Fi t ti l Utilit I l t ti fFirst practical Utility

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Fi t ti l Utilit I l t ti fFirst practical Utility Implementations of Monitored Withstand Diagnostics in the USA

C. L. Fletcher1, R. N. Hampton2, J. C. Hernandez3, J. Hesse1, M. G. Pearman4, J. Perkel2, C. T. Wall5, W. Zenger6

, S. Stangvik7

1 Duke Energy, 2NEETRAC, 3 Universidad de Los Andes,4 Georgia Power 5 Alabama Power 6PG&E & 7Snopud

2013 IEEE Rural Electric Power Conference (REPC)

4 Georgia Power, 5 Alabama Power, 6PG&E, & 7Snopud

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GTRI/DoE DisclaimerGTRI/DoE Disclaimer• The information contained herein is to our knowledge accurate and reliable at the

date of publication. • Neither GTRC nor The Georgia Institute of Technology nor NEETRAC will be

responsible for any injury to or death of persons or damage to or destruction of property or for any other loss, damage or injury of any kind whatsoever resulting from the use of the project results and/or data. GTRC, GIT and NEETRAC disclaim any and all warranties both express and implied with respect to analysis ordisclaim any and all warranties both express and implied with respect to analysis or research or results contained in this report.

• It is the user's responsibility to conduct the necessary assessments in order to satisfy themselves as to the suitability of the products or recommendations for the user's particular purposeuser s particular purpose.

• No statement herein shall be construed as an endorsement of any product or process or provider

• Any opinions, findings and conclusions or recommendations expressed in thisAny opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of Energy

• This material is based upon work supported by the Department of Energy under Award No DE-0E0000188

2013 IEEE Rural Electric Power Conference (REPC) 2

Award No DE 0E0000188

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Introduction• Simple Withstand (Pass / Fail) tests are commonly

l d b H

Introduction

employed by. However– No indication of the Pass margin– No indication if system is healthy enough for withstandNo indication if system is healthy enough for withstand– No indication if system is so healthy that withstand has

little value

• A diagnostic property that is monitored during the withstand test provides additional information– Helps to quantify the Pass margin

• Monitored Withstand data had yet to be collated and


Monitored Withstand data had yet to be collated and analyzed to give assessment criteria

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Preferred Test ProtocolPreferred Test ProtocolVoltage “Real Time decision

here if you wish to

HOLD

ycontinue Withstand

“Real Time decision here if you wish to curtail orif you wish to curtail or

extend Withstand

RAMP


Time30 Mins

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Ways Not to Pass a Monitored WithstandWays Not to Pass a Monitored Withstand

Failure – Insulation puncture

OROR

High value of Diagnostic Property

OR

High instability in Diagnostic Property – Measured by standardHigh instability in Diagnostic Property Measured by standard deviation in consecutive measurements at one voltage level


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Monitored Withstand Eq ipmentMonitored Withstand Equipment


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Example Tan δ Ramp & Monitored WithstandExample Tan δ Ramp & Monitored Withstand

180 Voltage Elb F il H t L180

160

140

0.51.01.51.7

[p.u.]Voltage

FailureSegment HL_23_22Elbow Failure Hampton Leas

elta

[1e

-3]

120

100

Tan-

de 80

60

40

76543210

40

20


Time [min]76543210

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After RepairAfter Repair…

180 Voltage Elb F il H t L180

160

140

0.51.01.51.7

[p.u.]Voltage

FailureSegment HL_23_22Elbow Failure Hampton Leas

elta

[1e

-3] 120

100

80

Tan-

de

80

60

40

76543210

20

0

After Failure


Time [min]76543210

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DukeCarolinasMid West

KeyspanKeyspan


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Duke


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Aged XLPE StableAged XLPE - StableAged XLPE

5.0 5

elta

[E-

3]

Low and stable

1.0

Tan

De Low and stable

0.5


302520151050Time [min]

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3 Phase PILC Not all Phases Test the Same110

100

10.03-Phase Aged PILC

3-Phase PILC – Not all Phases Test the Same

100

90

80

70

E-3

]

A

CriteriaExtension60 Min

minuteDifference 10 minute to 0

60

50

hst

an

d L

ev

el

[E

1.0

Dev

iatio

n (E

-3)

Phase A performs differently from B & C

40

30TD

@ t

he

Wit

h

ABC

Stan

dard

C

CriteriaReduction 15 Min

80604020020

76543210.1

B

magnitudeto Tan DeltacorrespondsSymbol size


806040200Measurement Sequence

7654321Difference 10 mins to 0 mins (E-3)

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Keyspan


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Aged EPR UnstableAged EPR - Unstable117

15 30 60117

Aged EPR

116

[E-3

] 116unusualdielectric loss is veryExtended cycle trends of

115

leve

l (2.

2Uo)

115

D [

E-3

]

Mean data50% of

114

D @

IEE

E400

.2

114

TD Mean

Median

boxw ithin

113

112

TD 113

112


6050403020100112

Time (mins)

112

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How do we know what is Stable & Unstable?

Where do the Criteria come from?


