1 ercot lrs precision analysis pwg presentation february 27, 2007

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ERCOT

LRS Precision Analysis

PWG Presentation

February 27, 2007

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Options for Determining Round Two Sample Size Increases

• Option 1: – Determine minimum sample size needed to obtain ±10% Accuracy at 90% Confidence for a selected

percent of intervals for the year independently for each Profile Type / Weather Zone Combination

• For Options 2 – 5 ERCOT recomputed daily energy totals and dollars– Used SAS data aggregation tool developed for transition analysis– Applied load profiles from new models to spread monthly LSEG totals from Lodestar to intervals– Multiplied by weather zone weighted MCPE to associate a dollar value with each interval

• Option 2:– Determine minimum sample size needed to obtain ±10% Accuracy at 90% Confidence for enough intervals

to account for a selected percent of the MWh for each Profile Type / Weather Zone Combination

• Option 3:– Determine minimum sample size needed to obtain ±10% Accuracy at 90% Confidence for enough intervals

to account for a selected percent of the dollars (ΣMWh * MCPE) for each Profile Type / Weather Zone Combination

• Option 4:– Iteratively allocate increments of 20 sample points to the Profile Type / Weather Zone Combination which

produces the most gain in terms of reducing MWh estimation error

• Option 5:– Iteratively allocate increments of 20 sample points to the Profile Type / Weather Zone Combination which

produces the most gain in terms of reducing Dollar estimation error

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Percent of Intervals 0 1 5 10 25 50 75 90 95 99 100BUSHILF_COAST 1 3 4 5 7 11 19 28 38 71 1,678BUSHILF_EAST 1 3 4 5 7 10 16 40 65 95 250BUSHILF_FWEST 3 7 11 15 23 40 65 92 105 141 282BUSHILF_NCENT 2 5 7 9 12 17 27 38 48 63 129BUSHILF_NORTH 3 5 7 7 10 15 22 28 34 46 105BUSHILF_SCENT 1 5 4 6 7 10 14 17 20 28 225BUSHILF_SOUTH 2 5 7 8 12 19 28 40 48 74 210BUSHILF_WEST 1 3 4 5 7 10 15 20 27 42 98

Total 14 36 48 60 85 132 206 303 385 560 2,977

Percent of Intervals 0 1 5 10 25 50 75 90 95 99 100BUSMEDLF_COAST 42 74 101 118 153 220 322 472 618 1,263 3,488BUSMEDLF_EAST 27 46 58 65 85 126 182 250 305 437 1,251BUSMEDLF_FWEST 88 141 187 230 352 538 801 1,138 1,585 12,847 23,759BUSMEDLF_NCENT 30 55 74 95 161 230 346 501 634 927 8,762BUSMEDLF_NORTH 34 58 79 95 129 191 282 403 501 783 1,959BUSMEDLF_SCENT 32 53 74 88 122 165 225 305 390 728 3,665BUSMEDLF_SOUTH 68 105 133 157 220 340 562 907 1,194 2,092 4,483BUSMEDLF_WEST 44 74 101 122 157 215 293 410 538 917 2,308

Total 365 606 807 970 1,379 2,025 3,013 4,386 5,765 19,994 49,675

Option 1• To obtain ±10% Accuracy at 90% Confidence By Profile Type

and Weather Zone - Independent of Interval

For example: to obtain ±10% Accuracy at 90% Confidence for 50% of the intervals for BUSHILF_COAST would require a sample size of 11 points

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Percent of Intervals 0 1 5 10 25 50 75 90 95 99 100BUSLOLF_COAST 9 20 28 34 51 79 115 141 161 205 1,149BUSLOLF_EAST 7 19 27 36 55 88 122 161 187 250 626BUSLOLF_FWEST 40 71 88 105 145 201 255 310 352 444 14,224BUSLOLF_NCENT 20 30 40 48 63 79 101 122 137 178 288BUSLOLF_NORTH 8 22 34 44 77 141 235 346 410 501 858BUSLOLF_SCENT 6 9 14 17 25 40 55 77 95 133 316BUSLOLF_SOUTH 9 20 27 34 53 82 126 161 187 240 437BUSLOLF_WEST 10 20 27 30 42 58 74 92 105 137 305

Total 109 211 285 348 511 768 1,083 1,410 1,634 2,088 18,203

Percent of Intervals 0 1 5 10 25 50 75 90 95 99 100BUSNODEM_COAST 79 133 174 205 277 444 634 897 1,572 2,876 5,263BUSNODEM_EAST 58 101 129 149 187 255 390 593 746 1,138 4,395BUSNODEM_FWEST 48 88 118 145 196 277 403 585 783 1,275 3,353BUSNODEM_NCENT 92 122 137 149 178 322 523 719 887 1,358 2,965BUSNODEM_NORTH 118 174 205 225 277 358 479 676 887 1,520 4,201BUSNODEM_SCENT 85 178 220 245 288 371 531 773 1,116 2,469 6,235BUSNODEM_SOUTH 30 92 118 141 182 277 423 676 907 1,638 3,527BUSNODEM_WEST 32 60 85 105 169 282 434 618 764 1,251 3,184

Total 542 948 1,186 1,364 1,754 2,586 3,817 5,537 7,662 13,525 33,123

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Percent of Intervals 0 1 5 10 25 50 75 90 95 99 100RESHIWR_COAST 25 58 82 101 149 220 310 430 531 820 2,652RESHIWR_EAST 20 44 63 79 122 201 305 430 531 868 2,371RESHIWR_FWEST 28 58 82 101 153 235 358 508 642 1072 5,383RESHIWR_NCENT 32 53 71 88 141 255 377 486 562 737 2,062RESHIWR_NORTH 15 38 60 77 126 215 340 479 593 897 3,392RESHIWR_SCENT 23 48 68 85 126 205 316 451 546 783 2,859RESHIWR_SOUTH 27 48 68 85 126 215 346 479 585 897 3,449RESHIWR_WEST 27 48 68 85 133 215 310 410 486 685 2,568

Total 197 395 562 701 1,076 1,761 2,662 3,673 4,476 6759 24,736

Percent of Intervals 0 1 5 10 25 50 75 90 95 99 100RESLOWR_COAST 12 28 42 53 79 115 165 250 328 609 2,245RESLOWR_EAST 19 40 51 60 85 137 225 316 384 531 937RESLOWR_FWEST 28 53 74 88 122 178 271 423 546 829 3,449RESLOWR_NCENT 19 30 44 58 92 137 191 245 288 384 792RESLOWR_NORTH 19 46 63 77 105 161 240 328 397 546 1,482RESLOWR_SCENT 20 40 55 71 105 149 210 282 340 479 1,251RESLOWR_SOUTH 10 32 51 65 98 161 266 410 538 1,029 4,461RESLOWR_WEST 19 40 55 68 95 137 196 282 346 516 1,346

