PDCWG Report to ROS

August 12, 2010

Sydney Niemeyer

In This Report

• PDCWG August 11 meeting items.• ERCOT Frequency Control Performance.

– CPS, RMS1 through July 2010.

• Update on Governor setting changes and impact on frequency profile.– Does it cost more to have a smaller governor

dead band?

• June 23, 2010 DCS event Interconnection Primary Frequency Response detail.

PDCWG Meeting August 11, 2010

• Nodal 24 hour LFC test review:– Regulation deployments utilize CPS 1 control

strategy. Is this appropriate for a single Balancing Authority Interconnection?

– QSE performance• GREDP• QSE AGC strategy

• Review July 2010 Frequency Events.• Wind Generator Primary Frequency Response

implementation.

• BAL-001-TRE-1 update on next draft posting.– LCRA, Eric Armke developing a manual on

using the Resource performance evaluation tool.

• Frequency Event review.– June 23, 2010 15:20 DCS event Primary

Frequency Response evaluation completed.– White paper review and discussion.

PDCWG Meeting August 11, 2010 continued

ERCOT CPS1 15 Minute Average - Monthly Score

0

20

40

60

80

100

120

140

160

180

200

Interval Ending

July-2010 CPS1 = 161.13

ERCOT CPS1 By Day - July 2010

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Day

NE

RC

CP

S1

0

3500

7000

10500

14000

17500

21000

24500

28000

31500

35000

38500

42000

45500

49000

52500

56000

59500

63000

66500

70000

ER

CO

T P

eak

En

erg

y

CPS1 Avg CPS1 ERCOT Pk Energy

161.13 Monthly CPS1 for ERCOT

ERCOT CPS2 - July 2010

60

62

64

66

68

70

72

74

76

78

80

82

84

86

88

90

92

94

96

98

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Day

NE

RC

CP

S2

- E

RC

OT

has

wai

ver

60

62

64

66

68

70

72

74

76

78

80

82

84

86

88

90

92

94

96

98

100

Cu

mu

lati

ve N

ER

C C

PS

2

CPS2 Avg CPS2

93.12 Monthly CPS2 for ERCOT

Daily RMS1

0.0100

0.0150

0.0200

0.0250

0.0300

0.0350

0.0400

1/1/2

000

7/1/2

000

1/1/2

001

7/1/2

001

1/1/2

002

7/1/2

002

1/1/2

003

7/1/2

003

1/1/2

004

7/1/2

004

1/1/2

005

7/1/2

005

1/1/2

006

7/1/2

006

1/1/2

007

7/1/2

007

1/1/2

008

7/1/2

008

1/1/2

009

7/1/2

009

1/1/2

010

7/1/2

010

of ERCOT Frequency

Daily RMS1

0.0100

0.0150

0.0200

0.0250

0.0300

0.0350

0.0400

1/1/

2004

4/1/

2004

7/1/

2004

10/1

/200

4

1/1/

2005

4/1/

2005

7/1/

2005

10/1

/200

5

1/1/

2006

4/1/

2006

7/1/

2006

10/1

/200

6

1/1/

2007

4/1/

2007

7/1/

2007

10/1

/200

7

1/1/

2008

4/1/

2008

7/1/

2008

10/1

/200

8

1/1/

2009

4/1/

2009

7/1/

2009

10/1

/200

9

1/1/

2010

4/1/

2010

7/1/

2010

100

110

120

130

140

150

160

170C

PS

1 A

vera

ge

100

110

120

130

140

150

160

170

Monthly Average 12 Month Rolling AverageTrend

ERCOT CPS1 Score

CPS1 12 Month Rolling Average = 147.04

ERCOT Frequency Profile

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

59.9

59.9

159

.92

59.9

359

.94

59.9

559

.96

59.9

759

.9859

.99 60

60.0

160

.02

60.0

360

.0460

.05

60.0

660

.07

60.0

860

.09

60.1

On

e M

inu

te O

ccu

ran

ces

2008

January through July of 2008 2008 First 7 months

2008 Jan thru July

0

20000

40000

60000

80000

100000

120000

59.9

59.9

159

.9259

.9359

.9459

.9559

.9659

.9759

.9859

.99 60

60.0

160

.0260

.0360

.0460

.0560

.0660

.0760

.0860

.09

60.1

MW

2008 MW Response of 0.036 db

439947.0 2008 MW Response of 0.036 db

MW-minute Response of a 600 MW Generator with Governor setting per ERCOT Protocols and Operating

Guides

Single 600 MW unit MW movement due to frequency.

600 MW Generator Governor Change

• Protocol and Guide settings:– 5% droop curve that steps to the 5% droop curve at

the dead-band.– Allows up to +/-0.036 Hz dead-band.

