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HYDERABAD
GAS TURBINE ENGINEERING - FES
2
OBJECTIVES
To smoothly start,Accelerate and bring the Gas Turbine to full Speed No LoadCondition / Spinning reserve
HYDERABAD
GAS TURBINE ENGINEERING - FES
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PRE START UP CHECKS - Operator
• All MCC modules are switched ‘ON' andare kept on ‘Auto’
• Lube Oil Level is OK & Oil temp. normal • Select “Cooldown On” and ensure that the AC
Lube Oil Pumps starts.• Ensure the Hydraulic oil pump and Jacking oil
pump starts. • Start EOP and ensure that the pressure
developed is OK• Ensure the unit comes on to slow roll
HYDERABAD
GAS TURBINE ENGINEERING - FES
4
PRE START UP CHECKS - Operator
• Cooling Water level is OK• Visual Inspection of Machine is OK• Ensure the LCI is healthy with out any faults• Coolant in the LCI reservoir is normal• Resistivity of coolant of LCI is normal• Cooling water to the LCI coolant is lined up• AC’s in the LCI compartment are healthy• Purge valves positions / feedback are healthy• Others like IBH, Gas valves, Fire system OK
HYDERABAD
Protections System checks Ready to Start Permisives:01. Generator Lockout Relay is Reset02. Turbine is at Zero Speed03. Flame is not Detected in all Scanners04. Compressor Bleed valves are Open05. ‘OFF ’ is not Selected06. IGV is Closed07. Master protective ‘4’ Logic is Reset08. <R> <S> and <T> Master Protectives agree 09. Emergency Lube Oil Pump Voltage is Normal10. <R> <S> and <T> Communication links are Healthy 11. Generator Breaker is Open12. Generator Earth switch is open during startup for LCI mode13. Auxiliaries are healthy and Fuel System Faults are Reset14. Lube oil temperature normal15. Bleed Heat System Fault / Trip is Reset.16. Diffusion Purge Valves VA36-1&2 are CLOSE (refer site specific software)17. PM4 Purge Valves VA36-9 and 10 are OPEN (refer site specific software)
GAS TURBINE ENGINEERING - FES
5Normal Start
Operator selects “CRANK / FIRE /AUTO” then ‘Execute’
Cont’d
Select “UNIT CONTROL” Display
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GAS TURBINE ENGINEERING - FES
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‘READY TO START’ displayed
Operator presses “START” then ‘Execute’
GT ready to start Start Counter is incremented. Lift oil solenoid energizes DC Lube oil pump test starts AC Lube Oil Pumps (AOP,AHP, Jacking ) are started, if not
already started. LO pressure Normal Master Protective System Energizes (L4) Trip oil solenoid 20FG & 20VS4 energised AC Hydraulic oil pump starts Mist Eliminator is started IGV strokes to minimum position 28.5 DGA Lift oil pressure Normal, Turning gear is started (TNH>0.13%) Generator is started in LCI mode. LCI connect sequence enabled 89ND Earth switch opens, 52SS and 89 SS close LCI speed setpoint set to purge speed reference 23.3%
Cont’d
“STARTING” Displayed
Cont’d
HYDERABAD
GAS TURBINE ENGINEERING - FES
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“CRANKING” Displayed
Turbine speed > 1.5%
Load compartment vent fan starts
Turning gear motor stops
Cooling water pumps start
TNH>14.0 – Purge timer starts
Turbine at purge starts – LCI holds at purge speed
Purge timer complete – LCI torque commanded off & turbine
coasts to firing speed
TNH<13.5% - LCI speed set point set to firing speed 14.5%,
LCI torque commanded on, 20FG closes, Aux stop valve opens
Cont’d
Cont’d
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GAS TURBINE ENGINEERING - FES
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“CRANKING” Displayed
Turbine speed > 14%
LCI regulates to hold 14.5%
Gas control valves enabled
Diffusion mode enabled
PM4 purge circuit enabled
SRV – P2 press regulator set to ignition pressure
GCV set to firing position
Ignition relay energized
Flame detected in 2 out of 4
GCV set to minimum fuel for warmup,
Turbine warmup timer starts, No-2 bearing cooling fan starts
Cont’d
Cont’d
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GAS TURBINE ENGINEERING - FES
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“FIRING” Displayed
Turbine cooling fan starts
Acc compartment cooling fan starts
If flame is not established within firing timer failure to ignite
alarms and unit goes for trip.