Total 146 309 435 540 781 1,175 1,764 2,536 3,167 4,923 15,963

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% of Intervals 0 1 5 10 25 50 75 90 95 99 100BUSHILF 14 36 48 60 85 132 206 303 385 560 2,977BUSMEDLF 365 606 807 970 1,379 2,025 3,013 4,386 5,765 19,994 49,675BUSLOLF 109 211 285 348 511 768 1,083 1,410 1,634 2,088 18,203BUSNODEM 542 948 1,186 1,364 1,754 2,586 3,817 5,537 7,662 13,525 33,123RESHIWR 197 395 562 701 1,076 1,761 2,662 3,673 4,476 6,759 24,736RESLOWR 146 309 435 540 781 1,175 1,764 2,536 3,167 4,923 15,963

Total 1,373 2,505 3,323 3,983 5,586 8,447 12,545 17,845 23,089 47,849 144,677

To

tal

Option 1• To obtain ±10% Accuracy at 90% Confidence By

Profile Type - Independent of Interval

For example: to obtain ±10% Accuracy at 90% Confidence for 50% of the intervals for all Profile Type/Weather Zone combinations would require a sample size of 8,447 points

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Option 2• To obtain ±10% Accuracy at 90% Confidence for Intervals Accounting

for Selected Percents of the MWH within Each Profile Type and Weather Zone

For example: to obtain ±10% Accuracy at 90% Confidence for intervals accounting for 50% of

the BUSMEDLF MWh would require a sample size of 1677 points

Percent of MWH 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSHILF_COAST 1 3 4 4 7 11 14 16 19 20 23 28 36 58 1,678BUSHILF_EAST 1 2 4 4 7 10 11 14 16 19 23 34 60 85 250BUSHILF_FWEST 3 7 11 14 23 40 48 58 63 71 79 88 105 133 282BUSHILF_NCENT 2 4 7 8 11 16 19 23 25 28 32 38 46 60 129BUSHILF_NORTH 3 4 7 7 9 14 16 19 20 22 25 27 32 42 105BUSHILF_SCENT 1 3 4 6 7 10 11 12 14 15 16 17 20 25 225BUSHILF_SOUTH 2 4 7 8 11 17 22 25 27 30 34 38 46 68 210BUSHILF_WEST 1 3 4 5 7 10 11 14 14 15 17 20 27 38 98

BUSHILF Sub-Total 14 30 48 56 82 128 152 181 198 220 249 290 372 509 2,977

Percent of MWH 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSMEDLF_COAST 42 63 85 101 133 182 215 250 277 310 358 423 554 988 3,488BUSMEDLF_EAST 27 40 51 60 74 105 122 145 161 178 196 225 271 377 1,251BUSMEDLF_FWEST 88 126 161 187 266 430 508 609 668 746 848 988 1,310 5,852 23,759BUSMEDLF_NCENT 30 46 60 71 101 178 215 255 288 322 365 423 531 783 8,762BUSMEDLF_NORTH 34 48 65 77 105 157 182 220 240 266 299 346 430 634 1,959BUSMEDLF_SCENT 32 46 60 71 98 141 161 182 196 215 240 271 328 577 3,665BUSMEDLF_SOUTH 68 92 122 141 196 293 352 423 479 546 634 773 998 1,598 4,483BUSMEDLF_WEST 44 63 85 105 141 191 215 245 266 288 316 365 451 737 2,308

BUSMEDLF Sub-Total 365 524 689 813 1,114 1,677 1,970 2,329 2,575 2,871 3,256 3,814 4,873 11,546 49,675

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Percent of MWH 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSLOLF_COAST 9 16 25 30 42 65 79 95 101 111 118 133 149 187 1,149BUSLOLF_EAST 7 15 23 30 46 74 88 101 108 118 129 145 169 220 626BUSLOLF_FWEST 40 63 82 98 133 187 210 235 245 255 277 299 334 403 14,224BUSLOLF_NCENT 20 25 36 42 58 74 82 88 95 98 105 115 126 161 288BUSLOLF_NORTH 8 16 28 36 60 126 149 178 201 235 271 310 377 458 858BUSLOLF_SCENT 6 8 12 15 22 34 40 46 51 53 60 68 85 115 316BUSLOLF_SOUTH 9 16 23 28 44 71 82 98 108 118 133 149 169 210 437BUSLOLF_WEST 10 17 23 27 38 53 58 65 71 74 79 85 98 122 305

BUSLOLF Sub-Total 109 176 252 306 443 684 788 906 980 1,062 1,172 1,304 1,507 1,876 18,203

Percent of MWH 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSNODEM_COAST 79 122 165 196 266 423 479 546 593 642 702 801 1,310 2,551 5,263BUSNODEM_EAST 58 88 126 145 187 250 288 340 384 430 494 577 711 1,019 4,395BUSNODEM_FWEST 48 79 118 145 201 288 328 377 410 458 508 585 755 1,183 3,353BUSNODEM_NCENT 92 118 133 145 169 255 346 437 472 523 585 659 801 1,149 2,965BUSNODEM_NORTH 118 165 205 230 282 358 397 444 472 516 569 651 829 1,298 4,201BUSNODEM_SCENT 85 161 210 235 282 358 403 465 501 554 618 719 988 2,183 6,235BUSNODEM_SOUTH 30 82 115 133 178 266 316 371 410 465 546 659 887 1,533 3,527BUSNODEM_WEST 32 53 79 98 149 250 299 358 397 437 486 562 685 1,019 3,184

BUSNODEM Sub-Total 542 868 1,151 1,327 1,714 2,448 2,856 3,338 3,639 4,025 4,508 5,213 6,966 11,935 33,123

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Percent of MWH 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100RESHIWR_COAST 25 46 71 88 126 191 225 260 282 310 346 390 479 693 2,652RESHIWR_EAST 20 38 55 68 105 178 215 255 277 305 340 390 472 676 2,371RESHIWR_FWEST 28 48 71 85 129 205 245 288 316 352 390 458 569 848 5,383RESHIWR_NCENT 32 44 60 74 111 201 250 305 328 365 397 444 508 642 2,062RESHIWR_NORTH 15 28 48 63 101 178 220 266 293 328 371 423 516 737 3,392RESHIWR_SCENT 23 40 60 74 105 178 215 260 288 316 352 403 486 668 2,859RESHIWR_SOUTH 27 42 60 71 105 174 215 271 305 340 384 437 531 755 3,449RESHIWR_WEST 27 40 58 71 108 182 220 255 277 305 334 371 437 577 2,568

RESHIWR Sub-Total 197 326 483 594 890 1,487 1,805 2,160 2,366 2,621 2,914 3,316 3,998 5,596 24,736

Percent of MWH 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100RESLOWR_COAST 12 22 32 40 58 92 105 126 137 153 174 201 260 430 2,245RESLOWR_EAST 19 34 46 53 71 115 137 169 191 220 245 282 340 458 937RESLOWR_FWEST 28 44 63 74 101 149 174 205 230 255 293 358 465 676 3,449RESLOWR_NCENT 19 25 34 40 60 105 126 149 161 174 191 215 255 328 792RESLOWR_NORTH 19 36 53 63 85 129 153 182 205 225 255 288 346 465 1,482RESLOWR_SCENT 20 32 46 55 77 122 141 165 178 191 215 240 288 397 1,251RESLOWR_SOUTH 10 23 42 53 82 137 165 205 230 260 299 358 465 810 4,461RESLOWR_WEST 19 30 46 55 77 115 133 157 169 187 210 245 299 423 1,346

