Rate of Change (Trend) PPM, PPM/day or PPM/Year What make sense? - - PowerPoint PPT Presentation

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Rate of Change (Trend) PPM, PPM/day or PPM/Year What make sense? - - PowerPoint PPT Presentation

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Rate of Change (Trend) PPM, PPM/day or PPM/Year What make sense? C. Beauchemin IEEE Transformer Committee TJH2b Analytical Services Inc. Fall 2013 Meeting C57.104 St-Louis, October 20 24, 2013 Fall 2012 Luiz Cheim presentation

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SLIDE 1

Rate of Change (Trend)

∆ PPM, PPM/day or PPM/Year What make sense?

  • C. Beauchemin

TJH2b Analytical Services Inc. IEEE Transformer Committee Fall 2013 Meeting C57.104 St-Louis, October 20 – 24, 2013

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SLIDE 2

Fall 2012

  • Luiz Cheim presentation (On the Web)
  • Review of work done to date
  • Review of factors influencing limits
  • Presentation also covered various aspect
  • f rate computation
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SLIDE 3

Rate of Gas Increase (ppm/year) vs Sampling Interval???

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SLIDE 4

Rate of Gas Increase (ppm/year) vs Sampling Interval???

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SLIDE 5

Food for Thought…

Rate of Gas Increase (ppm/year) vs Sampling Interval???

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SLIDE 6

Further work to clarify this question

  • Study of a new set of data
  • Single source (one lab)
  • North America
  • Mix of industrial and utilities
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SLIDE 7

Data set

  • One source
  • 123 469 DGA
  • 44 266 Transformers
  • Delta computed between actual and

previous DGA

  • 78 660 pairs of DGA
  • All Gas + TDCG
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SLIDE 8

Sampling Interval

Time between sampling

0.001 0.002 0.003 0.004 0.005 0.006 0.007 200 400 600 800 1000 1200 1400

Sampling Interval Days Density

26 Days 91 Days 186 Days 365 Days 735 Days 942 Days 1107 Days 551 Days

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SLIDE 9

Sampling Interval

Time between sampling

0.001 0.002 0.003 0.004 0.005 0.006 0.007 200 400 600 800 1000 1200 1400

Sampling Interval Days Density

1 Month 3 Months 6 Months 1 Year 2 Years 2.5 Years 3 Years 1.5 Years

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SLIDE 10

Data set

  • Table 3 use TDCG rates of 10 - 30 ppm/day
  • ppm/year or ml/day is also used to evaluate

gassing rate

  • Preliminary study (last meeting) has been

done in ppm/year

  • 1 ppm/day = 365 ppm/year
  • 10 ppm/day = 3650 ppm/year
  • 30 ppm/day = 10950 ppm/year
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SLIDE 11

DGA “Noise”

  • Oil sampling, transport and analysis do

introduce DGA variations from one sample to the next

  • The same difference between two samples

could give different ppm/day (or ppm/year) depending of the period between samples

  • It is of particular importance for on-line data
  • How that affect interpretation?
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SLIDE 12

An Example: CH4

  • The data set was splits in 8 Groups

corresponding to 8 different average sampling periods

  • Week, Month, Quarter, Half-Year, Year,

2 Years, 3 Years and > 4 years

  • For each DGA, ppm/year was computed
  • For each groups, a standard statistic study

was performed

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SLIDE 13

Time between sampling

0.001 0.002 0.003 0.004 0.005 0.006 0.007 200 400 600 800 1000 1200 1400

Sampling Interval Days Density

Month Quarter Half Year 1 Year 2 Years 3 Years Long Week

Sampling Interval

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SLIDE 14

Data Set

Sampling Intervals

2% 5% 7% 11% 57% 10% 4% 4%

Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

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SLIDE 15

Some Definitions

95 Percentile: 95% of the samples are below that value Absolute Change (Delta)

Delta PPM = PPMnow – PPMlast sample

Normalised Change (Trend)

Trend = Delta PPM / (Datenow – Datelast sample) in PPM/Day in PPM/Year (PPM/Day * 365)

BoxPlot Graph

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SLIDE 16

BoxPlot Graph

First Quartile (25%) Third Quartile (75%) Median 50% of Population Q1 - 1.5 IQR Q3 + 1.5 IQR Outliers Outliers Inter Quartile Range

