EMC York 2004 July 1 & 2, 2004
Comparison of the booster transformer and aut o t r ansf ansf or mer r ail ai l w ay f eedin di n g syst yst ems, F eedin di n g f eatu at u r es and in i n duc du ct i on t o t el ecom l i n es Prof. Gy György Varju e-mail:
[email protected] [email protected] Budapest University of Technology & Economics
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Presentation items: 1. Rail Railwa way y fee feedi ding ng volt voltag ages es and and re rece cent nt alte altera rati tion onss of the feeding systems in Europe 2. Qual Qualit itat ativ ivee anal analyse ysess of of the the ac. ac. fe feed edin ing g syste systems ms 3.
Mode Modeli ling ng and and par param amet eter erss of of rrai ailw lway ay fe feed edin ing g sys syste tem ms
4. Systems comparison 5. Conclusions
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Presentation items: 1. Rail Railwa way y fee feedi ding ng volt voltag ages es and and re rece cent nt alte altera rati tion onss of the feeding systems in Europe 2. Qual Qualit itat ativ ivee anal analyse ysess of of the the ac. ac. fe feed edin ing g syste systems ms 3.
Mode Modeli ling ng and and par param amet eter erss of of rrai ailw lway ay fe feed edin ing g sys syste tem ms
4. Systems comparison 5. Conclusions
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1.
Railway feeding voltages and recent alterations of the feeding systems in Europe
Feeding voltages in Europe 3000 V dc. 1500 V dc. 50 Hz 25 kV ac. ac. 16 2/3 2/3 Hz Hz 16 kV ac. ac.
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Recent alterations in feeding systems • dc. feeding replaced by ac. 50 Hz, 25kV or 2x25 kV – for high speed train (e.g. TGV) – for high density traffic (e.g. Netherlands)
• BT system replaced by AT – for heavy freight train traffic (e.g. Sweden iron ore transport) – for high speed train
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2. Qualitative analyses of the ac. feeding systems
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Feeding systems of ac. supply Simple feeding with rail (+ earth) return:
RR
Booster transformer with rail return:
BTRR
Booster transformer with return conductor: BTRC Auto transformer:
Combined systems:
AT
AT/BTRR
AT/BTRC; ATPF/BTRC; ATPF/SCBT
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Simple feeding with rail (+ earth) return:
RR system
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Simple feeding with rail (+ earth) return: RR system Quantities characterizing the current portion & profiles
Series impedance of the return rail(s)-to-earth loop, as per unit length values: o
Z RR , series impedance of the return rail(s)-to-earth loop,
o
Z CR , mutual impedance between the contact line system and return rail system with common earth return,
o
G RR the rail-to-earth leakage conductance,
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Simple feeding with rail (+ earth) return: RR system Quantities characterizing the current portion & profiles Derived quantities: •
rail current portion and screening factor behind the end/effect zones: Rail current portion:
Screening factor
Z CR q =− Z RR •
k = 1 + q = 1 −
length constant of the rail-earth circuit with the approximation, that
τ
=
1 α
≈
2 L RR G RR
ω
Z CR Z RR LRR >> R RR :
ω
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Simple feeding with rail (+ earth) return: RR system Rail current and point screening factor at 50 Hz supply
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Simple feeding with rail (+ earth) return: RR system Rail current and point screening factor at 16 2/3 Hz supply
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Booster transformer system with rail return:
BTRR system
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Booster transformer system with return conductor :
BTRC system
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Booster transformer system with return conductor:
BTRC system
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Continuity of the current return path BTRC system
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Auto transformer system AT (with 2U power source)
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Auto transformer system : AT (with 1U power source)
Auto transformer system with increased NF voltage
AT [16/25 kV]
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Auto transformer system with increased PF and NF voltages :
ATPF [16/2x25 kV]
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Combined feeding system AT / BTRR
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Combined feeding system AT / BTRC
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Combined feeding system ATPF / BTRC
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Combined feeding system ATPF and shunt connected BT
ATPF / SCBT
