GE Power SystemsGas Turbine

April 1998Replaces SUSFSS01

GEK106899

These instructions do not purport to cover all details or variations in equipment nor to provide for every possiblecontingency to be met in connection with installation, operation or maintenance. Should further information be desired orshould particular problems arise which are not covered sufficiently for the purchasers purposes the matter should bereferred to the GE Company. 1998 GENERAL ELECTRIC COMPANY

Starting/Shutdown Sequence and Control

I. GENERAL

Starting the gas turbine involves proper sequencing of command signals to the accessories, starting deviceand fuel control system. Since a safe and successful startup depends on proper functioning of almost all ofthe gas turbine equipment, it is important to verify the state of selected devices in sequence. Much of thecontrol logic circuitry is associated not only with actuating control devices, but enabling protective circuits,and obtaining permissive conditions before proceeding. Reference to the SPEEDTRONIC documentationis necessary for complete understanding of all the logic functions included for the particular equipment pro-vided with a gas turbine. The operating sequences of the Control Specifications are written to explain signifi-cant functions which pertain to a specific gas turbine.

A block diagram of all SPEEDTRONIC circuits which can interplay to control startup, is shown in Figure1. Detailed descriptions are found in the SPEEDTRONIC panel information included in this manual and inthe SPEEDTRONIC documentation. Utilize Figure 2, a plot of a typical startup, to aid in understanding thesequences described here.

Startup and shutdown cycle improvements have been included to reduce low cycle fatigue of hot gas pathparts.

II. SPEED DETECTORS

An important part of the startup/shut- down sequence control of the turbine is proper speed sensing. This isnecessary for the logic sequences in startup and shutdown of the gas turbine. The following speed detectorsand speed relays are used: L14HR Zero-Speed Detector (approximately 0% speed), L14HM Minimum Fir-ing Speed Relay Detector (approximately 15% speed), L14HA Accelerating Relay Speed Detector (approxi-mately 50% speed), and L14HS High-Speed Relay (approximately 95% speed), L14HP Purge Speed Relaydetector (approximately 25% speed), and L14HT Turning Gear Operation Speed Relay (approximately0.5% speed).

The zero-speed detector, L14HR, provides the signal when the turbine shaft starts rotating. The Purge SpeedRelay Detector indicates that the shaft has achieved purge speed. This speed is held until the Purge Timertimes out. Speed relay L14HT indicates that the turning gear is running which permits static starter opera-tion. The minimum speed detector L14HM indicates that the turbine has reached the minimum firing speedand initiates the purge prior to ignition. The dropout of the L14HM minimum-speed relay provides severalpermissive functions in the restarting of the gas turbine after shutdown.

GEK106899 Starting/Shutdown Sequence and Control

2

The acceleration speed relay L14HA pickup indicates that the turbine has reached approximately 50 percentin the acceleration cycle. The high-speed sensor L14HS pickup indicates that the turbine is at operatingspeed, and that the accelerating sequence is complete. Should the turbine and generator bog down, L14HSwill drop out at the under frequency speed setting. The compressor bleed valves will open and inlet guidevanes will close as a function of corrected speed. Approximately 1.5 seconds after 14HS drops out the gener-ator breaker will trip open and the digital setpoint will be reset to 100.3%. As the turbine accelerates, 14HSwill pick up, and the inlet guide vanes will open. The turbine will then require a start signal before the genera-tor breaker is permitted to close again.

The actual settings of the speed relays are programmed in the controllers as constants and are listed in theControl Specifications.

III. STARTUP CONTROL

The startup control operates as an open loop control in the use of preset levels of the fuel command signal,FSR. The levels set are FIRE, WARM-UP, and ACCELERATE LIMIT. The Control Specificationsprovide proper settings calculated for the fuel anticipated. The FSR levels must be set in the SPEEDTRONICstartup control.

Startup control FSR signals operate through the minimum value gate to insure that speed control and temper-ature control can limit FSR if required. During the starting sequence, rates of increase in speed and exhausttemperature are restricted to protect the turbine parts from excessive mechanical and thermal stresses. Therates of acceleration and temperature rise are controlled independently by the closed loops of the speed andtemperature control systems. The rate limits operate through the SPEEDTRONIC control circuits discussedin those control systems.