RESLOWR Sub-Total 146 246 362 433 611 964 1,134 1,358 1,501 1,665 1,882 2,187 2,718 3,987 15,963

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for Selected Percents of the MWH within Each Profile Type

For example: to obtain ±10% Accuracy at 90% Confidence for intervals accounting for 50% of the MWh for each of the Profile Type / Weather Zone combinations would require a sample size of 7,438 points

% of MWH 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSHILF 14 30 48 56 82 128 152 181 198 220 249 290 372 509 2,977BUSMEDLF 365 524 689 813 1,114 1,677 1,970 2,329 2,575 2,871 3,256 3,814 4,873 11,546 49,675BUSLOLF 109 176 252 306 443 684 788 906 980 1,062 1,172 1,304 1,507 1,876 18,203BUSNODEM 542 868 1,151 1,327 1,714 2,448 2,856 3,338 3,639 4,025 4,508 5,213 6,966 11,935 33,123RESHIWR 197 326 483 594 890 1,487 1,805 2,160 2,366 2,621 2,914 3,316 3,998 5,596 24,736RESLOWR 146 246 362 433 611 964 1,134 1,358 1,501 1,665 1,882 2,187 2,718 3,987 15,963

Total 1,373 2,171 2,990 3,539 4,879 7,438 8,765 10,342 11,334 12,544 14,066 16,214 20,529 35,548 144,777

To

tal

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for Selected Percents of the dollars within each Profile Type & Weather Zone

Note: Dollars = Σ (MWh * MCPE)

Percent of Dollars 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSHILF_COAST 1 3 4 4 7 10 12 16 17 20 23 27 36 60 1,678BUSHILF_EAST 1 2 4 4 7 9 10 12 14 16 19 25 48 79 250BUSHILF_FWEST 3 7 11 14 23 40 46 55 63 68 77 88 101 129 282BUSHILF_NCENT 2 4 7 8 10 16 19 23 25 28 32 42 51 60 129BUSHILF_NORTH 3 4 6 7 9 12 15 17 19 20 22 25 30 40 105BUSHILF_SCENT 1 3 4 5 7 9 10 12 12 14 15 16 19 25 225BUSHILF_SOUTH 2 4 7 7 10 17 20 23 25 28 32 36 44 65 210BUSHILF_WEST 1 2 4 4 7 9 10 12 14 15 16 19 23 34 98

BUSHILF Sub-Total 14 29 47 53 80 122 142 170 189 209 236 278 352 492 2,977

Percent of Dollars 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSMEDLF_COAST 42 55 82 95 122 165 191 225 245 277 310 371 465 783 3,488BUSMEDLF_EAST 27 38 48 53 68 95 111 133 145 161 178 205 250 352 1,251BUSMEDLF_FWEST 88 111 149 169 225 371 444 538 601 668 755 887 1,149 2,859 23,759BUSMEDLF_NCENT 30 44 58 65 85 157 191 230 260 293 334 390 494 728 8,762BUSMEDLF_NORTH 34 46 60 71 95 141 169 201 220 245 271 316 384 562 1,959BUSMEDLF_SCENT 32 42 55 63 82 129 149 169 182 201 220 250 305 516 3,665BUSMEDLF_SOUTH 68 88 115 133 182 271 328 397 437 494 569 693 897 1,395 4,483BUSMEDLF_WEST 44 58 77 92 126 174 201 230 245 266 293 334 423 693 2,308

BUSMEDLF Sub-Total 365 482 644 741 985 1,503 1,784 2,123 2,335 2,605 2,930 3,446 4,367 7,888 49,675

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Percent of Dollars 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSLOLF_COAST 9 15 22 27 38 58 68 82 88 98 108 122 141 187 1,149BUSLOLF_EAST 7 14 20 27 40 65 77 92 98 108 118 133 157 210 626BUSLOLF_FWEST 40 60 77 85 115 169 191 215 230 245 260 282 316 397 14,224BUSLOLF_NCENT 20 25 32 36 48 68 77 82 88 95 101 108 122 153 288BUSLOLF_NORTH 8 15 25 32 51 108 133 157 174 196 230 277 334 430 858BUSLOLF_SCENT 6 7 11 14 19 30 36 42 44 48 53 60 74 101 316BUSLOLF_SOUTH 9 14 22 25 38 60 74 85 95 105 115 133 157 196 437BUSLOLF_WEST 10 17 22 25 32 48 53 60 65 71 77 82 98 122 305

BUSLOLF Sub-Total 109 167 231 271 381 606 709 815 882 966 1,062 1,197 1,399 1,796 18,203

Percent of Dollars 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100BUSNODEM_COAST 79 118 169 201 293 451 508 562 601 651 711 820 1,407 2,652 5,263BUSNODEM_EAST 58 88 129 149 191 250 288 340 377 423 486 562 685 967 4,395BUSNODEM_FWEST 48 77 118 145 205 288 322 371 397 437 486 562 719 1,083 3,353BUSNODEM_NCENT 92 118 137 149 178 328 410 472 508 554 609 693 839 1,171 2,965BUSNODEM_NORTH 118 169 215 240 293 365 403 451 479 516 569 642 810 1,251 4,201BUSNODEM_SCENT 85 157 205 235 282 365 410 465 501 546 609 702 927 2,032 6,235BUSNODEM_SOUTH 30 82 118 141 191 293 346 410 465 531 618 755 1,072 1,973 3,527BUSNODEM_WEST 32 51 77 95 149 260 305 365 397 437 486 554 676 988 3,184

BUSNODEM Sub-Total 542 860 1,168 1,355 1,782 2,600 2,992 3,436 3,725 4,095 4,574 5,290 7,135 12,117 33,123

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Percent of Dollars 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100RESHIWR_COAST 25 42 63 77 108 169 201 235 255 282 316 358 444 642 2,652RESHIWR_EAST 20 36 48 60 85 149 182 220 240 271 305 346 423 601 2,371RESHIWR_FWEST 28 46 68 79 115 178 215 255 282 316 358 410 516 755 5,383RESHIWR_NCENT 32 44 55 63 88 157 201 250 282 310 352 397 465 593 2,062RESHIWR_NORTH 15 28 44 55 82 141 178 225 250 282 322 377 465 668 3,392RESHIWR_SCENT 23 38 53 65 92 149 187 225 250 277 310 358 437 593 2,859RESHIWR_SOUTH 27 38 53 63 88 141 182 235 271 305 352 403 494 702 3,449RESHIWR_WEST 27 38 53 63 92 153 187 220 245 266 299 334 397 523 2,568

RESHIWR Sub-Total 197 310 437 525 750 1,237 1,533 1,865 2,075 2,309 2,614 2,983 3,641 5,077 24,736