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Monitored Withstand Criteria• Data from multiple users of MW compiled into database

PG&E

Monitored Withstand Criteria

– PG&E– Duke – Carolinas and Midwest– Georgia Power

S d– Snopud– AEP– Ameren

NEETRAC CDFI– NEETRAC CDFI– IREQ

• Data are segregated by insulation type• Diagnostic properties (Tan δ)

– Stabilitystandard de iation


• standard deviation• difference between 0 & 10 min

– Mean value 16

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Distribution of Tan δ StabilityDistribution of Tan δ Stability

100

80 80

90

60

rcen

t

40Per

20

0 1.36

2.76


543210Std Dev Tan Delta for Monitored Withstand (E-3)

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PE B d d PILC R l Ti D i i M kiCondition

Assessment Test Time Tan δ Time Tan δ

PE-Based and PILC Real-Time Decision Making

Assessment after Hold

Period

Guidance within Hold

Period

Change(0 to 10 min)

[E-3]

Stability(std dev)

[E-3]

Mean Tan δ[E-3]

PE-based Insulations (i.e. PE, XLPE, WTRXLPE)( , , )No ActionRequired

Reduce to15 Mins <0.25

and<0.25

and<5

Further StudyAdvised Retain 30 Mins >0.25 and <17 >0.25 and <6 >5 and <45

ActionRequired

Extend to60 Mins >17 or >6 or >45

Paper Insulations (i.e. PILC)No Action Reduce to <1 3 <0 7 <75Required 15 Mins <1.3

and<0.7

and<75

Further StudyAdvised Retain 30 Mins >1.3 and <4 >0.7 and <3.5 >75 and <135

ActionRequired

Extend to 60 Mins >4 or >3.5 or >135


Required 60 Mins

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Comparison – Georgia Power

Simple Withstandversus

Monitored Withstand


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Georgia Power Roswell• Aged XLPE system

Georgia Power Roswell

– 25 kV system– 1000 kcmil conductor

LC shield– LC shield• 18 Segments (6 3-Phase runs) tested using Monitored

Withstand protocolp• All phases tested separately


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Simple Withstand PerspectiveSimple Withstand Perspective

Individual segment

No Failures On Test

1086420

18 Segments Tested


Length Tested (miles)1086420

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Monitored Withstand PerspectiveMonitored Withstand Perspective

Pass Un Stable Loss

Pass - Stable Loss

Pass Un Stable Loss

Pass - Stable Loss

18 Segments Tested

Pass - Un Stable LossPass - Un Stable Loss

30 min test30 min test

1086420 1086420 1086420 1086420

60 min test

1086420

60 min test


Sequence of Lengths Tested (miles)1086420





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SNOPUDTan Delta – pre test

Monitored WithstandTan Delta - post test


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Knowledge RuleField ToolField Tool

Monitored Withstand Criteria (PE)

ConditionAssessment

Change in Tan Delta between 0

and 10 mins

VLF-TD Stability (standard

deviation) at Maintenance

Mean VLF-TD at

Maintenance and 10 mins(E-3)

Maintenance Level [10-3] Level [10-3]

Reduce to 15 Mins <0.25 and <0.25 and <5

Extend to 60 Mins >17 or >6 or >45


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Unusual Tan δUnusual Tan δ

1000T t

0.51.01.5

[Uo]Voltage

TestTan δ Stability

Tip UpMean Tan δ

100

elta

[E-

3]

1.5Mean Tan δ

10

Tan

De

302520151050

1


302520151050Measurement Sequence [#]

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Monitored WithstandSnopud Segment 6912

Monitored Withstand

10

0.51.0

[Uo]Voltage

Test

Tip Up on Tip Up= 12 8Tip Up = 13.4Stability@Uo = 0

10

lta

[E-3

]

1.5

[email protected]=2.7E-3

TD@Uo=1.3Tip Up on Tip Up= 12.8

Tan

Del

3022000

1


302520151050-5Test Time [min]

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0 to 10 minsSnopud Segment 6912

0 to 10 mins

0.51.0

[Uo]Voltage

Test

Difference between 10 & 0 mins= -4 5

Change in Tan Delta

b t

VLF-TD Stability

(standard deviation)

Mean VLF-TD at

10

ta [

E-3]

01.52.2

= -4.5 between 0 and 10

mins(E-3)

deviation)at

Maintenance Level[10-3]

TD at Maintenance Level [10-3]

Reduce to

Tan

Del

t Reduce to15 Mins <0.25 <0.25 <5

Extend to60 Mins >17 >6 >45

1


302520151050-5Test Time [min]

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0 to 30 mins0 to 30 minsSnopud 6912

0.51.0

[Uo]Voltage

Test

10

ta [

E-3]

01.52.2

Tan

Del

t

1


302520151050-5Test Time [min]

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Final Classification RetestFinal Classification - Retest1000

100

0.51.01 5

[Uo]_2Voltage

TestTan δ StabilityTip Up

Mean Tan δ100

elta

[E-

3]

1.5

10

Tan

De

1


302520151050Measurement Sequence [#]

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Conclusion• Monitored Withstand data enhances information

il bl f t d d di ti t

Conclusion

available from standard diagnostic measurements

• Practical criteria are available for VLF Tan δ Monitored With t d t tWithstand tests.– Currently in use at several US utilities

• Dual Monitored Withstand tests are also possible but difficult to perform.

Unclear what property/properties to look at– Unclear what property/properties to look at– Combines the benefits of all commonly used offline

diagnostics


g

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Fi t ti l Utilit I l t ti fFirst practical Utility