Gas turbine control system
Control of gas turbine is done by Control of gas turbine is done by Startup control Startup control Acceleration control Acceleration control Speed control Speed control Temperature control Temperature control Shut down control Shut down control Manual controlManual control
How to determine operating condi How to determine operating conditiontion
The sensors ,( detected turbine spe ed, exhaust thermocouple ,compre ssor discharge pressure,and other
parameter)are used to determine t he operating condition of the gas tu
rbine
Fuel stroke reference (FSR)
FSR is the command signal for fuel flow
Control of gas turbine is done by th e lowest FSR(FSR SU, FSR ACC ,FSR N, FSRT,FSR SD,FSR MAN)
The lowest FSR value of the six cont rol loop is allowed to fuel control sy
stem
Simplify control schematic
Control shem. block diagram
Start up/Shut down sequen ce
and control
Start up function objective Start up function objective
Bring the gas turbine from zero spee Bring the gas turbine from zero spee d to full speed safely by providing pro d to full speed safely by providing pro
per fuel to established flame and acc per fuel to established flame and acc elerate the turbine safely elerate the turbine safely
Minimize the low cycle fatigue of the Minimize the low cycle fatigue of the hot gas parts during the sequence hot gas parts during the sequence
Speed detector
Speed is the important parameter d uring start up because the sequenc
e of start up is the relation of speed Turbine speed is measured by mag
netic pick up Speed detector sent signal to Mark
V to convert electrical signal to be t he turbine speed in percent or rpm.
Speed converter
Speed relay
The speed relay that are used to co ntrol the sequence of start up
L14 HR Zero speed L14 HM Minimum speed L14 HA Acceleration speed L14 HS Full speed
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
006. %
031. %
18%
19%
95%
90%
18%
15%
50%
4 6 %
964. %
948. %
60%
50%
84. %
32. %
Start up control
Operate as an open loop control usi ng preset level of the fuel comman
d signal FSR(Zero , Fire ,Warm up,Accelerate,)
FSR level are set as control constan t and calculation in the Mark V
144. %
175. %
306. %
005
5%/s
sss1 Start up FSR
Start up curve
Fire shut down
Fire shut down is an improvement o ver the former fuel shut off at L1
4 HS drop out by maintaining flam e down to lower speed to reduction
the strain develop on hot gas pathpart
-- FSRMAX Max Fuel Reference
L83 -- SDSET Preset FSRSD to Existing FSR
L83 -- SDMIN SetFSRSD to FSRMIN
-- FSR Fuel Stroke Reference %
-- FSRMIN FSR: Minimum %
-- FSKSDn Shutdown FSR Ramp n
L83 -- JSDn SetFSRSD Ramp Rate to FSKSDn
L83 -- SDL FSRSD Lower Logic
L83 -- SDR FSRSD Raise Logic
-- FSRMIN FSR: Minimum %
-- FSKSDB Shutdown FSR Ramp Deadband 01. %
FSRSD -- Shut down FSR Signal %
L60SDM -- FSRSD atMin FSR
100%
L83SDSET
L94 -- SD Shutdownwi thBreaker Open
L94 -- SDY T.D. L94SD
L83 -- SDSET Preset FSRSD to Existing FSR
025. s
L83SDMIN
L83 -- SDMI N Set FSRSDtoFSRMI N
L60 -- SDM FSRSDat Mi nFSR
L28 -- CAN Any Can Flamed Out
L83 -- RB Ramp to Blowout Selected
L94 -- SD Shutdownwi thBreaker Open
L 4 -- Master protective signal
FSR Shut down ramp rate
01. %/sec
5%/sec
005. %/sec
01. %/sec
1%/sec
01. %/sec
01. %
L83JSD1
L94 -- X Turbine Shutdown
L83 -- SDR FSRSDRai se Logi c
L 4 -- Master protective signal
L83JSD1 -- SetFSRSDRampRate toFSKSD1
L83SDL FSR Lower logic
- L- L6060 - SDM logic false when FSRSD FSRMIN - SDM logic false when FSRSD FSRMIN >0.1 % >0.1 %
- L- L8383 RB logic true when Flame out RB logic true when Flame out 1>1> sec sec or Flame ON but TNH or Flame ON but TNH 30< %30< %
LL8383 SDL will be logic true in the case of below SDL will be logic true in the case of below
- One can out(L- One can out(L2828CAN)CAN)
L83JSD2 to 5 logic
Flame ONTNH 30< %
- FSRSDFSRMI N- FSRSDFSRMI N > 0 .1 % > 0 .1 %
GT. Trip
1 Can off
Speed control The speed control system control the
speed and load of the gas turbine to m aintain speed at100% at any load
Speed control software will change FS R in proportion to the difference betw
een TNH(turbine speed)and TNR(spee d ref.)