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SLIDE 17

BoxPlot Graph

  • Usefully to visually evaluate a group of

data

– Spread of data – Middle Value – Symmetry of distribution – Outliers

  • Easy to compare several groups of data
  • So, what do we have with trend data ?
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SLIDE 18

CH4 Normalised Rate

CH4 PPM / Year

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 19

CH4 PPM / Year

Week Month Quarter Half Year Year 2 Years 3 Years Long

CH4 Normalised Rate

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SLIDE 20

CH4 PPM / Year

Week Month Quarter Half Year Year 2 Years 3 Years Long

CH4 Normalised Rate

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SLIDE 21

95 Percentile Rate VS Sampling Interval

500 1000 1500 2000 2500 3000 3500 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval 95 Percentile Rate (ppm/year)

CH4 Normalised Rate

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SLIDE 22

From Last Presentation

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SLIDE 23

CH4 Normalised Rate

A ratio of 463 between “weekly” and “long term” sampling !!

Sampling Period PPM/Year PPM/Day Week 3115 8.5 Month 1028 2.8 Quarter 235 0.64 Half Year 55 0.15 1 Year 19 0.052 2 Years 12 0.033 3 Years 8.3 0.023 Long 6.7 0.018 95 Percentile of Rate

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SLIDE 24

CH4 Normalised Rate

  • If we want to use PPM/year (or PPM/Day)

we obviously need a method to handle this spread

  • Should we have a table for each period?
  • Which periods ?
  • How many ?
  • How complex ?
  • Added to the “other” complexities ?
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SLIDE 25

Normalised Rate and noise

  • Maybe we are looking at it the wrong way ?
  • If we have noise in the data, it would

probably be the same for short and long period

  • If we divide a fixed value by an increasing

period, we will obtain a log like curve

  • As an example, let take 25 ppm / 1 day,

/7 days, /14 days … to ppm / year…..

  • Then:
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SLIDE 26

Simulation of a Constant PPM Delta

Example of Fixed Delta / Increasing Sampling Period

1000 2000 3000 4000 5000 6000 7000 < 3 3 - 5 5 - 10 10 - 15 15 - 30 30 - 60 60 - 90 90 - 120 120 - 180 180 - 240 240 - 365 > 365

Sampling Period Days PPM / Year

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SLIDE 27

Simulation of a Constant PPM Delta

Example of Fixed Delta / Increasing Sampling Period

1 10 100 1000 10000 < 3 3 - 5 5 - 10 10 - 15 15 - 30 30 - 60 60 - 90 90 - 120 120 - 180 180 - 240 240 - 365 > 365

Sampling Period Days PPM / Year

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SLIDE 28

From Previous Presentation

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SLIDE 29

Change of Perspective

  • So, let try to drop the notion of normalised

rate (Trend) (PPM/day or PPM/year)

  • Let look at the ABSOLUTE difference (in

PPM) between two samples (Delta)

  • Let group results by sampling period, as a

few slides before

  • What do we have ?
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SLIDE 30

CH4 Absolute Change

CH4 Delta PPM

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 31

CH4 Absolute Change

95 Percentile Absolute Change VS Sampling Interval

20 40 60 80 100 120 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

All samples

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SLIDE 32

CH4 Absolute Change

  • Ratio has been reduced by a factor of 100
  • A lot more manageable !!
  • The use of absolute variation between

consecutive samples, without day or year normalisation, give more uniform results and is simpler to use

  • What else could we learn from this data set ?
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SLIDE 33

CH4 Gas Level in PPM

90 Percentile PPM

50 100 150 200 250 300 350 400 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval 90 Percentile PPM

1 2 3 4 5 6 7 8 9 10 % Samples > Condition 4

All samples

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SLIDE 34

CH4 Gas Level in PPM

Percentage of Samples above condition 4

20 40 60 80 100 120 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

1 2 3 4 5 6 7 8 9 10 % Samples > Condition 4

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SLIDE 35

95 Percentile Absolute Change and % of Samples above Condition 4

20 40 60 80 100 120 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

1 2 3 4 5 6 7 8 9 10 % Samples > Condition 4

CH4 Absolute Change

Percentage of points With CH4 in Condition 4 PPM Change between samples

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SLIDE 36

CH4 Absolute Change

95 Percentile Absolute Change VS Sampling Interval

20 40 60 80 100 120 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

All Points Points Condition 4 Removed

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SLIDE 37

95 Percentile Absolute Change VS Sampling Interval

20 40 60 80 100 120 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

CH4 Absolute Change

All Points Points Condition 4 Removed Points Condition 3 & 4 Removed

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SLIDE 38

95 Percentile Absolute Change VS Sampling Interval

20 40 60 80 100 120 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

CH4 Absolute Change

All Points Points Condition 4 Removed Points Condition 3 & 4 Removed Points Condition 2 & 3 & 4 Removed

