modeling tres-amigas update modeling work group meeting february 10, 2011 wecc staff
TRANSCRIPT
Modeling Tres-Amigas Update
Modeling Work Group Meeting
February 10, 2011
WECC Staff
Adjustments to the Modeling of the Tres-Amigas Project
Background
Background
● Modeling the Tres-Amigas Project This model was developed by Z-Global. This model consists of a set of energy cost curves
that describes the price at which the SPP and ERCOT markets are willing to buy or sell power with WECC.
The cost curves do not represent the entire supply curves for the ERCOT and SPP markets. Rather the cost curves represent the subset of the generation fleet in SPP and ERCOT that is expected to participate in the WECC energy market.
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Background
● At the last Modeling Work Group meeting it was suggested that this approach may be overly optimistic. The subset of generation that was assumed to be
available to participate in the WECC market may not always be available due to high loads, forced outages, lack of transmission, etc…
Potential over-generation problems during off peak hours in ERCOT and SPP are not accounted for in the current modeling.
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Background
● During the last MWG meeting it was proposed to address the concerns stated above as follows: The unavailability of SPP and ERCOT generation to
participate in the WECC market could be modeled with an 8760 load shape.
Potential over-generation problems during off peak hours in ERCOT and SPP could be modeled with an 8760 generator shape.
These load and generator shapes would then be netted against the output of the current Tres-Amigas model.
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Implementation of the Model Adjustments
Terminology
● Unavailable Generation Adjustment Accounts for the occasional unavailability of SPP and
ERCOT generation to participate in the WECC market.
Modeled with an 8760 Load Shape.
● Over-Generation Adjustment Accounts for potential over-generation problems in
SPP and ERCOT in the off peak hours. Modeled with an 8760 Generator Shape.
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Unavailable Generation Adjustment
● The Unavailable Generation Adjustment hourly shapes were created as follows:1. All hours were selected in the 2006 ERCOT and SPP
historical load shapes that were within a given ‘percentage’ of the shapes monthly peaks. ERCOT -> 28% SPP -> 20%
2. The monthly peak was multiplied by one minus this ‘percentage’ and then subtracted from the selected values.
3. The values were then normalized by multiplying each value by the ratio of the monthly peak divided by the annual peak.
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0
10000
20000
30000
40000
50000
60000
70000
1 2190 4379 6568 8757
MW
Hour of Year
ERCOT 2006 Load Step 1 - Select values above the black line
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
1 2190 4379 6568 8757
MW
Hour of Year
ERCOT 2006 Load Step 2 - ('selected values' - 'black line')
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
1 2190 4379 6568 8757
MW
Hour of Year
ERCOT 2006 Load Step 3 - Normalized selected values
Unavailable Generation Adjustment
● Reasoning behind assumptions Since generation supply shortages and transmission
congestion problems tend to occur at times of high load it seems reasonable to use ERCOT and SPP historical load shapes as a starting point.
Since many utilities tend to schedule units out for maintenance during the winter and shoulder months it seems reasonable to allow the adjustment to be non zero during these months. Although there is a non zero adjustment during the winter and
shoulder months the magnitude of the adjustment during these months is significantly less than the adjustment during the summer months.
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0
10
20
30
40
50
60
70
80
90
100
0 2193 4386 6579 8772
pu
Hour of Year
ERCOT (Unavailable Gen Adjustment)
0
10
20
30
40
50
60
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
ERCOT (Unavailable Gen Adjustment)
winter
fall
summer
spring
annual
0
10
20
30
40
50
60
70
80
90
100
0 2193 4386 6579 8772
pu
Hour of Year
SPP (Unavailable Gen Adjustment)
0
5
10
15
20
25
30
35
40
45
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
SPP (Unavailable Gen Adjustment)
winter
fall
summer
spring
annual
Over-Generation Adjustment
● The Over-Generation Adjustment hourly shapes were created as follows:1. All hours were selected in an ERCOT and SPP wind
profile that were within a given ‘percentage’ of the profiles maximum value. ERCOT -> 40% SPP -> 60%
2. The profiles maximum value was multiplied by one minus this ‘percentage’ and then subtracted from the selected values.
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0
10
20
30
40
50
60
70
80
90
1 2190 4379 6568 8757
MW
Hour of Year
ERCOT Wind Shape Step 1 - Select values above the black line
0
5
10
15
20
25
30
35
1 2190 4379 6568 8757
MW
Hour of Year
ERCOT Wind Shape Step 2 - ('selected values' - 'black line')
Over-Generation Adjustment
● Reasoning behind assumptions Since over-generation problems in off peak hours can
be aggravated by wind generation it seems reasonable to use wind shapes as a starting point for this adjustment.
Only the hours of high wind generation were selected since these are the hours when wind will tend to aggravate over generation problems.
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0
20
40
60
80
100
120
0 2193 4386 6579 8772
pu
Hour of Year
ERCOT (Over-Gen Adjustment)
0
10
20
30
40
50
60
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
ERCOT (Over-Gen Adjustment)
winter
fall
summer
spring
annual
0
20
40
60
80
100
120
0 2193 4386 6579 8772
pu
Hour of Year
SPP (Over-Gen Adjustment)
0
5
10
15
20
25
30
35
40
45
50
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
SPP (Over-Gen Adjustment)
winter
fall
summer
spring
annual
Composite Shape
● The adjustment shapes for ERCOT and SPP were scaled and then combined into a Composite Shape. The adjustment shapes were scaled so that the Over-
Gen shapes and the Unavailable Gen shapes had about the same energy.
The shapes were then combined by subtracting the Unavailable Gen shapes from the Over-Gen shapes.
The Composite shape can be thought of as an adder to the generation in SPP and ERCOT that will be exported to the WECC energy market.
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0
5
10
15
20
25
30
35
40
45
50
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
ERCOT (Shapes)
Unavailable-Gen
Over-Gen
0
5
10
15
20
25
30
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
ERCOT (Scaled Shapes)
Unavailable-Gen
Over-Gen
-25
-20
-15
-10
-5
0
5
10
15
20
25
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
ERCOT (Composite Shape)
-100
-80
-60
-40
-20
0
20
40
60
0 2193 4386 6579 8772
pu
Hour of Year
ERCOT (Composite Shape)
-60
-50
-40
-30
-20
-10
0
10
20
30
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
ERCOT (Composite Shape)
winter
fall
summer
spring
annual
-100
-80
-60
-40
-20
0
20
40
60
0 2193 4386 6579 8772
pu
Hour of Year
SPP (Composite Shape)
-50
-40
-30
-20
-10
0
10
20
30
1 3 5 7 9 11 13 15 17 19 21 23
pu
Hour of Day
SPP (Composite Shape)
winter
fall
summer
spring
annual
Major Assumptions Summary What percentage of the monthly load peaks should be
used when deriving the Unavailable Gen shape? Current Assumption (ERCOT -> 28% SPP -> 20%).
What percentage of the wind profiles maximum value should be used when deriving the Over-Gen shape?
Current Assumption (ERCOT -> 40% SPP -> 60%).
How should the Over-Gen and Unavailable Gen shapes be scaled before they are combined?
Current Assumption (The shapes were scaled to contain the same energy).
How should the ERCOT and SPP Composite Shapes be scaled relative to each other?
Current Assumption (Both shapes were scaled with a multiplier of one).
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