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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%
Following UFE adjustmentQSE 1 is over-estimated by 7.69%QSE 2 is under-estimated by 7.69%UFE understates actual error
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 0.500 105 -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
Scenario 2 – Negative UFE
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
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 0.500 105 -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
Scenario 2 – Positive UFE
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
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 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
Scenario 3 – Negative UFE
QSE 1 load = QSE 2 loadQSE 1 over-estimated by 4%, QSE 2 over-estimated by 1%
UFE is -2.5%
Following UFE adjustmentQSE 1 is over-estimated by 1.46%QSE 2 is under-estimated by 1.46%UFE overstates actual error
QSE 1 & QSE 2 Over-estimated Disproportionately QSE 1 & QSE 2 Under-estimated Disproportionately
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 0.500 104 -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
Scenario 3 – Positive UFE
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
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 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
Scenario 4 – Negative UFE
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
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 0.500 102.5 -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%
Following UFE adjustmentQSE 1 is over-estimated by 1.09%QSE 2 is under-estimated by 1.82%UFE overstates actual error
QSE 1 & QSE 2 Over-estimated Disproportionately QSE 1 & QSE 2 Under-estimated Disproportionately
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 1 125 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%
Following UFE adjustmentQSE 1 is under-estimated by 1.16%QSE 2 is over-estimated by 1.93%UFE overstates actual error
QSE 1 & QSE 2 Under-estimated Disproportionately
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 1 125 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
Scenario 6 – Negative UFE – QSEswith Different Load Ratio Shares
QSE 1 load > QSE 2 loadQSE 1 over-estimated by 1%, QSE 2 over-estimated by 4%
UFE is -2.12%
Following UFE adjustmentQSE 1 is under-estimated by 1.10%QSE 2 is over-estimated by 1.84%UFE overstates actual error
QSE 1 & QSE 2 Over-estimated Disproportionately QSE 1 & QSE 2 Under-estimated Disproportionately
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 1 125 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
Scenario 6 – Positive UFE – QSEswith Different Load Ratio Shares
QSE 1 load > QSE 2 loadQSE 1 under-estimated by 1%, QSE 2 under-estimated by 4%
UFE is +2.12%
Following UFE adjustmentQSE 1 is over-estimated by 1.15%QSE 2 is under-estimated by 1.92%UFE overstates actual error
QSE 1 & QSE 2 Under-estimated Disproportionately
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 1 125 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
Scenario 7 – Negative UFE – QSEswith Different Load Ratio Shares
QSE 1 load > QSE 2 loadQSE 1 over-estimated by 4%, QSE 2 under-estimated by 1%
UFE is -2.13%
Following UFE adjustmentQSE 1 is over-estimated by 1.84%QSE 2 is under-estimated by 3.06%UFE overstates 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
Percent Error
Estimated Load Ratio Share
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
Scenario 7 – Positive UFE – QSEswith Different Load Ratio Shares
QSE 1 load > QSE 2 loadQSE 1 over-estimated by 1%, QSE 2 under-estimated by 4%
UFE is -0.88%
Following UFE adjustmentQSE 1 is over-estimated by 1.89%QSE 2 is under-estimated by 3.15%UFE understates actual error
QSE 1 Over-estimated, QSE 2 Under-estimated
True Load + True Loss
True Load Ratio Share
Estimated Load
Percent Error
Estimated Load Ratio Share
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
Scenario 8 – Negative UFE – QSEswith Different Load Ratio Shares
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
True Load + True Loss
True Load Ratio Share
Estimated Load
Percent Error
Estimated Load Ratio Share
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
Scenario 8 – Positive UFE – QSEswith Different Load Ratio Shares
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
True Load + True Loss
True Load Ratio Share
Estimated Load
Percent Error
Estimated Load Ratio Share
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
WZPercentTL = (PI Load-LSegTL)/PI Load*100
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
Range of WZPercentTL
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
WZPercentTL = (PI Load-LSegTL)/PI Load*100
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
Range of WZPercentTL
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
WZPercentTL = (PI Load-LSegTL)/PI Load*100
0
2
4
6
8
10
12
Range of WZPercentTL
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
WZPercentTL = (PI Load-LSegTL)/PI Load*100
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
Range of WZPercentTL
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
WZPercentTL = (PI Load-LSegTL)/PI Load*100
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
Range of WZPercentTL
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
Range of WZPercentTL
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
WZPercentTL = (PI Load-LSegTL)/PI Load*100
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
Range of WZPercentTL
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
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
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
R S
qu
are
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