The HVDC-OLPD Monitor for High Voltage Direct Current (HVDC) Cable and Plant

Condition Monitoring

Presented by Malcolm Seltzer-Grant, HVPD LtdOctober 21st, LCNI Conference 2014

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Contents

• Introduction to Partial Discharge • HVDC OLPD Monitoring System Project Summary• Sensors Installation and Monitoring Results • Conclusions

Introduction

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Why test for partial discharge?

PD activity is an indication of an ‘incipient fault’ in HV insulation and is widely regarded as the best ‘early warning’ indicator of insulation deterioration.The detection of PD at an early stage enables preventative maintenance action to avoid unplanned outages.

What is partial discharge?

“A localised electrical discharge that only partially bridges the insulation between conductors and which can or can not occur adjacent to a conductor”IEC60270 Definition

Why are SP Energy Networks interested?

SP Energy Networks are looking to use partial discharge condition monitoring on the Western HVDC Link, the subsea high-voltage interconnector being built between the west coasts of Scotland and England and have chosen to sponsor the development of devices from HVPD capable of providing this.

Most Likely Sites of PD Activity in Subsea Cables

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Land Termination(Indoor/Outdoor)

Subsea Termination(Indoor)

Land-Subsea Cable Joint

LandCable Joint

Land Cable Subsea Cable

HVDC Monitoring System Project Summary

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• Condition monitoring technology for High Voltage Direct Current HVDC subsea export cables and interconnectors

• The application has been expanded to include the state and condition monitoring of the connected AC/DC converter technology.

HVDC Monitoring System Project Summary

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• Suitable for the HVDC export cables and interconnectors that will be critical for to the development of a European electricity transmission supergrid and Round 3 offshore wind farms.

• The system will use on-line partial discharge (OLPD) detection combined with other electrical and thermal CM modules.

• The system is expected to enhance fault findings and provide early warning system for HVDC cable operators.

• Reduce electricity costs through lower operational and maintenance costs.

HVDC-OLPDHVDC-OLPD Monitoring System Project Lifetime: 24 months (01/10/13 to 30/09/15)HVDC Subsea Export Cable and Interconnector Monitoring System

Supported by

Developed with

HVDC Monitoring System Project Summary

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• Definition of the first system functional specification was based on the topology of the HVAC/HVDC converter station and aims to monitor the state and condition of parameters which can interfere and undermine the reliability of the HVDC system.

Monopole HVDC converter station [Bahrman, M.P. ; Johnson, B.K. “The ABCs of HVDC transmission technologies”, IEEE Power & Energy Magazine March/April 2007 Vol. 5 No. 2]

HVDC Monitoring System Project Summary

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• The system will be based upon non-intrusive PD detection methods and investigatory work will include:

– Evaluation of PD behaviour in HVDC cables – Cable Attenuation and PD Pulse Propagation – Noise and interference evaluation under DC – Power convertor monitoring – OLPD Sensor requirements – Cross-Correlation of OLPD Data with VSC Ripple, Transient

Overvoltage and PQM Sensor requirements

HVDC OLPD Monitoring System

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Computer Modem

Remote Access

Monitor

Digitisers

Control ElectronicsSensors

Auxiliary Parameters

Photos of installed HVDC OLPD Alpha monitor systems at Alstom Grid HVDC Cable Ageing

Facility and a HVDC interconnector

Block Diagram of the Alpha Monitor System

Sensors Installation and Monitoring Results

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Positioning of three types of OLPD Sensor on the cable test Rig

Alstom Grid HVDC Cable Ageing Facility

Sensors Installation and Monitoring Results

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Sharp edges generating Corona discharge

Corona caps generating Corona discharge source

Corona Discharge Sources within the HVDC cable test bed

PEA Pulses

Corona

Monitoring of Peaks of Discharge Activities in (dB)

Alstom Grid HVDC Cable ageing

Facility

Sensors Installation and Monitoring Results

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Monitoring sensors installation of a HVDC cable interconnector

Sensors Installation and Monitoring Results

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Acquired signals within the HVDC cable

• Signals peaks are the results of the 12 pulse quadruple valves (serial connection of two 6-pulse converter bridges coming from the two 3-phase systems).

