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