2GTG - Know How Training 14 March 2013 - Participants 2pg_2

By: Bambang Tri PriatmokoFOR TRAINING PURPOSE ONLY

Information SharingInformation SharingGTG MS6001A GTG MS6001A

Know HowKnow HowPrepared by:

Bambang Tri PriatmokoPT CHANDRA ASRI PETROCHEMICAL Tbk

March 2013

(FOR INTERNAL USE IN PT CAP)(Courtesy of General Electric & Alstom)


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Table of ContentsTable of Contents1. GTG Overview

GTG Basic Components2. GT Mechanical System

Compressor Section Combustion System Turbine Section

3. GT Maintenance Schedule4. GT Accessory & Support System5. GT Control Philosophy6. GT Control System7. GT Protection System8. Generator Control & Protection System


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Lesson 1Lesson 1GTG GTG OVERVIEWOVERVIEW


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GTG GTG OVERVIEWOVERVIEW


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GTG Basic ComponentsGTG Basic Components

CompressedAir

Exhaust Stack

IgnitionFUEL

Atm Air Intake

Starting Engine Compressor

Combustion Chamber

GasTurbine

Generator

Reduction Gear

Exciter

11KV3Phs, 50Hz


GE GT MS 6001

6


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Lesson 2Lesson 2GAS TURBINEGAS TURBINE

MECHANICAL SYSTEMMECHANICAL SYSTEM


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EXHAUST EXHAUST PLENUMPLENUM

TURBINE TURBINE BASEBASE

INLET INLET PLENUMPLENUM

BEARING BEARING NO.1NO.1

BEARING BEARING NO.2NO.2

AXIAL FLOW AXIAL FLOW COMPRESSOR COMPRESSOR 11STST STG ROTOR STG ROTOR

BLADEBLADE

ATOMIZING AIR ATOMIZING AIR MANIFOLDMANIFOLD COMBUSTION COMBUSTION LINERLINER

FUEL FUEL NOZZLENOZZLE 3RD STG 3RD STG

TURBINE TURBINE BUCKETBUCKET

DISTANCE DISTANCE PIECEPIECE

11STST STG STG TURBINE TURBINE NOZZLENOZZLE

3RD STG 3RD STG TURBINE TURBINE NOZZLENOZZLE

EXHAUST EXHAUST STAKESTAKE

LOAD LOAD COUPLINGCOUPLING1717

THTH STG STG WHEELWHEEL

Heat Heat ExchangerExchanger

GT & COMPRESSORGT & COMPRESSOR

ACCESSORY COUPLING


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COMPRESSOR SECTIONCOMPRESSOR SECTION Lower half Lower half

Compressor Compressor casingcasing

Compressor & Compressor & Turbine RotorTurbine Rotor

Compressor Compressor StatorStator

Inlet plenumInlet plenum


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Axial Flow CompressorAxial Flow Compressor Axial Flow Compressor Axial Flow Compressor is to compress air efficiently at high blade tip is to compress air efficiently at high blade tip

velocities. Consist of velocities. Consist of 17 Stages compressor rotors (17 Stages compressor rotors (15 wheels, 2 15 wheels, 2 stubshaftsstubshafts) and stator blades) and stator blades Rotor wheels are assembled/stacked by 4 horizontal joint bolts Rotor wheels are assembled/stacked by 4 horizontal joint bolts Inlet Guide vaneInlet Guide vane 2 exit guide vanes2 exit guide vanes

In the compressor, air is confined between the rotor and stator In the compressor, air is confined between the rotor and stator bladesblades Rotor blades supply the force needed to compress the air in eachRotor blades supply the force needed to compress the air in each stagestage Stator blades guide the air so the it enters the following rotorStator blades guide the air so the it enters the following rotor stage at stage at

proper angleproper angle The compressed air exits through the compressor discharge casingThe compressed air exits through the compressor discharge casing to the to the

combustion chambers combustion chambers 55thth and 11and 11thth extractions ports of compressed air are used for turbine coolinextractions ports of compressed air are used for turbine cooling, g,

bearing sealing and during start up and shutdown for pulsation cbearing sealing and during start up and shutdown for pulsation controlontrol


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Compressor CasingCompressor Casing Inlet casing to direct air to the compressor

uniformly from inlet plenum. Consist of inner and outer bellmouth. The inner bellmouth is positioned to the outer

bellmouth by 7 airfoil-shaped radials struts and 7 axial tiebars

Forward Compressor casing contains 1st 10thcompressor stages

Compressor discharge casing finally portion of the compressor section (11th 17th stages), is used to form inner and outer of compressor diffuser, provide inner support for 1st stage nozzle, turbine stator and support combustion stator

Outer casing continuation of the compressor casing Inner casing surround the compressor rotor, has 10 circular opening to 10

Combustion chambers In conjunction with Turbine Shell and Exhaust Frame form the primary structure of the

gas turbine The rotor is supported by bearing #1 and #2 points constitute the outer wall of the gas

path annulus


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BearingsBearings Contains 2 journal bearings (elliptical type) to

support GT rotor, includes thrust bearings to maintain rotor-to-stator axial position

Pressure - lubricated by fluid supplied from main lube oil system at turbine base

Use pressurized air seals (from 5th stg compressor) in each annular space labyrinth on both end sides of the bearing housing to prevent lube oil escaping along from the turbine shaft

Bearing #1 Contains Active (loaded) thrust bearing, Inactive

(unloaded) thrust bearing and Journal Bearing Located and supported by inlet casing, Bearing #1 Lower half of the cast integral with the

inner bellmouth The upper half bearing housing is a separate casting,

flanged and bolted to the lower half Bearing #2

Located inside the exhaust frame inner tunnel. Labyrinth seals at each end of bearing housing are

pressured with air extracted from compressor 5thstage


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COMBUSTION SYSTEMCOMBUSTION SYSTEM Consist of Combustion Liner, Flow

sleeves, Transition Pieces, Includes Cross Fire Tube, Flame Detector,

Spar plugs and Fuel Nozzles Hot gases generated from burning fuel

in CC are used to drive the turbine Reverse flow of Compressed air is

directed around transition piece and into annular space around 10 combustion chamber lines (flow radially inward to the combustion chamber)

10 CC are inter connected by Cross fire tubes which enable flame spreading from fire chamber (#1 and #10) to other chamber


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Reverse Flow Reverse Flow COMBUSTION SYSTEMCOMBUSTION SYSTEM


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COMBUSTION Parts COMBUSTION Parts 22

Fuel Nozzle

Combustion Liner

Transition PieceRetaining ring

Transition Piece

Support

Liquid Fuel connector

Atomizing Air Flange

Atomizing Air Flange


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Combustion Chamber ArrangementCombustion Chamber ArrangementUV FLAME DETECTOR

UV FLAME DETECTOR

Cross fire Tube Nozzle

Holes Counterclockwise arrangement 2 high volateg retractable-

electrode Spark plugs (at Chambers 1, 10). As rotor speed increases, chamber pressure cause the spark plugs to retracts the electrodes

4 UV Flame Detectors (chambers 2,3,7,8)

Each CC is connected with cross fire tube

Each CC has Fuel nozzle hole False start drain manifold at

piping of Chambers 3-7 to drain unburned fuel out in case of GT fail to start up after firing.