With flame detection unit goes for 1 minute warmup,
Acceleration fuel control takes over
LCI speed reference set to full speed 100%
GCV set to startup fuel schedule
When TNH >50% Lift oil solenoid closes
At Turbine corrected speed >81.06% IGV begins to open @
corrected speed schedule (minimum 49 DGA)
Cont’d
Cont’d
“ACCEL” Displayed
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GAS TURBINE ENGINEERING - FES
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During the unit loading till BASE LOAD following changes
takes place
Piloted premix transfer
Fuel gas performance heater permissive energised
IGV’s begin to open @ part load schedule
PREMIX transfer
D5 Purge circuit enabled
Temperature fuel control min FSR
Cont’d
“ACCEL” Displayed
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GAS TURBINE ENGINEERING - FES
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TNH 100.3 %
“ FULL SPEED NO LOAD “ Displayed
Enables Manual Raise/Lower of Turbine Speed Reference toSynchronize the Unit.
If Auto Synch permissive are OK, Generator and line are presentand above minimums, the Control System will modulate FSR to
bring Speed to match the station line frequency and closesGenerator Breaker when Phase angle is OK. Compressor bleed valves closes at 10.0 MW
“SPINNING RESERVE/PART LOAD / PRE SELECTED LOAD/ BASE LOAD “ Displayed
Depending upon Load Mode Selection , Turbine is Loaded to the Reference and load maintained.
Cont’d
Cont’d
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GAS TURBINE ENGINEERING - FES
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Start up control controls the amount of fuel to the GT from zero speed to Full Speed No Load
FSRSU is minimum of the six control loops
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GAS TURBINE ENGINEERING - FES
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0 0.3 0.42 0.67 1 1.33 1.46 1.82 2 .27 2.79 3.39 3 .87 4 .31 4.76 4.98 5 .18 5.34 5.44 5.64 5 .82 5.950
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
start ing curve
rpmpower-KWcurrent-am pvoltage-v
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GAS TURBINE ENGINEERING - FES
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• Major Control loops Secondary control loopsStart-up AccelerationSpeed and Manual FSR andTemperature Shutdown
• Output of these control loops is fed to a minimum value gate circuit
Start Up
Shut Down
Manual
MIN
Display
Speed
To Turbine
Fuel
FSR
Display
Display
AccelerationRate
Temperature
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GAS TURBINE ENGINEERING - FES
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Example of Minimum FSR of Six Control Loops on HMI Screen
Min Value
HYDERABAD
GAS TURBINE ENGINEERING - FES
18Start-up Control - FSRSU• Open loop control
– Uses preset levels of fuel commandVarious Fuel levels – Zero, Fire, Warm-up, Accelerate and Max.Typical values for Frame-9FA
– Fire 15.62% – Warm-up 11.62%– Accelerate 19.82%– Maximum 100%
Open Loop Control
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GAS TURBINE ENGINEERING - FES
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Acceleration Control - FSRACC• Acceleration reference is a Control constant
programmed in <RST> EEPROMS
TNH
0.35 %/sec
100%0%0.10 %/sec
40% 50% 75% 95%
Typical
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GAS TURBINE ENGINEERING - FES
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Speed Control - FSRN• Speed Control System software
– controls the speed and load of the gas turbine generator
– in response to the actual turbine speed signal (TNH) and the called-for speed reference(TNR)
TNHTNR
FSRN
FSRN = FSKRN1 + FSKRN2(TNR-TNH)FSKRN1 = FSNL FSRFSKRN2 = BASE FSR – FSNL FSR
% DROOP
HYDERABAD
GAS TURBINE ENGINEERING - FES
21Fuel 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 spring-loaded 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
SRV GCV
P1 P2 P3
Fuel Supply
To Turbine
P2= % TNH * FPKGNG + FPKGNOP2 at firing = 35 psig & 325 PSIG at 100%
HYDERABAD
GAS TURBINE ENGINEERING - FES
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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 %
100 %
Low Speed Stop
FSNL
Rat
ed F
SR
Full
Spee
d N
o Lo
ad F
SR
FSR95%
Min TNR
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GAS TURBINE ENGINEERING - FES
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Temperature Control Bias program
TTKn_C
TTKn_ITTKn_K
Isothermal
CPD FSR
Exhaust Temp Control Setpoints
DIGITALINPUTDATA
COMPUTERMEMORY
TEMPERATURECONTROL
BIASPROGRAM
COMPUTER MEMORY
CONSTANT STORAGE
SELECTED TEMPERATURE
REFERANCETABLE
Temperature Control Bias Temp control Bias program calculates the Exhaust
temp control setpoint TTRXB based on CPD data stored in computer memory and constants from theselected temp-reference table.