Percent of Dollars 0 1 5 10 25 50 60 70 75 80 85 90 95 99 100RESLOWR_COAST 12 20 30 36 51 77 92 111 122 137 157 187 240 390 2,245RESLOWR_EAST 19 34 44 51 68 105 126 161 178 201 230 266 328 437 937RESLOWR_FWEST 28 44 60 71 95 133 157 187 205 235 271 322 417 634 3,449RESLOWR_NCENT 19 23 30 36 48 82 101 126 141 153 169 196 235 305 792RESLOWR_NORTH 19 34 51 58 77 115 137 165 182 205 230 266 322 437 1,482RESLOWR_SCENT 20 30 42 48 65 101 122 145 157 174 191 220 260 352 1,251RESLOWR_SOUTH 10 22 40 51 79 133 161 201 225 255 293 352 458 829 4,461RESLOWR_WEST 19 30 42 51 71 105 122 141 157 174 196 225 277 397 1,346

RESLOWR Sub-Total 146 237 339 402 554 851 1,018 1,237 1,367 1,534 1,737 2,034 2,537 3,781 15,963

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• To obtain ±10% Accuracy at 90% Confidence for Intervals Accounting for Selected Percents of the dollars within each Profile Type

Continues on next slide

For example: to obtain ±10% Accuracy at 90% Confidence for intervals accounting for 50% of the Dollars for each of the Profile Type / Weather Zone combinations would require a sample size of 6,969 points

% of Dollars 0 1 5 10 25 50 60 70BUSHILF 14 29 47 53 80 122 142 170BUSMEDLF 365 482 644 741 985 1,503 1,784 2,123BUSLOLF 109 167 231 271 381 606 709 815BUSNODEM 542 860 1,168 1,355 1,782 2,600 2,992 3,436RESHIWR 197 310 437 525 750 1,237 1,533 1,865RESLOWR 146 237 339 402 554 851 1,018 1,237

Total 1,373 2,086 2,871 3,357 4,557 6,969 8,238 9,716

To

tal

Option 3

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• To obtain ±10% Accuracy at 90% Confidence for Intervals Accounting for Selected Percents of the dollars within each Profile Type

% of Dollars 75 80 85 90 95 99 100BUSHILF 189 209 236 278 352 492 2,977BUSMEDLF 2,335 2,605 2,930 3,446 4,367 7,888 49,675BUSLOLF 882 966 1,062 1,197 1,399 1,796 18,203BUSNODEM 3,725 4,095 4,574 5,290 7,135 12,117 33,123RESHIWR 2,075 2,309 2,614 2,983 3,641 5,077 24,736RESLOWR 1,367 1,534 1,737 2,034 2,537 3,781 15,963

Total 10,648 11,798 13,238 15,318 19,526 31,250 144,777

To

tal

Option 3

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Class Level MWH & Dollars

Not all Profile Type / Weather Zone Combinations are created equal in either MWh or Total Dollars (ΣMWh * MCPE) !

19 Month 19Month MWh % - Profile Total % 19Month MWhProfile / Wzone MWh * MCPE (Dollars) 19Month MWh * MCPE LWAP

BUSHILF_COAST 7,012,401 440,544,629 31.9% 31.7% 62.82BUSHILF_EAST 664,628 42,102,131 3.0% 3.0% 63.35BUSHILF_FWEST 1,212,446 75,408,364 5.5% 5.4% 62.20BUSHILF_NCENT 9,289,014 595,340,798 42.2% 42.9% 64.09BUSHILF_NORTH 619,778 39,307,134 2.8% 2.8% 63.42BUSHILF_SCENT 317,290 19,811,017 1.4% 1.4% 62.44BUSHILF_SOUTH 2,375,129 144,688,043 10.8% 10.4% 60.92BUSHILF_WEST 499,266 30,928,517 2.3% 2.2% 61.95

BUSHILF Sub-Total 21,989,953 1,388,130,633 100.0% 100.0% 63.13


BUSMEDLF_COAST 8,612,974 586,474,328 33.9% 33.5% 68.09BUSMEDLF_EAST 1,126,287 78,322,602 4.4% 4.5% 69.54BUSMEDLF_FWEST 992,852 68,460,782 3.9% 3.9% 68.95BUSMEDLF_NCENT 9,882,020 697,329,751 38.9% 39.8% 70.57BUSMEDLF_NORTH 813,779 56,508,105 3.2% 3.2% 69.44BUSMEDLF_SCENT 394,925 27,132,509 1.6% 1.5% 68.70BUSMEDLF_SOUTH 2,816,609 185,696,415 11.1% 10.6% 65.93BUSMEDLF_WEST 767,768 52,046,991 3.0% 3.0% 67.79

BUSMEDLF Sub-Total 25,407,213 1,751,971,485 100.0% 100.0% 68.96

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BUSLOLF_COAST 11,405,935 753,826,626 32.8% 32.7% 66.09BUSLOLF_EAST 1,209,610 80,858,842 3.5% 3.5% 66.85BUSLOLF_FWEST 1,103,530 72,034,036 3.2% 3.1% 65.28BUSLOLF_NCENT 15,449,309 1,030,463,871 44.4% 44.8% 66.70BUSLOLF_NORTH 940,794 62,626,744 2.7% 2.7% 66.57BUSLOLF_SCENT 544,524 35,848,725 1.6% 1.6% 65.84BUSLOLF_SOUTH 3,207,940 205,503,900 9.2% 8.9% 64.06BUSLOLF_WEST 940,393 61,519,838 2.7% 2.7% 65.42

BUSLOLF Sub-Total 34,802,034 2,302,682,583 100.0% 100.0% 66.17


BUSNODEM_COAST 1,304,968 82,914,041 36.0% 36.2% 63.54BUSNODEM_EAST 207,477 13,509,530 5.7% 5.9% 65.11BUSNODEM_FWEST 167,689 10,811,421 4.6% 4.7% 64.47BUSNODEM_NCENT 1,537,514 95,849,300 42.4% 41.8% 62.34BUSNODEM_NORTH 143,908 9,433,035 4.0% 4.1% 65.55BUSNODEM_SCENT 74,986 4,714,248 2.1% 2.1% 62.87BUSNODEM_SOUTH 111,224 6,950,418 3.1% 3.0% 62.49BUSNODEM_WEST 81,379 5,093,591 2.2% 2.2% 62.59

BUSNODEM Sub-Total 3,629,145 229,275,584 100.0% 100.0% 63.18

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RESHIWR_COAST 13,228,059 906,412,483 24.5% 24.4% 68.52RESHIWR_EAST 2,574,739 176,656,091 4.8% 4.8% 68.61RESHIWR_FWEST 1,340,030 90,813,567 2.5% 2.4% 67.77RESHIWR_NCENT 25,170,472 1,752,749,197 46.5% 47.2% 69.64RESHIWR_NORTH 1,499,513 102,836,931 2.8% 2.8% 68.58RESHIWR_SCENT 911,327 62,010,580 1.7% 1.7% 68.04RESHIWR_SOUTH 7,924,123 524,229,612 14.7% 14.1% 66.16RESHIWR_WEST 1,436,721 96,312,637 2.7% 2.6% 67.04

