Combined Cycle Plant
Fuel
Air
Heat
Recovery
Steam
Generator
G
155 MW
Compressor
Combustion Turbine
80 MW
S
LP
LP
IP
HP
3
Temperature-Dependency
PDX TEMPERATURE
232.91
100
76.988
F
MW
250
85
245
75
65
55
8/2/2014 12:00:00 AM
240
10.00 days
8/12/2014 12:00:00 AM
RIVER ROAD
235
250
245
232.91
MW
230
240
235
225
230
225
220
220
55
8/2/2014 12:00:00 AM
10.00 days
8/12/2014 12:00:00 AM
60
65
76.988 F
T EM PERATURE
70
75
80
85
90
95
100
RIVER ROAD
River Road usually operates at full throttle
5
Duct Firing
Grays Harbor: Blue = GT1, Green = GT2, Yellow = ST
Plot-0
300
159.98
MW
280
160.39
MW
173.02
260
MW
240
220
200
180
160
140
8/13/2014 12:00:00 AM
3.00 days
8/16/2014 12:00:00 AM
Duct firing: Grays Harbor, Mint Farm, HPP, …
6
Combined Cycle Plant
• Gas turbines can provide very fast and sustained
frequency response, as seen with UK experience
– But they likely will not:
– On high demand peak hours, gas turbines will operate
close or at temperature limit
– Otherwise, they are likely to operate under load
control
• Steam-turbine will follow gas turbine with a time
constant of minutes
7
Combined Cycle Plant
485 MW Combined cycle plant at temperature limit
500
60.05
495
60
490
59.95
485
59.9
480
59.85
475
59.8
470
160
170
180
190
200
210
Time (sec)
220
230
240
Frequency (Hz)
Power (MW)
Hermiston Generating Project
59.75
250
8
Combined Cycle Plant
485 MW Combined cycle plant under load control
400
60.05
395
60
390
59.95
385
59.9
380
59.85
375
10
20
30
40
50
60
Time (sec)
70
80
90
Frequency (Hz)
Power (MW)
Hermiston Generating Project
59.8
100
9
Combined Cycle Plant
485 MW Combined cycle plant under load control
Frequency (Hz)
System Frequency
60
59.95
59.9
59.85
59.8
0
20
40
60
80
100
120
Combined Cycle Power Plant Under Load Control
Power (MW)
345
340
335
330
325
0
20
40
60
Time (sec)
80
100
120
10