2909148-GAS-TURBINE-13

Gas Turbine Control Philosophy

Gas Turbine Rotating Blow Torch Designed to Run at the Ragged Edge of  Self Destruction

C

T

G

Gas Turbine Rotating Blow Torch Designed to Run at the Ragged Edge of  Self Destruction

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T

G

Speedtronic Control System

Control System for Gas Turbine 

Gas turbine is controlled Speedtronic control system



Control loops includes 

Start-up



Acceleration



Speed



Temperature



Shutdown and



Manual Control functions

Speedtronic Control loops 



Major Control loops  

Secondary control loops



Start-up Start-up          Acceleration Acceleration



Speed and         



Temp Temper era ature ture          Shut hutdow down

Manual FSR and

Output of these control loops is fed to a minimum value gate Display circuit Fuel Temperature Display

Speed

Acceleration Rate Display Start Up Shut Down

M I N

FSR

To Turbine

Speedtronic Control loops 

Fuel Stroke Reference (FSR) 





Command signal for fuel flow

Controlling FSR 

Lowest of the six control loops



Establishes the fuel input to turbine @ rate required by system which is in control

Only ONE control loop will be in control at anytime. 

The control loop which controls FSR is displayed in operator  friendly CRT.

Startup/Shutdown Sequence and Control 

Startup control brings the gas turbine 



Allows proper fuel to establish 



Command signals to Turbine Accessories, Starting device and Fuel control system

Safe and successful start-up 



Flame & Accelerate the turbine in such a manner as to minimize the Low cycle Fatigue of the hot gas path parts during the sequence

Software Sequencing involves 



Zero speed up to Operating speed.

depends on proper functioning of GT equipment.

Software Sequencing ensures safe operation of  Turbine

Startup/Shutdown Sequence and Control 

Control logic circuitry is associated not only with actuating control devices, but enables protective circuits and obtains permissive conditions before proceeding.



Control settings play a vital role in determining the proper  sequencing. 



Actual site specific control settings are generated by     M/s GEICS,USA.

Speed detection - by magnetic pickups    

L14HR Zero-Speed (Approx. 0% TNH) L14HM Min Speed (Approx.. 16% TNH) L14HA Accelerating Speed (Approx. 50% TNH) L14HS Operating speed (Approx..95% TNH)

Startup/Shutdown Sequence and Control 

Actual settings of speed relays are listed in Control specification.



The control constants are programmed in processors EEPROM.



Always ensure correct site specific, machine specific control specification.



Consult your system designer for any queries.

Start-up Control - FSRSU 

Open loop control 



Uses preset levels of fuel command

Various Fuel levels 

Zero, Fire, Warm-up, Accelerate and Max.

Typical values for Frame-6 

Fire

15.62%



Warm-up

11.62%



Accelerate

19.82%



Maximum

100%

Open Loop Control

Start-up Control - FSRSU 

Startup control FSR (FSRSU) signal operates through the MIN value gate to ensure other control functions can limit FSR as required.

FSRSU FSRACC FSRN FSRT

FSR MIN

FSRSYN FSRMAN

FSR = FSRSU

Start-up Control - FSRSU 

Speedtronic Control Start-up software generates Fuel command signal (FSR).



Speedtronic Control Software also sets the MAX and MIN limits for FSR for Manual Control FSR [ FSRMIN < FSRMAN < FSRMAX ]



When Turbine Breaks away (starts to rotate) 

L14HR pick-up



Starting clutch solenoid 20CS de-energizes



Shuts down the hydraulic ratchet motor (88HR)

Acceleration Control - FSRACC 

Acceleration control software 



compares the present value of Speed signal with the value at the last sample time. Difference between these two numbers is a measure of acceleration.



When actual acceleration is greater acceleration reference, FSRACC is reduced, which reduces FSR, thus reduction in fuel supply to turbine.



During startup-acceleration reference is a function of turbine speed.



Acceleration control takes over after Warm-up state.

Acceleration Control - FSRACC 

Acceleration reference is a Control constant programmed in EEPROMS Typical

0.35 %/sec

0.10 %/sec 0%

40% 50% 75% 95% 100%

TNH

Acceleration Control - FSRACC FSRSU FSRACC FSRN FSRT

FSR MIN

FSRSYN FSRMAN

FSR = FSRACC

Speed Control - FSRN 

Speed Control System software 



controls the speed and load of the gas turbine generator  in response to the actual turbine s peed signal (TNH) and the called-for speed reference(TNR)

TNH

TNR

FSRN

Speed/Load Control 

Speed/Load Reference: 

Speed control software will change FSR in proportion to the difference the actual turbine generator speed (TNH) and the called-for reference (TNR)



Reference Speed (TNR) range 



Start-up speed reference is 100.3%. 



