ERCOT UFE Analysis

ERCOT UFE Analysis

UFE Task Force

February 21, 2005

Introduction

• UFE Cost and Scenario Analysis

• UFE by Weather Zone

• UFE Allocation

• Calculation of Distribution Losses

UFE Cost

• Associating dollar values (not costs) with UFE … can we get some sense of whether/how much investment to make improvements is justified?

• MCPE × UFE is a reasonable approximation

• How to handle intervals with negative MCPE and/or negative UFE? (note: negative MCPE is rare ~ 0.5% of intervals in 2003)

• Consider some slides from ERCOT’s presentation at September 14 UFE Workshop

Average Interval % UFE

-3%-2%-1%0%1%2%3%4%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Month - Jan 03 to July 04

Pos Only Neg Only

Average Interval % UFE

-3%-2%-1%0%1%2%3%4%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Month - Jan 03 to July 04

Abs Net

UFE in Dollars (MCPE)

-20,000,000

-10,000,000

0

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7

Month Totals- Jan 2003 to Jul 2004

$

Net PosOnly Neg Only Total

MCPE * UFE

2003 2004 (J an 1 - J ul 14)

Net 170,888,230$ 30,863,873$ Positive Intervals Only 236,198,494$ 69,401,081$ Negative intervals Only (65,310,264)$ (38,537,209)$ Absolute Value 301,508,758$ 107,938,290$

UFE Scenario Analysis

• Consider some simplified scenarios to aid in the understanding of the implications of negative UFE and disproportionate UFE

Scenario 1 – Negative UFE

QSE 1 load = QSE 2 loadQSE 1 over-estimated by 10%, QSE 2 under-estimated by 5%

UFE is -2.5%

Following UFE adjustmentQSE 1 is over-estimated by 7.32%QSE 2 is under-estimated by 7.32%UFE understates actual error

QSE 1 Over-estimated, QSE 2 Under-estimated QSE 1 Over-estimated, QSE 2 Under-estimated

True Load + True Loss

True Load Ratio Share

Estimated Load + Loss (Unadj)

Percent Error

Estimated Load Ratio Share

UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 100 0.500 110 -10.00% 0.537 -2.683 107.317 -7.32%QSE 2 100 0.500 95 5.00% 0.463 -2.317 92.683 7.32%

Market Total 200 1.000 205 -2.50% 1.000 200.000

UFE -5

Scenario 1 – Positive UFE

QSE 1 load = QSE 2 loadQSE 1 over-estimated by 5%, QSE 2 under-estimated by 10%

UFE is +2.5%


QSE 1 Over-estimated, QSE 2 Under-estimated




Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 100 0.500 105 -5.00% 0.538 2.692 107.692 -7.69%QSE 2 100 0.500 90 10.00% 0.462 2.308 92.308 7.69%

Market Total 200 1.000 195 2.50% 1.000 200.000

UFE 5


QSE 1 load = QSE 2 loadQSE 1 over-estimated by 5%, QSE 2 is correct

UFE is -2.5%

Following UFE adjustmentQSE 1 is over-estimated by 2.44%QSE 2 is under-estimated by 2.44%UFE overstates actual error

QSE 1 Over-estimated, QSE 2 Correct QSE 1 Under-estimated, QSE 2 Correct




Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 100 0.500 105 -5.00% 0.512 -2.561 102.439 -2.44%QSE 2 100 0.500 100 0.00% 0.488 -2.439 97.561 2.44%

Market Total 200 1.000 205 -2.50% 1.000 200.000

UFE -5


QSE 1 load = QSE 2 loadQSE 1 under-estimated by 5%, QSE 2 is correct

UFE is +2.5%

Following UFE adjustmentQSE 1 is under-estimated by 2.56%QSE 2 is over-estimated by 2.56%UFE understates actual error

QSE 1 Under-estimated, QSE 2 Correct




Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 100 0.500 95 5.00% 0.487 2.436 97.436 2.56%QSE 2 100 0.500 100 0.00% 0.513 2.564 102.564 -2.56%

Market Total 200 1.000 195 2.50% 1.000 200.000

UFE 5


QSE 1 load = QSE 2 loadQSE 1 over-estimated by 4%, QSE 2 over-estimated by 1%

UFE is -2.5%


QSE 1 & QSE 2 Over-estimated Disproportionately QSE 1 & QSE 2 Under-estimated Disproportionately




Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 100 0.500 104 -4.00% 0.507 -2.537 101.463 -1.46%QSE 2 100 0.500 101 -1.00% 0.493 -2.463 98.537 1.46%

Market Total 200 1.000 205 -2.50% 1.000 200.000

UFE -5


QSE 1 load = QSE 2 loadQSE 1 under-estimated by 4%, QSE 2 under-estimated by 1%

UFE is +2.5%

Following UFE adjustmentQSE 1 is under-estimated by 1.54%QSE 2 is over-estimated by 1.54%UFE overstates actual error

QSE 1 & QSE 2 Under-estimated Disproportionately




Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 100 0.500 96 4.00% 0.492 2.462 98.462 1.54%QSE 2 100 0.500 99 1.00% 0.508 2.538 101.538 -1.54%

Market Total 200 1.000 195 2.50% 1.000 200.000

UFE 5


QSE 1 load = QSE 2 loadQSE 1 over-estimated by 2.5%, QSE 2 over-estimated by 2.5%

UFE is -2.5%

Following UFE adjustmentQSE 1 and QSE 2 are correctly estimatedUFE overstates actual error

QSE 1 & QSE 2 Over-estimated Proportionately QSE 1 & QSE 2 Under-estimated Proportionately




Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 100 0.500 102.5 -2.50% 0.500 -2.500 100.000 0.00%QSE 2 100 0.500 102.5 -2.50% 0.500 -2.500 100.000 0.00%

Market Total 200 1.000 205 -2.50% 1.000 200.000

UFE -5

Scenario 5 – Negative UFE – QSEswith Different Load Ratio Shares

QSE 1 load > QSE 2 loadQSE 1 over-estimated by 4%, QSE 2 over-estimated by 1%

UFE is -2.88%






Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 125 0.625 130.00 -4.00% 0.632 -3.633 126.367 -1.09%QSE 2 75 0.375 75.75 -1.00% 0.368 -2.117 73.633 1.82%

Market Total 200 1.000 205.75 -2.88% 1.000 200.000

UFE -5.75

Scenario 5 – Positive UFE – QSEswith Different Load Ratio Shares

QSE 1 load > QSE 2 loadQSE 1 under-estimated by 4%, QSE 2 under-estimated by 1%

UFE is +2.88%






Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 125 0.625 120.00 4.00% 0.618 3.552 123.552 1.16%QSE 2 75 0.375 74.25 1.00% 0.382 2.198 76.448 -1.93%

Market Total 200 1.000 194.25 2.88% 1.000 200.000

UFE 5.75


QSE 1 load > QSE 2 loadQSE 1 over-estimated by 1%, QSE 2 over-estimated by 4%

UFE is -2.12%






Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 125 0.625 126.25 -1.00% 0.618 -2.627 123.623 1.10%QSE 2 75 0.375 78.00 -4.00% 0.382 -1.623 76.377 -1.84%

Market Total 200 1.000 204.25 -2.12% 1.000 200.000

UFE -4.25


QSE 1 load > QSE 2 loadQSE 1 under-estimated by 1%, QSE 2 under-estimated by 4%

UFE is +2.12%






Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 125 0.625 123.75 1.00% 0.632 2.687 126.437 -1.15%QSE 2 75 0.375 72.00 4.00% 0.368 1.563 73.563 1.92%

Market Total 200 1.000 195.75 2.12% 1.000 200.000

UFE 4.25


QSE 1 load > QSE 2 loadQSE 1 over-estimated by 4%, QSE 2 under-estimated by 1%

UFE is -2.13%


QSE 1 Over-estimated, QSE 2 Under-estimated QSE 1 Over-estimated, QSE 2 Under-estimated



Estimated Load

Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 125 0.625 130.00 -4.00% 0.636 -2.705 127.295 -1.84%QSE 2 75 0.375 74.25 1.00% 0.364 -1.545 72.705 3.06%

Market Total 200 1.000 204.25 -2.13% 1.000 200.000

UFE -4.25


QSE 1 load > QSE 2 loadQSE 1 over-estimated by 1%, QSE 2 under-estimated by 4%

UFE is -0.88%


QSE 1 Over-estimated, QSE 2 Under-estimated



Estimated Load

Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 125 0.625 126.25 -1.00% 0.637 1.114 127.364 -1.89%QSE 2 75 0.375 72.00 4.00% 0.363 0.636 72.636 3.15%

