention!
Electric railway at
Skærum Teglværk 1909
Electric railway at
Ørestad 2012
Questions?
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