The document describes the control system of a gas turbine. It discusses the various control loops for startup control, speed control, temperature control and shutdown control. It explains how fuel control is done through fuel stroke reference signals and describes the liquid and gas fuel control systems. It also discusses temperature reference selection, inlet guide vane modulation and dual fuel control functionality.

1. Gas turbine control system
 Control of gas turbine is done by
 Startup control
 Acceleration control
 Speed control
 Temperature control
 Shut down control
 Manual control

2. How to determine operating condition
 The sensors ,( detected turbine speed,
exhaust thermocouple ,compressor
discharge pressure,and other
parameter)are used to determine the
operating condition of the gas turbine

3. Fuel stroke reference (FSR)
 FSR is the command signal for fuel flow
 Control of gas turbine is done by the
lowest FSR(FSR SU, FSR ACC ,FSRN,
FSRT,FSR SD,FSR MAN)
 The lowest FSR value of the six control
loop is allowed to fuel control system

4. Simplify control schematic

5. Control shem.
block diagram

6. Start up/Shut down sequence
and control
 Start up function objective
 Bring the gas turbine from zero speed
to full speed safely by providing proper
fuel to established flame and accelerate
the turbine safely
 Minimize the low cycle fatigue of the
hot gas parts during the sequence

7. Speed detector
 Speed is the important parameter
during start up because the sequence
of start up is the relation of speed
 Turbine speed is measured by magnetic
pick up
 Speed detector sent signal to Mark V to
convert electrical signal to be the
turbine speed in percent or rpm.

8. Speed converter

9. Speed relay
 The speed relay that are used to control
the sequence of start up
 L14HR Zero speed
 L14HM Minimum speed
 L14HA Acceleration speed
 L14HS Full speed

10. L14HR Zero Speed
L14HP Spare speed signal
L14HF At field flashing speed
L14HM Minimum Firing Speed
L14HA Accelerating speed
L14HS Min operating speed
L14HC Auxiliary Cranking
Speed Relay
L14HT Cool down Slow Roll
Start Speed Relay
0.06 %
0.31%
18%
19%
95%
90%
18%
15%
50%
46%
96.4%
94.8%
60%
50%
8.4%
3.2%

11. Start up control
 Operate as an open loop control using
preset level of the fuel command signal
FSR(Zero , Fire ,Warm up,Accelerate,)
 FSR level are set as control constant
and calculation in the Mark V

12. 14.4%
17.5%
30.6%
0.05%/s
5%/s
1 sec Start up
FSR

13. Start up curve

14. Fire shut down
 Fire shut down is an improvement over
the former fuel shut off at L14HS drop
out by maintaining flame down to lower
speed to reduction the strain develop
on hot gas path part

15. FSRMAX -- Max Fuel Reference
L83SDSET-- Preset FSRSD to Existing FSR
L83SDMIN-- Set FSRSD to FSRMIN
FSR -- Fuel Stroke Reference %
FSRMIN -- FSR: Minimum %
FSKSDn -- Shutdown FSR Ramp n
L83JSDn -- Set FSRSD Ramp
Rate to FSK SDn
L83SDL-- FSRSD Lower Logic
L83SDR -- FSRSD Raise Logic
FSRMIN-- FSR: Minimum %
FSKSDB -- Shutdown FSR Ramp
Dead band 0.1%
FSRSD
-- Shut
down
FSR
Signal %
L60SDM
-- FSRSD
at Min FSR
100 %

16. L83SDSET
L94SD -- Shutdown with Breaker Open
L94SDY -- T.D. L94SD
L83SDSET -- Preset FSRSD to Existing FSR
0.25 s

17. L83SDMIN
L83SDMIN -- Set FSRSD to FSRMIN
L60SDM -- FSRSD at Min FSR
L28CAN -- Any Can Flamed Out
L83RB -- Ramp to Blowout Selected
L94SD -- Shutdown with Breaker Open
L4 -- Master protective signal