Market Total 200 1.000 198.25 0.88% 1.000 200.000

UFE 1.75


QSE 1 load > QSE 2 loadQSE 1 under-estimated by 1%, QSE 2 over-estimated by 4%

UFE is -0.88%

Following UFE adjustmentQSE 1 is under-estimated by 1.86%QSE 2 is oveer-estimated by 3.10%UFE understates actual error

QSE 1 Under-estimated, QSE 2 Over-estimated QSE 1 Under-estimated, QSE 2 Over-estimated



Estimated Load

Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 125 0.625 123.75 1.00% 0.613 -1.073 122.677 1.86%QSE 2 75 0.375 78.00 -4.00% 0.387 -0.677 77.323 -3.10%

Market Total 200 1.000 201.75 -0.88% 1.000 200.000

UFE -1.75


QSE 1 load > QSE 2 loadQSE 1 under-estimated by 4%, QSE 2 over-estimated by 1%

UFE is +2.13%

Following UFE adjustmentQSE 1 is under-estimated by 1.92%QSE 2 is over-estimated by 3.19%UFE understates actual error

QSE 1 Under-estimated, QSE 2 Over-estimated



Estimated Load

Percent Error


UFE Allocation

UFE Adjusted Load

Percent Error

QSE 1 125 0.625 120.00 4.00% 0.613 2.605 122.605 1.92%QSE 2 75 0.375 75.75 -1.00% 0.387 1.645 77.395 -3.19%

Market Total 200 1.000 195.75 2.13% 1.000 200.000

UFE 4.25

Scenario Analysis Conclusions

• ERCOT level UFE is not likely to be an accurate indicator of settlement error, UFE as a percent can be higher or lower than settlement error.

• Settlement for QSEs which have errors in the opposite direction of ERCOT level UFE is made worse by UFE allocation

• If UFE is proportionately distributed across QSEs, UFE is a non-issue

• If UFE is disproportionately distributed across QSEs, UFE being positive or negative is irrelevant to settlement accuracy

• The smaller QSE consistently ends up with more settlement error than the larger QSE

Frequency Analysis of UFE By Weather Zone

Frequency AnalysisStudy Definition

• Comparison of retail load build-up (LSegTL) with net load (generation) including actual losses

• LSegTL includes ESI ID Kwh + NOIE Kwh assigned to a Weather Zone because Operations data represents total load in Weather Zone

• Net_Load (PI_Load) by Weather Zone is calculated by operations as a small control area (∑Gen – ∑Interchange = Load) with generation and metering (interchange) points assigned to a Weather Zone

• Date Range: 7/21/2003 - 7/21/2004

• Frequency plots are included for difference and percent of difference by Weather Zone

• Difference = (PI_Load – LSegTL) for each Settlement Interval

• Percent of Difference = Difference / PI_Load * 100

Weather Zone Median Std Dev Median Std Dev

South Central -54.88 85.12 -4.7 6.62

North -51.67 54.82 -22.18 52.71

Far West -20.18 29.68 -7.64 11.32

West -15.54 30.89 -7.78 19.34

East 39.11 47.06 11.44 11.47

North Central 67.34 290.36 2.59 10.09

South 108.22 63.15 16.06 28.29

Coast 305.57 282.57 11.86 10.98

Notes:

PI Load = Net Generation by Settlement Interval

LSegTL = Retail Load Calculation by Settlement Interval

Date Range = 7/21/2003 - 7/21/2004

Percent = Difference/PI Load * 100

Difference = PI Load - LSegTL

Summary Statistics

Comparison of Retail Load Calculation and Net Generation By Settlement Interval

Difference (Mw) Percent of Difference

South Central WZoneFreq Distribution of WZDiffTL

WZDIffTL = PI Load - LSegTL (Mw)

0

2

4

6

8

10

12

14

16

18

20

-171 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 93

Range of WZDiffTL

Perc

ent F

req

of W

ZDiff

TL

Date Range = 7/21/2003 - 7/21/2004

South Central WZoneFreq Distribution of WZPercentTL

WZPercentTL = (PI Load-LSegTL)/PI Load*100

0

5

10

15

20

25

-14.1 -13.0 -12.0 -11.0 -10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 1.9 2.8