RESHIWR Sub-Total 54,084,985 3,712,021,098 100.0% 100.0% 68.63


RESLOWR_COAST 28,755,663 2,058,500,827 43.7% 43.7% 71.59RESLOWR_EAST 1,795,949 125,803,195 2.7% 2.7% 70.05RESLOWR_FWEST 1,444,265 102,313,952 2.2% 2.2% 70.84RESLOWR_NCENT 25,932,725 1,889,284,910 39.4% 40.1% 72.85RESLOWR_NORTH 1,580,573 111,940,734 2.4% 2.4% 70.82RESLOWR_SCENT 1,305,328 92,277,972 2.0% 2.0% 70.69RESLOWR_SOUTH 3,707,166 245,428,322 5.6% 5.2% 66.20RESLOWR_WEST 1,285,798 88,755,604 2.0% 1.9% 69.03

RESLOWR Sub-Total 65,807,466 4,714,305,518 100.0% 100.0% 71.64

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• Totals from previous three slides.

Is accuracy more important for RESLOWR (33.4% of Dollars) than for BUSNODEM (1.6% of Dollars)?

19 Month 19Month MWh % - Profile Total % 19Month MWhProfile / Wzone MWh * MCPE (Dollars) 19Month MWh * MCPE LWAPBUSHILF 21,989,953 1,388,130,633 10.7% 9.8% 63.13BUSMEDLF 25,407,213 1,751,971,485 12.4% 12.4% 68.96BUSLOLF 34,802,034 2,302,682,583 16.9% 16.3% 66.17BUSNODEM 3,629,145 229,275,584 1.8% 1.6% 63.18RESHIWR 54,084,985 3,712,021,098 26.3% 26.3% 68.63RESLOWR 65,807,466 4,714,305,518 32.0% 33.4% 71.64

Total 205,720,796 14,098,386,902 100.0% 100.0% 68.53

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Class Level MWH & Dollars - Descending Order by Dollars

* Note: Dollars = Σ (MWh * MCPE)Continues on next slide

Top 5 classes account for 53% of the MWh and 54% of the dollars

19-Month Cumlt. Cumlt.% Cumlt. Cumlt.%rank Profile / Wzone MWh Dollars* MWh Ttl MWh Dollars Ttl Dollars

1 RESLOWR_COAST 28,755,663 2,058,500,827 28,755,663 14% 2,058,500,827 15%2 RESLOWR_NCENT 25,932,725 1,889,284,910 54,688,388 27% 3,947,785,737 28%3 RESHIWR_NCENT 25,170,472 1,752,749,197 79,858,859 39% 5,700,534,934 40%4 BUSMEDLF_NCENT 15,449,309 1,030,463,871 95,308,169 46% 6,730,998,806 48%5 RESHIWR_COAST 13,228,059 906,412,483 108,536,228 53% 7,637,411,289 54%6 BUSMEDLF_COAST 11,405,935 753,826,626 119,942,163 58% 8,391,237,915 60%7 BUSLOLF_NCENT 9,882,020 697,329,751 129,824,183 63% 9,088,567,666 64%8 BUSHILF_NCENT 9,289,014 595,340,798 139,113,197 68% 9,683,908,464 69%

9 BUSLOLF_COAST 8,612,974 586,474,328 147,726,171 72% 10,270,382,792 73%10 RESHIWR_SOUTH 7,924,123 524,229,612 155,650,294 76% 10,794,612,404 77%11 BUSHILF_COAST 7,012,401 440,544,629 162,662,695 79% 11,235,157,033 80%12 RESLOWR_SOUTH 3,707,166 245,428,322 166,369,861 81% 11,480,585,355 81%13 BUSMEDLF_SOUTH 3,207,940 205,503,900 169,577,801 83% 11,686,089,255 83%14 BUSLOLF_SOUTH 2,816,609 185,696,415 172,394,409 84% 11,871,785,670 84%15 RESHIWR_EAST 2,574,739 176,656,091 174,969,148 85% 12,048,441,762 85%16 BUSHILF_SOUTH 2,375,129 144,688,043 177,344,277 86% 12,193,129,805 86%

21


* Dollars = Annual MWh * MCPEContinues on next slide


17 RESLOWR_EAST 1,795,949 125,803,195 179,140,226 87% 12,318,933,000 87%18 RESLOWR_NORTH 1,580,573 111,940,734 180,720,799 88% 12,430,873,735 88%19 RESHIWR_NORTH 1,499,513 102,836,931 182,220,312 89% 12,533,710,666 89%20 RESLOWR_FWEST 1,444,265 102,313,952 183,664,577 89% 12,636,024,618 90%21 RESHIWR_WEST 1,436,721 96,312,637 185,101,299 90% 12,732,337,255 90%22 BUSNODEM_NCENT 1,537,514 95,849,300 186,638,813 91% 12,828,186,556 91%23 RESLOWR_SCENT 1,305,328 92,277,972 187,944,141 91% 12,920,464,528 92%24 RESHIWR_FWEST 1,340,030 90,813,567 189,284,171 92% 13,011,278,095 92%25 RESLOWR_WEST 1,285,798 88,755,604 190,569,969 93% 13,100,033,699 93%26 BUSNODEM_COAST 1,304,968 82,914,041 191,874,937 93% 13,182,947,740 94%27 BUSMEDLF_EAST 1,209,610 80,858,842 193,084,547 94% 13,263,806,582 94%28 BUSLOLF_EAST 1,126,287 78,322,602 194,210,834 95% 13,342,129,184 95%29 BUSHILF_FWEST 1,212,446 75,408,364 195,423,279 95% 13,417,537,548 95%30 BUSMEDLF_FWEST 1,103,530 72,034,036 196,526,810 96% 13,489,571,585 96%31 BUSLOLF_FWEST 992,852 68,460,782 197,519,662 96% 13,558,032,367 96%32 BUSMEDLF_NORTH 940,794 62,626,744 198,460,455 97% 13,620,659,111 97%