• Decreasing peak height due to the transition of the signal through the quadruple valves

Available Waveform Display

Chan 1 Chan 2 Chan 3 Curs 1 Chan 4 Curs 2

Time (mSec)20191817161514131211109876543210

Cha

n 1

3.8

3.6

3.4

3.2

3

2.8

2.6

2.4

2.2

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

-0.2

-0.4

-0.6

-0.8

-1

-1.2

-1.4

-1.6

-1.8

-2

-2.2

-2.4

-2.6

-2.8

-3

-3.2

-3.4

-3.6

-3.8

-4

Cha

n 2

0.019

0.018

0.017

0.016

0.015

0.014

0.013

0.012

0.011

0.01

0.009

0.008

0.007

0.006

0.005

0.004

0.003

0.002

0.001

0

-0.001

-0.002

-0.003

-0.004

-0.005

-0.006

-0.007

-0.008

-0.009

-0.01

-0.011

-0.012

-0.013

-0.014

-0.015

-0.016

-0.017

-0.018

-0.019

Cha

n 3

3.8

3.6

3.4

3.2

3

2.8

2.6

2.4

2.2

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

-0.2

-0.4

-0.6

-0.8

-1

-1.2

-1.4

-1.6

-1.8

-2

-2.2

-2.4

-2.6

-2.8

-3

-3.2

-3.4

-3.6

-3.8

-4

Cha

n 4

0.007

0.007

0.006

0.006

0.005

0.005

0.004

0.004

0.003

0.003

0.002

0.002

0.001

0.001

0.000

0

-0.001

-0.001

-0.002

-0.002

-0.003

-0.003

-0.004

-0.004

-0.005

-0.005

-0.006

-0.006

-0.007

-0.007

-0.008

-0.008

Sensors Installation and Monitoring Results

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Available Waveform Display

Chan 1 Chan 2 Chan 3 Curs 1 Chan 4 Curs 2

Time (mSec)20191817161514131211109876543210

Cha

n 1

3.8

3.6

3.4

3.2

3

2.8

2.6

2.4

2.2

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

-0.2

-0.4

-0.6

-0.8

-1

-1.2

-1.4

-1.6

-1.8

-2

-2.2

-2.4

-2.6

-2.8

-3

-3.2

-3.4

-3.6

-3.8

-4

Cha

n 2

0.019

0.018

0.017

0.016

0.015

0.014

0.013

0.012

0.011

0.01

0.009

0.008

0.007

0.006

0.005

0.004

0.003

0.002

0.001

0

-0.001

-0.002

-0.003

-0.004

-0.005

-0.006

-0.007

-0.008

-0.009

-0.01

-0.011

-0.012

-0.013

-0.014

-0.015

-0.016

-0.017

-0.018

-0.019

Cha

n 3

3.8

3.6

3.4

3.2

3

2.8

2.6

2.4

2.2

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

-0.2

-0.4

-0.6

-0.8

-1

-1.2

-1.4

-1.6

-1.8

-2

-2.2

-2.4

-2.6

-2.8

-3

-3.2

-3.4

-3.6

-3.8

-4

Cha

n 4

0.007

0.007

0.006

0.006

0.005

0.005

0.004

0.004

0.003

0.003

0.002

0.002

0.001

0.001

0.000

0

-0.001

-0.001

-0.002

-0.002

-0.003

-0.003

-0.004

-0.004

-0.005

-0.005

-0.006

-0.006

-0.007

-0.007

-0.008

-0.008

Representation of the source of signals based on the circuit diagram of the quadruple valves

Conclusion

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• The OLPD-HVDC project aims to further the understanding of PD and insulation degradation on HVDC cable systems through both laboratory and field tests along with the development of monitoring hardware.

• Development monitoring systems are being deployed on operating HVDC cables to verify the functionality in a field environment.

• The system aim is to identify ‘incipient’ insulation defects prior to failure in order to enable preventative maintenance interventions to support condition-based management (CBM) and avoid unplanned outages.