04 seminar electrical

8/8/2019 04 Seminar Electrical

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JICA Study Team for Enhancing Eff ici ency of Operating Thermal Power Plants in NTPC-India

Issued in Feb 2010

Summary of

Generator Assessment&

GT Assessment

2010


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1. Generator Assessment procedures

2. Generator assessment results of Korba#6,Rihand#2, Singlauli#4

3. GT Assessment procedures

4. GT assessment results of Korba#6, Rihand#2,Singlauli#6

Contents


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Generator Assessment procedures


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3Generator Assessment procedures

Required specification of stator

Insulator : MicaResin: EpoxyResin process: VPI (Vacuum Pressure Impregnation)

Target for the assessment

235.3MVA, 15.75kV, Stator: water cooledSingrauli #4

605MVA, 20kV, Stator: water cooledRihand #2

588MVA, 16.2kV, Stator: water cooledKorba #6Main specification

Target specification is the same as required specification of stator.


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4Assessment procedures

Assessment type

Current condition assessmentJudging from the latest test resultsRemaining l ife assessment (RLA)

Judging from lots of historical test data

Generator part for the assessment

Assessment Is conducted according to Japanese criteria.

Stator coil insulationStator coil insulation is most deteriorated.

Sorts of stator coil insulation diagnosis for assessment1)Insulation resistance test (IR test)2) Polarization index test (PI test)3) Tan test

4) Step voltage test5) Parti al discharge test (Corona test)


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Generator assessment results of Korba#6, Rihand#2, Singlauli#4


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6Korba#6 assessment results

Not available PI test

RLA

= IR (8 min) / IR (1 min) Not available0.994PI test

Not available0.0628930 M IR test

Cur rent condition assessment

Remark EvaluationTest r ecordTest item

Korba#6 does not drain and dry stator coil.So, Korna#6 test data is meaningless for the assessment.


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No more than one test r esult Notavailable

Tan test

Fluctuates PI da ta Notavailable

3-phasePI testRemaining life assessment

Good1.24%BGood1.08%Y

JP: tan < 2.5%Good0.74%R Tan test

( Tan )

JP, NTPC 2.0Good3.753-phasePI test

JP 50 M , NTPC 21 M

Good1000 M 3-phaseIR testCur rent condition assessment

Remark/standardEvaluationTest r ecordPhaseTest item

Rihand#2 assessment results


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y = 0.0093e 0.0574x

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

0 2 4 6 8 10 12 14

Test voltage (kV)

T a n

( % )

Tan

test (Y phase)

Estimation of Tan 0 & Tan max (Y phase)


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9Rihand#2 RLA

y = -0.1933x + 6.6281

0

1

2

3

4

5

6

7

8

0 5 10 15 20O peration year (year)

P I d a t a

Dange rous crite ria: Le s s than 1.0

Cautio n crite ria: L es s than 2.0

I test historical trend (Whole phases test)

(Jul-1989)

Multiple historical Tan data is not available. ThereforeRLA is conducted by m ult iple historical PI test

Ave.=3.7

PI data has fluctuated recentlyNo deterioration trend

Impossible to conduct RLA


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10Singraulii#4 assessment results

The evaluation items differ from those in J apan.

Not available Partialdischar ge test

Not available0.02%B

Not available-0.03%Y

JP: tan < 2.5%The test voltage is low.

Not available0.01%R Tan test( Tan )

Good2.11B

Good2.86YJP, NTPC 2.0Good2.58R PI test

Good1900 M B

Good3500 M Y

JP 50 M , NTPC 17 M Good3100 M R IR test

Remark/standardEvaluationTestrecord

Phase

Current condition assessment


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Results of Tan

Impossible to conduct Current condition by Tan test

Singrauliu#4 current condit ion assessment

y = 0.8567e -3E-05x

y = 0.8791e 0.0028x

0.840.850.860.87

0.880.89

0.90.910.920.93

0 1 2 3 4 5 6Test voltage (kV)

T a n ( % )

: R phase: Y phase: B phase

Technically, the higher test vol tage is, the higher tan data become.But Y-phase data declines. So, these data are not reliable.


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12Singraulii#4 assessment results

RLA

The test voltage is low. Not available AllTan

The PI data does not show adeteriorating trend.