Bottom 28 classes account for only 10% of the MWh and dollars

22


* Dollars = Annual MWh * MCPE

Continues on next slide


33 RESHIWR_SCENT 911,327 62,010,580 199,371,783 97% 13,682,669,691 97%34 BUSMEDLF_WEST 940,393 61,519,838 200,312,175 97% 13,744,189,529 97%35 BUSLOLF_NORTH 813,779 56,508,105 201,125,954 98% 13,800,697,634 98%36 BUSLOLF_WEST 767,768 52,046,991 201,893,722 98% 13,852,744,626 98%37 BUSHILF_EAST 664,628 42,102,131 202,558,350 99% 13,894,846,757 99%38 BUSHILF_NORTH 392,006 39,307,134 202,950,357 99% 13,934,153,891 99%39 BUSMEDLF_SCENT 544,524 35,848,725 203,494,880 99% 13,970,002,616 99%40 BUSHILF_WEST 499,266 30,928,517 203,994,146 99% 14,000,931,133 99%41 BUSLOLF_SCENT 394,925 27,132,509 204,389,071 99% 14,028,063,642 100%42 BUSHILF_SCENT 317,290 19,811,017 204,706,361 100% 14,047,874,659 100%43 BUSNODEM_EAST 207,477 13,509,530 204,913,838 100% 14,061,384,189 100%44 BUSNODEM_FWEST 167,689 10,811,421 205,081,528 100% 14,072,195,609 100%45 BUSNODEM_NORTH 143,908 9,433,035 205,225,435 100% 14,081,628,644 100%46 BUSNODEM_SOUTH 111,224 6,950,418 205,336,659 100% 14,088,579,063 100%47 BUSNODEM_WEST 81,379 5,093,591 205,418,038 100% 14,093,672,654 100%48 BUSNODEM_SCENT 74,986 4,714,248 205,493,024 100% 14,098,386,902 100%

23

Precision vs Sample Size

Precision at 90% Confidenceas a Function of Error Ratio and Sample Size

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 50 100 150 200 250 300 350 400

Sample Size

Pre

cisi

on er=0.10

er=0.50

er=1.00

er=1.50

ratioerror er

1.645Z,Confidence%90For

sizesample

erZPrecision

•Increasing sample size has a diminishing return on precision improvement

•Error Ratio (thus Precision improvement) varies across Profile Types / Weather Zones and across intervals

•Thus the impact of adding sample points varies by Profile Type and Weather Zone

24

Options 4 & 5• Options 4 & 5 iteratively allocate increments of 20 sample points to the next Profile Type /

Weather Zone Combination in order to produce the most gain in

– Reducing MWh (Option 4) estimation error (Precision × MWh) summed across all intervals– Reducing Dollar (Option 5) estimation error (Precision × Dollars) summed across all intervals

• The allocations are based on

– The MWh (or Dollars) associated with each of the Profile Type / Weather Zone combinations in each interval– The Error ratio in each interval for each Profile Type / Weather Zone combination– The cumulative number of sample points allocated by preceding iterations (including the original sample

size)– The precision improvement that would be realized by adding 20 sample points, and the diminishing return

on that improvement

• Minimum Sample Size

– Profile to profile migration resulted in numerous instances of small sample sizes within strata– Small sample sizes resulted in both accuracy degradation and the need to drop strata from load research

analysis – A minimum of 3 strata will be specified for each Profile Type / Weather Zone combination– A minimum of 40 sample points will be allocated to each stratum– Minimum sample size per Profile Type / Weather Zone combination will be 120

• Maximum Sample Size

– Maximum for Business Profile / Weather Zone combinations set to 400 – Maximum for Residential Profile / Weather Zone combinations set to 600

25

Option 4 – MWh Error Reduction Optimization

Cumulative sample sizes are shown in increments of 1,000; they were determined iteratively in increments of 20 sample points

Sample Size 8000 9000 10000 11000 12000

BUSHILF_COAST 120 120 140 220 280BUSHILF_EAST 120 120 120 120 120BUSHILF_FWEST 120 120 120 120 120BUSHILF_NCENT 120 120 240 320 400BUSHILF_NORTH 120 120 120 120 120BUSHILF_SCENT 120 120 120 120 120BUSHILF_SOUTH 120 120 120 120 120BUSHILF_WEST 120 120 120 120 120BUSMEDLF_COAST 260 400 400 400 400BUSMEDLF_EAST 120 120 120 120 140BUSMEDLF_FWEST 120 120 140 200 260BUSMEDLF_NCENT 300 400 400 400 400BUSMEDLF_NORTH 120 120 120 120 120BUSMEDLF_SCENT 120 120 120 120 120BUSMEDLF_SOUTH 120 180 320 400 400BUSMEDLF_WEST 120 120 120 120 120BUSLOLF_COAST 200 300 400 400 400BUSLOLF_EAST 120 120 120 120 120BUSLOLF_FWEST 120 120 120 120 160BUSLOLF_NCENT 280 400 400 400 400BUSLOLF_NORTH 120 120 120 120 120BUSLOLF_SCENT 120 120 120 120 120BUSLOLF_SOUTH 120 120 160 240 300BUSLOLF_WEST 120 120 120 120 120BUSNODEM_COAST 120 120 160 240 300BUSNODEM_EAST 120 120 120 120 120BUSNODEM_FWEST 120 120 120 120 120BUSNODEM_NCENT 120 120 160 220 300BUSNODEM_NORTH 120 120 120 120 120BUSNODEM_SCENT 120 120 120 120 120BUSNODEM_SOUTH 120 120 120 120 120BUSNODEM_WEST 120 120 120 120 120

Sample Size 8000 9000 10000 11000 12000

RESHIWR_COAST 380 560 600 600 600RESHIWR_EAST 120 120 220 300 360RESHIWR_FWEST 120 120 120 160 220RESHIWR_NCENT 600 600 600 600 600RESHIWR_NORTH 120 120 120 180 240RESHIWR_SCENT 120 120 120 120 140RESHIWR_SOUTH 240 360 580 600 600RESHIWR_WEST 120 120 120 160 220RESLOWR_COAST 540 600 600 600 600RESLOWR_EAST 120 120 120 180 220RESLOWR_FWEST 120 120 120 160 200RESLOWR_NCENT 520 600 600 600 600RESLOWR_NORTH 120 120 120 160 200RESLOWR_SCENT 120 120 120 120 160RESLOWR_SOUTH 120 160 280 380 460RESLOWR_WEST 120 120 120 120 160

Percent Reduction MWH Error 76.5% 77.5% 78.1% 78.4% 78.7%

26

Iterative Sample Allocation toMaximize Dollar Error Reduction

70%

71%

72%

73%

74%

75%

76%

77%

78%

79%

80%

5,000 6,000 7,000 8,000 9,000 10,000 11,000 12,000 13,000 14,000 15,000 16,000

Sample Size

Do

llar

Err

or

Red

ucti

on

(%

)

Option 5 – Dollar Error Reduction Optimization

RESHIWR_COAST 380 560 600 600 600RESHIWR_EAST 120 120 220 300 360RESHIWR_FWEST 120 120 120 180 220RESHIWR_NCENT 600 600 600 600 600RESHIWR_NORTH 120 120 120 180 220RESHIWR_SCENT 120 120 120 120 140RESHIWR_SOUTH 220 360 560 600 600RESHIWR_WEST 120 120 120 160 220RESLOWR_COAST 560 600 600 600 600RESLOWR_EAST 120 120 120 180 240RESLOWR_FWEST 120 120 120 160 220RESLOWR_NCENT 520 600 600 600 600RESLOWR_NORTH 120 120 120 160 220RESLOWR_SCENT 120 120 120 120 160RESLOWR_SOUTH 120 160 280 380 480RESLOWR_WEST 120 120 120 120 160