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Fuel NozzleFuel Nozzle To spray fuel into the combustion

liner Liquid fuel is atomized in the fuel

nozzle swirl chamber by means of high pressure air and then pass into the combustion chamber

The atomized fuel/air mixture is sprayed and burnt simultaneously in the CC

Action of swirl tip to get more complete combustion and smoke free operation of the GT

Gas Fuel

Atomizing Air

Liquid Fuel


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Spark PlugSpark Plug Used to initiate combustion from spar plug

installed at Combustion chambers #1 and #10 Spring-injected and pressure retractable

electrode spark plug receive energy from ignition transformer

At Time of firing, one or two spark plugs ignites the gas in CC.

Other CCs are ignites by crossfire tubes As the GT speed increases, chamber pressure

causes the spark plug to retract and the electrodes are removed from the combustion zone

Electrode


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TURBINE SECTIONTURBINE SECTION Consists of Turbine rotor and stator, turbine shell, turbine nozzle, shroud,

exhaust frame and exhaust diffuser Turbine Rotor and Stator are used to convert high energy, pressured gas

is produced by the compressor and combustion sections to mechanical energy

Turbine buckets in size from 1st to the 3rd stage

TURBINE ROTORTURBINE ROTOR 1st stg Turbine Bucket 1st rotating surfaces encountered by the extremely

got gases leaving the 1st stg nozzle 2nd stg Turbine bucket, bigger than 1st stg bucket. Tip of this bucket has

shroud as tip seal. 3rd stg turbine bucket the biggest one. It has also shroud as tip seal on

tip of the bucket This shroud interlock from bucket to bucket dampen vibration


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Turbine Rotor CoolingTurbine Rotor Cooling Turbine rotor must be cooled to

maintain reasonable temperature and a longer life turbine service life

Each bucket contains longitudinal air passage for bucket cooling

Space between Turbine wheel & Bucket and the stator (Wheelspace) is cooled by compressed air radially outward. The cooling air flow discharges into the main gas stream aft of the 1st nozzle

1st stgNozzle

2nd stgNozzle

3rd stgNozzle

1st stgBucket

2nd stgBucket

3rd stgBucket

FORWARDAFT

1ST & 2ND STG Nozzles

1ST Stg Npzzle retaining ring


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Turbine StatorTurbine Stator 3 stages of stationary Turbine Nozzles Directs high velocity flow of the expanded

hot combustion gas against the turbine buckets, causing the rotor to rotate

High pressure drop across these nozzles, seals are required at both inside and outside diameter to prevent energy loss by leakage.

1st stg Nozzle, consist of 18 nozzle segments (2 partitions airfoils), receives hot gas from transition pieces

2nd stg Nozzle, consist of 16 nozzle segments (3 partitions airfoils), receives hot gas leaves from 1st stg buckets and expands and redirect it against the 2nd stgturbine buckets

3rd stg Nozzle, consist of 16 nozzle segments (4 partitions airfoils), receives hot gas leaves from 2nd stg buckets and increase its velocity by pressure drop and redirect the flow against the 3rd stg turbine buckets


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Turbine Shell Turbine Shell Turbine Nozzles, Shrouds, no.2 bearing and turbine exhaust diffuser

are supported by turbine shell Control the axial and radial position of Shrouds, nozzles. Resultantly, controls turbine clearance and the relative position of

nozzles to the turbine buckets turbine performance Hot gases contained by the turbine shell are source of heat flow into

the shell To control shell diameter, reduce heat flow into the shell by cooling it

to its design temperature Cooling air come from the 5th stg air flowing axially through the shell

and out through holes in the aft vertical flange into the exhaust frame Cooling air is also used for further cooling of the exhaust frame struts

and turbine 3rd stg aft wheelspace


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Variable Inlet Guide VaneVariable Inlet Guide Vane INLET GUIDE VANES

located at the aft end of the inlet casing

Position of vanes has an effect on the quantity of compressor air flow

Movement of IGV is actuated by a hydraulic cylinder connected to the IGV control ring that turns the individual pinion gears of each vane


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Inlet and Exhaust SystemInlet and Exhaust SystemConsists of: Inlet System: Atmospheric air flows into compressor

through Air duct, silencer, screen system, inlet elbow transition duct and Inlet Plenum (forward inlet casing) Silencer is to attenuate the high frequency noise in the air inlet,

caused by the rotating compressor blades Exhaust Stack: to direct hot gas air (which has been

used to power the turbine wheel) either to atmosphere or to furnace

On the exhaust plenum wall, exhaust thermocouples are installed to provide feedback signal of exhaust temperature to the controller


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Couplings Couplings Accessory Gear Coupling

Splined flexible coupling (hub of male teeth and sleeve of female teeth) connects the accessory gear drive to GT shaft at compressor end

Lubricated by lube oil Used to transmit starting torque from accessory gear to the GT axial

compressor and transmit power from the turbine to a driven reduction gear Load Coupling

Rigid hollow coupling, connects the turbine rotor shaft to the reduction gear


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Gas Turbine MS 6001Gas Turbine MS 6001 Inlet Plenum Compressor rotor

and stator Turbine Rotor and

Stator Inlet Guide Vanes Combustion

Chamber Bearing #1 Bearing #2 Accessory Gear &

Load Coupling Exhaust Stack

GE GT MS5002eGE GT Frame 7


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Lesson 3Lesson 3GTG MAINTENANCE GTG MAINTENANCE

SCHEDULESCHEDULE


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Type of MaintenanceType of Maintenance Combustion Inspection (1 year)

Combustion chambers Combustion liners Cross fire tubes Fuel Nozzles Spark Plugs

Hot Gas Path Inspection (3 years) Combustion parts 1st Turbine Nozzles and Buckets Exhaust Plenum

Major Overhaul Inspection (5 years) All sections, include generator, reduction gear


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GTG Maintenance IntervalGTG Maintenance Interval


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Lesson 4Lesson 4GT ACCESSORIES AND GT ACCESSORIES AND

SUPPORT SYSTEMSUPPORT SYSTEM


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GT ACCESSORIES and GT ACCESSORIES and SUPPORT SYSTEMSUPPORT SYSTEM Accessory Drive Starting System Lubricating System Cooling System Dual Fuel System Atomizing Air System Hydraulic Supply

System Trip Oil System

Cooling & Sealing Air System

Fire Protection System

Ventilation and Heating System


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NOMENCLATURESNOMENCLATURESANSI/IEEE C37.2-2008

1 Master Element 2 Time Delay Starting or Closing Relay 3 Checking or Interlocking Relay 4 Master Contactor 5 Stopping Device 6 Starting Circuit Breaker 7 Rate of Change Relay 8 Control Power Disconnecting Device 9 Reversing Device 10 Unit Sequence Switch 11 Multi-function Device 12 Overspeed Device 13 Synchronous-speed Device 14 Underspeed Device 15 Speed or Frequency, Matching Device 16 Data Communications Device 17 Shunting or Discharge Switch 18 Accelerating or Decelerating Device 19 Starting to Running Transition Contactor 20 Electrically Operated Valve (Solenoid Valve)

21 Distance Relay 22 Equalizer Circuit Breaker 23 Temperature Control Device (heater) 24 Volts Per Hertz Relay 25 Synchronizing or Synchronism-Check Device 26 Apparatus Thermal Device (Thermo Switch) 27 Undervoltage Relay 28 Flame detector 29 Isolating Contactor or Switch 30 Annunciator Relay 31 Separate Excitation Device 32 Directional Power Relay (Reverse Power

Relay) 33 Position Switch 34 Master Sequence Device 35 Brush-Operating or Slip-Ring Short-Circuiting

Device


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NOMENCLATURES NOMENCLATURES --22


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AbbreviationsAbbreviations


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Accessory GearAccessory Gear To transmit power from DE to

GT to drive each GT accessory at its proper speed and connect/ disconnect the GT from DE