Range of WZPercentTL

Perc

ent F

req o

f WZP

erce

ntTL

Date Range = 7/21/2003 - 7/21/2004

North WzoneFreq Distribution of WZDiffTLWZDIffTL = PI Load - LSegTL

0

2

4

6

8

10

12

-181 -170 -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 99

Range of WZDiffTL

Perc

ent F

req

of W

ZDiff

TL Date Range = 7/21/2003 - 7/21/2004

North WZoneFreq Distribution of WZPercentTL


0

2

4

6

8

10

12

14

16

18

-101.9 -50.0 -45.0 -40.0 -35.0 -30.0 -25.0 -20.0 -15.0 -14.0 -13.0 -12.0 -11.0 -10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0


Perc

ent F

req

of W

ZPer

cent

TL Date Range = 7/21/2003 - 7/21/2004

Far West WzoneFreq Distribution of WZDiffTLWZDIffTL = PI Load - LSegTL

0

5

10

15

20

25

30

35

40

45

-70 -61 -50 -40 -30 -20 -10 0 99

Range of WZDiffTL

Perc

ent F

req

of W

ZDiff

TL

Date Range = 7/21/2003 - 7/21/2004

Far West WZoneFreq Distribution of WZPercentTL


0

2

4

6

8

10

12

14

16

-25.2 -20.0 -15.0 -14.0 -13.0 -12.0 -11.0 -10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 4.6


Perc

ent F

req

of W

ZPer

cent

TL

Date Range = 7/21/2003 - 7/21/2004

West WzoneFreq Distribution of WZDiffTLWZDIffTL = PI Load - LSegTL

0

5

10

15

20

25

30

-60 -50 -40 -30 -20 -10 0 100

Range of WZDiffTL

Perc

ent F

req

of W

ZDiff

TL

Date Range = 7/21/2003 - 7/21/2004

West WZoneFreq Distribution of WZPercentTL


0

2

4

6

8

10

12


Perc

ent F

req

of W

ZPer

cent

TL Date Range = 7/21/2003 - 7/21/2004

East WzoneFreq Distribution of WZDiffTLWZDIffTL = PI Load - LSegTL

0

10

20

30

40

50

60

70

80

90

100

-40 -30 -20 -10 0 100 187

Range of WZDiffTL

Perc

ent F

req

of W

ZDiff

TL

Date Range = 7/21/2003 - 7/21/2004

East WZoneFreq Distribution of WZPercentTL


0

2

4

6

8

10

12

14

16

18

-11.0 -10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 20.0 25.0 29.9


Perc

ent F

req

of W

ZPer

cent

TL

Date Range = 7/21/2003 - 7/21/2004

North Central WzoneFreq Distribution of WZDiffTLWZDIffTL = PI Load - LSegTL

0

5

10

15

20

25

30

35

40

45

-130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 100 200 250 300 350 399

Range of WZDiffTL

Perc

ent F

req

of W

ZDiff

TL

Date Range = 7/21/2003 - 7/21/2004

North Central WZoneFreq Distribution of WZPercentTL


0

2

4

6

8

10

12

-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0


Perc

ent F

req

of W

ZPer

cent

TL

Date Range = 7/21/2003 - 7/21/2004

South WzoneFreq Distribution of WZDiffTLWZDIffTL = PI Load - LSegTL

0

10

20

30

40

50

60

70

-24 -10 -1 100 200 250 300

Range of WZDiffTL

Perc

ent F

req

of W

ZDiff

TL

Date Range = 7/21/2003 - 7/21/2004

South WZoneFreq Distribution of WZPercentTL

WZPercentTL = (PI Load-LsegTL)/PI Load*100

0

5

10

15

20

25

30

35

40

45

50

6 7 8 9 10 11 12 13 14 15 20 25 30 36


Perc

ent F

req

of W

ZPer

cent

TL

Date Range = 7/21/2003 - 7/21/2004

Coast WzoneFreq Distribution of WZDiffTLWZDIffTL = PI Load - LSegTL

0

2

4

6

8

10

12

14

16

18

20

-100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 100 200 250 300 350 400 500 600 700

Range of WZDiffTL

Perc

ent F

req

of W

ZDiff

TL

Date Range = 7/21/2003 - 7/21/2004

Coast WZoneFreq Distribution of WZPercentTL


0

2

4

6

8

10

12

14

16

18

20

-7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 20.0 25.0


Perc

ent F

req

of W

ZPer

cent

TL

Date Range = 7/21/2003 - 7/21/2004

• There is a significant bias (positive or negative) in the difference and percent of difference by Weather Zone

• Possible causes of the bias:– Weather Zone assignment of interchange (meter) points and

generation used in the net load (generation) calculation– Weather Zone assignment of ESI ID’s used in the LSegTL

calculation– Inaccurate transmission loss calculation or allocation– Inaccurate distribution loss calculation– Inaccurate profiles by weather zone

Observations

UFE Allocation

• Should the current UFE allocation proportions be maintained?