Percent Reduction Dollar Error 76.5% 77.5% 78.1% 78.5% 78.7%

Sample Size 8000 9000 10000 11000 12000

BUSHILF_COAST 120 120 140 200 260BUSHILF_EAST 120 120 120 120 120BUSHILF_FWEST 120 120 120 120 120BUSHILF_NCENT 120 120 240 320 400BUSHILF_NORTH 120 120 120 120 120BUSHILF_SCENT 120 120 120 120 120BUSHILF_SOUTH 120 120 120 120 120BUSHILF_WEST 120 120 120 120 120BUSMEDLF_COAST 260 400 400 400 400BUSMEDLF_EAST 120 120 120 120 140BUSMEDLF_FWEST 120 120 140 200 240BUSMEDLF_NCENT 300 400 400 400 400BUSMEDLF_NORTH 120 120 120 120 120BUSMEDLF_SCENT 120 120 120 120 120BUSMEDLF_SOUTH 120 180 300 400 400BUSMEDLF_WEST 120 120 120 120 120BUSLOLF_COAST 200 300 400 400 400BUSLOLF_EAST 120 120 120 120 120BUSLOLF_FWEST 120 120 120 120 160BUSLOLF_NCENT 280 400 400 400 400BUSLOLF_NORTH 120 120 120 120 120BUSLOLF_SCENT 120 120 120 120 120BUSLOLF_SOUTH 120 120 160 220 280BUSLOLF_WEST 120 120 120 120 120BUSNODEM_COAST 120 120 180 240 300BUSNODEM_EAST 120 120 120 120 120BUSNODEM_FWEST 120 120 120 120 120BUSNODEM_NCENT 120 120 180 240 300BUSNODEM_NORTH 120 120 120 120 120BUSNODEM_SCENT 120 120 120 120 120BUSNODEM_SOUTH 120 120 120 120 120BUSNODEM_WEST 120 120 120 120 120

Sample Size 8000 9000 10000 11000 12000

27

Dollar Error Reduction Based on Sample Size Increases

Sample Size

Incremental Dollar Error Reduction (19 Month)

Error Reduction per Incremental Sample Point (Annualized)

Incremental MWh Error Reduction (19 Month)

Error Reduction per Incremental Sample Point (Annualized)

4560 -- -- -- --5760 170,368,683 89,668 2,630,122 1,384 6000 59,872,350 157,559 916,007 3,817 6500 74,081,985 93,577 1,129,530 2,259 7000 51,048,186 64,482 782,336 1,565 7500 39,920,390 50,426 615,328 1,231 8000 32,550,371 41,116 500,334 1,001 8500 26,378,457 33,320 406,100 812 9000 20,806,066 26,281 325,652 651 9500 15,530,764 19,618 245,482 491

10000 11,461,324 14,477 181,097 362 10500 9,341,106 11,799 146,094 292 11000 7,917,458 10,001 123,359 247 11500 6,822,516 8,618 106,161 212 12000 6,002,526 7,582 93,068 186 12500 5,338,340 6,743 82,843 166 13000 4,817,731 6,086 75,127 150 13500 4,399,533 5,557 68,435 137 14000 4,015,099 5,072 62,632 125 14500 3,626,681 4,581 56,494 113 15000 3,282,507 4,146 50,961 102

Non - Optimized

Allocation of points

Optimized Allocation of Additional Points

28

Impact of UFE Allocation

• The precision of estimates produced by a sample design will affect the accuracy of the resulting profile models

• The profile model outputs will be adjusted for UFE

• Sample design should take the UFE adjustment into consideration

• Intuitively the iterative sample design process should minimize the impact of UFE adjustment

– Used iterative design based on dollar error minimization

• ERCOT ran Monte Carlo simulations to evaluate the impact of UFE

– Simulated sample outcomes for 48 Profile Type / Weather Zone combinations for all intervals of the 19 month analysis period

– Adjusted sample outcomes for UFE– Compared MAPE before and after UFE adjustment– Replicated this process 500 times for 3 sample designs (8000, 9000, 10000 sample

points)

29


MAPE MAPE MAPE MAPE MAPE MAPEBefore UFE After UFE Difference Before UFE After UFE Difference Before UFE After UFE Difference

Total Sample Size = 8,000 Total Sample Size = 9,000 Total Sample Size = 10,000

BUSHILF_COAST 1.61% 1.82% -0.22% 1.61% 1.81% -0.21% 1.49% 1.65% -0.16%BUSHILF_EAST 1.60% 1.87% -0.27% 1.60% 1.86% -0.26% 1.60% 1.80% -0.20%BUSHILF_FWEST 2.85% 3.01% -0.15% 2.86% 3.02% -0.16% 2.85% 2.96% -0.10%BUSHILF_NCENT 1.91% 2.05% -0.14% 1.91% 2.05% -0.14% 1.35% 1.51% -0.17%BUSHILF_NORTH 1.71% 1.95% -0.24% 1.71% 1.94% -0.24% 1.71% 1.88% -0.17%BUSHILF_SCENT 1.40% 1.68% -0.29% 1.39% 1.67% -0.28% 1.40% 1.61% -0.21%BUSHILF_SOUTH 1.96% 2.16% -0.20% 1.96% 2.16% -0.20% 1.96% 2.10% -0.14%BUSHILF_WEST 1.44% 1.72% -0.28% 1.44% 1.71% -0.27% 1.44% 1.65% -0.21%BUSMEDLF_COAST 4.72% 4.63% 0.09% 3.81% 3.79% 0.02% 3.81% 3.74% 0.07%BUSMEDLF_EAST 5.13% 5.19% -0.07% 5.13% 5.22% -0.09% 5.13% 5.17% -0.04%BUSMEDLF_FWEST 10.44% 10.44% 0.01% 10.46% 10.44% 0.02% 9.71% 9.70% 0.01%BUSMEDLF_NCENT 4.42% 4.34% 0.08% 3.83% 3.81% 0.02% 3.83% 3.75% 0.08%BUSMEDLF_NORTH 6.35% 6.41% -0.06% 6.35% 6.43% -0.08% 6.35% 6.38% -0.03%BUSMEDLF_SCENT 5.90% 5.97% -0.08% 5.89% 6.00% -0.10% 5.90% 5.94% -0.05%BUSMEDLF_SOUTH 8.88% 8.83% 0.05% 7.26% 7.26% 0.00% 5.62% 5.61% 0.01%BUSMEDLF_WEST 6.73% 6.78% -0.05% 6.73% 6.81% -0.07% 6.73% 6.76% -0.03%BUSLOLF_COAST 3.03% 3.02% 0.01% 2.48% 2.53% -0.05% 2.14% 2.18% -0.03%BUSLOLF_EAST 4.12% 4.21% -0.09% 4.12% 4.22% -0.11% 4.12% 4.17% -0.06%BUSLOLF_FWEST 6.20% 6.24% -0.04% 6.19% 6.25% -0.06% 6.21% 6.22% -0.01%BUSLOLF_NCENT 2.59% 2.56% 0.03% 2.16% 2.20% -0.03% 2.16% 2.14% 0.02%BUSLOLF_NORTH 5.38% 5.45% -0.07% 5.38% 5.47% -0.09% 5.38% 5.42% -0.04%BUSLOLF_SCENT 2.77% 2.93% -0.16% 2.77% 2.94% -0.17% 2.77% 2.88% -0.11%BUSLOLF_SOUTH 4.07% 4.12% -0.05% 4.07% 4.14% -0.07% 3.52% 3.56% -0.04%BUSLOLF_WEST 3.33% 3.45% -0.12% 3.33% 3.46% -0.14% 3.33% 3.41% -0.08%BUSNODEM_COAST 9.79% 9.79% 0.00% 9.79% 9.82% -0.02% 8.01% 8.01% 0.00%BUSNODEM_EAST 7.59% 7.66% -0.06% 7.60% 7.69% -0.09% 7.60% 7.64% -0.04%BUSNODEM_FWEST 7.78% 7.85% -0.07% 7.78% 7.87% -0.09% 7.78% 7.82% -0.04%BUSNODEM_NCENT 8.31% 8.32% -0.01% 8.31% 8.34% -0.04% 6.78% 6.79% 0.00%BUSNODEM_NORTH 8.80% 8.86% -0.05% 8.80% 8.89% -0.09% 8.80% 8.84% -0.03%BUSNODEM_SCENT 9.25% 9.31% -0.06% 9.25% 9.34% -0.09% 9.25% 9.28% -0.04%BUSNODEM_SOUTH 7.90% 7.97% -0.07% 7.90% 7.99% -0.09% 7.90% 7.94% -0.04%BUSNODEM_WEST 7.64% 7.71% -0.07% 7.65% 7.75% -0.11% 7.64% 7.68% -0.05%