After self sustaining speed, to transmit power from GT to accessory pumps (main hydraulic, main Lube oil pumps, AA compressor)


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Accessory Gear Accessory Gear -- 22 Consist of 4 parallel axis, interconnected shafts which provides

torque for the various driven accessories except Lube oil pump and hydraulic supply pump shaft

To transmit power to turbine accessory systems from gas turbine main shaft during normal operation or diesel engine during start-up

Proper gear reduction to transmit power to drive the accessory devices as required speed and correct torque during start up or normal operation- Shaft No.1 => Diesel Engine and Gas Turbine Main Shaft- Shaft No.2 => Cooling water pump (but now already obsolete)- Shaft No.3 => Liquid Fuel Pump and Main AA Compressor- Shaft No.4 => Main Lube Oil Pump and Main Hydraulic Pump

Turbine over speed trip bolt and mechanism Starting clutch assembly mounted on the DE side, the outboard end

of the main gear shaft During start up sequence, GT is driven through the accessory gear

by DE, torque converter, output gear and starting clutch,


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STARTING MEANS STARTING MEANS Diesel EngineDiesel Engine


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STARTING MEANS STARTING MEANS Diesel EngineDiesel Engine Driver to rotate initial GT Engage the starting clutch (33CS) to rotate accessory gear connected to compressor

shaft Variable speed governor controls the DE speed through lever positioning 20DV DE STOP solenoid valve, provide zero fuel position. Manual stop by screw

drive on top of 20DV 20DA-1 and -2 DE accelerating solenoid valve

20DA-1 for idle, constant , acceleration, speed and exercising 20DA-2 - for accelerating up to Maximum speed),

63QD DE low lube oil pressure switch 88DS DC Electric starter to DE Basic control of DE include starter, speed control system, stop mechanism, and

electronic logic in GT control panel for unattended and automatic protection VR-13 DE Throttle PCV supplies controlled flow rate of engine oil DE carking during startup is controlled by GT control system


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Starting Means DEStarting Means DE


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Starting Means DEStarting Means DE Torque Converter to transmit power from DE to accessory gear through starting

clutch Ratchet System

required to achieve breakaway of the rotor shaft using 88HR used during cooldown period to rotate GT shaft about 15 deg every 3 minutes

During ratchet, a forward stroke advances starting clutch about 47 deg during 10 sec and Reset stroke is about 4.7 sec.

Can be manually jog using 43HE


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Starting SystemStarting System


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Lubricating SystemLubricating SystemCirculating to Bearing #1 and2, Generator

Bearings Reduction gear, Turbine

Accessory gear Some of them is

diverted and filtered to be used for Control Fluid by Hydraulic Control Devices


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Lubricating System Lubricating System -- 22


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Lubricating System Lubricating System -- 33Components: Lube reservoir Main Lube oil pump (Shaft driven,

positive displacement) Aux Lube Pump and Emergency pump Pressure relief Valve VR-1 in the main

pump discharge Lube Fluid HE Lube Filters Bearing Header Press Regulator VRP-2 20QN 1: to prevent GT start if LO temp

is low Lubrication fluid for Main, Aux and

emergency pumps from reservoir Lubricating fluid for Control from

Bearing Header 925psig = 1.75 bar) Lubricant must be regulated and maintain

its pressure to meet bearing requirement, acc lube system and hydraulic control and trip oil system

HE to cool the lubricant Cooling water flow is controlled by

regulator VTR-1 in responding to the water temperature changes

26QA-1 high temp alarm 26QN-1 normal temp 26QL-1 Low temp alarm 26Qt-1A/1B High temp trip 63QA-2 low LO pressure, will start

Aux LO Pump 88QA 63QL Low LO emergency pressure,

will start Emergency LO pump 88QE 77QL-1 - Low lube oil level 77QH-1 High Lube oil level 88QA Aux LO pump motor 88QE Emergency LO pump motor VPR-1 - Maintains Supply pressure VRP-2 Maintains Bearing header

regulating pressure (maintain 25 psig = 1.75bar)

VR-1 main LO pump relief valve


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Lubricating System Lubricating System -- 44 Main Lube Oil Pump

Shaft driven pump by acc gear Auxiliary LO supply pump (driven by 88QA), initiated by 63QA-2

Provide lubricant oil during start up and shut down of GT Run until turbine reach 95% speed when main LO pump has provided

adequate LO supply During shut down, the aux pump is start after L14HSX relay drop (at 75

90% speed) Continue running until cooldown period

Emergency LO supply pumps (driven by 88QE) 88QE is running when 88QA is not available during start up and shut

down (energized by 63QL) Provide lubricant oil during start up until 50% speed and shut down of

GT Can be tested using a test valve


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Lubricating System Lubricating System -- 55 Pressure Protective Devices: Low Lubricating LO emergency pressure is

detected by 63QT-2A / 2B (at piping of Generator bearing) and by 63QA-2 (at LO feed piping)

Temperature Protective Devices: 26QA-1 and 26QT-1A /1B installed at bearing header piping, initiated an alarm or trip the GT is the LO temp > setpoint

Bearing LO temp is maintained by VTR-1 to control flow of water accordance to temperature changes


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Cooling Water SystemCooling Water System


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Cooling Water System Cooling Water System -- 22 Coolant flows to the DE water pump and Turbine shaft-driven water pump DE is equipped with its own coolant pump which drive water through the DE

cooling jacket Shaft-driven water pump drives water through the LO and AA HE After absorbing heat, the coolant is supposed to flows to the radiator, BUT This cooling water system has been modified which received water supply

from Sea water. The coolant flows to ditch canal VTR-1 and VTR-2 : temperature actuated 3 way valve to control lube oil and

AA HE temperature respectively by controlling flow of coolant through AA inlet compressor and Lube oil HE

It has manually operated devices that can override the thermal element when the thermal element leaks


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Hydraulic Supply SystemHydraulic Supply System


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Hydraulic Supply System Hydraulic Supply System --22 Deliver high pressure oil from bearing header to all

equipment which motions are controlled and hydraulically operated: IGV, Servo valves

Hydraulic supply pump, is a positive displacement, axial piston type pump drive by accessory gear shaft

VR-21 relief valve controls pump output pressure as a back up of VPR-3

VAB1 air bleed valve vent any air present in the pump discharge line

VCK3-1 Check valve FH2-1 and FH2-2 0.5 micron Filter, only one filter in

service any time If pressure drop to 60 psig- the filter needs to be replaced 63HQ-1 senses low hydraulic supply pressure and initiate

an alarm


Atomizing Air Schematic


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Atomizing Air SystemAtomizing Air System Use a single stage, flange mounted, centrifugal type compressor (CA1)

driven by in board shaft of Turbine accessory gear Atomizing air system is used to supply air to atomize liquid fuel at

nozzle when running on liquid fuel and purge nozzle when changeover fuel from liquid to gas

It will direct to spray the fuel jet discharging from each fuel nozzle through orifices inside the nozzle

The stream of atomizing air breaks the fuel jet up into the mist, permitting ignition and combustion with significantly increase

efficiency and decrease of combustion particles discharging through the exhaust

into atmosphere The air is extracted from compressor discharge casing passes through

the air-to-water HE (HX-1) to reduce air temp sufficiently to maintain uniformity of air inlet temp to the AA compressor

26AA-1 adjustable heat sensitive thermoswitch to initiate alarm when air temp is excessive (>135C), Operating beyond this temperature for long time may result in failure of the AA compressor


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Atomizing Air System Atomizing Air System --22 63AD-1 Diff pressure switch is used to monitor the air pressure and initiate

alarm if the pressure across the compressor drops to a level inadequate for proper atomizing the fuel

AA leaves the compressor and is piped to the AA Manifold, with pigtail piping providing equal pressure distribution of AA to the 10 Fuel nozzles.