95% (min) to 107% (max) for a generator drive turbine

This is preset when START signal is initiated.

Turbine follows 100.3% TNH for synchronization

Speed/Load Control 

Turbine Speed is held constant when Generator Breaker is closed onto Power grid



Fuel flow in excess of the necessary to maintain FSNL will result in increased power produced by the generator.



Thereby Speed control becomes Load control loop



Speed Control: 

Isochronous Speed control



Droop Speed Control

Isochronous Speed Control

TNH

FSRNI

TNR FSRSU FSRACC FSRN (or FSRNI) FSRT

MIN

FSR

FSRSYN FSRMAN

FSR = FSRN

Droop Speed Control 

Droop Control is a proportional control. 

Any change in actual speed (grid frequency) will cause a proportional change in unit load.



This proportionality is adjustable to the desired regulation or  ‘Droop’ 104 % R N

d  e  e  p  S 

T e  c  n er  ef  e  R

D  r  oo  p    10  4%    s  e  tt  i    ng    FSNL

100 %

95% ll

R S  F d  a  o  L o  N d  e  e  p  S  u 

1  0  0  %  S  e  tp  o    in  t   

Low Speed Stop

R S  F d  e  t  a  R

Speed/Load Control loop Raise

Lower 

Rate

LOG SETPOIINT

Speed Ref. Command

Rate

Speed Target MANUAL SETPOINT

Power 

Primary Os

Speed Error 

Preset Ememrgency Os

Mechanical Os Load Raise

Rate

Load Lower 

LOG SET POIINT

Load Rate

Speed

Load Ref. Cmd MANUAL SET POINT

Preset

Load Setpoint

SPEED CONTROL

Speed Control Schematic SPEED CONTROL



FSNL TNR SPEED REF.

+

+

ERROR +

-

FSRN

SIGNAL

TNH SPEED DROOP

RST>

SPEED CHANGER LOAD SET POINT MAX. LIMIT L83SD RATE L70R RAISE

L83PRES PRESET LOGIC

L70L LOWER

MEDIAN SELECT

PRESET OPERATING

START-UP

L83TNROP MIN. SELECT LOGIC

or SHUT DOWN

MIN.

TNR SPEED REF.

Synchronising - FSRSYN 

Automatic synchronization software 



Bus and Generator voltage are input signals to Protective core . 



Isolation transformers are built into core

software drives the synch check and system permissive relays. 



Algorithms programmed into controller and software.

Sequencing and algorithms are programmed into EEPROM

hardware and software sends voted command to actual breaker  closure.

Auto Synchronisation Speed

stem

Raise Speed Speed Matching Lower Speed

requency Speed Raise Volts Generator Volts

System Volts

Voltage Matching Lower Volts

Synchronising Scheme AUTO  SYNCH PERMISSIVE Gen Volts

A A>B

REF

B AND

Line Volts

L83AS Auto  Synch Permissive

AUTO SYNCH

A A>B

REF

B

Calculated  Phase within Limits Calculated slip within Limits Calculated  Acceleration Calculated  Breaker Lead Time

AND

L25 Breaker  Close

Temperature Control - FSRT 

Temp.Control software/algorithms 

limit fuel flow to the turbine to maintain internal operating temperatures within design parameters of turbine hot gas path parts.



Highest temperature is in the flame zone of  combustion chambers.

TTXM TTREF

FSRT

Firing Temperature 

Firing temperature - temperature of gas as it exits the first stage nozzle.



Speedtronic limits this firing temperature.



Firing temperature is calculated by    

thermodynamic relation ships GT performance calculations, and site conditions as a function of Exhaust Temp(Tx) and CPD fuel

air 

C

T

ISO FIRING TEMP T

)  x T(  er  u  t  ar  e  p  m e  t  t  s  u  a  h x

C  Isothermal o  n  s  t  F  i  r  in  g    T  e  m  p  (  Li    ne    a  r  i  ze    d  ) 

Firing Temperature 

Firing temperature can also be approximated as 

a function of Tx and Fuel flow (FSR) and



as a function of Tx and Generator MW output



Line of constant firing temperature are used in control software to limit the gas turbine operating temp



whereas the constant exhaust temperature limit protects the exhaust system during start-up.