Turbine drive generator operating spe ed range normally from -95% 107%
Start up reference speed is1003. %
Speed droop
Droop speed control is the proporti onal control changing the FSR in pr
oportion to the difference between actual turbine speed and turbine sp
eed reference as the equation belo w
- (TNR TNH)x Droop gain+FSRNL =F SRN
Droop control algorithm
100%
147. %
1sec
105
Droop control curve
Synchronizing control
TNR for synchronizing is1003% to keep the generator faster than
the grid If frequency has varied enough the
speed matching circuit adjust TNR t o maintain turbine speed02 to
04. % faster than the grid
Turbine speed reference TNR
Speed control schematic
Auto synch logic
Synch permissive logic
109%
865. %
109%
865. %
505
495. Hz
505
495. Hz
System line voltage
Generator volts
Generator frequency
Line Frequency
Synch speed matching permissive
Auto synch permissive logic
Temperature control
The temperature control system will li mit fuel flow to gas turbine to maintain
internal operating temperature within gas turbine limitation of turbine hot ga
s path parts. Firing temperature is the temperature
exists at first stage nozzle. This temper ature must be limited by control syste
m
Firing temperature
It is impractical to measure temperatur e direct to the combustion chamber or at the turbine inlet So, the control syste m control the exhaust temperature inst
ead. Firing temperature as a function of fuel
flow (FSR) FSR temp. control curve are used as ba
ck up to primary CPD. Bias temp.
Exhaust temperature control
1818 Chr omel al umel TC ar e i nst al Chr omel al umel TC ar e i nst al
l ed at exhaust pl enumt o sent si gn l ed at exhaust pl enumt o sent si gn al t o Mar k V al t o Mar k V
Exhaust t emper at ur e cont r ol sof twar e
11 Temper at ur e cont r ol command Temper at ur e cont r ol command
2.2. Temp control bias calculation Temp control bias calculation 3.3. Temp r ef er ence sel ect i on Temp r ef er ence sel ect i on
Temperature control FSR.
Exhaust temp control command
Is the temperature control command (TT RXB)compare the exhaust temperature c
ontrol set point(TTXM).The soft ware pro gram converts the temperature error to f
uel stroke reference signal FSRT
Temperature control bias
Firing temperature limit by linearized function of exhaust temperature and
CPD backed up by linearized function of exhaust temperature and FSR
Temperature control Bias
Isothermal Isothermal
Exhaust
tem
pera
ture
(T
X)
Exhaust
tem
pera
ture
(T
X)
Constant firing temp
(liberalized)
Constant firing temp
(liberalized)
Compressor discharge pressure(CPD) Fuel stroke reference(FSR)
Temperature control bias
Temperature control bias
FF F FF FF F . . . If CPD bias >FSR bias Alarm will sho
w GT.Operate by heavy oil(monitor no
zzle plugging) if FSR bias >CPD bias alarm will sho
w
CPD & FSR bias temp control
Temperature reference select program
For temperature reference select,th ree digital input signal are decode (
L83 J TN) t o sel ect one set of co nstant i.e.
