SUPERCONDUCTING POWER CABLE FOR RAILWAYS

1. 1
P.RAMESH
152622
NITW

2. CONTENT
 INTRODUCTION
 DC TRACTION SYSTEM
 ANALYSIS MODEL USING HTS CONDUCTOR
 ANALYSIS OF DIFFERENT CHARACTERISTICS OF
TRACTION
 CONCLUSION
 REFERENCES
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3. INTRODUCTION
 Power cables using HT Super conductors have been
developed recent times in many applications.
 Most of the Super conducting power cables projects
are in AC supply in grid applications.
 Recently DC Super conducting power cables have
attracted and now there are some projects running on
DC Super conducting power cables.
 Here we are discussing about the prospective
application of the Super conducting power cable in DC
Electric railway system.
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4. Super conducting power cables
•
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5. 5
• Super conducting power cables can transmits 5 to
10 times the electric current of traditional copper
or alluminium cables with significantly improved
efficiency.
• Super conducting power cables consists of the
cable,which is comprised of 100’s of strands of
superconducting wire wrapped around a copper
core ,and the cryogenic cooling system to
maintain proper operating conditions.
• Comercially available Bi-2223 tapes are used to
design the dc super conducting power cables for
the application in electric railways.

6. 6
• High power copper based cables endure a great
deal of heat at high voltages.
• As electrical current increases,the copper heats
and causes the wire to expand.
• .The effect of heating,cooling,expanding and
contracting causes fatigue known as thermal
cycling and degrades the reliability of the insulation
layer.
• But these HTS cables operated at liquid nitrogen
temperatures(at 77 kelvins)& will not fatigue from
changes in electrical current.

7. ELECTRIC TRACTION
 DC TRACTION
 Operating voltages 600,750,1500,3000v
 DC Traction units use direct current drawn from either
a conductor rail or an over head line.
 most suitable and used operating voltage level in dc
traction system is 1500v and 3000v.
• DC series motors are used as regenerative traction
motors
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8.  Low voltage range in urban and sub urban areas uses
600v and 750v DC for third rail systems.
 A means of providing electric power to a railway train
through a semi continuous rigid conductor placed
along side or between the rails of a railway track and
that additional rail is called conductor rail.
 For these expensive substations are required at
frequent intervals and overhead wires or third rail
must be relatively large and heavy.
 Another issue is how to respond to increasing number
of passengers or speed up of trains while the existing
substations are still used.
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9.  Because of limited spacing for the substations,we look
the feasibility of applying super conducting power
cables to DC Electric Railway systems.
 DC Elecric railways have some problems such as
relatively low voltage,regeneration cancellation and
energy losses etc.
 Super conducting technology would be effective for
novel design & efficient operation of next generation
DC Electric Railway systems.
 Introduction of Super conducting power cable can also
improves the regenative braking operation of electric
traction.
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10. MODEL ANALYSIS
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A Numerical analysis of a power feeding systems a
model line is shown in fig.

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 The total length of the line is 26.5kms
 There are 24 stations and 5 substations along the line
are assumed.
 Cases of four and three substations were also analysed.
 Electric current flows from substations through the
feeder to a train & returns through rail to the
substation.
 A super conducting power cable is placed in parallel to
the feeder & connected to all the substations as shown.
 The length of the super conducting cable is 22.2kms.

12. key parameters of the model line are summerised in table.
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13.  The analysis model line with substations,trains and super
conducting cables was built as a electric circuit as shown.
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14.  The part having 2 trains between 2 adjacent
substations.
 A Substation was modeled as a set of a no load voltage
v0,resistance rs & a diode.
 The train is modeled as a current source It and a
resistance rt.
 The current It is controlled to supply the reactance
power under the voltage Vt.
 A resistance rlr includes both feeder resistance &rail
resistance.
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15.  An equivalent resistance of current lead rc is also
included in the circuit.
 MATLAB Simulink & SIMPOWER systems was used
to analyse the model.
 Relative train operation characteristics considering
different parameter variations are obtained and
analysed.
 For with and without super conducting power cable
cases were examined.
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16.  The fig. shows a set of train operation curves assuemed
in the analysis for a train operation interval of 5 minuts.

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TRAIN OPERATION:

17.  Each curve indicates a trajectory of an operated train.
 Locations of 24 stations and 5 substations are also shown
 A periodic operation of trains with a period of 5 minuts
was assuemed in the analysis for the evaluation of the
system.
 In the analysis 2 track conditions were analysed,single
track and double track conditions.
 The single track case included in the case where the
route was a double track but their electric circuits were
independent of each other.
 The analysis for 5 minutes is enough for evaluation of the
system.
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18. Tracive Force and Power charestics:
 Tractive effort characteristics of a train have three
regions as shown in fig.
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• The fig shows the curves of tractive and breaking forces of a
train running from one station to an adjacent station with
and without the train resistance taken in to account.

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• At higher speeds the tractive force decreases a
little and the braking force increases when the
train resistance is taken in to account.
• In the present line conditions a coasting period
operation period is short,So the train resistance is
ignored during the coasting operation for
simplification of the analysis model.
• Coasting period is the process of turn off of engine
to save fuel at some particular speed,but the train
continues to run due to the momentum attained.
• As power will be removed and the speed falls an
account of friction & windage etc.

21. Acceleration,Power and Speed curves
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 Fig.shows the acceleration and speed curves of the
train.

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0 20 40 60 80 100
Time(s)
0 20 40 60 80 100
Time(s)
0 20 40 60 80 100
Time(s)

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Table indicates the train operation conditions.

24.  When the voltages of the breaking trains becomes
higher and reach the upper limit of the train
voltage VUL(=1800),then the regeneration
cancellation occurs.
 Table 3 indicates the assumptions of cooling
component characteristics.
 For a super conducting cable system the heat load
along the cables of 1kw/km, the heat load cable
terminals of 0.25kw/tonne.
 Coefficient of performance (cop)of the cooling
system of 0.1 were assuemed.
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25. Analysis results
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Influence of the number of substations

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• Fig shows the influence of the number of substations
on the maximum substation current.
• The open symbols indicates the conventional cases
without super conducting cable.
• The solid simbols indicate the cases with
superconducting cable.
• Although the energies are not much influenced by the
number of substations.
• Even so it is still lower in the super conducting cable
system with three substations than that of the
conventional system with 5 substations both for single
track and double track cases.
• The introduction of super conducting cables would
make it possible to reduce the number of substations
or to improve the redundancy of substations.

30. CONCLUSION
 The results showed that the introduction of super
conducting power cables increased the regeneration
rate and improved the energy saving.
 It could reduce the substation capacity,and/or improve
the redundancy of the substations.
 Therefore, if the transportation capacity of a railway
line needs to be increased,the introduction of super
conducting cables could achieve it without changing
the existing substations.
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31. References
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32. THANKS
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