TA TB TC

TA > TB > TC

)  x T(  er  ut    ar  e  p  m e  t  t  s  u  a  h x E

C  Isothermal o  n  s  t  F  i  ri    ng    T  e  m  p  (  Li    ne    a  r  i  ze    d  )  Fuel Stroke Reference (FSR)

Exhaust Temp control software 

Series of application programs written to 

perform critical exhaust temperature control and monitoring.



Major function is –



Exhaust temperature control.

Software is Programmed for  

Temperature control command



Temperature control bias calculations



Temperature reference selection.

Temperature Control Schematic

If ONE Controller should fail, this ogram ignore the readings from the

TTXDR TTXDS TTXDT

iled Controller. TTXM is based on

To Comb. Monitor 

TTXD2 SORT HIGHEST TO LOWEST

maining controllers thermocouples. Alarm will be generated Temp Control Ref 

QUANTITY of TC’s Used

CORNER

REJECT HIGH AND LOW

AVERAGE REMAINING

TTXM

Temperature Control -

CPD

REJECT LOW TC’s

+

-

FSRMIN FSRMAX

+

SLOPE

TTRXB

SLOPE

-

+

FSR

MIN. SELECT

CORNER

TTXM

+

+ -

MEDIAN MEDIAN SELECT

+

FSRT

+

GAIN

FSR ISOTHERMAL 

The temp-control-command program in compares the exhaust temp control setpoint (calculated in the temp-control-bias program and stored in computer memory) TTRXB to the

Temperature Control Bias program DIGITAL INPUT DATA

SELECTED TEMPERATURE REFERANCE TABLE

T  T  K  n  _B 

COMPUTER MEMORY

TEMPERATURE CONTROL BIAS PROGRAM

COMPUTER MEMORY

x E

CONSTANT STORAGE

TTKn_K Isothermal TTKn_C

F 

S  C  R  P  B  D  I  AS    B  I  A  S 

CPD FSR

Temperature Control Bias Temp control Bias program calculates the Exhaust

er  ut    ar  TTKn_I e  p  m e  T t  s  a  u  h

T  T  K  n  _M 

Exhaust Temp Control Setpoints 

TTKn_C (CPD bias corner) and TTKn_S (CPD bias slope)

temp control setpoint TTRXB based on CPD data

are used with the CPD data to determine the CPD

stored in computer memory and constants from the

bias exhaust temperature setpoint. TTKn_K (FSR bias corner) and TTKn_M (FSR bias slope)

selected temp-reference table.



This Program also calculates another setpoint based

are used with the FSR data to determine the FSR

on FSR and constants from another temperature-

bias exhaust temperature setpoint.

Temperature Control Bias Program 

This Program selects the minimum of the three set points, CPD bias, FSR bias, or isothermal setpoint for the final exhaust temperature control reference.



During normal operation with Gas or light Distillate fuels, t his selection results in a CPD bias control with an isothermal limit. 



CPD bias setpoint is compared with the FSR bias setpoint by the program and an alarm occurs when the CPD setpoint exceeds the FSR bias setpoint.

During normal operation with Heavy fuels, FSR bias setpoint will be selected to minimize the turbine nozzle plugging on firing temperature. 

FSR bias setpoint is compared with CPD bias setpoint and an alarm occurs when the FSR bias setpoint exceeds the CPD bias setpoint.



A ramp function is provided in the program to limit the rate of setpoint change. Both Max (TTKRXR1) and Min (TTKRXR2) change in ramp rates (slopes) are programmed.Typical rate change limit is 1.5deg F.



The output of this ramp function is the Exhaust temp.control setpoint which is stored i n the computer memory.

Temperature Reference Select Program 

Exhaust temperature control function selects control set points to allow GT operation at firing temperatures.



Temperature-control-select program determines the operational level for control set points based on Digital input information representing temperature control requirements.



Three digital input signals are decoded to select one set of  constants which defines the control set points necessary to meet the demand. Typical digital signals are BASE SELECT, PEAK SELECT   and HEAVY FUEL SELECT

Digital Input Data

• When appropriate set of constants are selected they are stored in the selected-temperature-reference memory.