Not available BUp to the dangerous level *1201936 years

Up to the caut ion level *1201229 yearsY

Up to the dangerous level *1202239 years

Up to the caut ion level *1201532 yearsR PI t est

Year Operationyears

PhaseTest

*1: PI data is easily changeable due to stator dryness level


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13Singrauli #4 RLA

RLA by PI test (R phase)

y = -0.1371x + 6 .3445

0

1

2

3

4

5

6

7

0 10 20 30 40

O peration year (year)

P I

PI historical trend (R-phase)

Dangerous crite ria: Less than 1.0

Caution criteria: Less than 2.0

(1983)

Although PI data fluc tuate due to stator coil d ryness,the deterioration trend is shown.

Approximation formula byExcel function


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1. Conduct ing insulation diagnosis without cool ing water (Korba)

It is recommended that Korba#6 conduct the insulationdiagnosis without cool ing water so that Korba#6 can grasp thecurrent condi tion, the deterioration trend.

2. Conduct test by appropriate test vol tage (Singrauli)When Tan test is conducted, it is required to conduct i t byappropriate test voltage. Because it mainly focuses on partial

discharge in voids of the insulation. The partial discharge doesnot occur at low test voltage.

1. Continue to conduct the insulation diagnosis

NTPC should conduct the insulation diagnosis periodically inthe future so that NTPC can grasp the deterioration t rend.

2. Get reliable and accurate test dataSome test data is not consistent with technical theory. Check

the test data and get reliable and accurate test data .

Recommendations


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Rihand#2

*3

PD Remarks

( )*4Japan

*2Singrauli#4

*1 *1Korba#6

Tan S-VPIIRPlant

S-V: Step-voltage test PD:Partial discharge test*1: Test with cooling water is meaningless.*2: Max test voltage is low.*3: Measurement data is different f rom Japanese one

*4: Some OEMs do, the others do not in Japan.

Status of conducting insulation diagnosis test

Insulation diagnosis is totally evaluated by all the tests inJapan.


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GT Assessment procedures


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17Required specification & Target GT

Required specification of GT

Oil immersed transformer Insulation paper : craft paper Sealed typeNo absorbent in oil

Target for the assessment

Target specification is the same as required specif ication.

Single phase 200 MVA 1 unit, OFWF, Sealed typeSingrauli#6Single phase 201.7 MVA 3 units, OFWF, Sealed typeRihand#2Single phase 200 MVA 3 unit s, OFAF , Sealed typeKorba#6

Main specificationUnit


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18Assessment method

Assessment type

Current condition assessmentJudging from the latest test dataRemaining l ife assessment (RLA)

Judging from lots of historical test data

GT part for the RLA

Assessment Is conducted according to Japanese criteria.

Coil insulation paper Because Coil insulation paper is most deteriorated.

Sorts of GT assessment1)Insulation resistance test (IR test)2) Dissolved gas analysis (DGA)3) Furfural analysis

4) CO+CO2 analysis


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Judgment criteria in Japanese criteria (ppm)

300CO

5 0.5 0.5C2H2

100 & TCG 700 or 100 & the increasing r atioof TCG 70 per mont h

10 & TCG 500 10C2H4

150C2H6

100CH4

400H2

500TCG

Abnormal levelCaution level 2Caution level 1CriteriaItem

*1: Caution level-1The level that transformer is out of normal condi tion although it i s not judged to be abnormal

and dangerous condition*2: Caution level-2The level that transformer becomes abnormal condition gradually*3: Abnormal levelThe level that transformer i s clearly abnormal cond ition. (aggravating fu rther from Cautionlevel-2) TCG means the gap of TCG between the test and the previous test

DGA Judgment criteria in Japan


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20CO+CO2 Analysis Judgment Criteria7. Japanese assessment criteria

Ave. DP of insulation paper

( C O + C O 2 v o

l u m e )

/ ( I n s u

l a t i o n p a p e r w e i g

h t )

( m L / g )

Ave. DP=450 level(*2)

2.0mL/g

Dangerouslevel


0.2mL/g

Cautionlevel

RemarksCriteriaLevel

*1 Transformer wi th DP of 450, withthe lowest CO+CO2 volume per insulation paper weight

*2 Transformer wi th DP of 450, withthe highest CO+CO2 volume per insulation paper weight

Assessment is conductedaccording to the criteria.