The fuel command signals are generated by the SPEEDTRONIC startup software. See the Control SequenceProgram. In addition to the three startup levels, the software sets maximum and minimum FSR and providesfor manual control of FSR. Pressing the switches for MANUAL CONTROL and FSR GAG RAISE ORLOWER allows manual adjustment of FSR setting between FSRMIN and FSRMAX.While the turbine is at rest, electronic checks are made of the stop/speed ratio valve, the gas control valve,the accessories, and the voltage supplies. At this time, the operator display will be normal and the SHUT-DOWN STATUS will be displayed on the CRT. Activating the Master Operation Switch L43 from OFFto an operating mode will activate the ready circuit. If all protective circuits and trip latches are permissivethe STARTUP STATUS and READY TO START messages will be displayed and indicates the turbinewill accept a start signal. Depressing the START Master Control Switch (L1. START) will introduce thestart signal to the panel.

The start signal energizes the Master Control and Protection circuits (the L4 circuit), and starts the necessaryauxiliary equipment. The turning gear is started. The start-up status message STARTING is displayed. Seepoint A on Figure 2.

The turbine rotor breaks-away, and the turning gear breaks away the turbine rotor to approximately 6 RPM.The purge timer is started once the static starter has brought the unit to Purge Speed. The purge cycle purgesthe turbine of any combustible mixture by forcing about four changes of air through the exhaust. At the endof the purge cycle, the torque converter is drained if applicable and the turbine speed is allowed to decaybelow firing speed (14HM drop-out speed). At this point the SPEEDTRONIC will require the static starterto maintain the turbine at the minimum firing speed.

Starting/Shutdown Sequence and Control GEK106899

3

When turbine speed reaches the firing level (14HM pickup), startup control FSR is set at the FIRING level,the firing timer, L2F, is started, and fuel flow is enabled. See Point B on Figure 2. When flame detector outputsignals indicate flame is established in the combustion chambers, the warmup timer, L2W, starts and the start-up fuel command FSR is set at the WARM UP FSR level. The warmup time is provided to minimize ther-mal stresses during the initial part of the startup. During warmup the starting device is set at the maximumacceleration torque position.

At the completion of the warmup period, the startup control FSR command is ramped to the maximum allow-able startup value. This setting is called the ACCELERATE LIMIT. The static starter begins to roll offonce the unit reaches 85% speed and begins its reset sequence upon reaching 95% speed.

During startup the startup control establishes the maximum FSR fuel command. Other controls may reduceFSR to perform their control functions. It is possible to reach the temperature control limit, speed control,or acceleration rate limit. The lowest FSR command is always selected to control fuel. The control parameterwhich is limiting or controlling is displayed on the control panel.

IV. CONTROL MODE DISPLAY AND OPERATING CONDITION

Display Condition

STARTUP Startup Program

ACCEL Acceleration Control

DROOP SPEED Speed Control

TEMP Temperature Control

The startup cycle has been designed to moderate the highest firing temperature produced during acceleration.This is done by programming a low acceleration rate control setting during startup. It also aids smooth transi-tion to speed control at the end of the startup sequence. The startup sequence time is extended to an optimumtime to minimize strains produced on the hot gas path parts in mid-acceleration cycle.

The minimum FSR limit is incorporated into temperature, acceleration and speed control circuits. This pre-vents these controllers from driving FSR below the value which would cause flameout during a transientcondition.

When the generator breaker closes, the startup control FSR command is quickly ramped to MAX FSR.Refer to Figures 1, 2, and 3 for starting sequence and control descriptions.

V. FIRED SHUTDOWN

A normal shut-down is initiated by selecting STOP from the control panel followed by execute. This acti-vates the L94X signal. If the generator breaker is closed when the stop signal is initiated, FSR and load arereduced until the reverse power relay operates to open the generator breaker. When this occurs, FSR isramped down as a function of corrected speed until the turbine reaches L14HM. Fuel to the turbine is shutoff when the flame detectors indicate a loss of flame. Fuel is shut off by clamping FSR to zero and trippingthe stop valve closed. In the event flame detection is maintained, fuel is turned off 60 seconds after turbinespeed falls below the run-back speed setpoint (K60RB approximately 20% TNH).