18. FSR Shut down ramp rate
0.1 %/sec
5 %/sec
0.05 %/sec
0.1 %/sec
1 %/sec
0.1 %/sec
0.1 %

19. L83JSD1
L94X -- Turbine Shutdown
L83SDR -- FSRSD Raise Logic
L4 -- Master protective signal
L83JSD1 -- Set FSRSD Ramp Rate to FSK SD1

20. L83SDL FSR Lower logic
- L60SDM logic false when FSRSD-FSRMIN >0.1 %
- L83RB logic true when Flame out >1 sec
or Flame ON but TNH <30%
L83 SDL will be logic true in the case of below
- One can out(L28CAN)

21. L83JSD2 to 5 logic
Flame ON TNH<30%
FSRSD-FSRMIN >0.1 %
GT. Trip
1 Can off

22. Speed control
 The speed control system control the
speed and load of the gas turbine to
maintain speed at 100% at any load
 Speed control software will change FSR
in proportion to the difference between
TNH(turbine speed)and TNR(speed ref.)
 Turbine drive generator operating speed
range normally from 95%-107%
 Start up reference speed is 100.3%

23. Speed droop
 Droop speed control is the proportional
control changing the FSR in proportion
to the difference between actual turbine
speed and turbine speed reference as
the equation below
 (TNR-TNH)x Droop gain+FSRNL =FSRN

24. Droop control algorithm
100 %
14.7 %
1sec
10.5

25. Droop control curve

26. Synchronizing control
 TNR for synchronizing is 100.3% to
keep the generator faster than the grid
 If frequency has varied enough the
speed matching circuit adjust TNR to
maintain turbine speed 0.2 to 0.4 %
faster than the grid

27. Turbine speed reference TNR

28. Speed control schematic

29. Auto synch logic

30. Synch permissive logic
109%
86.5%
109%
86.5%
50.5Hz
49.5Hz
50.5Hz
49.5Hz
System line voltage
Generator volts
Generator frequency
Line Frequency

31. Synch speed matching permissive

32. Auto synch permissive logic

33. Temperature control
 The temperature control system will
limit fuel flow to gas turbine to maintain
internal operating temperature within
gas turbine limitation of turbine hot gas
path parts.
 Firing temperature is the temperature
exists at first stage nozzle. This
temperature must be limited by control
system

34. Firing temperature
 It is impractical to measure temperature
direct to the combustion chamber or at
the turbine inlet So, the control system
control the exhaust temperature
instead.
 Firing temperature as a function of fuel
flow (FSR)
 FSR temp. control curve are used as
back up to primary CPD. Bias temp.

35. Exhaust temperature control
 18 Chromel alumel TC are installed at
exhaust plenum to sent signal to Mark V
 Exhaust temperature control soft ware
 1.Temperature control command
 2.Temp control bias calculation
 3.Temp reference selection

36. Temperature control FSR.

37. Exhaust temp control command
 Is the temperature control command
(TTRXB)compare the exhaust temperature
control set point(TTXM).The soft ware
program converts the temperature error to
fuel stroke reference signal FSRT

38. Temperature control bias
 Firing temperature limit by linearized
function of exhaust temperature and
CPD backed up by linearized function of
exhaust temperature and FSR

39. Temperature control Bias
Isothermal Isothermal
Exhaust
temperature
(TX)
Exhaust
temperature
(TX)
Compressor discharge pressure(CPD) Fuel stroke reference(FSR)

40. Temperature control bias

41. Temperature control bias
 GT. Operate by FG. or FO.
If CPD bias >FSR bias Alarm will show
 GT.Operate by heavy oil(monitor nozzle
plugging)
if FSR bias >CPD bias alarm will show

42. CPD & FSR bias temp control

43. Temperature reference select program
 For temperature reference select,three
digital input signal are decode (L83JTN)
to select one set of constant i.e.
 Base load open cycle select
 Base load combined cycle select
 Peak load select

