A Sustainable UK Electrical Energy Infrastructure

J.W. Spencer.

Centre for Intelligent Monitoring Systems (CIMS)

Dept of Electrical Engineering and Electronics

Scope of Research

Energy is a broad theme encompassing a wide range of activities,including enabling and supportive technologies (e.g. control, condition monitoring

etc)

CIMS research addresses issues to do with:

High Current phenomena.

• Mainly relating to the electrical network at Transmission and Distribution levels.

• Includes electric arc discharges, current interruption, alternatives to SF6.

• Electrical transients in gas insulated coaxial systems etc following current interruption (i.e. high rates of rise of voltages are induced).

• Electromagnetic control of high current discharges (up to 100kA).

Scope of Research

Monitoring of complex conditions.

• Including optical and non optical fibre sensors and systems.

• Use of a generic methodology for extracting latent information from data/sensor output.

• Condition monitoring.

• A method for dealing with complex systems.

• Cost effective monitoring.

EPSRC funded SUPERGEN V Programme(Tackling the sustainable energy infrastructure)

Part of a consortium of 6 universities (Edinburgh, Liverpool, Manchester, Queens Belfast, Strathclyde, Southampton) involved in a programme on Asset Management for Performance of Energy Systems (AMPerES).

Supported by the major transmission and distribution companies in the UK.

Liverpool is involved in 2 themes: Environmental and Monitoring. Environmental – exploring the possible removal of Sulphur

Hexafluoride from High Voltage plant. Monitoring – cost effective monitoring of distribution and

transmission substations and systems.

Example of High Current ResearchReplacement for SF6?

Priority theme (specifically mentioned in the Kyoto accord, National Grid, EPRI (US))

Research work in China. SF6 is a very good arc quenching medium due to its electronegative

properties. The chemical components at current interruption are in their

dissociated state. It is these components that aid arc extinction. Within micro-seconds the gas changes from a conductor to an

insulator as the dissociate gas recombines. Can particulates in a neutral gas (e.g. Nitrogen) provide the right

chemical components to aid arc extinction and dielectric withstand?

Chemical components of SF6 and PTFE vapour.

SF6 PTFE

Computer simulation of a circuit breaker

Computer simulation with expansion chamber

Finding the best arc quenching conditions e.g. gas flow, Finding the best arc quenching conditions e.g. gas flow, thermodynamic reactions, the right chemical species?thermodynamic reactions, the right chemical species?

Experimental unit

Metallic clamping discs

Expansion chamber

Polymeric powder

PTFE nozzle

Measured pressure rise for PTFE particles.

PTFE at arc column

1st row of flow passage 2nd row nozzle throat widening

Arc current waveform

No podwer

PTFE at expansion volume

-1

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 9 10

Contact gap length (cm)

Pre

ss

ure

(B

ar)

Measured pressure rise for PE particles.

PE at arc column

1st row of flow passage 2nd row nozzle throat widening

Arc current waveform

No podwer

PE at expansion volume

-1

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 9 10

Contact gap length (cm)

Pre

ss

ure

(B

ar)

Influence of polymeric particulates on arc voltage extinction peaks from the expansion chamber.

0

200

400

600

800

1000

1200

1 2 3 4

Arc Current (kA)

Ex

nti

cti

on

Pe

ak

(V

)

No powder in expansionchamber

PMMA powder in expansionchamber

PTFE powder in expansionchamber

PE powder in expansionchamber

2.5 4 6 9

Influence of polymeric particulates on arc voltage extinction peaks from injection.