UFE Allocation

• UFE is currently allocated with arbitrary weighting factors

– 0.10 - Distribution Voltage level IDR Non Opt-in Entities– 0.10 - Transmission Voltage level IDR Premises– 0.50 - Distribution Voltage level IDR Premises– 1.00 - Distribution Voltage level Profiled Premises

• Alternatively could allocate UFE based on the category’s estimated load plus estimated loss

• IDRs settled with actual data would only be allocated UFE based on losses

• Profiled load and estimated IDRs would be allocated based on both load and loss

• Would have a different allocation factor in each interval

ERCOT Total: 12,415.21 UFE: 519.59

Current UFE Allocation Method

At Meter Distribution Transmission Unadjusted UFE Weight UFE Wt * Load Percent UFE UFELosses Losses Total (Protocols) Allocation Allocation

Profiled Load 5,869.02 278.78 117.28 6,265.09 1.00 6,265.09 86.83% 451.17IDR Load Served at Dist Voltage (10% Estimated) 157.74 7.49 3.15 168.39 0.50 84.19 1.17% 6.06

IDR Load Served at Dist Voltage (90% Actual) 1,419.70 67.44 28.37 1,515.51 0.50 757.75 10.50% 54.57IDR Load Served at Trans Voltage 1,061.05 0.00 20.24 1,081.29 0.10 108.13 1.50% 7.79

NOIE Load 2,793.07 0.00 53.28 2,846.35 0.00 0.00 0.00% 0.00Exempt Load 18.64 0.00 0.36 19.00 0.00 0.00 0.00% 0.00

Sum 11,319.23 353.71 222.68 11,895.62 7,215.16 100.00% 519.59

Suggested UFE Allocation Method

At Meter Distribution Transmission Unadjusted Estimated Percent UFE UFE UFE PercentLosses Losses Total Load + Loss Allocation Allocation Change Change

Profiled Load 5,869.02 278.78 117.28 6,265.09 6,265.09 95.66% 497.02 45.85 10.16%IDR Load Served at Dist Voltage (10% Estimated) 157.74 7.49 3.15 168.39 168.39 2.57% 13.36 7.30 120.33%

IDR Load Served at Dist Voltage (90% Actual) 1,419.70 67.44 28.37 1,515.51 95.81 1.46% 7.60 (46.97) -86.07%IDR Load Served at Trans Voltage (100% Actual) 1,061.05 0.00 20.24 1,081.29 20.24 0.31% 1.61 (6.18) -79.38%

NOIE Load 2,793.07 0.00 53.28 2,846.35 0.00 0.00% 0.00 0.00 -Exempt Load 18.64 0.00 0.36 19.00 0.00 0.00% 0.00 0.00 -

Sum 11,319.23 353.71 222.68 11,895.62 6,549.52 100.00% 519.59

Hypothetical Example Based on July 12, 2004 at 13:45

Distribution Loss Calculation

• PRR 565 is going through stakeholder approval

• Primary change is to base loss calculations on Actual Ercot System Load rather than the day ahead

• Should result in more accurate distribution loss estimates (and consequently have an effect on UFE) and use the same basis as is currently used for transmission losses

Examining the Calculations

• The distribution loss factors for a selected TDSP are calculated using the following formula:

• SILFi = ADLF * [K + (1 - K) * (SIELi/AAL)]

• Where: i = Interval

• SILF = Settlement Interval Distribution Loss Factor

• ADLF = Annual Distribution Loss Factor (based on TDSP Loss Study)

• K = constant representing the no load loss factor (based on TDSP Loss Study)

• SIEL = Settlement Interval ERCOT Load (ERCOT Day Ahead Forecasted MW Load divided by 4)

• AAL = ERCOT Annual interval Average Load (ERCOT will use 8,073 MWh for year 2004 calculations)

• ADLF, K and AAL are all based on historical actual load … the most accurate application of the loss factor formula will be to base it on actual ERCOT load