During starting up when Accessory gear is not rotating at full speed, so AA compressor does not provide enough air, Starting AA booster compressor (CA-2) is started and driven using a belt by starting means till 60% of GT Speed Starting AA compressor at this time has high pressure ration and discharging through the main AA compressor which as low pressure ratio.

The main AA compressor press ratio increases within increasing turbine speed (60% speed self sustaining speed) when GT speed > max capability of starting AA Compressor, DE speed is reduced to idle, the starting AA compressor speed reduce to 1/3 of the previous speed

The main AA compressor supplies air from the precooler thought check valve, bypasing the starting AA compressor completely

Pneumatic valve VA-22 to isolate the compressor inlet as soon as the conditions are fulfilled.

VA-22 will be actuated by regulated air (VPR 68-1) only if 20AB is energized


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AA System on AA System on Duel Fuel OperationDuel Fuel Operation

Recirculation Cooling System Discharge of Main AA Compressor (AD) is re-circulated through the AA system when

GT is operating on 100% Gas Fuel, except for a small air flow is bled off to purge oil passage in the fuel nozzle

When 100% on gas fuel, re-circulation air is passed through a piston bypass valve (VA-18) controlled by 20AA to AA precooler (HX-1), to be cooled before re-enter to the compressor

Purge Air Bypass valve is open, AA is recirculated. After a short time delay, AA system reaches

a lower level, 20PL-1 id energized, to allow air purging the oil passages during running on gas fuel, to prevent accumulation of oil fuel and fuel oil coking in the fuel nozzle.

AD is used to operate VA19-1 (purge valve) which is controlled by 20PL-1 to allow purge air flow in to purge air manifold

Purge air system is to minimize fouling, keep fuel nozzle clean, and ready for operation on liquid fuel

Small flow of air through AA passages of the fuel oil nozzle prevents entry of any combustion products

VCK 2 1 to 10 check valves to prevent oil fuel enter the purge air system when running on oil fuel.

Similarly, oil fuel check valves installed in the oil piping to the oil fuel nozzles to insure purge air is directed to the nozzle, not to the oil fuel system

If any leaks should occur through the purge air check valves when operating on oil fuel, it will drain out of the purge air manifold through the NO port of VA19-1 to the Tell-Tale leak off piping.


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Trip Oil SystemTrip Oil System


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Trip Oil SystemTrip Oil System--22

As a primary protection interface between GT control, protection system and components to shut off fuel to the GT

Lubricating Oil passes through an orifice to limit flow result OLT, supplying to Trip oil system (Turbine Overspeed system (12HA), Fuel system through 20FL and 20FG)

Low press sw 63HL-1,2,3 and HG-1,2,3 to provide feedback to controller and permissive circuitry and to ensure tripping the GT if oil pressure is too low

20FL-1 and 20FG-1, if de-energized, will dump low press oil to the stop valve. Fuel stop valve or GCV can individually be dumped dumping valve 20FL or 20FG

Overspeed trip mechanism 2nd trip device. Actuated by overspeed bolt when GT speed > setpoint (112%). It will drain OLT (low pressure oil) to shut the fuel supply to GT


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Cooling & Sealing Air SystemCooling & Sealing Air System


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Cooling & Sealing Air SystemCooling & Sealing Air System--22 Provide necessary cooling air flow from GT compressor (5th and 11th Stages

and compressor discharge) to parts of GT rotor and stator, covering Seal turbine bearing Cool internal parts of GT (turbine nozzles, rotating wheels) Cool turbine outer shell and exhaust frame Provide an operating air supply for air operated valve

88TK-1 and 2, mounted on Turbine compartment roof, supply cooling air to turbine shell, exhaust frame and its struts and aft side of 3rd stg turbine wheel

Bearing seal air. Taken from 5th stg compressor, through 2 centrifugal separators to remove any particles of dirt, to provide sealing air in the both end site of bearing, contains fluid in the bearing housing

Air Bleed Valve (CB). Air is extracted from 11th stg compressor, to prevent compressor pulsation the GT is accelerating during start up, or decelerating during shutdown

Start up compressor bleed valve Open, 11th air flows toward to exhaust plenum. When FSNL, generator breaker close, air bleed valve close

Shut down - compressor bleed valve Open when Generator breaker Open or 14HS drops


59

Cooling & Sealing Air SystemCooling & Sealing Air System--33Turbine rotor cooling: Air from compressor discharge cools forward face of 1st wheel and buckets 16th stg air flows to the rotor, to cool 1st and 2nd stg turbine wheel buckets, and

aft face of 2 stg wheel and forward face of 3rd stg wheel Cooling air from turbine shell and exhaust frame cools 3rd stg aft wheelspaceTurbine stator cooling 1st stg nozzle. Located at the hot gas path immediately after transition pieces.

It is cooled from compressor discharge 2nd stg nozzle and 1st stg shroud. Is cooled from part of discharge air from

compressor Turbine shell and exhaust frame compartment. Cooling air is provided by

88TK-1 and TK-2. Pressure switches, on each blower discharge to monitor should the blower fails.


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Fire Protection SystemFire Protection System Halon 1301 Fire Protection System Designed in accordance with NFPA (National Fire Protection Association)

standard 12A Use Heat sensitive fire detector 45FA or 45FT 45FA-1A and 1B - Accessory compartment 45FA-2A and 2B - Accessory compartment 45FT-1A and 1B - Turbine compartment 45FT-2A and 2B - Turbine compartment 45FT-3A and 3B - Turbine compartment 45HT-1 and -2 - Turbine compartment 45FT-9A, B and 10A - load reduction gear compartment 45HA-1 - Gas detector - Accessory compartment 45HA-3 - Gas detector Inlet plenum 14HT-1, and 2 - Turbine compartment combustible gas detector


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Fire Protection System Fire Protection System --22


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GT Ventilation and Heating SystemGT Ventilation and Heating System


63

Lesson 5Lesson 5GAS TURBINEGAS TURBINE

CONTROL PHILOSOPHYCONTROL PHILOSOPHYTOTAL CONTROL SYSTEM CONTROL SYSTEM PROTECTION SYSTEM SEQUENCING POWER SUPPLY


64

GT CONTROL SYSTEMGT CONTROL SYSTEM Start-up / Shutdown sequence and control

(manual and Automatic) Acceleration Control Speed/load control (during start up and

Synchronizing) Exhaust Control (limit turbine internal

components) Fuel Control System (Liquid and Gas Fuel

Control System) Dual Fuel System Modulated VIGV


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GT PROTECTION SYSTEMGT PROTECTION SYSTEM Functions

Trip GTG when critical parameters are exceeded or control equipment fails

Shut off fuel flow to the combustion chamber Contains electrical operated system or mechanical devices

Covers Flame Detection and Protection System Over Speed Protection System Over Temperature Protection System Vibration Protection Combustion Monitoring (if any)


66

General PhilosophyGeneral Philosophy When GTG is started up, clutch is engaged,

the GT unit is rotated by Diesel Engine Ambient air is drawn through inlet plenum

assembly, filtered, compressed in the 17thstage of axial flow compressor

11th extraction bleed valve (33CB) valves are open, VIGV is in closeposition (30% opening)

When reaching 95% speed, 11th extraction bleed valve close automatically, VIGV start to open up to operation position (92% opening)

Compressed air from compressor flows into 10 Combustion chambers (CC) through outer combustion casing and combustion liner

Fuel Nozzle introduce fuel mixed with combustion air into 10 CC and is ignited by both Spark Plugs installed at CC# 1 and 10

Either one of the sparkplug is ignited, flame is spread out by crossfire tubes that connect combustion chambers.