Temperature Reference Select

Constant Storage

Selected Temperature Reference Table

Temperature Reference Select Program

Fuel Control system 

Turbine fuel control system will change fuel flow to the combustors in response to the fuel stroke reference signal(FSR).



FSR actually consists of two separate signals added together. FSR = FSR1 + FSR2 FSR1 = Called-for liquid fuel flow FSR2 = Called-for gas fuel flow



Standard fuel systems are designed for operation with Liquid fuel and/or gas fuel.

Servo Drive System

Servo drive System 

The heart of Fuel Control System 

3 coil Electro Hydraulic Servo Valve

Servo valve is the interface between the electrical and mechanical systems  Servo valve controls the direction and rate of motion of a hydraulic actuator based on the input current to the servo.  Servo valve contains three electrically isolated coils on the torque motor.  Each coil is connected to one of the three controllers , thereby redundancy is ensured if one of the controller fails.  A null-bias spring positions the servo so that actuator  goes to the fail safe position when ALL power and/or  control signal is lost. 

Liquid Fuel System 

Liquid Fuel system consists of  



Fuel handling components –

Primary fuel oil filter (low pressure)

–

Fuel oil stop valve

- Fuel pump

–

Fuel bypass valve

- Fuel oil pressure relief valve

–

Secondary fuel oil filter (High pressure)

–

Flow dividers

- Combined Selector valve

–

False start drain valve

- Fuel lines & fuel nozzles

Electrical Control components –

Liquid fuel press sw (upstream) 63FL-2

–

Fuel oil stop valve limit sw 33FL

–

Fuel pump clutch solenoid 20CF

–

Liquid fuel pump bypass valve Servo valve 65FP

–

Flow divider magnetic pickups 77FD-1,2,3 and

–

Speedtronic Control cards TCQC and TCQA

Liquid Fuel System P&ID FQ1



FSR1



FQROUT

TCQA TCQA TCQC

TNH L4 L20FLX

PR/A Flow Divider 

By-pass Valve Asm

77FD-1

65FP

Typical Fuel Nozzles Combustion Chamber 

Diff Press Guage

63FL-2

Fuel Stop Valve

Conn.For Purge When Required OFV

AD

VR4

OF Main Fuel Pump Accessory Gear  Drive

33FL OLT-

Atomizing Air  77FD-2 77FD-3

To Drain

False Start Drain Valve Chamber OFD

Fuel oil Control - Software 

Control system checks the permissive L4 and L20FLX to allow FSR1 (closing bypass valve sends fuel for closing the Bypass valve to the combustors)

These signals control the opening and closing of the fuel oil stop valve.  Fuel pump clutch solenoid (20CF) is energised to drive the pump when the Stop valve opens.  Fuel splitter algorithm ensures requisite FSR when FSR1 is active  FSR1 is multiplied by TNH - to make it a function of speed (an important parameter of Turbine) 



 

to ensure better resolution at the lower, more critical speeds where air  flow will be low. Net result is FQROUT- a digital liquid fuel flow command At Full speed, TNH does not change

Therefore  FQROUT ~~ FSR

Fuel oil Control - Software 

Analog signal is converted to digital counts and is used in the controllers’ software to compare to certain limits as well as for  display in CRT.



The checks performed by software program 

L60FFLH  - Excessive fuel flow on start-up



L3LFLT     - Loss of LVDT position feedback



L3LFBSQ  - Bypass valve is not fully open when the stop             is closed



L3LFBSC  - Servo Current is detected when stop valve is              



L3LFT       - Loss of flow divider feedback

(L60FFLH persists for 2 sec and this fault initiates trip, L3LFT also initiates trip during start-up)

clos

Fuel Gas System 

Fuel gas is controlled by  

Gas Speed ratio/stop valve (SRV) Gas Control Valve (GCV)

(Both are servo controlled by signals from Speedtronic control panel and actuated by spring acting hydraulic cylinders moving against springloaded valve plugs) 



GCV controls the desired gas fuel flow in response to the FSR command signal. SRV is designed to maintain a predetermined pressure (P2) at the inlet of the GCV as a function of turbine speed