(CO+CO2 volume) (Insulation paper weight)


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21Furfural Analysis Judgment Criteria7. Japanese assessment criteria


0.015mg/g

Dangerouslevel


0.0015mg/g

Cautionlevel

RemarksCriteriaLevel

*1 Transformer wi th DP of 450, withthe lowest furfural weight per insulation paper weight

*2 Transformer wi th DP of 450, withthe highest furfural weight per insulation paper weight

( F u r f u r a

l w e i g

h t ) / ( I n s u l a

t i o n p a p e r w e i g

h t )

( m g / g

)

Ave. DP of insulation a er

Assessment is conductedaccording to the criteria.

(Furfural weight) (Insulation paper weight)


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GT assessment results of Korba#6, Rihand#2, Singlauli#6R


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23Korba#6R DGA ResultH2 CH4 C2H4 C2H6 C2H2 C3S CO CO2 TCG TCG increase

ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm/month 400 100 10 150 0.5 300 500

10 0.5 500 C2H4

10+TCG

500 orC2H2 0.5

100 700 70C2H4 100+TCG 700 or TCG 70ppm/month

Apr-1990 387 3 0 2 51 0 34 47 477 Abnormal level *1Nov-1990 11 8 0 0 0 0 82 819 101 -53.7Feb-1995 80 17 0 30 0 10 15 1723 152 1.0Sep-1995 75 16 0 22 0 23 10 1855 146 -0.9Jun-2000 85 56 50 58 0 28 381 2853 658 8.8 Caution level-2Oct-2000 84 54 52 84 0 12 398 3606 684 6.0 Caution level-2

Jul-2005 20 60 22 66 0 28 450 3810 646 -0.7 Caution level-2Oct-2005 16 70 20 70 0 30 440 3890 646 0.0 Caution level-2Jan-2006 42 60 16 67 0 25 420 3710 630 -5.5 Caution level-2Apr-2006 32 62 2 118 0 60 262 4135 536 -26.9 Caution level-1Jul-2006 23 15 1 50 0 10 130 1906 229 -99.0Oct-2006 29 24 1 26 0 8 128 1903 216 -4.9Apr-2007 16 30 2 38 0 5 91 1597 182 -5.2Jul-2007 12 42 0 45 0 10 75 2062 184 0.9Oct-2007 102 24 0 31 0 9 34 1394 200 4.9Dec-2007 91 35 0 51 0 12 43 2111 232 17.8

Mar-2008 70 30 0 29 0 8 40 1922 177 -17.6Jun-2008 71 2 2 8 0 0 127 1865 210 10.8Aug-2008 60 20 0 25 0 7 25 1229 137 -32.7Jul-2009 21 81 1 76 0 31 111 1869 321 16.8Dec-2009 18 61 2 58 0 21 109 1916 269 -9.8Mar-2010 25 32 0 33 0 2 92 1790 184 -26.8Jun-2010 21 49 3 91 0 4 112 1896 280 30.0

Date Remarks

Abnormal level

Caution level-2

Caution level-1

Recently within criteriaSo, Good condition


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y = 0.0283x

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 5 10 15 20O peration year (Years)

C

O + C O 2 ( m L / g )

Caution level =0.2

Dangerous level =2.0

(1989 Jan.)

Average RLA level = 1.1

The generation speed of CO+CO2 per insulation paper weight is estimated by approximation formula funct ion of Excel soft and the current condit ion & the RLA areestimated.

Estimation of CO+CO2 generation speed (R phase)(Korba#6)

Approximation formula of CO+CO2generation speed (ml/g-year)


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25DP estimation by CO+CO2 analysis(Korba#6)

R phase: 0.4400Y phase: 0.5194B phase: 0.6074

R phase: 335Y phase: 318B phase: 295


( C O + C O 2 v o

l u m e )

/ ( I n s u


h t ) ( m L / g )



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26Furfural generating trend (Korba#6)

0.000

0.001

0.002

0.0030.004

0.005

0.006

0.007

0.008

0.009

0.010

0 5 10 15 20 25O peration years (years)

F u r f u r a l ( m g / g )

(Jan.1989)

R phase

Y phase

B phase

Caution Level=0.0015

Dangerous level=0.015

Average RLA leve l=0.00825

Because 2010 data is lit tle bit larger than 2009 data, furfuralgenerating speed increases.