67

General PhilosophyGeneral Philosophy--22 Flame is detected by 4 Flame detectors

(installed at CC #2,3,7 and 8) After the turbine rotor approximates operation

speed, CC pressure causes the spark plug to retract to remove their electrode from the hot flame zone

The hot gas from CC expand into the 10 separate transition pieces and increase kinetic energy that flows to the 3-stages turbine section (consist of fixed turbine nozzles and rotatable turbine buckets

The kinetic energy will rotate turbine rotor down to load reduction gear and Generator

After passing through the 3rd stage turbine buckets, exhaust gases are directed into the exhaust hood and diffuser which has series of turning vanes to turn gases from axial direction to a radial direction to the atmosphere

Resultant shaft rotation is used to turn the generator rotor and drive accessories gear

The Turbine speed is reduced by a Reduction gear from 5100 rpm to rotate and maintain generator speed at 3000 rpm (50Hz)


68

SpeedtronicSpeedtronic GT Control ConceptGT Control Concept Major Control Loops

START UP SPEED TEMPERATURE

Secondary Control Loops ACCELERATION MANUAL CONTROL (FSR) SHUTDOWN SYNCHRONIZING (NOT in the

Turboline control) Monitor - Turbine speed (77NH-1,2,3)

- Temperature (TTXD)- Compressor discharge pressure (96CD)

Output of these loops is fed to a minimum value gate circuit to control FSR (FUEL STROKE REFERENCE)

Controlling FSR is the lowest value of the 7 control loops by establishing the fuel input to turbine at rate required system

Only ONE CONTROL LOOP will be in CONTROL at anytime


69

Start Up/Shutdown Start Up/Shutdown Sequence and ControlSequence and Control Bring the turbine speed from zero to Operating speed GT is started using Diesel Engine until reaching firing speed (approximately

20%) Most GT would go through a purge cycle to allow air to purge the

Combustion chamber of any unburnt combustion fuel Adjust proper fuel to establish Flame & Accelerate the turbine in such

manner as to minimize the low cycle fatigue of the hot gas path parts during sequence

Upon completion of a warm up time, it would continue to accelerate the GT speed

Sequencing involves command signals to turbine accessories, starting device, and fuel control system to ensure safe operation of GTG Include actuating control devices, protective circuit and obtain permissive for

proceeding All control setting should follow GT GE MS 6001 control specification generated

by Manufacturer


70

Start Up/Shutdown Start Up/Shutdown Sequence and ControlSequence and Control--22 Speed detection by magnetic speed pickup (77NH-1,2,3)

L14HR: Zero Speed (approx 0% of TNH speed) to start ratchet gear in auto cool down sequence, and allow cranking sequence

L14HM: Min Speed (approx 18% of speed) or min fire speed, purging if required. If L14HM drops, will provide several permissive functions for restarting the GT after shutdown

L14HA: Accelerating speed (approx 58% of speed). Indicates when GT has reached aprox. 40-50% in acceleration cycle. Acceleration control is used to control rate of acceleration until Operation speed is reached.

L14HS: Operating speed (approx 95% of speed), almost complete acceleration sequence and the GT reach its operating speed. VIGV will fully open, compressor bleed valve will fully close

If L14HS drops, VIGV will close, open bleed valve and start AC lube oil pump till turbine shutdown

During normal shut down, L14HS will drop at Under Freq setting, digital setpoint will be counted down to minimum, Generator breaker will open by reverse power.

Flame will be maintained to shut down speed where L14HA will drop out and drive FSR to zero

Should the turbine & generator bog down, L14HS will drop out at Under Freq speed setting, VIGV will close and CB valve will open. 1.5 seconds later, Generator breaker will open, DSP back to 100.3%. As the turbine accelerates, L14HS will pick up, VIGV will open and CB valve will close. The turbine need a START signal before the generator breaker is permitted to close again.


71

Start Up Control (FSRSU)Start Up Control (FSRSU) Open loop control use preset

levels of fuel command Various Fuel Levels typical

for Frame 6 Zero : 0% Fire : 15.62% Warm-up : 11.62% Accelerate : 19.82% Min-Max : 0-100%

During startup, FSR command to control speed and temperature within limit

Rate of increase of speed and temperature is restricted to protect the GT parts from excessive mechanical & thermal stress

FSRMAN manual FSR control can be adjusted within MIN-Max limits

18% -L14HM (L2TV)

(L2F) 15.62%

(L2W) 11.62%

TempRatedegC

t sec

58% -L14HAClutch disengaged

19.82% 100.3% -FSNL

95% L14HS

TTXD


72

Start Up Control (FSRSU) Start Up Control (FSRSU) --2 2 When Turbine break away (start to rotate) L14HR pick up Starting clutch solenoid 20CS de-energizes Shut down the hydraulic ratchet motor (88HR) The starting clutch the required torque from DE to maintain engagement L14HM indicates that the Turbine is turning at the speed required for

proper purging and ignition Completion of purge timers (L2TV), FSR continue to initiate ignition timer

(L2F) When Flame Detector(s) detect flame established in the combustion

chamber, start Warm up timer (L2W). Fuel command signal is reduced to WARM-UP level

If flame is not established till L2F times out, the GT can be re-started but waiting for purging completed L2TV to avoid accumulation of fuel


73

Acceleration Control (FSRACC)Acceleration Control (FSRACC) Upon completion of warm up period, FSR ACC increase its fuel

command. Acceleration control will compare rate of change of Temperature and rate

of change of Speed (compare the present value of speed signal with the value at the last sample time)

When actual acceleration > acceleration reference, FSRACC is reduced, the will reduce fuel supply to the combustors

During Startup - acceleration reference (control constant in RST computer) is a function of turbine speed

Acceleration control take over after warm-up state As the fuel increase, the turbine speed begins the acceleration phase of

start-up. Starting clutch is held as long as the DE provides torque to the GT. When the GT overruns (GT speed is higher than DE speed), the starting

clutch is kicked back to disengaged, shutting down the DE. Thiscondition is call self-sustaining speed. L14HA picks up


74

Speed Control (FSRN)Speed Control (FSRN) Speed control system controls the speed and load of GTG Compares between the actual turbine speed signal (TNH) and called-for

speed reference (TNR) Output FSR will control Fuel Valve or GCV to maintain turbine speed

5100 rpm (equal to 50Hz) at any load from FSNL up to base load


75

Speed/Load ControlSpeed/Load Control To prevent the GT overspeeding in case of a load rejection occurrence

(Load rejection is usually done during commissioning of after Overhaul the GT)

Speed control will change FSR in proportional the difference the actual GTG speed (TNH) and the called-for reference (TNR)

Reference speed (TNR) range: 95% (min) - 107% (max) for a generator drive turbine

Start up speed reference is 100.3%. This is preset when START signal is initiated

Turbine follows 100.3% TNH for synchronization. During attempt to synchronize, the GT speed and generator voltage are adjusted separately

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 the Speed control becomes Load Control

Speed Control Isochronous Speed control Droop Speed control


76

Fired Shut Down TypicalFired Shut Down Typical The shut down control is used to minimize

component stress and affect on components lifetimes

When normal Shutdown is initiated by giving a STOP signal on Master Control Selector, will produce L94X signal.

