Comparison Booster Transformer
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Transcript of Comparison Booster Transformer
EMC York 2004July 1 & 2, 2004
Prof. György Varjue-mail: [email protected]
Budapest University of Technology & Economics
Comparison of the booster transformer and auto transformer railway feeding systems,
Feeding features and induction to telecom lines
2
Presentation items:
1. Railway feeding voltages and recent alterations of the feeding systems in Europe
2. Qualitative analyses of the ac. feeding systems
3. Modeling and parameters of railway feeding systems
4. Systems comparison
5. Conclusions
3
1. Railway feeding voltages and recent alterations of the feeding systems in Europe
4Feeding voltages
in Europe
3000 V dc.1500 V dc.50 Hz 25 kV ac.16 2/3 Hz 16 kV ac.
5
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
6
2. Qualitative analyses of the ac. feeding systems
7
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: AT
Combined systems: AT/BTRR
AT/BTRC; ATPF/BTRC; ATPF/SCBT
8Simple feeding with rail (+ earth) return:
RR system
9Simple 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 ZRR, series impedance of the return rail(s)-to-earth loop,
o ZCR, mutual impedance between the contact line system and return rail system with common earth return,
o GRR the rail-to-earth leakage conductance,
10Simple feeding with rail (+ earth) return:
RR systemQuantities characterizing the current portion & profiles
Derived quantities: • rail current portion and screening factor behind the end/effect zones:
Rail current portion: Screening factor
RR
CR
ZZq −=
RR
CR
ZZqk −=+= 11
• length constant of the rail-earth circuit with the approximation, that ωLRR >> RRR:
RRRRGLωατ 21 ≈=
11Simple feeding with rail (+ earth) return: RR system
Rail current and point screening factorat 50 Hz supply
12Simple feeding with rail (+ earth) return: RR system
Rail current and point screening factorat 16 2/3 Hz supply
13
Booster transformer system with rail return: BTRR system
14Booster transformer system with return conductor:
BTRC system
15
Booster transformer system with return conductor: BTRC system
16
Continuity of the current return path BTRC system
17Auto transformer system
AT (with 2U power source)
18Auto transformer system :
AT (with 1U power source)
19Auto transformer system
with increased NF voltageAT [16/25 kV]
20Auto transformer system
with increased PF and NF voltages:ATPF [16/2x25 kV]
21Combined feeding system
AT / BTRR
22Combined feeding system
AT / BTRC
23Combined feeding systemATPF / BTRC
24Combined feeding system
ATPF and shunt connected BTATPF / SCBT
25
3. Modeling and parameters of railway feeding systems
• Multiconductor line representation
• Representation by two phase sequence networks
26
Multiconductor line representation of railway feeding (AT) system
27Two phase sequence network representation
BTRC system
Zm ZmZm
28Two phase sequence network representation
AT system
Ztm Ztm Ztm
29Two phase symmetrical componentsbasic voltage & current expressions
Phase quantities Symmetrical components:
U U UC = +0 1 ( )PC UUU +=21
0 Voltages:
10 UUU P −= U U UC P112
= −( )
Note: UCP = 2U1
10 IIIC += ( )PC III +=21
0
Currents
10 IIIP −= ( )PC III −=21
1
Notes: current in the balanced loop: IC = -IP = I1
current in the return path (rail+earth): Ireturn = IC + IP = 2 I0
30Two phase symmetrical component representation of two coupled lops
Coupled loop circuit Equivalent of the coupled loop
Positive sequence loop Zero sequence loop
CPself ZZZ −=0 CPself ZZZ +=0
( )PPCCself ZZZ +=21
31Representation of the network elements
Line configuration (Rsi – Svv line)
32Representation of the network elements
Multiconductor line parametersDistributed series and shunt elements
of the railway line model
Ic(x) ZCC
IR(x) ZRR
IP(x) ZPP
ZCR
ZRP
C
R
P
ZCP
UP(x)
UR(x)
UC(x)
R
C P
CP0
CCP
CCR CRP
CC0GR0 CR0
33Representation of the network elements
Line system
Multi-conductor network Sequence networks
positive sequence
zero sequence
34Representation of the network elements
Power supply (converter or transformer station)
Multi-conductor network Sequence networks
35Representation of the network elements
Traction unit (engine, motor coach)Multi-conductor network Sequence networks
36View of auto & booster transformers
(Installed at the Kiruna – Råtsi – Svappavaara line in Sweden)
37
Representation of the network elementsBooster transformer: detailed circuit diagram
38Representation of the network elements
Booster transformer: magnetizing impedance
39Representation of the network elements
Booster transformer: simplified circuit diagram
Multi-conductor network Sequence networks
Zm
40Representation of the network elements
Bond (between RC and RR)
Multi-conductor network Sequence networks
41Representation of the network elements
Auto transformer: magnetizing impedance neglected
Multi-conductor network Sequence networks
42
S tudy item s: a) Equivalent im pedance, voltage stability b) System losses c) Power rating of auto transform ers d) Induction effect:
o Inducing earth current profiles o Length-current integrals o Induced longitudina l em f
e) Rail-to-earth potentia l f) Rail-to-ra il potentia l
4. Systems comparison
43
a) Equivalent impedance, voltage stability
44Equivalent impedance
vs. train position (spacing 6 km)
BTRR BTRC
45
Equivalent impedance vs. train positionAT system (spacing 12 km)
46Comparison of impedances vs. train pos.