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3. Modeling and parameters of railway feeding systems • Multiconductor line representation • Representation by two phase sequence networks
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Multiconductor line representation of railway feeding (AT) system
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Two phase sequence network representation
BTRC system
Zm
Zm
Zm
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Two phase sequence network representation
AT system
Ztm
Ztm
Ztm
Two phase symmetrical components basic voltage & current expressions Phase quantities
Symmetrical components:
U C = U 0 + U 1
U 0 =
U P = U 0 − U 1
U1 =
Voltages:
1
(U C + U P )
2 1 2
(U C − U P )
Note: U CP = 2U 1
I C = I 0 + I 1
I 0 =
I P = I 0 − I 1
I 1 =
Currents
1 2 1 2
( I C + I P ) ( I C − I P )
Notes: current in the balanced loop: I C = -I P = I 1 current in the return path (rail+earth): I = I + I = 2 I
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Two phase symmetrical component representation of two coupled lops Coupled loop circuit
Equivalent of the coupled loop
Z self =
Positive sequence loop
Z
Z
Z
1 2
( Z CC + Z PP ) Zero sequence loop
Z
Z
Z
Representation of the network elements Line configuration (Rsi – Svv line)
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Representation of the network elements Multiconductor line parameters Distributed series and shunt elements of the railway line model Ic(x)
ZCC
C IR(x)
ZRR
ZCR Z CP
ZPP
ZRP
R IP(x) P
CCP
UR(x)
P
CCR CRP
CC0 UC(x)
UP(x)
C
R GR0
CR0
CP0
Representation of the network elements Line system Multi-conductor network
Sequence networks
positive sequence
zero sequence
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Representation of the network elements Power supply (converter or transformer station)
Multi-conductor network
Sequence networks
Representation of the network elements Traction unit (engine, motor coach) Multi-conductor network
Sequence networks
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View of auto & booster transformers (Installed at the Kiruna – Råtsi – Svappavaara line in Sweden)
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Representation of the network elements Booster transformer: detailed circuit diagram
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Representation of the network elements Booster transformer: magnetizing impedance
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Representation of the network elements Booster transformer: simplified circuit diagram Multi-conductor network
Sequence networks
Zm
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Representation of the network elements Bond (between RC and RR)
Multi-conductor network
Sequence networks
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Representation of the network elements Auto transformer: magnetizing impedance neglected Multi-conductor network
Sequence networks
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4. Systems comparison S tud y item s: a) b) c) d)
E qu ivalent im pe da nce , voltag e stab ility System losses Po we r rating o f auto transform ers Indu ction effect: o Ind ucing ea rth current profiles o Le ng th-current integrals o Ind uce d long itud ina l em f e) R ail-to-ea rth po tential f) R a il-to-rail p o ten tia l
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a) Equivalent impedance, voltage stability
Equivalent impedance vs. train position (spacing 6 km) BTRR
BTRC
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Equivalent impedance vs. train position AT system (spacing 12 km)
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Comparison of impedances vs. train pos. for BTRC & AT systems
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Equivalent impedance vs. train position AT systems
Comparison of voltage drop for AT and BT systems (Traction power 8 MVA)
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Comparison of normalized values of the equivalent impedances for BTRR, BRRC & AT systems
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Voltage drop, versus train location for different AT supply options Train load: 10 MW, cosϕ = 0.8 16 14 12
5AT 4AT 3AT
2U
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∆U
[%]
3U
8 6 4 2 0
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d) Characterization of the induction effect o
Inducing earth current profiles
o
Current-length integrals
o
Induced longitudinal emf
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Inducing earth current profiles Cases studied for demonstration
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Earth current profiles at different train locations BTRR system Spacing: 6 km, G=0.25 S/km, Train current: 500A
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Earth current profiles at different train locations BTRC system Spacing: 6 km, G=0.25 S/km, Train current: 500A
