Determining Plant Capacity for a Combined Cycle Power Plant
Using PEPSEJustin Strupp
Scientech, a business unit of Curtiss-Wright Flow Control
Company
2013 Scientech Symposium – Managing Plant Assets and PerformanceClearwater Beach, Florida
August 6-9, 2013
Rex Featherston, Matthew Goodwin, Jason Lee, and
Andre NorwoodArizona Public Service
Company
Redhawk Power Station
Two 2-on-1 Combined Cycles 492 MW Net Base LoadGeneral Electric 7FA gas turbines (~150 MW
each)Supplemental firing in the HRSGAlstom Power steam turbines (~200 MW each) Located in Arlington, ArizonaBegan operating in mid-2002
Problem
Current Operating Assumptions (OAs)Current OA at 2-on-1 base load conditions
-20-15-10-505
101520
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
MW
Effe
ct (M
W)
Operating Assumption - RH 2-on-1 Base Load
Net Maximum Capacity = 492 MW
Solution Needs
Use Ambient ConditionsMonthlyAccurateDocumentedRepeatableDay-ahead and/or Real-timePerformance Monitoring
Background
Operating Assumptions used for dispatch– Max Output– Heat Rate
Current Performance up to date– Degradation and/or Repairs– Ambient Conditions
Power Correction
Power Correction Factor for Temperature and Humidity
Data Collection
PI Data for Ambient Conditions– Temperature– Humidity– Pressure
Collection Intervals and TimeData Collection Schemes
– Monthly Average– Peak Time Monthly Average– Conservative Monthly Outlook– Hybrid Outlook
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
Pres
sure
(PSI
A)
Tem
p (°
F) a
nd H
umid
ity (%
)
Month #
Monthly Average
Temperature Humidity Pressure
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
Pres
sure
(PSI
A)
Tem
p (°
F) a
nd H
umid
ity (%
)
Month #
Peak Time Monthly Average
Temperature Humidity Pressure
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
Pres
sure
(PSI
A)
Tem
p (°
F) a
nd H
umid
ity (%
)
Month #
Conservative Monthly Outlook
Temperature Humidity Pressure
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
Pres
sure
(PSI
A)
Tem
p (°
F) a
nd H
umid
ity (%
)
Month #
Hybrid Monthly Outlook
Temperature Humidity Pressure
PEPSE - Modeling
Translate Heat Balance and Plant Schematics into PEPSE Components
PEPSE –Schematic With Components
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
Other Modeling Assumptions
Evaporative Cooler considerations– On above 75 °F– Off below 75 °F
Condenser PressurePump PressuresDuct Firing – Max at 1198 °FOthers
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
Net
Pow
er O
utpu
t (M
W)
Redhawk 2-on-1 Base Load Comparison
Original OAs Actual Max AveragePeak Average Conservative Outlook Hybrid Outlook
2-on-1 Max Duct Fired Comparison
460470480490500510520530540550560
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Net
Pow
er O
utpu
t (M
W)
Redhawk 2-on-1 Max Duct Fired Comparison
Original OAs Average Peak Average Conservative Outlook Hybrid Outlook
1-on-1 Base Load Comparison
210215220225230235240245250255260
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Net
Pow
er O
utpu
t (M
W)
Redhawk 1-on-1 Base Load Comparison
Original OAs Average Peak Average Conservative Outlook Hybrid Outlook
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
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
Questions?