44. Temperature reference select program

45. Fuel control system
 Fuel control system will change fuel
flow to the combustion in response to
the fuel stroke reference signal(FSR)
FSR1 call for liquid fuel flow
FSR2 call for gas fuel flow FSR
= FSR1 + FSR2

46. Liquid fuel control system

47. Liquid fuel bypass servo valve

48. Liquid fuel control system
 When liquid fuel is selected and start. The
control system will check L4 logic(1). At
minimum speed L20FLX(FO. trip valve) and
L20CF(fuel oil clutch) will energized.
 When GT. Firing FSRSU will go to control
turbine through fuel splitter and liquid fuel
flow command FQROUT will demand to fuel
oil by pass valve to control liquid fuel flow to
combustion chamber.

49. Liquid fuel flow diagram
Min
sel
FSRSU
FSRSD
FSRT
FSRN
FSRMAN
Fuel
Splitter
Fuel
flow
Com-
mand
Bypass
Servo
Com-
mand
Servo
valve
FSR FSR1 FQROUT
DC
mA

50. Liquid fuel flow control

51. FSR1V1 Fuel splitter
Fuel change permissive
Fuel Split Transfer Rate
3.3 %SP/s
Fraction of Liq Fuel Set point Command
Increase Liquid Fuel
Increase Gas Fuel
Fuel Stroke Reference
Fuel Splitter Liquid Fuel Purge Level
Fuel Splitter Gas Fuel Purge Level
Fraction of Liquid Fuel
Mixed Fuel Operation
Completely on Gas Fuel
Completely on Liquid Fuel
Liquid Fuel Stroke Ref
from Fuel Splitter
Gas Fuel Stroke Ref
from Fuel Splitter
0.5 %
0.5 %

52. Liquid Fuel Stop Valve
Control Signal
Flow divider mag
pickup speed
Liq fuel bypass valve
servo current
Liquid Fuel Stroke Ref
from Fuel Splitter %
Turbine Speed %
Master protective signal
Calibration position reference %
Calib selection command pass code
Excessive Liq Fuel Startup
8.5 %
Liq Fuel Bypass Valve Flow Detection
Trouble Set point 3 %
LF. Byp. Vlv. Servo Current
Trouble Alarm
30 %
10 sec
Master reset
Liq Fuel Bypass Valve Flow
Detected Trouble Alarm
Liquid Fuel Flow High (trip )
Liq Fuel Flow Reference Angle %
Liquid fuel bypass valve
servo command[65FP-1]
ALM171:'LIQUID FUEL CONTROL FAULT'

53. System check from flow
divider and servo valve
 Excessive flow on start up (trip GT. If
excessive flow exist during warm up
period) L60FFLH
 LVDT. Position feed back
 Bypass valve is not fully open when
stop valve is close
 Loss of flow divider feed back

54. Fuel gas control system
 Fuel gas flow is controlled by the gas speed
ratio stop valve (SRV) and Gas control valve
(GCV)
 SRV is designed to maintain a predetermined
pressure(P2)at the inlet of gas control valve
as a function of gas turbine speed
 GCV plug is intended to be proportional to
FSR2 for fuel gas flow

55. GVC & SRV control block diagram
Min
sel
FSRSU
FSRSD
FSRT
FSRN
FSRMAN
Fuel
Splitter
GCV.
Com-
mand
Gas
Servo
Com-
mand
Servo
valve
96GC
FSR FSR2 FSROUT
DC
mA
SRV.
Com-
mand
SRV.
Servo
Com-
mand
Servo
valve
90SR
FPRGOUT
DC
mA
FG. Flow Control
FG. Press Control

56. GCV. Schematic diagram

57. Gas control valve out put
Gas Fuel Stroke Ref
from Fuel Splitter
GCV servo command
[65GC-1] %
Calibration position reference %
Calibration selection command pass code
Gas Fuel Stop Valve Open
Master protective signal