P 2

P1

Fuel Supply

SRV

P3

GCV

To Turbine

Fuel Gas System 

Gas Fuel System consists of  



Fuel handling components –

Gas Strainer - Speed Ratio/Stop Vlv assembly

–

Control valve assembly

- Dump valves

–

Three pressure gauges

-

–

Gas manifold with ’pigtails’ to respective fuel nozzles

Electrical control components –

Gas supply press sw 63FG

- Fuel gas press xducer(s) 96FG

–

Gas fuel vent sol valve 20VG -LVDTs 96GC-1,2 & 96SR-1,2

–

Electro hydraulic servo vlv 90SR & 65GC

–

Speedtronic control cards TBQB and TCQC

Fuel Gas System P&ID TCQC

FPRG POS2 FPG

FSR2

SPEED RATIO VALVE CONTROL

TBQB

TCQC

TCQC

GAS CONTROL VALVE SERVO

GAS CONTROL VALVE POSITION FEEDBACK

POS1

96FG-2A 96FG-2B 96FG-2C TRANSDUCERS

63FG-3

20 VG

COMBUSTION CHAMBER

Gas Control Valve

Stop Ratio Valve

GAS

VENT

P2 LVDT’S 96SR-1.2 TRIP

LVDT’S 96GC-1.2

Vh5-1 Dump Relay 90SR SERVO

90GC SERVO

GAS MANIFOLD

Gas Control Valve 

Gas Control Valve 

GCV position is proportional to FSR2

(Actuation of spring-loaded GCV is by a hydraulic cylinder controlled by an Electrohydraulic servo valve) 

GCV will open only when permissive L4, L20FGX and L2TVX (purge complete) are true. –

Stroke of the valve is proportional to FSR OFFSET



GAIN

FSR2



L4

HI SEL

L3GCV

GCV stem position is sensed by LVDTs and

Analog I/O

FSROUT

FSR2 goes through Fuel splitter algorithm. TCQC converts FSROUT to an analog signal.

TBQC

GCV GAS P2 GCV Position Loop Calibration

fed back to an op-amp on TCQC card to compare with FSROUT input signal at summing junction. Op-amp on TCQC converts error signal and sends

LVDT’S 96GC -1,-2

Servo

T D V L

n oi  t  i s  o  P

Speed Ratio/Stop Valve 

TNH

It is dual function valve



OFFSET

As a Stop Valve - integral part of protection system

FPRG

+

D

-

FPG

L4 L3GCV

During a trip or no-run condition, a posive voltage bias is placed on servo coils holding them in the “valve closed” position

SRV GAS

Op Cyl Posn Trip Oil

Servo Valve

A HI SEL

Speed Ratio/Stop Vlv has Two control loops  Position loop similar to GCV  Pressure control loop • Fuel gas pressure P2 at the inlet of GCV is controlled by the pressure loop as a function of  turbine speed (in proportion to the turbine speed TNH) to become Gas fuel press Ref FPRG • TCQC card converts FPRG to analog signalP2 (FPG) is compared to the FPRG and the error  signal is in turn compared with the 96SR LVDT feedback to reposition the valve as in GCV loop

–



GAIN

(It serves as a pressure regulating valve to hold a desired fuel gas pressure ahead of GCV) 



POS2

96FG-2A 96FG-2B 96FG-2C

96SR-1,2 LVDTs

Analog I/O Module

TBQB

Dump Relay

Hydraulic Oil

SRV Pres Calibration

P2

GCV & SRV schematic GAS FUEL CONTROL VALVE

GAS CONTROL FQROUT SERVO GAS CONTROL VALVE VALVE OUTPUT COMMAND OUTPUT

GAS FUEL REFERENCE

GAS CONTROL VALVE POSITION

GAS RATIO VALVE CONTROL

SPEED

GAS CONTROL VALVE` OUTPUT

REQUIRED PRESSURE

MIDVALVE GAS FUEL PRESSURE

SPEED RATIO VALVE POSITION

SERVO OUTPUT

SPEED RATIO VALVE COMMAND

Duel Fuel Control 

Turbines designed to operate on both liquid and gaseous fuel systems are equipped with Control software accordingly. 

Control software performs the following: – – – –



Transfer of one fuel to other on command Allow time for filling lines with the type of fuel to which turbine operation is being transferred. Mixed fuel operation Operation of liquid fuel nozzle purge when operating totally on gas fuel.

