Nonlinear Shielded Multipair Railway Cable Modeling with COMSOL Multiphysics
23/10/2017 ENGINEERING & PROJECTS
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Y. Jin1, S. Karoui1, M. Cucchiaro1, G. Papaiz Garbini1
1Department of Telecommunications, SNCF Reseau, Paris, France
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
CONTENTS
1. RAILWAY CONTEXT 1.1 EMC in the railway environment 1.2 Objective
2. Model Description 2.1 Shielded cable with reduction factor 2.2 COMSOL Modeling
3. RESULTS 3.1 Convergence study 3.2 Shielding behaviour 3.2 Reduction factor
4. Conclusions
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
1.1 EMC in the railway environment
System A
System B
Coupling
J J
EMC (Electromagnetic Compatibility):
Strong-current systems that produce the disturbance
Low-current Systems that suffer the consequences
- High voltage lines (e.g. the Electricity Transmission Network lines)
- Lightning - Electrical equipments
- Signaling and telecommunication cables
- Cathode screens - Humans
Coupling
Signaling and telecommunication cable
High voltage alternatuing current line
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
• Signaling cable: transmission of information and connection between the components of signaling system
• Telecommunication cable: communications between the railway systems
1.1 EMC in the railway environment
fem = −𝑑Ф
𝑑𝑡
Faraday’s law:
Figure 1. Inductive coupling between two cables
Figure 2. Railway network
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
Estimate the induced voltage in the cable
Reduce the risque of inductive interference:
- Decrease the induction loop
- Improve the shielding efficiency of the cable
Study the behaviour of the signaling and telecommunication cables in the face of railway electromagnetic interfernce by COMSOL modeling.
« Reduction factor k »: shielding efficiency
Unknown behaviour strong electromagnetic fields
Unknown nonlinear behaviour material’s magnetic property
1.2 Objective
results from measurements
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
Figure 3. Signaling cable ZPAU
copper screen
steel armor
Copper conductor pairs isolated by polyethylene
2.1 Shielded cable with reduction factor
Construction of signaling cable ZPAU:
3. Shielding: against the disturbance
2. Sheath: electrical isolation, watertightness and
mechanical protection
1. Cable core: transmission of
information
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
Figure 4. µr and B en fonction in terms of H for mild steel GO
2.1 Shielded cable with reduction factor
Magnetic behaviour of steel (ferromagnetic material)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10 100 1000 10000 100000
Mag
net
ic f
lux
den
sity
B, T
esla
Rel
ativ
e p
erm
eab
ility
µr
Magnetic field H, A/m
Electrical steel NGO
µr-H Curve
B-H Curve
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
2.1 Shielded cable with reduction factor
Calculation of reduction factor = 𝑒
𝐸
induced voltage in the conductors of the cable core with the shielding
induced voltage in the cable core without the shielding =
[1] G. Papaiz Garbini, Contribution to calculation of the soil potential rise in the railway context GeePs, Paris, 2015.
• Without shielding: E = M𝐼ωj
High voltage conductor 𝐼
M
High voltage conductor 𝐼
M
E
• With shielding: 𝑒 = 𝐸 + 𝑒′ < 𝐸
• Reduction factor
0 < 𝑘 = 𝑒
𝐸< 1
𝑘 = 1 −𝑚
𝑍𝑠ℎ𝑖𝑒𝑙𝑑𝑖𝑛𝑔 + 𝑅𝐴 + 𝑅𝐵
e RA RB
m
𝑖
Zshielding
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
2.2 COMSOL Modeling
2D AC/DC Module Magnetic fields (mf), frequency-domain
Translational symmetry
PVC
Steel
Copper
Coton
Polyethylene
Figure 6. Geometry of signaling cable ZPAU with 7 pairs
Figure 7. Geometry of cable ZPAU of 1 pair
Infinite Element
External source of interference : Jex
Signaling cable ZPAU
Figure 8. COMSOL Multphysics modeling
H=0 A/m
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
3.1 Convergence study
Mesh quality
Figure 12. Mesh quality for nb=10
Figure 10. Mesh quality for nb=3 Figure 9. Mesh quality for nb=1
Figure 11. Mesh quality for nb=6
• Mesh size
Maximum element size : 𝑋
𝑛𝑏
« nb » : 1 – 10
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
3.1 Convergence study
Mean magnetic field norm in the space (A/m) in terms of mesh size M
ean
mag
net
ic f
ield
no
rm in
th
e sp
ace,
A/m
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
Convergence of magnetic field norm for several points
3.1 Convergence study
Mag
net
ic f
ield
no
rm, A
/m
Point 1
Point 2
Point 3
Point 4
Point 5
2 3 1 4
5
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
3.2 Shielding behaviour H B = µr µ0 H
Cable of 7 pairs
Cable of 1 pair
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
3.3 Reduction factor
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 50 100 150 200 250
k M
EASU
REM
ENT
20
*k C
OM
SOL
Current flowing through the shielding (A)
Reduction factor k for 50Hz
Cable ZPAU of 7 pairsCOMSOL
Cable ZPAU of 7 pairsMEASUREMENT
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
3.3 Reduction factor
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0 50 100 150 200 250
k C
OM
SOL
Current flowing through the shielding (A)
Reduction factor k from COMSOL Simulation for 50 Hz
Cable ZPAU of 7 pairs
Cable ZPAU of one pair
1 pair
7 pairs
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
3.3 Reduction factor
[2] M. Alejandra MORA RIVEROS, Contribution to the EMC modeling in the railway environment: the influence of infrastructure, Lab-STICC, 2010. [3] Schelkunoff, S. A., “The electromagnetic theory of coaxial transmission line and cylindrical shields” Bell Syst. Technical Journal, vol. 13, 1934, pp. 352-579.
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0.11
5 10 15 20 25 30 35 40 45 50 55 60
k C
OM
SOL
Frequency (Hz)
Reduction factor from simulation for a shieding current of 7A
Cable ZPAU of 7 pairs
Cable ZPAU of 1 pair
7 pairs
1 pair
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics
4. Conclusions
• 2D Shielded railway signling cable model has been built: cable of one pair, cable of 7 pairs
• Nonlinearities of cable’s behaviour have been simulated • Future work: different cable configurations
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National Society of French Railways Nonlinear Shielded Multipair Twisted Railway Cable Modeling with COMSOL Mutiphysics