58. SRV. Schematic
Turbine Speed
Gas Ratio Valve Open
Master protective

59. SRV. Out put signal
Fuel Gas Press Ratio
Control Gain 3.5146 psi/%
Fuel Gas Press Ratio Control Offset
-17.88 psi
Stop/Speed Ratio Valve
Shutdown Command Set point
-40 psi
Gas Ratio Valve Control Press Ref psi
Stop/speed ratio valve servo
command [90SR-1] psi
Gas Ratio Valve Control Press Ref (psi)

60. Fuel gas control and monitor alarm
 Excessive fuel flow during start up
 Loss of LVDT feed back on SRV and
GCV
 Servo current to SRV. detected prior to
permissive to open
 Servo current to GCV. detected prior to
permissive to open
 Inter valve pressure low

61. Gas control valve
servo current %
Position fdbck gas
controlvalve [96GC-1] %
Gas Fuel Stroke Ref
from Fuel Splitter %
Position fdbck gas
controlvalve [96GC-1] % 3 %
3 sec
5 %
5 sec
Gas control valve not
following reference
Gas control valve not
following reference trip
Gas Control Valve
Position Feedback Fault
Gas Control Valve
Open Trouble Alarm
Gas Control Valve
Servo Current Fault
ALM133:'GAS CONTROL
VALVE SERVO TROUBLE'
-5 %
5 %
37.5 %
Gas Fuel Stop Valve Open
3 sec
COMMAND PB Master reset

62. Speed ratio valve
servo current %
Interstage fuel gas press
xmitter [96FG-2A] psi
Position fdbck srv
[96SR-1] %
ALM134:'GAS FUEL INTERVALVE
PRESSURE TROUBLE'
Gas Ratio Valve Open
Stop/Ratio Valve Position
FeedbackTrouble Alarm Lo
ALM132:'GAS RATIO VALVE
POSITION SERVO TROUBLE'
Stop/Ratio Valve
Open Trouble Alarm
Stop/Ratio Valve Servo
Current Trouble Alarm
Startup Gas Fuel Stroke High
COMMAND PB Master reset
-5 psi
2 sec
-6.67 %
6.67 %
15 %
33.3 %

63. Dual fuel control
 Gas turbine are designed to operate by
both FG & FO. The control has provide
the following feature
 Transfer from one fuel to another
 Allow time for filling the line
 Mix fuel operation
 operation of liquid fuel nozzle purge
when operating totally on Gas fuel.

64. Fuel splitter schematic

65. Fuel transfer

66. Mix Fuel operation
 Limit on the fuel mixture are required to
ensure
 Proper combustion
 Liquid fuel distribution
 Liquid fuel flow velocity
 Combustion ratio

67. Fuel transfer limit (For GE.9E)
 Transfer(select one fuel)prior to startup
 Do not transfer fuel below 30 MW.
 Do not operate mix below 30% rated
gas flow or 60% gas at 30MW.(to avoid
nozzle pressure ratio dropping below
1.25 and possibly causing combustion
chamber pulsation.)

68. Fuel transfer limit (For GE.9E)
 Do not mixed below 10% rated liquid
flow(to avoid excessive liquid fuel
recalculation flow resulting in fuel over
heating and possibly causing fuel oil
pump damage.)

69. Mix fuel Allowable range curve
30 MW
0
100
30
70
60
40
90
10
100
0
% GAS
% LIQ
No
MIX
NO MIXED
NO
MIXED
MW
LOAD
Rated
MIXED OK

70. Modulate Inlet Guide Vane
 Protect compressor pulsation by
modulate during the acceleration of gas
turbine to rated speed.
 IGV modulation maintain proper flow
and pressure to combustion.
 Maintain high exhaust temperature at
low load when combined cycle
application.