This Program also calculates another setpoint based on FSR and constants from another temperature-reference table.
TTKn_C (CPD bias corner) and TTKn_S (CPD bias slope)
are used with the CPD data to determine the CPD bias exhaust temperature setpoint.
TTKn_K (FSR bias corner) and TTKn_M (FSR bias slope)
are used with the FSR data to determine the FSR bias exhaust temperature setpoint.
Program also selects isothermal setpointFinal temp control Ref=MIN(FSR bias, CPD bias, Isothermal setpoint (TTKn_I)
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GAS TURBINE ENGINEERING - FES
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Primary Exhaust temperature Control ReferenceTTRXP = TTKn_I - TTKn_S * (CPR – TTKn_C) + TTRXDSP + CT_BIAS + WQJG
Secondary Exhaust temperature Control Reference (Fuel Stroke Ref Bias)TTRXS = TTKn_I - TTKn_M * (FSR – TTKn_K) + TTRXDSP + CT_BIAS + WQJG + TNH_BIAS
HYDERABAD
GAS TURBINE ENGINEERING - FES
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Combustion Monitoring
• Exhaust Temperature Spreads are the Result of Uneven Combustion in all the Combustion Chambers
• Combustion Monitoring is Built in Mark VI
• Combustion Monitoring is Enabled after Machine Reaches FSNL
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GAS TURBINE ENGINEERING - FES
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Exhaust Spread Calculations• Actual Spread
))TTXSP1 : Highest - Lowest TC))TTXSP2 : Highest - 2 nd Lowest TC))TTXSP3 : Highest - 3 rd Lowest TC
• Allowable Spread ( TTXSPL ) = 0.12 TTXM - 0.08 CTDA + 47 deg F
• During Dynamic Conditions the Allowable Spread is Increased
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GAS TURBINE ENGINEERING - FES
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Trip Conditions1. TTXSP1 > TTXSPL and
TTXSP2 > 0.8 TTXSPL andThe two Lowest TCs are adjacent
2. TTXSP1 > 5 TTXSPL andTTXSP2 > 0.8 TTXSPL and
The 2nd and 3rd Lowest TCs are Adjacent3. All Spreads are > TTXSPLTrip : Any of the above Conditions existsfor more than 9 Sec
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GAS TURBINE ENGINEERING - FES
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CHECKS DURING STARTUP
• Flame is sensed in all Flame Scanners
• Exhaust Temperatures are uniform and Spread is normal
• Acceleration is Smooth and Time taken is in line with earlier values
• Rise in Exhaust Temperature is Uniform
• Exhaust Temperature profile is OK and Spread Values are
within Limits
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GAS TURBINE ENGINEERING - FES
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• Rise in Wheelspace Temperature is Uniform
• Vibrations are within Limits and as per earlier values
• Bearing Oil Drain Temperatures are Normal
• Opening of Jaw Clutch is at approx. at the same Speed as earlier
CHECKS DURING STARTUP
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GAS TURBINE ENGINEERING - FES
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PARAMETERS -to be monitored
Pressure
• Lube Oil• Hydraulic Oil• Trip Oil• Comp. Discharge• Inlet Air Filter DP• Cooling water
Temperatures
• Lube Oil Header• Brg. Drains• Comp. Inlet• Comp. Discharge• Exhaust• Wheelspace• Cooling Water Outlet
HYDERABAD
GAS TURBINE ENGINEERING - FES
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OTHERS
• Vibrations• Noise, Rubs• Startup Time• Coast Down Time• Fired Starts• Fired Hours
GENERATOR
• Voltage• Current• Load• Stator Temperatures
PARAMETERS -to be monitored
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GAS TURBINE ENGINEERING - FES
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Shut Down Operation