Base load open cycle select Base load open cycle select Base load combined cycle select Base load combined cycle select Peak load select Peak load select
Temperature reference select program
Fuel control system
Fuel control system will change fuel flow to the combustion in response
to the fuel stroke reference signal(F SR) FSRFSR11 call for liquid fuel flow call for liquid fuel flow
FSR2 call for gas fuel flow FSR = FSR FSR = FSR11 + FSR + FSR22
Liquid fuel control system
Liquid fuel bypass servo valve
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.
Liquid fuel flow diagram
Min sel
FSRSU
FSRSD
FSRT
FSRN
FSRMAN
FuelSplitter
Fuel flowCom-mand
BypassServoCom-mand
Servo valve
FSR FSR1 FQROUTDCmA
Liquid fuel flow control
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 %
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'
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
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
GVC & SRV control block GVC & SRV control block diagramdiagram
Min sel
FSRSU
FSRSD
FSRT
FSRN
FSRMAN
FuelSplitter
GCV.Com-mand
GasServoCom-mand
Servo valve96GC
FSR FSR2 FSROUTDCmA
SRV.Com-mand
SRV.ServoCom-mand
Servo valve90SR
FPRGOUTDCmA
FG. Flow Control
FG. Press Control
GCV. Schematic diagram
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
SRV. SchematicTurbine Speed
Gas Ratio Valve OpenMaster protective
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)
Fuel gas control and monitor alarm
Excessive fuel flow during start up Loss of LVDT f eed back on SRV and G
CV Servocur r ent t o SRV. det ect ed pr i or t o
permissive to open Servo current to GCV. detected prior
to permissive to open I nt er val ve pr essur e l ow
s ss sssssss sssss servo current %
s sssssss sssss sss - controlvalve [96GC 1]
%
Gas Fuel Stroke Ref
from Fuel Splitter %
s sssssss sssss sss controlvalve - [96GC 1]
% 3 %
sss3
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
ALM1 3 3 :'GASCONTROL VALVE SERVO TROUBLE'
- 5%
5%
375. %
Gas Fuel Stop Valve Open sss3
COMMAND PB Master reset
Speed ratio valve
servo current %
ssssssssss ssss sss sssss - sss[ 9 6 2 ]
Position fdbck srv - 96 1[ SR ] %
ALM1 3 4 :'GASFUEL INTERVALVE PRESSURE TROUBLE'
Gas Ratio Valve Open
Stop/Ratio Valve Position FeedbackTrouble Alarm Lo
ALM1 3 2 :'GASRATIO 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 sss
2 sss
- 6 .6 7 %
667. %
1 5 %
333. %
Dual fuel control
Gas turbine are designed to operate by both FG & FO. The control has pro
vide the following feature Tr ansf er f r omone f uel t o anot her Al l owt i me f or fi l l i ng t he l i ne Mi x f uel oper at i on operationof l i qui d f uel nozzl e pur ge when
operating totally on Gas fuel.
Fuel splitter schematic
Fuel transfer
Mix Fuel operation
Limit on the fuel mixture are requir ed to ensure
Proper combustion Liquid fuel distribution Liquid fuel flow velocity Combustion ratio
Fuel transfer limit (For GE.9E)
Transfer(selectonef uel )pr i or t o st ar t up Do not transfer fuel below30 MW. Do not operate mix below30 r at e
d gas fl owor 6 0 % gas at 30MW.( to avoid nozzle pressure ratio droppi ng below 1 .2 5 and possibly causi ng combustion chamber pulsation.)
Fuel transfer limit (For GE.9E)
Do not mixed below10% rated li quid flow(to avoid excessive liquid f
uel recalculation flow resulting in fu el over heating and possibly causin g fuel oil pump damage.)