Earth current profiles at different train locations AT system Spacing: 12 km, G=0.25 S/km, Train current: 500A
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3D surface of the inducing current BT system
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3D surface of the inducing current BT system
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Current-length integrals Calculation principle of the current-length integral
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Maximum of the the current-length integral AT system Integration window: 6 km
Integration window: 42 km
Maximum of the normalized current-length integrals, base the current-length integral of the BT system
AT system
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Current-length integrals for different feeding systems Parameter: rail-to earth leakage, G
Average inducing current for different feeding systems Parameter: rail-to earth leakage, G
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Induced longitudinal emf
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Map of the measured line (Kiruna – Råtsi – Svappavaara)
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C - R short circuit locations, for 16 2/3 Hz measurements BT system
C - R short circuit locations, for 16 2/3 Hz measurements AT system
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Longitudinal voltage measurements Sections of telecommunication cable
Induced longitudinal voltage vs. train location in total cable section
AT system V
120 calculated G=0.5 S/km calculated G=0.24 w S/km
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measured 80 60 40 20 0 9 2
4 1
8 2
0 3
2 2
4 7
3 2
2 1
2 7
0 9
0 1
4 2
0 0
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Induced longitudinal voltage vs. train location Comparison of BT and AT systems Measured cable sections: total AT
V
BT
120 100 80 60 40 20 0 9 2 3 .
1 3 6 . 2
8 8 7 . 5
9 2 1 . 7
8 1 . 0
2 8 2 .
3 2 2 . 2
4 7 1 . 5
3 2 4 . 7
2 3 2 . 9
2 9 4 .
4 2 8 . 3
0 9 4 . 5
0 1 8 . 8
5 3 3 . 0
8 0 3 . 4
0 0 6 . 6
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e) Rail-to-earth potential
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Real-to-earth voltage profile vs. length BTRR system Train at 9.01 km
Train at 41.99 km
(BT location)
(at the middle of BT spacing)
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Maximum rail-to-earth voltages vs. train position p osition BTRR system, spacing 6 km
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Real-to-earth voltage profile vs. length BTRC system Train at 2.99 km
Train at 39.01 km
(BT location)
(at the middle of BT spacing)
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Maximum rail-to-earth voltages vs. train position BTRC system, spacing 6 km
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Real-to-earth voltage profile vs. length AT system Train at 17.90 km
Train at 24.01 km
(middle of an AT spacing)
(AT location)
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Maximum rail-to-earth voltages vs. train position AT system, spacing 12 km
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Maximum rail-to-earth voltages for different feeding systems BT spacing 3 km
BT spacing 6 km
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Conclusions The results of simulation calculations and site experiences a) The equivalent impedance is significantly (about 3 times) less for the AT system than that for the BT system. b) Induction to telecommunication lines: • the BT and AT systems are, practically, identical . • the maximum longitudinal voltage occurred in the whole line length with the current injection at the Svv end • the induction effect could significantly be reduced by the improvement of the balance ◊ for BT system balancing the mutual impedances of the catenery system and the return conductor to rail ◊ for AT system balancing the self impedances of the catenery system and the inverted feeder
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Conclusions cont. c) The rail potentials in personnel safety point of view, they are also similar in AT and BT supply systems with the following remark: • in case of AT supply the rail-to-earth voltage can reach higher value in the relatively big AT spacing • in case of BT supply, the voltages over insulated joints are higher in certain places. d) Both the induction effect and the rail potential are significantly affected by: • spacing of BT or AT • rail-to-earth leakage conductance, G
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Conclusions cont. Proposals for further study (1) The feasibility of the use of positive feeder. (2) The feasibility of the combined feeding systems. (3) Methods for balancing the AT feeding by: • optimised negative feeder arrangement • use of current unbalance suppression unit (CUS).
