GT Control

(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

(4)

(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

(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)

(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

(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

(12)

14.4% 17.5% 30.6% 0.05%/s 5%/s 1 sec _{Start up} FSR

(13)

(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

(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

(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

(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

(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

(21)

L83JSD2 to 5 logic

Flame ON TNH<30%

FSRSD-FSRMIN >0.1 %

GT. Trip

(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%

(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

(24)

Droop control algorithm

100 %

14.7 %

1sec

(25)

(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)

(28)

(29)

(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

(31)

(32)

(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

(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)

(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

Exhaus

t

temper

atur

e

(TX)

Exhaus

t

temper

atur

e

(TX)

(40)

(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)

(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)

(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 =

(46)

(47)

(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)

(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 %

(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]

(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

(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

(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)

(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

(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

(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

(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

(64)

(65)

(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

(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)

(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

(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

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

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

+

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)

(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