Digital setpoint counts down to reduce FSR, load reduces at normal rate till reverse power relay operates to open generator breaker, FSR will be down to allow the turbine to coast down to the L14HA dropout setting in 3-4 minutes

It will maintain the combustion process until low speed is reached at which the combustion process can be safely extinguished

When L14HA drops, FSR drops to zero fuel will be shut off, the stop valve closes

During coasting down, Motor drive AA booster compresor will be started up at L14HS drop out to prevent exhaust smoke during shut down


77

Used for sharing load on a grid where many GTG/STG units running at the same time.

Power Grid will hold a synchronous generator speed at grid frequency

Droop control is proportional control Any change is speed (grid frequency)

will cause a proportional change in GTG load

This proportionality is adjusted to the desired regulation or DROOP

If total system tends to be overloaded, Grid frequency (speed) will decrease and cuase FSR increase in proportional to the droop setting

The all units have the same droop, all will share a load increase equally (load sharing)

If 4% droop is selected, only a 1% change is speed will change in fuel flow equivalent to 25% of rated load

DROOP Speed Control DROOP Speed Control


78

ISOCHRONOUS Speed Control ISOCHRONOUS Speed Control (FSRN / FSRNI)(FSRN / FSRNI) It will respond to a change of Grid frequency (50 Hz) by changing load

quickly to maintain the system frequency (50Hz) Isochronous Speed Control compares the actual GTG speed and called-

for reference (TNR) Should the actual speed of GT is lower than TNR (due to over load), FSR

command will increase fuel, so load in GTG output will increase The running unit frequency is always maintained at the desired

frequency, regardless the load until it reached based load


79

SynchronizingSynchronizing Synchronizing Control drives the synch check and system permissive

relays The Speed matching control system compares the GTG running unit

frequency vs the system frequency. The different signal will adjust Fuel command accordingly resulting to adjusting the running frequency

The Voltage Matching system compares the GTG running unit Voltage vs the system voltage. The different signal will adjust the field excitation voltage resulting to adjusting the running generator output voltage

On Manual Synchronizing, both values are adjusted manually


80

Firing TemperatureFiring Temperature Firing temperature is a function of exhaust temperature (Tx) and Compressor

discharge pressure (CPD) Firing temperature is also a function of exhaust temperature (Tx) and fuel flow

FRS (Fuel Stroke Reference) Firing temperature is also a function of exhaust temperature (Tx) and generator

MW output Line of constant firing temperature are used to limit GT operating temperature Whereas, the constant exhaust temp limit protects the exhaust system during

start-up


81

Exhaust Temperature Exhaust Temperature Control Control FSRTFSRT Temperature control system performs critical exhaust temperature

control and monitoring Major function of the Temperature control system will limit fuel flow to the

turbine to maintain internal operation allowable temperature within parameters of turbine hot gas path parts (to prevent overfiring)

It will compare the actual firing temperature measured at exhaust stack vs exhaust temperature setpoint TTRXB (note: TTXM is based on remaining good TCs). The diff. values will converts to FSRT

The highest temperature is in the Flame zone of the combustion chambers

There are 18 Exhaust TC, which are divided into 3 groups (R-S-T) All Non critical Thermocouples signal are sent to C controller Major Function of Exhaust Temperature control consist of

Temperature Feedback Temperature Control reference Temperature reference section Cold Junction compensation Cold Junction Scan


82

Exhaust Temperature Exhaust Temperature Control Control FSRT FSRT --22 Temperature control software

Determines cold junction compensated Thermocouple readings

Selects the temp. control set point Calculates the control set point Calculates median exhaust temp. value Compares the value with the set point Generates FSR to control and limit exhaust

temperature


83

Temperature Control SchematicTemperature Control Schematic TTXD Average Exhaust TC,

read at screen monitor TTXM - TTXM is based on

average remaining good TCs(reject low and High TC)

TTRXB exhaust temp. control set point based on MIN SELECT between FRS, CPD and Isothermal limit value

FSRT (FSR for Temperature Control) is based on median select among TTRXB, TTXM and FSR command within min-max FSR limit

Final Temp Control Ref = MIN (FSR bias, CPD bias, Isothermal setpoint (TTKn_I)


84

Temperature Reference Temperature Reference Select ProgramSelect Program

Exhaust Temp Control function selects control set poits to allow GT operation at firing temperatures

Temp-control-select programs determines the operation level for control set point based on digital input information representing temp. control requirements (BASE SELECT; PEAK SELECT; HEAVY FUEL SELECT if any)


85

Temperature Control Relationship Temperature Control Relationship between FSR and CPDbetween FSR and CPD

Before reaching Temp. control setting, FSR could be increased as per load required, limited by Isothermal capability

When Temp. control setting has been reached, firing temperature will be maintained constant as refer to operation select (BASE, PEAK SELECT)


86

Lesson 6Lesson 6TURBINE CONTROL SYSTEMSTURBINE CONTROL SYSTEMS

Liquid Fuel Control Gas Fuel Control Temperature Control


87

FUEL CONTROL SYSTEMFUEL CONTROL SYSTEM Fuel Control System will change fuel flow to the combustors in

response to the FSR signal Standard fuel systems of GTG are designed for operation with liquid

and/or gas fuel FSR = FSR1 (Liquid Fuel) + FSR2 (Gas Fuel) Transfer fuel from liquid fuel to gas fuel can be employed by

reducing FSR2 signal and increasing FSR1 signal simultaneously after purging time is completed

Heart of Fuel Control System: 3 coil Electro Hydraulic Servo Valve 65FP liquid Fuel Servo valve 90SR Gas Fuel Speed/Stop ratio servo Valve 90GC Gas Fuel Control servo Valve


88


89

Liquid Fuel System SchematicLiquid Fuel System Schematic


90

Liquid Fuel SystemLiquid Fuel SystemFuel handling Components Primary fuel oil FILTER (LP) Fuel Oil STOP Valve Fuel Oil BYPASS Valve hydraulic

cylinder actuated valve Secondary Fuel Oil FILTER (HP) FLOW DIVIDER positive

displacement gear pump Fuel PUMP Fuel Oil Pressure RELIEVE VALVE Combined SELECTOR Valve False Start DRAIN Valve Fuel LINE and Fuel NOZZLE

Control Components: 63FL-2 - Liquid Fuel PRESSURE

SWITCH VS1 Fuel Oil STOP Valve 33FL Fuel Oil Stop Valve limit

switch 20CF - Fuel Pump Clutch Solenoid 65FP - Liquid Fuel Pump Bypass

Valve Servo Valve 77FD-1,2,3 - Flow Divider magnetic

pick up Control Cards

VS1 is an emergency valve operated by Protection System It will shut of the liquid fuel during normal or emergency shutdown within 0.5

seconds During Normal Shutdown, opened by hydraulic supply


91

Servo valve (65FP) is the interface between the electrical and mechanical system, furnished with mechanical null off set bias to cause GCV or SRV to go to zero stroke position on zero voltage

Servo valve controls the direction and rate of motion of a hydraulic actuator based on the input current to the servo

Servo valve consist of 3 electrically isolated coils on the torque motor

Each coil is connected to one of the 3 controller (R-S-T)

Hp oil is supplied to the valve at ports P. Port T or R is connected to the drain

A null-bias spring positions the servo, so that the actuator goes to the fail safe position when ALL power and/or control signal is lost

Servo Valve AssemblyServo Valve Assembly


92

Liquid Fuel ControlLiquid Fuel Control Bypass valve bypasses the excess fuel delivered by Main Fuel pump back to the