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27DP estimation by furfural analysis (Korba#6)

DP estimation by2010 June data.

( F u r f u r a

l w e i g

h t ) / ( I n s u


h t )

( m g

/ g )


R phase: 0.00463Y phase: 0.00541B phase: 0.00386




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Caution0.00386 mg/gB

Caution0.00541 mg/gY

Caution 0.0015 mg/gDanger 0.015 mg/g

Caution0.00463 mg/gR Furfuralanalysis

Caution0.5943 mL/gB

Caution0.5082 mL/gY

Caution 0.2 mL/gDanger 2.0 mL/g

Caution0.4305 mL/gR CO+CO 2analysis

GoodDGA dataB

GoodDGA dataY

GoodDGA dataR DGA

Good3250 M B

Good3500 M Y JP 80 M Good3500 M R IR test

Remark/standardEvaluationTest recordPhaseTest



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RLA

Nov-203445.9B

Oct-202132.8YUp to the average servicelife*2

Mar-202738.2R Fur fura l analysis

Dec.-202738.9B

Jul.-203445.5Y

Up to the average servicelife*1

Sep.-204253.7R CO+CO 2analysis

Year Operationyears

RLA

*1:The average service life point was set to 1.1 mL/g, which is the averagebetween the caution level (0.2 mL/g) and the danger level (2.0 mL/g).

*2:The average service life point was set to 0.00825 mg/g, which is theaverage between the caution level (0.0015 mg/g) and the danger level(0.015 mg/g).


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30Rihand#2 assessment results

Danger 0.07161 mg/gB

Danger 0.07161 mg/gYCaution

0.0015 mg/gDanger 0.015 mg/g

The measurement da ta isnot r eliable.

Danger 0.16328 mg/gR Furfuralanalysis

Caution0.97 mL/gB

Caution0.90 mL/gY

Caution 0.2 mL/gDanger 2.0 mL/g

Caution0.95 mL/gR CO+CO 2analysis

GoodDGA dataBGoodDGA dataY

GoodDGA dataR DGA

Good835 M B

Good979 M Y

JP 80 M Good707 M R IR test

Remark/standardEvaluationTest recordPhase



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31Rihand#2 assessment results

RLA

Not available B Not available Y

Up to the average servicelife*2The measur ement data is notreliable.

Not available R Furfuralanalysis

Nov.-201223.4B

Jul.-201425.1Y

Up to the average servicelife*1

May-201323.9R CO+CO 2analysis

Year Operationyears

PhaseTest




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32Singraulii#6R assessment resultsCurrent condition assessment

JP Caution 0.0015 mg/gJP Danger 0.015 mg/gThe measur ed values are

not r eliable.

Danger 0.0283 mg/gFur fural analysis

JP Caution 0.2 mL/gJP Danger 2.0 mL/g

Caution1.38 mL/gCO+CO 2 analysis

GoodDGA dataDGA

Good300 M HV-LV

Good150 M LV-E

JP 80 M Good250 M HV-EIR test

Remark/standardEvaluationTest record


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33Singraulii#6R assessment resultsRLA

Over danger levelThe measured values are not r eliable.

Not available Furfuralanalysis

Up to the danger levelSep-201932.7

Up to the average service life*1Jun-200518.0CO+CO 2analysis

Year Operationyears




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34Recommendations for GT assessment

1. Conduct DP measurement (Singrauli)To know actual GT condit ion, DP measurement of insulationpaper is effective. Conduct DP test when Singrauli GT isreplaced in order to confirm the correlation between CO/CO2 andDP.

1. Continue to conduct the tests

NTPC should conduct the tests periodically in the future so that

NTPC can grasp the deterioration trend.2. Get reliable and accurate test data

Some test data is not consistent with technical theory. Check thetest data and get reliable and accurate test data .

3. When NTPC purchases transformer, NTPC should get theinitial DP and the insulation paper weight from the manufacturer

in order to conduct CO+CO2/furfural analysis in the future.4. Accurate oil treatment records are required for CO+CO2 analysis.5. Accurate oil change records are required for Furfural analysis.


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Thank you!

04 seminar electrical

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