• Gas turbine Shut Down can be achieved by Two Means
• Normal or Fired Shut Down
• Emergency Shut downManual Emergency Shut Down
Protective Emergency Shut Down
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GAS TURBINE ENGINEERING - FES
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Fired Shut Down• Normal Shut Down Reduces the Fuel to the Turbine in
a Controlled way (up to 20% of speed and shuts of the
Fuel Totally)so as to Reduce overall Thermal Shock to
Turbine Internals
• It is Executed by using “STOP” Push Button on “Unit
Control Page”
• This is the most Preferred Shut Down Mode
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GAS TURBINE ENGINEERING - FES
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Fired Shut Down• Operator Starts STOP command
• GT Load select is cleared• GT begins to unload at normal rate (8.33% per min)• IGV begins to close @ part load schedule ( min 49 DGA)
• Premix to Piloted premix transfer• Piloted premix to Sub piloted premix transfer• PM4 purge circuit enabled• Fuel gas performance heater permissive deenergized• Sub piloted premix to Diffusion transfer• Compressor Bleed valves open a 7.5 MW
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GAS TURBINE ENGINEERING - FES
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Fired Shut Down• Generator reverse power detected
•Generator breaker opens•GCV ramps to min shutdown fuel schedule
• Turbine speed < 94%•IBH system disabled•Exhaust frame cooling fan stops•Combustion spread monitor disabled
• TNH corrected speed < 87.8%•IGV’s close to min electronic stop 28.5 DGA
• Turbine speed < 50%•Lift oil solenoid energizes
HYDERABAD
GAS TURBINE ENGINEERING - FES
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Fired Shut Down• Speed < 20%
• Ramp fuel to blowout• Shutdown timer expire without flame out – unit
trips but not counted as emergency trip.• Loss of flame
• De-energises all stop valves close• Accessory compartment cooling fan stop
• Speed < 1.2%• Load compartment vent fan stops•Turning gear motor starts
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GAS TURBINE ENGINEERING - FES
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Fired Shut Down• Cooldown timer expires – 24 hours• Operator selects COOLDOWN OFF
• AC lube oil pump stops• No-2 bearing cooling fan stops• Lift oil solenoid de-energizes• Turning gear motor stops• Hydraulic oil pump stops
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GAS TURBINE ENGINEERING - FES
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Emergency Shut Down
• Shuts of the Fuel immediately by closing Fuel
Stop Valves
• Manual Emergency Stop to be used Judiciously
• Emergency Push Buttons are Provided on
-Mark VI Panel / Control Desk
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GAS TURBINE ENGINEERING - FES
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STANDBY OPERATIONS
When Unit is not run for a long time
• Put the unit on Ratcheting / Barring for at least 30 mins daily
• Crank the Turbine once in a Fortnight to drive away Moisture
• Operate the GT to FSNL once every month to avoid corrosion of turbine wheel dovetails
• Check Battery system, Oil levels etc.
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GAS TURBINE ENGINEERING - FES
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MACHINE DO’S & DONT’S• Do not Force any Logic for Startup• Do not attempt Subsequent Starts Without
Troubleshooting if M/C trips during Startup• Record the trends & Analyze present Operation
>>Load Vs Exhaust Temperatures>>Load Vs CPD>>Load Vs FSR>>Load Vs Vibration
• Use trend Data from Mark IV/V to Notice incipient Problems