Select DSP

Input ERCOT Load

ERCOT MW Load 40,000

DLF for DSP Selected

CenterPoint 3.54%

All DSP Distribution Loss Factors

AEP - TCC A 6.81%

AEP - TCC B 2.65%

AEP - TNC A 7.55%

AEP - TNC B 1.23%

CenterPoint 3.54%

Nueces EC 11.04%

Sharyland 12.77%

TNMP A 9.13%

TNMP B 5.10%

TNMP C 3.77%

TNMP D 4.25%

TNMP E 4.83%

TXU A 4.34%

TXU B 1.84%

TXU SESCO A 4.34%

TXU SESCO B 1.84%

CenterPoint

ERCOT-Wide Loadfor October 9, 2003

5000

6000

7000

8000

9000

10000

11000

I 4 8 12

16

20

24

28

32

36

40

44

48

52

56

60

64

68

72

76

80

84

88

92

Intervals for October 9, 2003

Mw

h

LForecastMwh LMOSActualMWH

Frequency of Distribution LossesCalculated w/ Actual ERCOT Load Data

October 2003 - September 2004

0.01

2.64

4.71

3.66 3.89

4.97

6.58

8.12

10.57

8.21

6.51

5.34

4.46

3.452.86

2.472.03

9.25

6.13

2.84

1.02

0.28

0.00

2.00

4.00

6.00

8.00

10.00

12.00

Distribution Losses Calculated w/ Actual ERCOT Load Data

Per

cen

t o

f In

terv

als

Change in Distribution LossesCalculated w/ Actual ERCOT Load Data

and Forecast ERCOT Load DataOctober 2003 - September 2004

0.009

0.238

3.640

57.652

28.228

6.874

2.742

0.572

0.040

0.003 0.003

0.001

0.010

0.100

1.000

10.000

100.000

-30<=-20Mw

-20<=-10Mw

-10<=0 Mw 0<=10 Mw 10<=20Mw

20<=30Mw

30<=40Mw

40<=50Mw

50<=60Mw

60<=70Mw

70<=80Mw

Change in Distribution Losses

Per

cen

t o

f In

terv

als

Statistics for Distribution Loss and UFE Calculations

VariableNo of

Intervals Mean Std Dev Minimum Maximum

CurrentDLossMwh 34944 204.70 75.186 93.327 519.14

RevisedDLossMwh 34944 194.70 70.982 89.817 493.12

LossChangeMwh 34944 10.00 7.975 -20.367 73.95

ABSLossChangeMwh 34944 10.27 7.625 0.001 73.95

CurrentUFEMwh 34944 32.15 183.366 -968.853 1051.51

RevisedUFEMwh 34944 42.15 181.260 -922.976 1046.53

Linear Regression Analysis

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CNP LossCode D

TXU ED LossCode A

TXU ED LossCode B

AEP-N LossCode A

AEP-N LossCode B

AEP-C LossCode A

AEP-C LossCode B

TNMP LossCode A

TNMP LossCode B

TNMP LossCode C

TNMP LossCode D

LSegUFE for TDSP & Loss Code

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Actual Load from MOS - LACTERCOT Forecast Load from MOS - LFORERCOTDLF

LSegUFE for TDSP & Loss Code

Actual Load from MOS -

LACTERCOT

Forecast Load from MOS -

LFORERCOTDLF

CNP Loss Code D 0.8895 0.8258

TXU ED Loss Code A 0.9123 0.8104

TXU ED Loss Code B 0.2747 0.2110

AEP-N Loss Code A 0.8544 0.7572

AEP-N Loss Code B 0.4360 0.3850

AEP-C Loss Code A 0.8462 0.8069

AEP-C Loss Code B 0.5241 0.4753

TNMP Loss Code A 0.8891 0.7923

TNMP Loss Code B 0.9207 0.8166

TNMP Loss Code C 0.8832 0.8104

TNMP Loss Code D 0.8264 0.7835

R-Square Values

Linear Regression Analysis

Distribution LossCalculation Findings

• Forecast of ERCOT System Load contains error and is biased high

• Distribution loss calculations reflect the forecasting error/bias … distribution losses tend to be overstated

• TDSP losses are a function of the TDSP load; Actual ERCOT load has a stronger correlation to TDSP actual load than forecasted ERCOT load

• TDSP Loss Studies are based on actual TDSP and ERCOT loads … its more consistent to apply the DLFs produced by those studies to actual ERCOT load

ERCOT UFE Analysis

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