Frequency Control
Research Needs
Howard F. Illian, President
Energy Mark, Inc.
March 9, 2010
Overview
¾ Energy Mark’s Template for Funding
¾ Examples of Current Needs
¾ Conclusions
Energy Mark’s Template
¾ Define the “Big Picture”
¾ State the “Underlying Assumptions”
¾ Forecast how the “Future Differs”
¾ Define “Nature of Acceptable Solutions”
¾ Results support “Substantive Decisions”
General “Big Picture”
¾ All interconnections follow the
Law of Conservation of Energy.
¾ Therefore, electric energy must be
injected into an interconnection at
the same instant that it is extracted
by the customers.
¾ Frequency Control addresses this
requirement for the total electrical
interconnection.
General “Big Picture” (cont.)
¾ Operations must be planned and
studied to insure reliability
¾ Industry planning models address this
problem over many time horizons
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Frequency Response Modeling
Long-term & Mid-term Capacity
Day and Hour-ahead Operations
Hour-ahead & Short-term Operations
External Reliability Limits Modeling
Frequency Response Models
¾ “Big Picture”
‹
Simulate frequency disturbances for about
10 to 15 seconds following a disturbance.
¾ “Underlying Assumptions”
‹
The minimum frequency occurs within the
first 10-15 seconds.
¾ The “Future Differs”
‹
The Frequency Response Characteristic
changes.
Actual & Natural Simulated
Frequency Response 1990’s
Eastern Interconnection
Frequency Response 2007
60.02
60.01
60
No “Point C” to “Point B” Recovery
59.99
59.98
59.97
Response “Withdrawal”
59.96
59.95
59.94
0
6
12
18
24
30
36
42
Seconds
Eastern Interconnection
48
54
60
Frequency Response Models
¾ “Acceptable Solutions”
‹
‹
Modify the models to extend the effective
horizon to 30 seconds of more.
Reverse the changes in system operations
that have caused the change in the
Frequency Response Characteristic.
¾ “Substantive Decisions”
‹
‹
Demonstrate need to reverse the change.
Demonstrate models that match the
Frequency Response Characteristic.
External Reliability Models
¾ “Big Picture”
‹
‹
Most operations planning models are
deterministic.
Reliability requirements are estimated
externally and implemented by setting
model limits such as reserves.
¾ “Underlying Assumptions”
‹
This method of estimating reliability limits
externally provides appropriate reliability
risk levels.
External Reliability Models
¾ The “Future Differs”
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Current methods of setting external
reliability limits are deterministic and
unrelated to measureable levels of risk.
They depend on the future being similar
to the past.
Numerous events and responses jointly
contribute to frequency reliability risk.
The future will include risk drivers that
differ from any previously experienced.
ERCOT Wind Event
5500
60.20
5000
60.15
4500
60.10
4000
60.05
3500
60.00
3000
59.95
2500
59.90
9:00
10:00
11:00
12:00
Sample Time
Aggregated WGR Output
13:00
14:00
System Frequency
Texas Interconnection
15:00
Hz (Freq)
MW (Wind)
Wind Output and Frequency for 1/28/10
Contingency Reserve (RRS)
Wind Output, Regulation and RRS for 1/28/10
5500
1000
800
5000
600
400
200
4000
0
‐200
3500
‐400
‐600
3000
‐800
2500
‐1000
9:00
10:00
11:00
Aggregated WGR Output
12:00
13:00
Sample Time
Total Reg. Deployed
Texas Interconnection
14:00
15:00
Total RRS Deployed
MW (Reg, RRS)
MW (Wind)
4500
External Reliability Models
¾ “Acceptable Solutions”
‹
‹
Replace the deterministic models and
reserve rules with probabilistic models
that estimate the joint risks.
Modify these models as system
conditions change.
¾ “Substantive Decisions”
‹
Use the external reliability models to
provide risk parameters to the current
planning models.
Conclusions
¾ Energy Mark recommends five steps
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Define the “Big Picture”
State the “Underlying Assumptions”
Forecast how the “Future Differs”
Define “Nature of Acceptable Solutions”
Results support “Substantive Decisions”
¾ Energy Mark’s experience indicates
that good definitions and planning of
research leads to successful results
and ongoing funding.
Questions