1. Determining Plant Capacity for
a Combined Cycle Power Plant
Using PEPSE
Justin Strupp
Scientech, a business unit of
Curtiss-Wright Flow Control
Company
EPRI Heat Rate Improvement Conference
February 5-7, 2013
Rex Featherston, Matthew
Goodwin, and Jason Lee
Arizona Public Service
Company

2. Redhawk Power Station
 Two 2-on-1 Combined Cycles
 492 MW Net Base Load
 General Electric 7FA gas turbines (~150 MW
each)
 Supplemental firing in the HRSG
 Alstom Power steam turbines (~200 MW each)
 Located in Arlington, Arizona
 Began operating in mid-2002

3. Problem
 Current Operating Assumptions (OAs)
 Current OA at 2-on-1 base load conditions
-20
-15
-10
-5
0
5
10
15
20
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
MWEffect(MW)
Operating Assumption - RH 2-on-1 Base Load
Net Maximum Capacity = 492 MW

4. Solution Needs
 Use Ambient Conditions
 Monthly
 Accurate
 Documented
 Repeatable
 Day-ahead and/or Real-time
 Performance Monitoring

5. Background
 Operating Assumptions used for dispatch
– Max Output
– Heat Rate
 Current Performance up to date
– Degradation and/or Repairs
– Ambient Conditions

6. Power Correction
 Power Correction Factor for Temperature and
Humidity

7. Data Collection
 PI Data for Ambient Conditions
– Temperature
– Humidity
– Pressure
 Collection Intervals and Time
 Data Collection Schemes
– Monthly Average
– Peak Time Monthly Average
– Conservative Monthly Outlook
– Hybrid Outlook

8. Ambient Conditions
 Monthly Average – average over each month at 4-hour
intervals from PI. Similar to current OAs.
14.2
14.3
14.4
14.5
0
20
40
60
80
100
1 2 3 4 5 6 7 8 9 10 11 12
Pressure(PSIA)
Temp(°F)andHumidity(%)
Month #
Monthly Average
Temperature Humidity Pressure

9. Ambient Conditions
 Peak Time Monthly Average – average over each
month using data at 5 PM each day. Peak time scenario.
14.2
14.3
14.4
14.5
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12
Pressure(PSIA)
Temp(°F)andHumidity(%)
Month #
Peak Time Monthly Average
Temperature Humidity Pressure

10. Ambient Conditions
 Conservative Monthly Outlook – Peak Time Average
adding (Temperature) or subtracting (humidity and
pressure) the average standard deviation of the peak time
condition for those months to it. Worst case scenario.
14.0
14.1
14.2
14.3
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12
Pressure(PSIA)
Temp(°F)andHumidity(%)
Month #
Conservative Monthly Outlook
Temperature Humidity Pressure

11. Ambient Conditions
 Hybrid Outlook – average of Peak Time Monthly
Average and the Conservative Monthly Outlook. A
different level of conservatism.
14.1
14.2
14.3
14.4
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12
Pressure(PSIA)
Temp(°F)andHumidity(%)
Month #
Hybrid Monthly Outlook
Temperature Humidity Pressure

12. PEPSE - Modeling
 Translate Heat Balance and Plant Schematics
into PEPSE Components

13. PEPSE –Schematic With Components

14. Study Modeling
 Tuned PEPSE model to Heat Balances
 Three operating modes - each month
– 2-on-1 base load
– 2-on-1 with max supplemental firing
– 1-on-1 base load
 Ambient Conditions – monthly for each average
ambient condition

15. Other Modeling Assumptions
 Evaporative Cooler considerations
– On above 75 °F
– Off below 75 °F
 Condenser Pressure
 Pump Pressures
 Duct Firing – Max at 1198 °F
 Others

16. 2-on-1 Base Load Comparison
440
450
460
470
480
490
500
510
520
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NetPowerOutput(MW)
Redhawk 2-on-1 Base Load Comparison
Original OAs Actual Max Average
Peak Average Conservative Outlook Hybrid Outlook

17. 2-on-1 Max Duct Fired Comparison
460
470
480
490
500
510
520
530
540
550
560
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NetPowerOutput(MW)
Redhawk 2-on-1 Max Duct Fired Comparison
Original OAs Average Peak Average Conservative Outlook Hybrid Outlook

18. 1-on-1 Base Load Comparison
210
215
220
225
230
235
240
245
250
255
260
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NetPowerOutput(MW)
Redhawk 1-on-1 Base Load Comparison
Original OAs Average Peak Average Conservative Outlook Hybrid Outlook

19. Recommended Solutions
 Which to use as the new OAs for 2-on-1 Base
Load, 2-on-1 Max Duct Fired, and 1-on-1 Base
Load?
– Average
– Peak Average
– Conservative Outlook
– Hybrid Outlook

20. Additional Work
 Next Steps?
– Plant data at each Operating Mode
– Marketing involvement
– Implement Method(s) for OAs
– Day-ahead and Real-time instead of Monthly
– Performance Monitoring
 What could be done for better results?
– More Data
– Testing
– Plant Data Tunes

21. Questions?