Cooldown sequence circuits ensure slow roll on turning gear until the cooldown timer expires.

GEK106899 Starting/Shutdown Sequence and Control

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Figure 1. Startup Sequence Flow Diagram.

Operation Sel.Switch, L43

Master ControlSwitch, L1

ProtectiveCircuits

MasterProtection

Start/Stop

Circuits

(Start-up Status)Message on CRT

(Starting)

(Stop)

(Ready to Start)(Seq. in Progress)(Cranking)To Start Device

(Firing)Spark Plugs

StartingDeviceLogic

IgnitionCircuit

PurgeL2TV, FireL2F Logic(L14HM)

FlameDet.

FlameDet.

Warm-upL2W L28FD

CompleteSequence

Startup

Run StatusFull Speed No.

SpeedLevel

Detectors

L4

TNHSpeedLogicandAux.

SpeedRelays

L14HML14HAL14HSL14HR

L2TVX (Fire)L28FDZ (Warm-up)

I2WX (Accel)L52GX (Max)

L4

TNHTNH

TNH

TTXD

Speed

(Warming Up)

(Accelerating)

FSRMin.Gate

TemperatureControlSystem

L4Circuits

20TU1, 2, 20FG, 20FL

L14HPL14HT

Four (4)Flame

Detectors

Starting/Shutdown Sequence and Control

GEK1068995 Figure 2. Typical Startup/Loading (@ISO).

%FSR, %TNH, 10X (Modulating IGV with HRSG Application)

Time (in Minutes)

%TNH

Tx

%TNH

%FSR

Tx F

%FSR

MW

120

110

100

90

80

70

60

50

40

30

20

10

0

0 5 10 15 20 25 30 35 40

A B

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Standard Automatic Loading Rateof 12 Min. from No Load to Full Loadas Shown. (4%/12 Min.)

F, MW

GEK106899

Starting/Shutdown Sequence and Control

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Figure 3. Starting Sequence.

Select Operation:Master selector switchin Crank, Fire, Auto,Remote or Manual.

Start Signal:Master Control Switch.

Ready to Start:Energized if Power to Panel ServoValve Checks and Voltage Checks AreSatisfied and No Trip Signal.If Check Circuit Is Energized, ProtectiveStatus and Start Checks Are Satisfied.

The Master Control/Protective RelaysAre Energized, Which Results inEnergizing Relays To:1. Start Auxiliary Oil Pump

Pressurize the Control Oil Systemwith Solenoid 20FL or 20FGEngage the Starting Clutch

2.

3.

The Starting MeansIs Started.

Turbine Is Accelerated to

Turbine Vent Timer Complete:

2. Firing Timer Initiated.Firing FSR Set.Spark Plugs Are Energized.

3.4.

Full Speed No Load:

No Flame Detected:Before L2F Timer Times out,Turbine Master Control/Protective Circuit Tripsthe Turbine.

Flame DetectedFSR Reduced to Warm-up andWarm-up Timer Initiated.

Speed RelaysL14HA Indicates the Turbine Is in

the Acceleration Phaseof Start-up.Indicates the HP Turbine HasReached the Min Governing Speed.

L14HS

Warm-up Time Complete:

Acceleration Rate ofTurbine Held Below Low-CycleFatigue Schedule Which Is aFunction of TNH.

1 Turbine Speed Is ReducedFiring Speed.

purge speed. SpeedRelay L14HP is Energized &Turbine Timer (L2TV) StartedWhen Turbine Reaches MinimumFire Speed. Turbine Will HoldThis Purge Speed Until L2TVHas Completed its Cycle. FuelIs Held Shut off. FSR Is Zero.

Indicated When L14HSIs Satisfied. TheTurbine Will Trip ifComplete Sequence IsNot Reached Before In-complete Sequence TimerTimes out.

Startup Control PermitsFSR to Ramp to FSR

Accelerate Limit

PAGE LEFT INTENTIONALLY BLANK.