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SLIDE 39

Other Gas

  • H2, C2H4 and C2H2 have the same type of

distribution

  • CO and CO2 form a different group
  • C2H6 and TDCG are between the two groups
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SLIDE 40

Other Gas

  • “Type I”
  • Short Term Rate Higher than long term
  • Short Term Level Higher than long term

– Hydrogen – Methane – Eyhylene – Acethylene

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SLIDE 41

H2 Absolute Change

H2 Delta PPM

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 42

H2 Absolute Change

95 Percentile Absolute Change VS Sampling Interval

50 100 150 200 250 300 350 400 450 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

1 2 3 4 5 6 7 8 9 10 % Samples > Condition 4

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SLIDE 43

C2H4 Absolute Change

C2H4 Delta PPM

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 44

C2H4 Absolute Change

95 Percentile Absolute Change VS Sampling Interval

20 40 60 80 100 120 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

2 4 6 8 10 12 14 % Samples > Condition 4

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SLIDE 45

C2H2 Absolute Change

C2H2 Delta PPM

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 46

C2H2 Absolute Change

95 Percentile Absolute Change VS Sampling Interval

0.5 1 1.5 2 2.5 3 3.5 4 4.5 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

1 2 3 4 5 6 7 8 9 10 % Samples > Condition 4

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SLIDE 47

Other Gas

  • “Type II”
  • Short Term Rate Lower than long term
  • Short Term Level similar to long term

– Carbon Monoxide – Carbon Dioxide

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SLIDE 48

CO Absolute Change

CO Delta PPM

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 49

CO Absolute Change

95 Percentile Absolute Change VS Sampling Interval

100 200 300 400 500 600 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

1 2 3 4 5 6 7 8 9 10 % Samples > Condition 4

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SLIDE 50

CO2 Absolute Change

CO2 Delta PPM

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 51

CO2 Absolute Change

95 Percentile Absolute Change VS Sampling Interval

500 1000 1500 2000 2500 3000 3500 4000 4500 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

1 2 3 4 5 6 7 8 9 10 % Samples > Condition 4

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SLIDE 52

Other Gas

  • “Type III”
  • Middle Term Rate Lower than shorth

and long term

  • Short Term Level lower than long term

– Ethane – TDCG

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SLIDE 53

C2H6 Absolute Change

C2H6 Delta PPM

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 54

C2H6 Absolute Change

95 Percentile Absolute Change VS Sampling Interval

5 10 15 20 25 30 35 40 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

2 4 6 8 10 12 14 % Samples > Condition 4

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SLIDE 55

TDCG Absolute Change

TDCG Delta PPM

Week Month Quarter Half Year Year 2 Years 3 Years Long

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SLIDE 56

TDCG Absolute Change

95 Percentile Absolute Change VS Sampling Interval

100 200 300 400 500 600 700 800 900 1000 Week Month Quarter Half Year 1 Year 2 Years 3 Years Long

Sampling Interval Delta (ppm)

1 2 3 4 5 6 7 8 9 10 % Samples > Condition 4

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SLIDE 57

Conclusion

  • Use Delta PPM directly without

Normalisation (no ppm/day)

  • Use 90 or 95 Percentile of the whole

population (maybe excluding > cond X ?)

  • Determine sampling frequency on actual

level ppm value (Similar to actual Table 3)

  • Adjust Value per period for CO, CO2 and

maybe for C2H6 and TDCG

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SLIDE 58

Conclusion

  • A possible table could look like:

Period: <= 1.5 Year 1.5 - 2.5 Years >= 2.5 Years H2 CH4 C2H4 C2H2 C2H6 15 25 30 CO 200 300 400 CO2 2000 2500 3000 TDCG 300 400 500 Maximum PPM variation between sample 40 25 15 1

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SLIDE 59

Questions ?

  • To Be continued….