0

100

200

300

400

500

600

700

1 2 3 4

Arc Current (kA)

Ex

nti

cti

on

Pe

ak

(V

)

No powder injected

PTFE powder injected

PMMA powder injected

PE powder injected

2.5 4 6 9

Stills of particle / arc interaction

No particles PMMA PE

Cathode (moving contact)

Supports

PTFE ring

Power supply

cable

Anode(fixed

contact)

Interface tube

Insulated section

PTFE cylinder containing coil

HIGH SPEED PHOTOGRAPHS OF ARC CONVOLUTIONS

Arc in air, atmospheric pressure, quasi-dc 1.5kA (7500 frames per second)

136mm

22.5ms

A

C

21.6ms

A

C

130mm A

C21.6ms

Anode

Cathode

68mm 50mm

155mm

100mm

PTFE cylinder

A

C

112mm

18.9ms

A

C

A

C

118mm

19.8ms

A

C

20.7ms20.7ms

A

C

125mm A

20.7ms

Cathode (moving contact)

Supports

PTFE ring

Power supply

cable

Anode(fixed

contact)

Interface tube

Insulated section

PTFE cylinder containing coil

ARC MONITORING WITH THREE OPTICAL FIBRES

Fibre 1Anode

Cathode

PTFE cylinder

120 0

ArcFibre 2

Fibre 3

Locations of the three arc monitoring, optical fibres

Interrupter head

Arc rotation

Optical fibre sensors and monitoring systems

Convention was to use laser sources which are monochromatic with single mode optical fibres.

The chromatic approach uses wide band sources (e.g. white light) and multimode optical fibres.

A sensor modulates the white light and the chromaticity of the modulated signal returned to the detector is determined.

The chromatic approach provides a generic approach to optical fibre sensing and monitoring.

0

50

100

150

200

250

300

350

350 400 450 500 550 600 650 700 750

Wavelength (nm)

Ampl

itude

(a.u

.)

0

3000

6000

9000

12000

15000

18000

21000

P.S.

D. (

a.u.)

Integrate using three non-orthogonal Gaussian functions

Take a spectrum

Complex spectrum is reduced to

three RGB values

The RGB values are converted into

three chromatic numbers H (Hue),

L (Lightness) and S (Saturation)

Hue

Saturation

Lightness

White

Black

Hue

Saturation

Lightness

White

Black

(Dominant Wavelength)

(Spread or Bandwidth)

(Signal strength or Intensity)

How does Chromaticity differ from Colour?

Colour is a particular example of Chromaticity Chromaticity is extended outside the visible spectrum Responsivities of detectors and processors are variable Defines information in terms of a limited number of cross correlated

signals Chromatic methods may be deployed not only using wavelength but

also time, frequency, space, mass, acoustic etc domains Chromatic processing can extend to more than 3 spectral parameters,

generally up to 6. It is a highly flexible approach and uses readily available detectors

and sources but used in unconventional manners

BG

R

Freq.

Response

Amp.

Dominantfreq.

Bandwidth

Intensity

t1

t2

t3

Time

Chromatic process

Chromatic processing

Opto - Acoustic monitoring of a tap changing transformer at a distribution substation

Sample signal from tap changing transformerwith tap change.

Location of first tap change 5 -> 4

Chromaticity values from tap changer transformer

Transformer oil monitoring

Optical spectrum analyser

Light source and detection units

Sample of oil

Optical Spectra of Oil Samples

Chromatic values for oil samples

empty cuvetteFresh oil

Oil not of concern

Oil of concern

Process Monitoring (AMEC Waste Digestion Plant)

Monitoring AMEC Waste Digestion Plant

Chromatically processed mass spectrometer data

Combination of sensing planes

Technology Transfer

Ongoing

Fuel quality (KTP) Detection of Bacterial Growth (KTP) Optical fibre based temperature sensors for HV transformer winding

monitoring (KTP)

Future possible

Oil monitoring (Joule Centre) Opto-acoustic monitoring system (required ~ 37 units required for 2

DNOs) (Manufacturer and end user supported University’s KT bid).

Conclusions

There are direct technologies that lead to obvious savings in CO2 and CO2e emissions.

Enabling and supportive technologies are important and can assist in reducing CO2 and CO2e emissions.