Capacity Forecast Report
Mark Ruane
Director, Market Credit
CWG / MCWG
March 10, 2015
ERCOT Public
1
Capacity Forecast Model
ERCOT began posting of the capacity forecast model results
commencing February 24th for Operating Day February 23rd.
The report shows:
• Hourly forecast MW excess reserves for OD+1 through OD+6, with
partial day forecast for OD+7.
• For OD-1 through OD-7,
• Hourly MW forecast for the Operating Day generated on the
OD-1 relative to that day (eg the most recent capacity forecast
for that day)
• Actual MW excess reserves for that hour
• HUBBUSAVG price for the hour
Forecast values are P50. ERCOT may consider possible Px forecast
values.
ERCOT Public
2
Capacity Forecast Model
For the ODs for which results are available, the OD+1 forecast more
often than not underestimated reserves on the OD (consistent with
initial concept modelling).
OD+1 Forecast MW o/(u) Actual
Monday, March 02, 2015
Saturday, February 28, 2015
Thursday, February 26, 2015
Tuesday, February 24, 2015
Sunday, February 22, 2015
Friday, February 20, 2015
Wednesday, February 18, 2015
Monday, February 16, 2015
1 3
Hour
5
7
9 11 13 15 17 19 21 23
-10,000--5,000
False positive
ERCOT Public
-5,000-0
0-5,000
5,000-10,000
False negative
3
Capacity Forecast Model
Percentage error
OD+1 Forecast % o/(u) Actual
Monday, March 02, 2015
Saturday, February 28, 2015
Thursday, February 26, 2015
Tuesday, February 24, 2015
Sunday, February 22, 2015
Friday, February 20, 2015
Wednesday, February 18, 2015
Monday, February 16, 2015
1 3
Hour
5
7
9 11 13 15 17 19 21 23
-40%--20%
False positive
ERCOT Public
-20%-0%
0%-20%
20%-40%
40%-60%
False negative
4
Capacity Forecast Model
There are five ODs for which there are both OD+4 and actuals. For
each of the days the OD+4 forecast was higher than actual.
OD+4 Forecast MW o/(u) Actual
Tuesday, March 03, 2015
Monday, March 02, 2015
Sunday, March 01, 2015
Saturday, February 28, 2015
Friday, February 27, 2015
1
3
5
7
9
11 13 15 17 19 21 23
Hour
0-5,000
Lesser error
ERCOT Public
5,000-10,000
10,000-15,000
Greater error
5
Capacity Forecast Model
For the five days with both OD+1 and OD+4 forecasts there was
generally a material reduction in forecast error.
OD+1 Forecast Error o/(u) OD+4 Error
Tuesday, March 03, 2015
Monday, March 02, 2015
Sunday, March 01, 2015
Saturday, February 28, 2015
Friday, February 27, 2015
1 3
Hour
5
7
9
11 13 15 17 19 21 23
-15,000--10,000
Reduced error
ERCOT Public
-10,000--5,000
-5,000-0
0-5,000
Increased error
6
Capacity Forecast Model
Questions
ERCOT Public
7