Nonlinear Shielded Multipair Railway Cable Modeling with COMSOL Multiphysics

Transcription

1 Nonlinear Shielded Multipair Railway Cable Modeling with COMSOL Multiphysics Y. Jin 1, S. Karoui 1, M. Cucchiaro 1, G. Papaiz Garbini 1 1 Department of Telecommunications, SNCF Reseau, Paris, France 1

2 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 2

3 1.1 EMC in the railway environment EMC (Electromagnetic Compatibility): System A J Coupling System B J 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 Coupling - Signaling and telecommunication cables - Cathode screens - Humans 3

4 1.1 EMC in the railway environment Signaling cable: transmission of information and connection between the components of signaling system Telecommunication cable: communications between the railway systems High voltage alternatuing current line Signaling and telecommunication cable Figure 1. Inductive coupling between two cables Faraday s law: fem = dф dt Figure 2. Railway network 4

5 1.2 Objective Reduce the risque of inductive interference: Estimate the induced voltage in the cable - Decrease the induction loop - Improve the shielding efficiency of the cable «Reduction factor k»: shielding efficiency results from measurements Unknown behaviour strong electromagnetic fields Unknown nonlinear behaviour material s magnetic property Study the behaviour of the signaling and telecommunication cables in the face of railway electromagnetic interfernce by COMSOL modeling. 5

6 2.1 Shielded cable with reduction factor Construction of signaling cable ZPAU: 1. Cable core: transmission of information Copper conductor pairs isolated by polyethylene 2. Sheath: electrical isolation, watertightness and mechanical protection copper screen steel armor 3. Shielding: against the disturbance Figure 3. Signaling cable ZPAU 6

7 Relative permeability µr National Society of French Railways Magnetic flux density B, Tesla 2.1 Shielded cable with reduction factor Magnetic behaviour of steel (ferromagnetic material) Electrical steel NGO Magnetic field H, A/m Figure 4. µ r and B en fonction in terms of H for mild steel GO µr-h Curve B-H Curve 7

8 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 High voltage conductor I High voltage conductor I M i M m Z shielding E R A R B e Without shielding: E = MIωj With shielding: e = E + e < E Reduction factor 0 < k = e < 1 E m k = 1 Z shielding + R A + R B [1] G. Papaiz Garbini, Contribution to calculation of the soil potential rise in the railway context GeePs, Paris,

9 2.2 COMSOL Modeling 2D Translational symmetry AC/DC Module Magnetic fields (mf), frequency-domain PVC Steel Copper Infinite Element External source of interference : J ex Coton Polyethylene Figure 6. Geometry of signaling cable ZPAU with 7 pairs Signaling cable ZPAU H=0 A/m Figure 7. Geometry of cable ZPAU of 1 pair Figure 8. COMSOL Multphysics modeling 9

10 3.1 Convergence study Mesh quality Mesh size Maximum element size : X nb Figure 9. Mesh quality for nb=1 Figure 10. Mesh quality for nb=3 «nb» : 1 10 Figure 11. Mesh quality for nb=6 10 Figure 12. Mesh quality for nb=10

11 Mean magnetic field norm in the space, A/m National Society of French Railways 3.1 Convergence study Mean magnetic field norm in the space (A/m) in terms of mesh size 11

12 Magnetic field norm, A/m National Society of French Railways 3.1 Convergence study Convergence of magnetic field norm for several points Point 1 Point 2 5 Point Point 4 Point 5 12

13 3.2 Shielding behaviour H B = µ r µ 0 H Cable of 7 pairs Cable of 1 pair 13

14 k MEASUREMENT 20*k COMSOL 3.3 Reduction factor National Society of French Railways Reduction factor k for 50Hz Cable ZPAU of 7 pairs COMSOL Cable ZPAU of 7 pairs MEASUREMENT Current flowing through the shielding (A) 14

15 k COMSOL 3.3 Reduction factor National Society of French Railways 0.08 Reduction factor k from COMSOL Simulation for 50 Hz pair Cable ZPAU of 7 pairs Cable ZPAU of one pair pairs Current flowing through the shielding (A) 15

16 k COMSOL 3.3 Reduction factor National Society of French Railways 0.11 Reduction factor from simulation for a shieding current of 7A pair 7 pairs Cable ZPAU of 7 pairs Cable ZPAU of 1 pair Frequency (Hz) [2] M. Alejandra MORA RIVEROS, Contribution to the EMC modeling in the railway environment: the influence of infrastructure, Lab-STICC, [3] Schelkunoff, S. A., The electromagnetic theory of coaxial transmission line and cylindrical shields Bell Syst. Technical Journal, vol. 13, 1934, pp

17 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 17

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