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Developing an Adequacy Metric
Resource Adequacy Forum
Technical Subcommittee Meeting
October 16, 2009
Outline
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•
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Current Adequacy Metric: LOLP
The Problem with LOLP
LOLP Subcommittee Suggestions
Next Steps
October 16, 2009
Resource Adequacy Technical
Committee
2
Current NW Resource Adequacy
Metric: LOLP
GENESYS Simulation January 1930 Illustrative Example Only
Net Demand
NW Thermal
NW Hydro
Unserved
Net Imports
45000
40000
Cold
35000
25000
20000
Hydro Limited
15000
10000
5000
-5000
Hour in Month
October 16, 2009
Resource Adequacy Technical
Committee
4
729
703
677
651
625
599
573
547
521
495
469
443
417
391
365
339
313
287
261
235
209
183
157
131
105
79
53
27
0
1
Megawatts
30000
What do we Count?
•
•
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Ideally, we count “significant” events (those
that we want to avoid)
Energy threshold (or contingency resource) is
1,200 MW for one day or 28,800 MW-hours
from Dec-Mar
Capacity threshold (or contingency resource)
is 3,000 MW in any hour from Dec-Mar and
from Jun-Sep
October 16, 2009
Resource Adequacy Technical
Committee
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Curtailment Events
(Peaking problems and energy shortages)
Curtailed Megawatts
4000
3000
2000
Peak Event > 3,000 MW
Energy Event > 28,800 MW-hrs
1000
0
Hourly Curtailments Dec-Apr (Not all hours shown)
Each event has a peak and duration.
October 16, 2009
Resource Adequacy Technical
Committee
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Curtailment Events
(non-events not shown)
Reliability Events by Game
Curtailment (MW)
4000
3000
2000
Seattle
1000
0
3 12 12 12 12 12 12 15 15 18 18 22 22 25 25 25 25 25 25 33 33 33 33 34 36 36 36 36 36 36 36 37 39 39 39 39 39 39 39 39 41 44 44 46 46 46
Game
October 16, 2009
Resource Adequacy Technical
Committee
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Loss of Load Probability
Simulated 300 winters (December through March)
Out of 300 winters, 15 had an average curtailment greater
than 10 MW-seasons, which means that the
Winter Loss of Load Probability (LOLP) = 15/300 = 5 percent
October 16, 2009
Resource Adequacy Technical
Committee
8
Energy LOLP
Magnitude (MW-Seasons)
(Sum of Curtailed Energy Dec-Mar)
100
90
80
70
60
50
40
30
20
10
0
We plot the average seasonal curtailment for every
simulation in descending order. We then observe where that
curve crosses the 10 MW-Season level on the probability
axis -- that identifies the LOLP for this scenario.
0
October 16, 2009
1
2
3
4
5
6
Probability (%)
Resource Adequacy Technical
Committee
7
8
9
10
9
LOLP (%)
LOLP vs. Contingency Resource
40
35
30
25
20
15
10
5
0
10,000 MW-Hrs
LOLP = 12%
28,800 MW-Hrs
LOLP = 4%
0
10000
20000
30000
40000
Contingency Resource Generation (MW-Hours)
October 16, 2009
Resource Adequacy Technical
Committee
10
Study Statistics
Number of Simulations (Games)
Hours in the Dec-Mar period
Total number of hours simulated
50
2,904
145,200
Number of games with at least one hour of
curtailment
18
Number of curtailment hours (over all games)
275
Number of curtailment events
83
Average magnitude per event
1,953 MWhrs
Average duration per event
Average number of events per game with
curtailments
October 16, 2009
Resource Adequacy Technical
Committee
3.4 hours
4.6
11
LOLP Type Statistics
No. of
Games
LOLP
(%)
At least 1 hour of curtailment
18
36
Total curtailment > 28,800 mw-hrs
2
4
Total curtailment > 10,000 mw-hrs
6
12
At least one event > 4 hours
13
26
At least one event > 4,000 mw-hrs
9
18
At least one event > 4-hour & > 4,000 mw-hrs
5
10
At least five hours with curtailment > 1,000 mw
5
10
At least ten hours with curtailment > 1,000 mw
2
4
At least one hour with curtailment > 1,000 mw
11
22
Types of events
October 16, 2009
Resource Adequacy Technical
Committee
12
The Problem with LOLP
Potential Problem with LOLP
Same LOLP – Bigger Magnitude
1.2
Magnitude
1
0.8
0.6
0.4
0.2
0
1
2
3
4
5
6
Probability
October 16, 2009
Resource Adequacy Technical
Committee
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Magnitude
Potential Problem with LOLP
Lower LOLP – Bigger Magnitude
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1
2
3
4
5
6
Probability
October 16, 2009
Resource Adequacy Technical
Committee
15
Are LOLP curves well behaved?
(i.e. do they cross?)
Magnitude (MW-Seas)
30
Magnitude
20
LOLP
10
0
0
10
20
30
40
Probability of Excedence
October 16, 2009
Resource Adequacy Technical
Committee
16
LOLP vs. Magnitude
(If this relationship were dependable, the magnitude of the problem could
be estimated by knowing the LOLP)
2500
y = 64.333x + 54.308
R2 = 0.6418
Magnitude
2000
1500
1000
500
0
0
5
10
15
20
25
30
LOLP (%)
October 16, 2009
Resource Adequacy Technical
Committee
17
LOLP Subcommittee Report
and Recommendations
LOLP Subcommittee Report
• Clearly define all reserve requirements
– Operating reserves
– Planning reserves
– Wind integration reserves
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Determine which reserve curtailments count toward LOLP
Add temperature-correlated wind as a random variable
Decouple temperature and water condition
Define a “contingency” resource for each month of the
year instead of defining threshold events
• Record curtailment events across all months of the year
• Consider using other adequacy metrics
• Continue to assess climate change impacts
October 16, 2009
Resource Adequacy Technical
Committee
19
LOLP Review Status
• Reserves
– Work being done by PNUCC committee
• Temperature-correlated wind
– BPA working on a test data set
• Decouple temp and water
– Done
• Contingency resource
– Work needs to be assigned
• Annual metric
– Not yet started
• Other metrics
– BPA draft methodology
– PSRI review
• Climate change
– Ongoing
October 16, 2009
Resource Adequacy Technical
Committee
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Next Steps
Possible Modifications
to the Current Method
• Replace LOLP with an alternative metric
• Use LOLP in conjunction with an alternative
adequacy metric
• Use LOLP in conjunction with the
magnitude of the most severe event (or an
average of the worst 10% of events)
October 16, 2009
Resource Adequacy Technical
Committee
22
Examples of Other Adequacy Metrics
• LOLE: loss of load expectation (%)
– Number of hours with curtailment divided by the
total number of hours simulated
– Can be more intuitive, i.e. 99.5% reliable
– Does not address magnitude
• EUE: expected unserved energy (MW-hr)
– Average amount of unserved energy per year
– Lacks specific information about severe events
October 16, 2009
Resource Adequacy Technical
Committee
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Work Plan
• PSRI review complete by early 2010
• Benchmark GENESYS by early 2010
• Tech Committee propose new metric and
threshold by April of 2010
• Use new metric to assess 3 and 5 year
adequacy by June 2010
October 16, 2009
Resource Adequacy Technical
Committee
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