June 30, 2009
Wind Turbine Guidelines Advisory Committee
Integrating Wind Energy in ERCOT
Warren LasherManager, System Assessment
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The ERCOT Region is one of 3 NERC grid interconnections.
The ERCOT grid:-75% of Texas land-85% of Texas load -38,000 miles of transmission lines-550+ generation units-62,339 MW peak demand (set 8/17/06)
2,877 MW of Switchable Units
1,106 MW of Asynchronous Tie Capacity (820 MW with Eastern Interconnection)
North American Electric Grids
You are here
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So What is a Deregulated Electricity Market?
In ERCOT:• Any party can connect their generation to the
transmission system• Retail customers can choose their electricity service
provider• Transmission and distribution (T&D) are still regulated• ERCOT, Inc., operates the transmission system to
facilitate the deregulated wholesale and retail markets
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Why Is There So Much Wind in ERCOT• Marginal cost of electricity is set by gas generation in
most hours (high variable cost)• Generators do not pay for transmission system
upgrades (ERCOT has a postage-stamp transmission rate, paid by load)
• Wind resources in Texas are world-class: over 30 GW of wind generation potential with greater than 40% net capacity factor and over 100 GW of wind generation potential with greater than 35% net capacity factor
• ERCOT contains three of the ten largest cities in the United States (Houston [4], San Antonio [7] and Dallas [9]; Austin and Fort Worth are in the top 20)
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So How Much Wind Generation is in ERCOT?
2
(as of May 31, 2009)
8,13
5
8,13
5
1385
2875
116 116
1173977816
1854
4,785
8,005
8,13
5
8,13
52,
501
1,95
0
1,28
3
781
0
2,000
4,000
6,000
8,000
10,000
12,000
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Year
MW
Cumulative Planned (Signed Interconnection Agreement)Cumulative MW Installed
8,916
9,41810,085
10,63
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0.00
10000.00
20000.00
30000.00
40000.00
50000.00
60000.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
The Primary Challenge – Wind Integration
Coal
Nuclear
Combined-Cycle Gas Turbines
Simple-cycle gas turbines
Natural Gas Steam Units
Wind
DC Tie
Generation from private networks not included
ERCOT’s Peak Day (8/17/06) by Fuel Type
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Operations Must Maintain System Frequency
Coal
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
1200
6/9/07 9:00 6/9/07 9:30 6/9/07 10:00 6/9/07 10:30 6/9/07 11:00 6/9/07 11:30 6/9/07 12:00 6/9/07 12:30 6/9/07 13:00
Reg
ulat
ion
(MW
)
59.904
59.922
59.94
59.958
59.976
59.994
60.012
60.03
60.048
60.066
60.084
60.102
Freq
uenc
y (H
z)
Regulation Frequency
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Example Operations Report
Coal
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“Net-Load” Calculation – An Operator’s Viewpoint
Typical Spring Day (April 23)
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00
Hour of Day
Load
, Win
d, a
nd N
et L
oad
(MW
)
LoadWindLoad-Wind
Similar to load, operator can’t control wind generation output
Net load predictability is key to reliable operations
Additional large increases in wind generation will change the typical load shape
15,000 MW of nameplate wind
Minimum load: 26,100 MW
Minimum net load: 15,700 MW
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Wind Generation Alters Net Load Shape Load-15,000 MW Wind - April Time Series Plot
0
10000
20000
30000
40000
50000
60000
70000
1-Apr
8-Apr
15-Apr
22-Apr
29-Apr
Day
MW
WindLoadNet Load
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ERCOT Generation – December 26, 2008
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
0:15
1:15
2:15
3:15
4:15
5:15
6:15
7:15
8:15
9:15
10:1
5
11:1
5
12:1
5
13:1
5
14:1
5
15:1
5
16:1
5
17:1
5
18:1
5
19:1
5
20:1
5
21:1
5
22:1
5
23:1
5
MW
Other Hydro Wnd Gas_Turbine Gas_CombCycle Coal Nuclear
~$12/MWh
~$20/MWh
~$40/MWh
~$60/MWh
~$0/MWh
Prices shown are variable costs by generation type
Over 92,000 MWh of wind generation
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Components of State-of-the-Art Wind Forecast Systems
• Combination of physics-based (NWP) and statistical models
• Diverse set of input data with widely varying characteristics
• Importance of specific models and data types vary with look-ahead period
• Forecast providers vary significantly in how they use forecast models and input data
Input Data, Forecast Model Components and Data Flow for a State-of-the-Art Forecast System
June 30, 2009Wind Turbine Guidelines Advisory Committee
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Wind Generation Forecasting is Complex
• Two primary sources of uncertainty– Position on power curve– Predictability of weather
regime
• Useful to distinguish between sources– Estimate weather-related
uncertainty from spread of forecast ensemble
– Estimate power curve position uncertainty by developing statistics over all weather regimes
A real facility-scale power curve
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Example 48-Hour ERCOT Wind Generation Forecast
Red line represents expected wind generation
Green line represents 80% confidence forecast
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Wind Persistence
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Wind Generation is Intermittent
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Ancillary Services Requirements
As wind capacity increases, ancillary service requirements increase in order to maintain reliability
Ancillary Services include:• Regulation Service (Frequency Control)• Non-Spin Service (Off-line Quick Start Units)• Replacement Reserve Service (Off-line)• Responsive Reserve Service (On-line
resources for emergency replacement of energy)
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Annual Thermal Generation Impacts
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Annual Emissions Impacts
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The Future of Market Adaptation
• Other Renewable Sources• Nodal Market• Smart Meters – Load Response• Distributed Generation• Plug-In Hybrid Vehicles
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Additional Resources
• Utility Wind Integration Group maintains a library of integration studies
• http://www.uwig.org/opimpactsdocs.html• Over 20 different studies conducted by
operating regions throughout the United States, Canada, and Europe. Also contains several summary documents and the recently completed “NERC Integration of Variable Generation Task Force Report.”
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Integrating Wind Energy in ERCOT
Questions?
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Additional
Background
Materials
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Wind Resources in TexasMap shows areas of wind
potential in Texas, ranked from 1 (strongest)
to 25 (weakest)
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Where is the Wind Generation in ERCOT?
2
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June 30, 2009
Competitive Renewable Energy Zones
ZoneNew Wind Capacity (MW)
Panhandle A 3,200Panhandle B 2,400
Central 3,000Central West 1,100
McCamey 1,900
• Following statute, PUCT has designated CREZs in Texas and ordered 2,376 circuit miles of new 345-kV transmission
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Cost of New Generation