for BTRC & AT systems
47Equivalent impedance vs. train position
AT systems
48Comparison of voltage drop for AT and BT systems
(Traction power 8 MVA)
49Comparison of normalized values of
the equivalent impedances forBTRR, BRRC & AT systems
50Voltage drop, versus train location
for different AT supply options
2U
3U
0
2
4
6
8
10
12
14
16
0 5 10 15 20 25 30 35 40train position, km
∆U[%]
5AT4AT3AT
Train load: 10 MW, cosϕ = 0.8
51
d) Characterization of the induction effect
o Inducing earth current profiles
o Current-length integrals
o Induced longitudinal emf
52
Inducing earth current profilesCases studied for demonstration
53Earth current profiles at different train locationsBTRR system
Spacing: 6 km, G=0.25 S/km, Train current: 500A
54Earth current profiles at different train locationsBTRC system
Spacing: 6 km, G=0.25 S/km, Train current: 500A
55Earth current profiles at different train locations
AT systemSpacing: 12 km, G=0.25 S/km, Train current: 500A
563D surface of the inducing current
BT system
57
3D surface of the inducing current BT system
58
Current-length integralsCalculation principle of the current-length integral
59
Maximum of the the current-length integralAT system
Integration window: 6 km Integration window: 42 km
60Maximum of the normalized current-length integrals,
base the current-length integral of the BT systemAT system
61Current-length integrals for different
feeding systemsParameter: rail-to earth leakage, G
62Average inducing current for different
feeding systemsParameter: rail-to earth leakage, G
63
Induced longitudinal emf
64Map of the measured line(Kiruna – Råtsi – Svappavaara)
65
C - R short circuit locations, for 16 2/3 Hz measurements
BT system
66C - R short circuit locations,for 16 2/3 Hz measurements
AT system
67
Longitudinal voltage measurementsSections of telecommunication cable
68Induced longitudinal voltage vs. train location
in total cable sectionAT system
0
20
40
60
80
100
120
1.32
9
4.31
4
7.12
8
10.3
30
12.2
22
15.1
74
17.4
23
20.4
12
22.5
72
25.4
90
28.8
10
32.4
24
36.5
00
km
V
calculated G=0.5 S/km
calculated G=0.24 w S/km
measured
69Induced longitudinal voltage vs. train location
Comparison of BT and AT systemsMeasured cable sections: total
0
20
40
60
80
100
120
1.32
9
2.63
1
5.78
8
7.12
9
10.1
8
11.2
82
12.2
23
15.1
74
17.4
23
19.2
32
21.4
92
23.8
24
25.4
90
28.8
10
30.3
35
34.3
08
36.6
00
k
V AT
BT
70
e) Rail-to-earth potential
71Real-to-earth voltage profile vs. length
BTRR systemTrain at 9.01 km
(BT location)Train at 41.99 km
(at the middle of BT spacing)
72
Maximum rail-to-earth voltages vs. train positionBTRR system, spacing 6 km
73Real-to-earth voltage profile vs. length
BTRC systemTrain at 2.99 km
(BT location)Train at 39.01 km
(at the middle of BT spacing)
74
Maximum rail-to-earth voltages vs. train positionBTRC system, spacing 6 km
75
Real-to-earth voltage profile vs. lengthAT system
Train at 17.90 km(middle of an AT spacing)
Train at 24.01 km(AT location)
76
Maximum rail-to-earth voltages vs. train positionAT system, spacing 12 km
77Maximum rail-to-earth voltages for
different feeding systems
BT spacing 3 km BT spacing 6 km
78
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
79
Conclusionscont.
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
80
Conclusionscont.
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).
81
Thank you for your attention
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