Pump inlet Fuel pump clutch solenoid (20CF) will be energized to drive the pump when stop

valve (VS-1) is open (indicated by LS - 33FL) and liquid fuel pressure is enough (63FL-2)

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

Fuel Splitter ensures requisite FSR when FSR1 is active When 65FP receives signal from the controller, HP hydraulic supply will enter to

servo valve and actuate the bypass valve according to the signal is given from the controller. Higher signal is given will close the bypass valve

False start drain valve will open because compressor discharge is not high enough yet to close the valve

When turbine speed reaches firing speed, the DE will hold the firing speed until 2TV time has completed its cycle

When 20FL is energized, Fuel Oil stop valve (VS-1) will open, stop valve limit switch 33FL is switched to enable to energize fuel pump solenoid valve (20CF) and the fuel pump will be driven by the accessory gear


93

Liquid Fuel ControlLiquid Fuel Control--22 As fuel flow to the combustors, speed sensors at Flow divider (77FD-

1,2,3) send signal to the controller. When fuel flow rate = the called-for rate, Servo Valve 65FP is moved to null position and the bypass valve will remain stationary until the input signal changes

FSR is multiplied by TNH to make it a function of speed, Net result is FQROUT a digital liquid fuel commend

At full speed, TNH does not change therefore FQROUT = FSR Controller will check

Excessive fuel flow on start up (L60FFLH) Loss of LVDT position Feedback (L3LFLT) Bypass valve is not fully open when stop valve is closed (L3LFBSQ) Servo current is detected when stop valve is closed (L3LFBSC) Loss of Flow Divider Feedback (L3LFT)


94

Gas Fuel SystemGas Fuel SystemFuel Handling Component Gas Strainer SRV GCV Valve Assembly Control valve assembly 3 Pressure gauges Gas Manifold with pigtails to

respective fuel nozzles Dump valve

Control Components Gas Supply Pressure Switch 63FG

will initiate an alarm whenever pressure drops lower that setpoint

Gas Fuel Solenoid Valve 20 FG will vent gas in P2 line when the solenoid is de-energized. 20FG is energized to close the vent when L4 master control protection is energized

Fuel Gas Transducers 96FG-2A, - 2B, 2C

4 LVDT 96SR-1/2 and 96GC-1/2 2 Servo Valves - 65GC and 90SR


95

LVDTLVDT LVDT Linear Variable Differential Transformer, to provide

feedback signals of GCV or SRV stem position to the controller LVDT output is ac voltage which is propositional to the position of the

core of the LVDT The error between FSR signal given to the servo valve and LVDT

feedback signals will cause either to increase or to decrease fuel command (FSR).

LVDT output is 0.7 3.5 volts RMS ac (zero to max stroke)


96


97

GAS FUEL SYSTEMGAS FUEL SYSTEM Controlled by

Gas Speed Stop/Ratio Valve (SRV)

Gas Control valve (GCV) SRV GCV are combined in one

assembly SRV is designed to maintain a

predetermined pressure (P2) at the inlet of the GCV as a function of turbine speed

GCV controls the desired gas fuel flow in response to the FSR command signal

Both valves are servo controlled by signal from the controller and actuated by spring acting hydraulic cylinders moving against spring-loaded valve plugs

SRV GCV To Turbine

P1 P3 P3

Fuel Supply

VH-5

P1 P2 P3


98

Gas Control Valve Gas Control Valve -- GCVGCV

Stroke of GCV is propositional to FSR2 which represents called-for fuel

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

The GCV stem position is sensed by output of LVDTs and fed back to controller to compare with FSROUT input signal

LVDTs will be selected the highest output The output will increase of decrease

signal to drive hydraulic servo valve (90GC)n to decrease the error

Electrohydraulic servo (90GC) controls actuations of the spring loaded GCV

Gas Flow is a function of GCV inlet pressure (P2)

AN Open/a Short circuit in one of the two Servo coil does not cause a trip.

GCV has 2 LVDTs and can run correctly on one.

But the turbine wont start if one of any LVDTs fails or signal mismatched, need to be corected


99

Speed/Stop Ratio Valve Speed/Stop Ratio Valve -- SRVSRV Dual function valve, that serves as a pressure regulating valve

to hold a desired fuel gas pressure (P2) As a STOP VALVE integral part of protection system As a SPEED RATIO / STOP valve has 2 function

Stop Valve Pressure Regulating valve

SPEED RATIO FUNCTION Has 2 control loops

Position Control loop similar to GCV Pressure Control loop

P2 pressure at the inlet of GCV as is controlled by Pressure Control Loop as a function of Turbine speed TNH comparing it with pressure feed back signal from 96FG to become Gas Fuel pressure reference (FPRG)

Pressure control signal commands the controller to control the ration valve position loop in the same way the GCV drives its position loop in response to FSR

Any emergency Trip or normal shutdown will close the valve to shut off the gas fuel by dumping hydraulic oil supply to the tank


100

Speed/Stop Ratio Valve Speed/Stop Ratio Valve SRVSRV--22 STOP VALVE FUNCTION

SRV provides a shutoff of the fuel gas flow when required A hydraulic trip relay dump valve (VH-5) is located between

servovalve 96SR and the hydraulic cylinder When trip oil (OLT-2) is normal press, dump valve is maintained in

a position to allow 96SR to control the cylinder position When trip oil (OLT-2) is low press, dump valve spring shifts a spool

to dump hydraulic oil in SRV actuating cylinder to lube oil reservoir. A Closing spring on top of the SRV instantly shutoff the valve and stop the gas fuel flow

During trip or stop condition, a positive voltage bias is place on servo coils holding them in the Valve Closed position (FAIL SAFE)


101

SRV & GCV SchematicSRV & GCV Schematic


102

DUAL FUEL SYSTEMDUAL FUEL SYSTEM GTG is designed to operate on dual fuel (liquid and gas fuel) Control system includes

Fuel Splitter Fuel Transfer from Liquid to Gas Liquid Fuel Purge Fuel Transfer from Gas to Liquid Mixed Fuel Operation

Fuel Splitter FSR1 for Liquid fuel command FSR2 for Gas FSR = FSR1 + FSR2


103

Fuel Change OverFuel Change Over Fuel Change Over from Liquid to Gas

FSR1 remains at its initial value, FSR2 steps to value > zero (0.5%) to open GCV slightly to bleed down P2 press and fill the gas supply line

Presence of higher press in P2 line (by SRV wide open or leaks) would cause slow response in initiating gas flow

FSR2 to increase, FSR1 to decrease thought Median select gate. Complete transfer within 30 sec

Signal L84TG (total gas) will disengage the fuel pump cluth 20CF, de-energize 20FL to close Liq Fuel Stop Valve VS-1. Initiate to purge to prevent coking inside the Fuel Nozzles

20AA solenoid is energized to open AA bypass valve VA-18

After 10 sec delay, 20PL-1 is energized to actuate purge valve VA-19-1, result in a higher cooling/purging air flow through the fuel nozzle

Fuel Change Over from Gas to Liquid Initiated manually by 43F or 63FG-3 (low gas fuel

supply) FSR2 remains at its initial value, FSR1 steps to value >

zero, a small liquid flow in the piping FSR1 to increase, FSR2 to decrease thought Median

select gate. Complete transfer within 30 sec The rest sequence is the same


104

Liquid Fuel PurgeLiquid Fuel Purge Liquid Fuel Purge is to prevent

the coking of the liquid fuel nozzles

MIXED Fuel Mixing fuel is permitted. Operation of Mixed Fuel is

obtained by initiating a normal transfer and then select MIX when desired mixture is obtained

