nonlinear shielded multipair railway cable ... - uk.comsol.com · nonlinear shielded multipair...

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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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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• 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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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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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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Figure 4. µr and B en fonction in terms of H for mild steel GO


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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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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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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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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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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Convergence of magnetic field norm for several points


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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3.2 Shielding behaviour H B = µr µ0 H

Cable of 7 pairs

Cable of 1 pair


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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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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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[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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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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