71. Modulate IGV control scheme.

72. IGV. Control control reference
(CSRGV)
MIN
SEL
IGV
part
Speed
MAX
SEL
IGV
MAN
IGV
TEMP
CON
TROL
X
MIN
SEL
L83GVMAX
86 DGA
CPD.
TNH.
CSRGV
57 DGA
CLOSE
OPEN
L83GVMAN
TTRX
L83GVSS
371 c
1120 c
TTXM
(IGV CONTROL
REFERENCE)
CSRGVX
+

73. VIGV Temp Control Airflow Ref Offset
Turb inlet guide vane servo
vlv command [90TV-1] DGA
IGV. Control Algorithm from Mark V
IGV Part speed control
86 DGA
CPRS. OFF Line washing
VIGV. Reference Angle (DGA)
57 DGA
57 DGA
Permissive Inlet Guide Vane Ref
IGV Manual Control Permissive
0 DGA
Stator 17 IGV Gain
1 DGA/%
Airflow Control Reference % IGV on Temperature Control
IGV at Minimum Position
IGV at Maximum Position
Temp Control and
Manual Control Ref
Calibration selection
command pass code
Calibration position reference %

74. IGV. Part speed reference
Speed Correction Factor
Compressor Temperature Ratio
519 o F
Open IGV Position
86 DGA
VIGV Part Speed HP
Corr Speed Offset %
77.320 %
VIGV Part Speed
HP Corr Speed Gain
VIGV Part Speed Ref
Min Setpoint
Part Speed VIGV Reference
Max Comp Inlet Flange Temp
o F
HP Turbine Speed %
6.786 DGA/%
Turbine Speed HP, Iso Corrected
34 DGA

75. IGV. Control control reference
(CSRGV)
MIN
SEL
IGV
part
Speed
MAX
SEL
IGV
MAN
IGV
TEMP
CON
TROL
X
MIN
SEL
L83GVMAX
86 DGA
CPD.
TNH.
CSRGV
57 DGA
CLOSE
OPEN
L83GVMAN
TTRX
L83GVSS
371 c
1120 c
TTXM
(IGV CONTROL
REFERENCE)
CSRGVX
+
From Where ?

76. CSRGVX
L83GVMAN_CMD
Min
SEL
X
X
X
X X
T
V = OUT
1+TS
V
RESET
OUT =V
IGV
MAN
TTXM
TTRX
CSKGVDB
L83GVDB
TTRXGVB
700 F
2048 F
L83GVSS
TNGV
CSKGVTPG
CSKGVTC
CSRGV
CSRGVX
2 deg F
2 deg F
4 sec

77. TTRX
MED
SEL
X
X
Z-1
L83REC
TTRXC
TTRXR1
TTRXR2
TTRMINSEL
TTRX
1.5 F/sec
-1 F/sec

78. IGV Temperature control
(CSRGVX) Bias by FSR. , CPD.
L83JTN = Temperature select logic(by damper&fuel)
N = 0 Operate open cycle mode on Gas fuel
N = 1 Operate Combined cycle mode on Gas fuel
N = 2 Operate open cycle on mode Liquid fuel
N = 3 Operate Combined cycle mode on Liquid fuel
For example show value of curve N= 1
X X X
X X X
+
+
+
+
A
A < B
B
L60TRF
FSR
Conner
Slope
ISO thermal
Slope
CPD
Conner
L83JTN
MIN
SEL
TTRMINSEL
42.707 %
4.987 F/%
1140 deg F
8.058 prs_R
27.342 F/ prs

79. IGV. Operation curve

80. IGV. Fault detection
Position feedback
IGV [96TV-1]
31 DGA
35 DGA
-30 %
IGV Control Permissive
5 sec
COMMAND PB Master reset
IGV - Loss of Feedback Alarm
IGV - Vanes Open Alarm
IGV - Servo Current Alarm
- Neg. Saturation
TCQA-REG-CUR IGV
control servo current
DGA
%

81. IGV. Not following CSRGV.
Position feedback IGV
[96TV-1] DGA
VIGV Reference Angle DGA
ALM108:'INLET GUIDE VANE
CONTROL TROUBLE ALARM'
IGV Not Following CSRGV Trip
7.5 DGA
5 SEC
7.5 DGA
5 SEC