Mix fuel Allowable range curve
30 MW
0100
30
70
60
40
90
10
100
0 % GAS % LIQ
NoMIX
NO MIXED
NO
MIXED
MW
LOAD
Rated
MIXED OK
Modulate Inlet Guide Vane
Protect compressor pulsation by m odulate during the acceleration of g
as turbine to rated speed. IGV modulation maintain proper flo
w and pressure to combustion. Maintain high exhaust temperature
at low load when combined cycle application.
Modulate IGV control scheme.
IGV. Control control reference (CSRGV)
MINSEL
IGV part
Speed
MAXSELIGV
MAN
IGVTEMPCONTROL
XMINSEL
L83GVMAX
86 DGA
CPD.
TNH.
CSRGV
57 DGA
CLOSE
OPEN
L83GVMAN
TTRXL8 3 GVSS
371 s1120 s
TTXM
(IGV CONTROL REFERENCE)
CSRGVX+
VIGV Temp Control Airflow Ref Offset
Turb inlet guide vane servo vlv command [90TV-1] DGA
IGV. Control Algorithm from Mark V IGV. Control Algorithm from Mark V
IGVPart speed control
86 DGA
CPRS. OFF Line washing
VIGV. Reference Angle (DGA)
57 DGA
57 DGA
Permissive Inlet Guide Vane Ref
IGVManual Control Permissive
0 DGAStator 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 %
IGV. Part speed reference
Speed Correction Factor Compressor Temperature Ratio
519 o F
Open IGV Position86 DGA
VIGV Part Speed HP Corr Speed Offset %
77320. %
VIGV Part Speed HP Corr Speed Gain
VIGV Part Speed Ref Min Setpoint
Part Speed VIGV Reference
Max Comp InletFlange Temp o F
HP Turbine Speed %
6786. DGA/%
Turbine Speed HP, Iso Corrected
34 DGA
IGV. Control control reference (CSRGV)
MINSEL
IGV part
Speed
MAXSELIGV
MAN
IGVTEMPCONTROL
XMINSEL
L83GVMAX
86 DGA
CPD.
TNH.
CSRGV
57 DGA
CLOSE
OPEN
L83GVMAN
TTRXL8 3 GVSS
371 s1120 s
TTXM
(IGV CONTROL REFERENCE)
CSRGVX+
From Where ?
CSRGVX
L83GVMAN_CMD
MinSEL
X
X
X
X X
T V = OUT
1+TS V
RESET OUT =V
IGVMAN
TTXM
TTRX
CSKGVDB
L83GVDB
TTRXGVB
700 F
2048 F
L83GVSS
TNGV
CSKGVTPG
CSKGVTC
CSRGV
CSRGVX
2 deg F
2 deg F
4 sec
TTRX
MEDSEL
X
X
Z-1
L83REC
TTRXC
TTRXR1
TTRXR2
TTRMINSEL
TTRX
1.5 F/sec
-1 F/sec
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 fuelFor example show value of curve N= 1
X X X
X X X
+
+
+
+
AA < BB
L60TRF
FSR
Conner
Slope
ISO thermal
Slope
CPD
Conner
L83JTN
MINSEL
TTRMINSEL42.707 %
4.987 F/%
1140 deg F
8.058 prs_R
27.342 F/ prs
IGV. Operation curve
IGV. Fault detection
Position feedback IGV -96 1[ TV ]
31 DGA
35 DGA
-30 %
IGVControl Permissive
5 sss
COMMAND PB Master reset
- IGV Loss ofFeedback Alarm
- IGV Vanes Open Alarm
- IGV Servo CurrentAlarm - Neg. Saturation
- - TCQA REG CUR IGV control servo current
DGA
%
IGV. Not following CSRGV.
Position feedback IGV - 96 1[ TV ] DGA
VIGV Reference Angle DGA
ALM1 0 8 : 'INLET GUIDE VANE CONTROL TROUBLE ALARM'
IGVNotFollowing CSRGVTrip
75 DGA
5 SEC
75 DGA
5 SEC