June 30, 2009

Wind Turbine Guidelines Advisory Committee

Integrating Wind Energy in ERCOT

Warren LasherManager, System Assessment

2 Wind Turbine Guidelines Advisory CommitteeJune 30, 2009

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

12

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