30


MAPE MAPE MAPE MAPE MAPE MAPEBefore UFE After UFE Difference Before UFE After UFE Difference Before UFE After UFE Difference

Total Sample Size = 8,000 Total Sample Size = 9,000 Total Sample Size = 10,000

UFE Impact with the 3 selected sample size designs and levels is negligible

RESHIWR_COAST 3.78% 3.66% 0.12% 3.11% 3.07% 0.04% 3.00% 2.92% 0.09%RESHIWR_EAST 6.46% 6.45% 0.01% 6.46% 6.49% -0.03% 4.77% 4.78% -0.01%RESHIWR_FWEST 7.06% 7.09% -0.03% 7.07% 7.12% -0.05% 7.06% 7.07% 0.00%RESHIWR_NCENT 3.12% 2.87% 0.25% 3.12% 2.88% 0.24% 3.12% 2.82% 0.30%RESHIWR_NORTH 6.67% 6.70% -0.03% 6.67% 6.72% -0.04% 6.67% 6.68% 0.00%RESHIWR_SCENT 6.55% 6.60% -0.05% 6.55% 6.62% -0.07% 6.55% 6.57% -0.02%RESHIWR_SOUTH 4.95% 4.86% 0.09% 3.87% 3.86% 0.01% 3.10% 3.09% 0.01%RESHIWR_WEST 6.51% 6.54% -0.03% 6.51% 6.56% -0.05% 6.51% 6.52% -0.01%RESLOWR_COAST 2.30% 2.20% 0.10% 2.22% 2.14% 0.08% 2.22% 2.08% 0.14%RESLOWR_EAST 5.43% 5.48% -0.05% 5.43% 5.49% -0.06% 5.43% 5.44% -0.02%RESLOWR_FWEST 6.29% 6.32% -0.04% 6.29% 6.35% -0.06% 6.28% 6.30% -0.01%RESLOWR_NCENT 2.48% 2.37% 0.11% 2.31% 2.23% 0.07% 2.31% 2.18% 0.13%RESLOWR_NORTH 5.78% 5.82% -0.04% 5.78% 5.84% -0.06% 5.78% 5.80% -0.02%RESLOWR_SCENT 5.49% 5.55% -0.06% 5.50% 5.58% -0.08% 5.50% 5.53% -0.03%RESLOWR_SOUTH 6.02% 6.00% 0.02% 5.21% 5.24% -0.03% 3.94% 3.96% -0.02%RESLOWR_WEST 5.36% 5.42% -0.06% 5.35% 5.44% -0.08% 5.35% 5.38% -0.03%

All P rofile / Wzone 5.20% 5.25% -0.05% 5.06% 5.14% -0.07% 4.83% 4.86% -0.03%

31

Dealing with Oil and Gas Migrations

• Round two sample design and selection will be complete prior to BUSOGFLT implementation

• ERCOT has obtained list of Oil and Gas ESIIDs from TXU-ED and AEP

– ERCOT will check with other TDSPs for additional ESIIDs

• The ESIIDs will be eliminated from sample design, selection and the analysis population

• Sample estimates will be adjusted to reflect ESIIDs which have not migrated to BUSOGFLT

– Usage for these ESIIDs will be aggregated and profiled as flat load – No sample points will be needed for Oil and Gas ESIIDs

32

Dealing with Primary Voltage Migrations

• In Round one sample design for most Profile Type / Weather Zone combinations 3 – 4 separate strata were set up for Primary Voltage ESIIDs

– These strata usually had small sample sizes, many were 100% sampled– Profile migrations were particularly problematic in performing analysis as a result of empty or sparse

strata

• ERCOT has done preliminary statistical analysis of the Primary Voltage population (excluding Oil and Gas ESIIDs)

• Profile Type / Weather Zone combination– Appear to have significant differences from Secondary Voltage ESIIDs in the same weather zone and

profile type– Separate Primary Voltage strata will be beneficial for Round Two sample accuracy

• A single Primary Voltage stratum will be established in each Profile Type / Weather Zone combination were applicable

– Each stratum will be allocated a minimum sample size (40)– Profile migration issues should be less significant to future analysis

• ERCOT plans to evaluate the introduction of Primary Voltage as a potential new profile type

– Adoption would be contingent on significant sample (and load profile model) accuracy improvements for both Secondary and Primary Voltage ESIIDs

– If adopted, migrations to the new profile type would not create future analysis issues– Augmented samples would probably be necessary to build adequate models for Primary

33

Conclusions and Follow-up Actions

• The iterative sample point allocation process has intuitive appeal– Seems to allocate sample points where they do the most good– Would be expected to maximize UFE reduction– UFE allocation has negligible impact on the final accuracy

• ERCOT will be selecting a total sample size of 9,000 points for secondary voltage ESIIDs and also will select a sample of primary voltage ESIIDs … 40 per profile type / weather zone combination were applicable

• ERCOT will run MBSS to determine stratum boundaries based on annualized kWH and to allocate sample points to the strata

• ERCOT will then randomly select primary and replacement sample points based on the design and forward the sample lists to TDSPs in March

• ERCOT will update the sample tracking database with the new samples, sample points, and will add the sample points to the samples

1 ercot lrs precision analysis pwg presentation february 27, 2007

Documents

profile type independent

profile type weather

weather zone independent

intervals accounting

weather zoneoption

selected percent of

weather zone weighted

profile typefor example