Software programming involves:     

Fuel splitter  Fuel transfer- Liquid to Gas Liquid fuel purge Fuel transfer-Gas to Liquid Mixed fuel operation logics and algorithms

Fuel splitter - software 

FSR is splitter into two signals FSR1 & FSR2 to provide dual fuel operation. FUEL SPLITTER

A=B

L84TG Total Gas

A=B

L84TL Total LIQ

FSR is multiplied by the liquid fuel fraction FX1 to produce FSR1signal

MAX.LIMIT MIN.LIMIT

FSR1 is then subtracted from the

L83FZ Permissives

FSR signal to generate FSR2 signal

MEDIAN SELECT

RAMP

Rate

L83FG Gas Select

FSR = FSR1 + FSR2

L83FL Liquid Select FSR

LIQ Ref  FSR1 FSR2 GAS Ref 

Fuel Transfer - Liquid to Gas, Gas to Liquid Fuel transfer from Liquid to Gas

Transfer from Full Gas to Full Liquid FSR2

GT running on Liquid (FSR1) and GAS transfer  selected. FSR1 will remain at its initial value, FSR2 will step-up to slightly greater than

U  N IT S 

FSR1 PURGE

Zero value (0.5%). This opens the GCV

Transfer from Full Liquid to Full Gas.

slightly to bleed down the inter valve volume.

FSR1

The presence of a high pressure than that required by the SRV would cause slow response in initiating gas flow. fter delay of 30 sec to bleed down the P2

U  N IT S 

FSR2 PURGE SELECT GAS

pressure and fill the gas supply line, the

Transfer from Full Liquid to Mixture.

software program ramps the fuel commands

FSR1

FSR2 to increase and FSR1 to decrease at a programmed rate through median select gate. Fuel transfer completes in 30 sec.

TIME

SELECT DISTILLATE

U  N IT S 

FSR2 PURGE

TIME

Fuel Control System 

Liquid fuel Purge 



To prevent the coking of the liquid fuel nozzles

Mixed fuel Operation 

Gas Turbine can be operated on both GAS & LIQ in any proportion when operator choses to be on MIX mode.



Limits of fuel mixture are required to ensure proper combustion, gas fuel distribution and gas nozzle flow velocities.



% of gas flow must be increased as load is decreased to maintain the minimum pressure ratio across the fuel nozzle.

Modulated Inlet Guide Vane System 





IGV system 

Bang-Bang type (2 position)



Modulated

IGV modulates during 

acceleration of turbine at rated speed.,



loading and unloading of  the generator 



deceleration of gas turbine

IGV modulation maintains   

proper flows and pressures, and thus the stresses in the compressor. Maintains minimum pressure drop across fuel nozzles in Combined cycle operations maintains high exhaust temperatures at low loads.

Modulated Inlet Guide Vane Control IGV Operation:



CSRGV CSRGV

IGV REF

During start-up IGV is fully closed (34º)

CSRGVOUT

D/A HIGH SELECT

from 0% to 83% of corrected speed.

Analog I/O

Turbine speed is corrected to reflect the air  conditions at 80ºF, this compensates for changes in air density as ambient conditions change.

HM 3-1

CLOSE

HYD. SUPPLY

t Amb.Temp >80ºF  TNHCOR < TNH

I FH6 O N -1 U T

R         P OPEN

t Amb.Temp TNH 90TV-1 2           1 A OLT-1

bove 83% IGV open at 6.7º per  % increase in

C

TNHCOR. VH3-1

IGV open to minimum full speed angle 57º and

D

TRIP OIL

Inlet Guide Vane Operation By not allowing the guide vanes to close to an angle less than than the min full speed angle at 100%TNH, a min press drop is maintained across the fuel nozzles, thereby lessening combustion system resonance. For Simple Cycle operation

Fuel Open Max. Angle ) V G R S C ( G E D E L G N A V G I

IGV move to full open position at pre-selected exhaust temperature, usually 700ºF. For Combined Cycle operation, IGV begins to move to full open pos. as exh.temp approaches Temp. Control ref. temperature

Simple Cycle (CSKGVSSR)

Combined Cycle (TTRX)

MIN Full Speed Angle Startup Program

(Normally IGVs begin open when Tx is within

Region Of Negative 5th Stage Extraction Pressure

30ºF of temp control Ref.) 0

100

Corrected Speed -% 0 (TNCHOR) FSNL

100 BASE LOAD

IGV Control Schematic

Temp. Control Feedback

Temp. Control Reference

Compressor  Inlet Temp.

Speed

Manual Command

IGV Part IGV Part Speed Ref. Speed Ref.

IGV Position

Inlet Guide Vane Ref.

Servo IGV Output Command IGV Reference