2006.02.08 Fault Localization

8/22/2019 2006.02.08 Fault Localization

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Introduction

Physics

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Conclusion

Fault Localization in High Voltage Cable with

VLF Power SupplyMaster Thesis

Beat Schwaller

Telecommunications, Networks and Security

Department of Computer ScienceUniversity of Fribourgand PDTech AG Neuenhof

7.2.2006

Beat Schwaller Fault Localization in High Voltage Cable with VLF Power Supply


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Introduction

Physics

Development

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Outline

1 Introduction

2 Physics

3 Development

4

Schedule

5 Conclusion



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Physics

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Conclusion

Topic

The goal of this master thesis is to produce a softwarebased portable (low cost) measurement instrument for

localizing weak spot of high power cable insulation.

Supported by PDTech AG



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Introduction

Physics

Development

Schedule

Conclusion

Motivation

Replacement of underground cables is expensive

Detecting weak spot in cable insulation allows local

reparation



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Introduction

Physics

Development

Schedule

Conclusion

What is PD?

Partial discharges are caused by local irregularity/defect of

insulation material

The capacitance in such locations is much less than of the

surrounding insulation

Applying high voltage, partial discharges appear

Figure: Partial Discharge Pattern. Source: [1]


I d i


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Introduction

Physics

Development

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Conclusion

Why VLF 0,1 Hz?

For field-test, the power supply should be portableA very low frequency (0,1Hz) power supply offers a

compact portable design of test equipment

Low power requirement I= U 2 f C

(500 times less power than a regular 50Hz power supply)


I t d ti


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Development

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Conclusion

How to localize fault location?

Analyze the PD reflections against the velocity of

propagation of the signals and cable length

Figure: Reflectometry. Source: [1]


Introduction


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Introduction

Physics

Development

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Conclusion

Workflow

Development of a base application (I/O handling,calibration, etc)

Module for manual fault location detection (prototype)

Module for automatic detection (signal analyzing)


Introduction


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Introduction

Physics

Development

Schedule

Conclusion

Development

Picoscope (USB Oscilloscope)

LabView 7.1 (Graphical programming language)

Coupling capacitors

VLF power supply


Introduction


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Introduction

Physics

Development

Schedule

Conclusion

Screenshot PD Analyzer


Introduction


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Introduction

Physics

Development

Schedule

Conclusion

Schedule

first draft for a timeschedule

20.2. - 25.2. Testmeasurement in Ludwigshafen (AVISO)

3 weeks development of base application for manual

measurement

5 weeks development and implementation of automatic

signal detection

Testing and debugging

Documentation


Introduction


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Introduction

Physics

Development

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Conclusion

Conclusion

In a first draft, the system should detect weak spots in

cable insulation

Problems may arise when multiple discharges are detected

at the same time

The feasibility of detecting weak spots in a composite

cable system is not ensured


Introduction


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Physics

Development

Schedule

Conclusion

Bibliography

[1] M. de Nigris; G. Rizzi, et al. : CABLEDIAGNOSIS BASED ON DEFECT LOCATION

AND CHARACTERIZATION THROUGH PARTIAL

DISCHARGE MEASUREMENTS, Cesi (Cigre

15-109 session 2002).


Documents

2006.02.08 Fault Localization