1. Review of Abnormal MCPEs
April 19th through April 27th, 2004
May 12th, 2004
Market Operations Support
Brandon Whittle

2. April 19th, 2004 MCPEs NH Shadow Prices Interval Ending MCPE
Shadow Price
00-Jan-00
NORTH
SOUTH
WEST
HOUSTON
NORTHEAST
N-H
15:15
$39.99
$63.68
$42.48
$80.11
$40.36
$112.00
15:30
$78.94
$44.09
$105.95
$40.60
$185.00
15:45
$77.04
$43.89
$102.74
$40.57
$176.00
16:00
$37.30
$200.77
$54.49
$314.15
$39.86
$774.00
16:15
$33.23
$226.03
$53.51
$359.73
$36.24
$913.00
16:30
$37.63
$44.30
$38.33
$48.93
$37.73
$32.00
16:45
$39.00
$44.51
$39.58
$48.33
$39.09
$26.00
17:00
$45.92
$40.61
$50.03
$40.08
$28.00
MCPEs
NH Shadow Prices

3. April 19th, 2004 No Limit Changes on NH CSC
Operator Actions consistent with procedures, no evidence of over or under constraint
Flow controlled to 85-90% of posted limit – Why?
Blue – NH Limit
Red – NH Flow

4. April 19th, 2004 Why were flows managed fairly conservatively?
TDSP notified ERCOT of need for lower limit due to post-contingency voltage instability
ERCOT currently does not have tools to perform real-time voltage stability testing. (Release 3)
ERCOT Operations chose to be conservative and controlled to a lower than posted limit
New procedures being discussed to change posted limit

5. April 19th, 2004
Interval
Zone
Cleared UBES
Bid UBES
Cleared DBES
Bid DBES
1545
HOUSTON2004
349
509
2763
NORTH2004
468
1382
899
3455
NORTHEAST2004
110
400
2993
SOUTH2004
399
617 97
581
WEST2004 63
357
1171
ERCOT TOTAL
1389
3265
1106
10963
1600
508
458
1000 9
116
1591
1119
1615
555
606
2621
302
1397
908
3514
515
160
2858
514 16
587
164
361
1645
3496
1084
10751
Bid BES numbers do not reflect available BES – These are the bid totals, but they could have been constrained by actual resource availability.

6. April 19th, 2004 Contributing Factor – Load Change CSC flowcsc=
200 MW load forecast increase in ERCOT between 15:45 and 16:00
229 MW load forecast increase in load in Houston Zone
This causes the predicted flow across the N-H CSC to be significantly higher, requiring more BES to be cleared, thus higher prices
CSC flowcsc=

7. April 19th, 2004 Interval Zone Generation Scheduled Interval Forecast
Int. Forecast with Offset
Actual Load
Day Ahead Forecast 1600
Day Ahead Forecast 0600
1545
HOUSTON2004
7076
10377
10511
10616
10126
10062
NORTH2004
11619
11626
11776
11642
12275
12145
NORTHEAST2004
3453
751
761
747
731
726
SOUTH2004
9018
8457
8566
8511
8279
8287
WEST2004
2451
2257
2286
2234
2241
2238
ERCOT TOTAL
33617
33468
33900
33750
33652
33458
1600
7083
10668
10740
10666
10232
10192
11604
11646
11725
11690
12383
12279
3468
766
749
740
735
9022
8547
8605
8537
8395
8437
2248
2263
2242
2267
2265
33628
33870
34099
33884
34017
33908
1615
7117
10727
10820
10712
11661
11729
11831
11667
3570
757
764
8967
8594
8668
8554
2474
33789
34055
34350
33938

8. April 22nd, 2004 MCPEs NH, SH Shadow Prices Interval Ending MCPE
Shadow Prices
00-Jan-00
NORTH
SOUTH
WEST
HOUSTON
NORTHEAST NH SH
06:45
$49.41
$0.00
07:00
$25.13
$250.00
$147.67
$103.87
$290.01
$220.25
07:15
$38.68
$41.58
$38.98
$43.59
$38.72
$13.74
10:30
$55.58
10:45
$141.92
$101.71
-$298.00
$299.00
$5.00
$439.38
$500.61
11:00
$53.01
$53.99
$53.11
$54.67
$53.03
$4.63
13:45
$66.24
14:00
$174.45
$77.12
-$85.50
$196.72
$62.29
$303.48
14:15
$196.28
$103.27
-$999.01
$276.00
$14.10
$222.99
$438.29
14:30
$66.34
$47.10
$64.15
$83.50
$65.96
$92.36

9. April 22nd, 2004 Interval 14:15 West MCPE -999.01
Extremely high Shadow Prices and MCPEs were mitigated after market clearing. Prices shown are mitigated prices which are marginal bids cleared.
All available BES is used to solve a zonal constraint if necessary, using power balance as a limit.
Due to exhaustion of available bid stacks and West Zone BES bid of

10. April 22nd, 2004
April 22nd, 2004
Blue – NH Limit
Red – NH Flow

11. April 22nd, 2004 Significant Limit change on N-H for 0700
Related to planned outage of King to Kuykendall
NH and SH constraints active, in both cases Houston UBES is necessary to solve
N-H curtailment contributes to loading on SH constraint
Operator actions
No evidence of over constraint
Operator could have mitigated by easing into the limit change although not supported in procedures

12. April 22nd, 2004 New Development in Procedures
ERCOT recognized problem and proposed internal solution
Solution in Transmission and Security Desk Procedures step 2.2
Operator is to gradually reduce flows across a CSC in preparation for a limit change

13. April 26th, 2004 MCPEs 1645 Interval high, no congestion
Interval Ending
MCPE
00-Jan-00
NORTH
SOUTH
WEST
HOUSTON
NORTHEAST
16:30
$99.26
16:45
$194.95
17:00
$89.59

14. April 26th, 2004 1606 Generation Trip Low Frequency
Increase in Balancing Energy necessary to replace RRS deployment
Blue – ERCOT Frequency
Red – Balancing deployed

15. April 27th, 2004 MCPEs Shadow Prices Northeast to North
Interval Ending
Price
Shadow Price
27-Apr-04
NORTH
SOUTH
WEST
HOUSTON
NORTHEAST
E-N
16:00
$129.76
$126.23
$116.04
$128.02
$29.29
$242.10
16:15
$290.01
$280.79
$254.22
$285.46
$28.04
$631.25
16:30
$92.39
$90.33
$84.41
$91.38
$33.99
$140.72
16:45
$87.14
$85.27
$79.88
$86.22
$128.08
17:00
$71.05
$0.00

16. April 27th, 2004
Blue – EN Limit
Red – EN Flow

17. April 27th, 2004
Operator Actions were good, let off constraint as flow decreased
Limits were lowered on NE-N due to a combination of several outages
Increase in Balancing required to meet load contributed to rise in MCPEs

18. Recommendations Ease into planned CSC limit changes
Requires procedure change – DONE
Post limits CSC limits in Real Time
In discussion, enhancements to made progressively
Enhance BES market to limit use of zones with negligible affect on constraint solution
Currently planned for Release 5
Requires Protocol changes
Solutions currently being studied
Shadow Price Cap?
Virtual Bids?
Penalty Weight Change?