• Change Governor settings– 5% droop curve that is a straight line function from the

dead-band.– Decrease Governor Dead-band from:

• +/-0.036 Hz to +/-0.01666 Hz

Status as of August 5, 2010

• Units with Governors presently set with an intentional deadband less than or equal to +/-0.01666 Hz and droop curve with no step function.– 14,137 MW Total Capacity Identified by PDCWG

members.• 1690 MW Lignite• 5534 MW Coal• 3780 MW Combustion Turbine Combined Cycle• 1519 MW Combustion Turbine Simple Cycle• 1224 MW Steam Turbine – natural gas fired• 240 MW Hydro• 150 MW Wind Generators

ERCOT Frequency Profile Comparison

0

5000

10000

15000

20000

25000

30000

59.9

59.9

159

.92

59.9

359

.94

59.9

559

.96

59.9

759

.9859

.99 60

60.0

160

.02

60.0

360

.0460

.05

60.0

660

.07

60.0

860

.09

60.1

On

e M

inu

te O

ccu

ran

ces

2010 2008

January through July of each Year

January thru July 2008 0.036 db vs. 2010 0.016 db

0

20000

40000

60000

80000

100000

120000

59.9

59.9

159

.9259

.9359

.9459

.9559

.9659

.9759

.9859

.99 60

60.0

160

.0260

.0360

.0460

.0560

.0660

.0760

.0860

.09

60.1

MW

2008 MW Response of 0.036 db 2010 MW Response of 0.0166 db

439947.0

332694.6 2010 MW Response of 0.0166 db 24.38% Decrease in MW movement with lower deadband.

2008 MW Response of 0.036 db

MW Minute Movement of a 600 MW Unit @ 5% Droop

Same 600 MW unit MW movement due to frequency each year.

Benefits of Governor Change

• Generators move 24.38% less with lower dead-band compared to larger dead-band and poorer frequency control.

• Less maintenance on Generators.• Generators are more stable due to fewer and smaller

MW fluctuations.• Grid is more reliable due to higher probability that

frequency will be near 60 Hz at the time of a major event.

• Generators perform better during events since they are more stable before the event occurs.

• Potential fuel and emission savings.

June 23, 2010 DCS Event• Initial (Point B) Primary Frequency Response -486.77 MW/0.1 Hz.• Sustained (Point B+30 second) Primary Frequency Response

-416.33 MW/0.1 Hz.• Average Primary Frequency Response -458.85 MW/0.1 Hz.• Decreased performance at Point B+30 seconds due to 14,000 MW

of combustion turbine operating at HSL.– As turbine speed decreases with frequency, the mass flow through the

turbine decreases causing MW output to decrease.– Approximately 90 MW of total output was lost causing frequency to

decay from 59.775 Hz to 59.740 Hz.– This is a normal condition of combustion turbines operating at the

exhaust temperature limit of the turbine (HSL). Grid operators should be aware of this situation. In this scenario, if reserves are exhausted frequency would continue to decline instead of stabilizing.

Primary Frequency Response Evaluation

59.70

59.73

59.76

59.79

59.82

59.85

59.88

59.91

59.94

59.97

60.00

60.03

60.06

60.09

60.12

60.15

15:16 15:17 15:18 15:19 15:20 15:21 15:22 15:23 15:24 15:25 15:26

57550

57650

57750

57850

57950

58050

58150

58250

58350

58450

58550

58650

58750

58850

58950

59050

HZ ERCOT Load Total Generation ERCOT 60 HZ Calculated Load

6/23/10

Frequency, Load, & Generation

Generation Change -475 MW after 1253 MW tripped (net). PFR from governors = 778 MW

243 MW of LaaR Tripped (Load acting as a Resource)

252 MW of Load Dampening due to low frequency.

778 MW Pri Freq Response from Gen

246 MW of LaaR Response

252 MW of Load Dampening

1275 MW total Response.

1253 MW Tripped

22 MW error (load dampening, load growth or other data error)

June 23, 2010 DCS Event

59.70

59.72

59.74

59.76

59.78

59.80

59.82

59.84

59.86

59.88

59.90

59.92

59.94

59.96

59.98

60.00

60.02

60.04

60.06

60.08

60.10

15:1

8:50

15:1

9:00

15:1

9:10

15:1

9:20

15:1

9:30

15:1

9:40

15:1

9:50

15:2

0:00

15:2

0:10

15:2

0:20

15:2

0:30

15:2

0:40

15:2

0:50

15:2

1:00

15:2

1:10

15:2

1:20

15:2

1:30

15:2

1:40

15:2

1:50

15:2

2:00

15:2

2:10

Fre

qu

ency

- H

z

-1000

-900

-800

-700

-600

-500

-400

-300

-200

-100

0

MW

/0.1

Hz

Pri

mar

y F

req

uen

cy R

esp

on

se

Frequency Interconnection Frequency Response MW/0.1 Hz

Wednesday, June 23, 20101253

246

1007

Total MW Lost

MW Net Loss to Grid

LaaR Tripped

-458.85 Average Primary Frequency Response MW/0.1 Hz (BAL-001-TRE-1 measure)

-486.77 MW/0.1 Hz (Point B)

-416.33 MW/0.1 Hz (Point B+30 sec)

Poorer

Better

Secondary frequency decline.

59.70

59.73

59.76

59.79

59.82

59.85

59.88

59.91

59.94

59.97

60.00

60.03

60.06

60.09

60.12

60.15

15:16 15:17 15:18 15:19 15:20 15:21 15:22 15:23 15:24 15:25 15:26

57550

57650

57750

57850

57950

58050

58150

58250

58350

58450

58550

58650

58750

58850

58950

59050

HZ ERCOT Load Total Generation ERCOT 60 HZ Calculated Load

6/23/10

Frequency, Load, & Generation

688 MW Pri Freq Response from Gen

246 MW of LaaR Response

339 MW of Load Dampening

1273 MW total Response.

1253 MW Tripped

22 MW error (load dampening, load growth or other data error)

Approximately 90 MW output loss from combustion turbines operating at exhaust temperature limit when mass flow decreased during low frequency.

Approximately 14,000 MW of combustion turbines operating at HSL.

339 MW of Load Dampening due to new lower frequency.

Adequate reserves returned frequency to 60 Hz.