General Electric CompanyOne River Road, Schenectady, NY 12345518 385 2211 TX: 145354

GE Power Systems

GE Power SystemsGas Turbine

Revised, August 1999Replaces LCGD03

GEK 106866A

These instructions do not purport to cover all details or variations in equipment nor to provide for every possiblecontingency to be met in connection with installation, operation or maintenance. Should further information be desired orshould particular problems arise which are not covered sufficiently for the purchasers purposes the matter should bereferred to the GE Company. 1999 GENERAL ELECTRIC COMPANY

Loading Characteristics General

I. GENERAL

Once the unit has been synchronized either manually or automatically it can be loaded by several loadingsequences. For instance, a unit can be loaded manually or automatically up to a temperature control limit,or a (KW) output load limit. More details on the actual control panel features are described in the Operationsection of this manual.

II. SYNCHRONIZING

Automatic synchronizing is accomplished using a microprocessor synchronizing circuit. The circuit inputsare transmitted through an interface module. The interface module contains an isolation transformer for thegenerator and line input signals and the breaker closing relay. The synchronizing software is part of theSPEEDTRONIC computer.

For synchronizing, the unit is brought to 100.3% of rated speed. If the system frequency has varied enoughto cause an unacceptably high slip frequency a speed matching circuit in the synchronizer will adjust the tur-bine governor to reduce the slip frequency and permit synchronizing.

For added protection a synchronism check relay is provided. It is used in series with both the auto synchroniz-ing relay and the manual breaker close switch to prevent large out-of-phase breaker closures.

III. FULL-SPEED, NO-LOAD

The reason that the Full-Speed, No-Load adjustment is important is that it actually calibrates speed withthe called-for speed using the digital setpoint. The 100.3% setpoint will cause an increase in fuel commandnecessary to raise the speed 0.3% above synchronous grid frequency. It is essential that the generator andsystem frequency be matched within 0.33 Hz to synchronize quickly with the synchronizing relay. Full-Speed-No-Load therefore is an important setting to assure proper speed for synchronizing.

IV. LOAD CONTROL

Speed load control increases fuel through the digital setpoint to maintain output value. Most units have threevalues of output control; reference to the Control Specifications for settings is required.

General Electric CompanyOne River Road, Schenectady, NY 12345518 385 2211 TX: 145354

GE Power Systems

GEK 106866A Loading Characteristics General

1. Spinning Reserve Once the generator breaker is closed, the turbine will load to this setting.

2. Preselected Load This load is selected by giving the unit a second start signal after it is at spinningreserve.

3. Load Limit The load is not selectable but is an output protection beyond which the unit is notpermitted to operate. It is normally the material limit for the generator.

V. MANUAL LOAD

The operator may increase or decrease load between no-load and base temperature control line. The loadingis accomplished by raising or lowering the digital setpoint.

VI. TEMPERATURE CONTROL

Temperature control is initiated by the switch 43BP. In this mode of control load is increased automatically untila temperature control limit is reached. Load is then held at a constant firing temperature as more fully describedin the Temperature Control text. Turbine output in this mode of control is a function of ambient temperature.

VII. LOAD RATE

Load may be increased from FSNL to base load according to the following table for 4% droop:

Non-DLN DLNModel Series Manual Normal Fast Load Manual Normal Fast Load

MS5001P 30 sec 4 min 30 sec 30 sec 4 min 2 minMS6001B 30 sec 4 min 30 sec 30 sec 4 min 2 min

MS7001EA 6 min 12 min 90 sec 6 min 12 min 3 minMS7001FA 6 min 12 min 90 sec 6 min 12 min 4 minMS9001E 6 min 12 min 90 sec 6 min 12 min 3 min

MS9001EC 6 min 12 min 90 sec 6 min 12 min 3 minMS9001FA 6 min 12 min 90 sec 6 min 12 min 4 minMS6001FA 6 min 12 min N/A 6 min 12 min N/A

NOTEManual load control is provided for full convenient rapid adjustment of load. It is notintended to be used to raise load to rated output without interruption. Frequent use ofmanual setpoint control to reach rated load rapidly can reduce hot gas path parts life.Similarly excessive use of Fast Start can also reduce hot gas path parts life.