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

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


105

Modulated VIGV SystemModulated VIGV System VIGV is installed on the turbine to provide compressor pulsation

protection. IGV Modulates during Acceleration of turbine speed at rated speed (start up) Normal loading and unloading (under frequency) of the generator Deceleration of gas turbine (Shut down)

IGV Modulations maintains Maintains proper flow and pressure and thus the stresses in the

compressor Maintains minimum pressure drop across fuel nozzles For Normal Shut down, compressor bleed valve will open when

generator breaker is opened. IGV will ramp to full close position as a function of temperature corrected speed

When GT trip, 11th stg bleed valve will open and IGV will ramp to the close position as a function of temp corrected speed

In Combined Cycle operations, maintains high exhaust temperatures at low loads (Rich fuel of firing)


106

Modulated VIGV Hydraulic Modulated VIGV Hydraulic SchematicSchematic


107

Modulated VIGV System Modulated VIGV System --22 VIGV is actuated by a hydraulic actuator assembly (servo valve 90TV, LVDT

96TV-1/2, Solenoid valve 20TV and hydraulic dump valve VH3) having a closed feedback control loop to control the guide vane angle

During start-up IGV is fully closed (32) from 0% to 83% of corrected speed. At Amb. Temp >27C, TNHCOR < TNH At Amb. Temp TNH

Above 85% speed, IGV start opening at 6.7per % increase in TNHCOR And IGV will stop opening at 91% of speed (TNH) The vanes are automatically positioned within their operating range in

response to either Exhaust temperature limits for normal loaded operation (refer to ambient temp =

80F = 27C) The control system pulsation protection limits during start-up and shut-down

sequence If Hydraulic supply is low or the LVDT feedback is different from command,

guide vane protection system will trip solenoid 20TV, initiate a fast shutdown and an alarm.


108

Modulated VIGV Control SystemModulated VIGV Control System


109

Modulated VIGV System Modulated VIGV System --33 Pulsation protection control

IGVs are automatically positioned during a start-up and a shutdown sequence to avoid gas turbine compressor pulsation. The pulsation limit is expressed as a function of IGV angle and corrected speed.

Corrected speed is a function of the actual running speed of the compressor and the inlet air temperature.

The control system utilizes the measured variables of turbine speed and ambient temperature to determine the IGV angle and automatically modulate them to that position.

The control program is set to avoid IGV operation which would result in negative pressure at the 5th stage extraction, air used for bearing seals.

Exhaust Temperature Control For applications of Steam Generation, to maximize the exhaust temperature, The

controller will automatically hold the IGV at a minimum angle during part-load operations.

Program for the exhaust temperature control mode where the IGV is positioned to the minimum full speed angle at the end of the start-up.


110

Modulated VIGV System Modulated VIGV System -- Operation

During a normal start-up, IGVs are held in the full-closed position until the proper temperature corrected speed is reached, at which time, the IGV will begin to open.

The IGV remain in the minimum full-open position till 20 % load, The compressor bleed valves will close when the generator breaker is closed to maintain

compressor surge margin When in Simple Cycle mode (IGV temperature control mode is not activated), the IGVs are

held at the minimum full speed angle until the simple cycle IGV exhaust temperature setpointis reached (approximately 167C below the base temperature control setpoint with the same PCD bias ).

For Steam Generating applications which require exhaust temperature control by inlet guide vanes, the IGVs are held at the minimum full speed angle until combined cycle IGV exhaust temperature control setpoint is reached.

As output increases, the IGV is held at this minimum angle until IGV temperature control setpoint is reached (point B). Between point B and point C, IGV is opened to maintain setpoint temperatures as output is further increased.

At point C, IGV is at its full-open position and upon further increase in output the turbine will reach its BASE temperature limit (point D).

The operator can activate or deactivate the IGV temperature control mode at any time via the panel selector switch. The control system will automatically reprogram the IGV to the correct position in a controlled rate.

Manual open/close softswitches are provided to manually position the IGV between the minimum full speed angle and full open. This control should only be used in special circumstances to limit the travel (amount opened) of the IGV.

The manual control has authority to command an IGV angle only when LESS THAN that being called for by the automatic control system. In normal operations the manual control is set at full open.


111

Exhaust Temperature Exhaust Temperature Control Control vsvs IGV CurveIGV Curve

Adjusting IGV It is used for generating

steam, where maximum exhaust temperature is desired

It will automatically hold the IGV at minimum angle during part load operation

Curve shows the IGV is positioned to the minimum full speed angle at the end of start up.

Load increase

Min Full Speed Angle at FSNL

Full Open

Full Load, Base Load

Simple Cycle

Steam generation

Temp control

Setpoint


112

IGV Angle IGV Angle vsvs Corrected Corrected Speed and LoadSpeed and Load

(CSR

VPS)

320% 83% speed TNH

57 91%

92

6.7/% TNHCOR

TNHCOR

14HS

Held till IGV exhaust Temp setpoint is reached

Full Open at Full Load

Full Load steam

Base Load

FSNL

20% Load

167

C

belo

w

Base

TXSE

T

10

C

belo

wBa

se

TXSE

T

Rota

ting

Stal

l Reg

ion


113

IGV Control Block DiagramIGV Control Block Diagram

INLET GUIDE VANE REF.

SERVO OUTPUT

IGV PART

SPEED REF.

Compressor Inlet Temp

Speed TNH

Temp. Control Feedback

Temp. Control Reference

Manual Command

IGV Position LVDT

IGV Reference

IGV Command

IGV Part Speed Ref


114

Lesson 7Lesson 7GT PROTECTION SYSTEMGT PROTECTION SYSTEM


115

GT PROTECTION SYSTEMGT PROTECTION SYSTEM Flame Detection and

Protection System Over Speed

Protection System Over Temperature

Protection System Vibration Protection Combustion

Monitoring


116

FLAME DETECTION SYSTEMFLAME DETECTION SYSTEM Flame Detectors performed 2 functions

Normal start-up: Flame detectors indicate when a flame has been established in the combustion chambers and allow the start-up sequence to continue

Should loss-of-flame occurs while the GT is running, fuel is immediately shut off, to avoid any accumulation of fuel in the GT

Use 4 Ultraviolet radiation sensor (28FD), installed at Combustion chambers no. 2,3, 7 and 8

When GT is shut down, all channels must be NO FLAME. If it is not met, FLAME DETECTOR TROUBLE alarm will appear and GT cannot start

If 3 out of 4 detect NO FLAME, GT will trip Short circuit or open circuited detector will result NO FLAME


117

OVER SPEED OVER SPEED PROTECTION SYSTEMPROTECTION SYSTEM The control system is designed to protect

GT against damage caused by overspeedof the turbine shaft

During Normal Operation, the turbine shaft is controlled by Speed control & Temperature control loops

Overspeed protection systems will trip the Fuel Stop Valve(s) closed when the turbine speed exceeds the trip setting.

Overspeed Protections


118

Electronic Over Speed Electronic Over Speed PROTECTION SYSTEMPROTECTION SYSTEM Consist of magnetic p.u., speed detection software and

control logic circuits Speed signal (TNH) from Magnetic pick-up sensors

(77NH1,2,3 )is compared to an Overspeed setpoint(TNKHOS)

If TNH > the set point, the overspeed signal (L12H) is transferred to Master Protection circuit to shut down the turbine

During Mechaincal overspeed test, the electronic overspeed protection system is switched to the test set point (TNKHOST) to set the overspeed trip speed slightly higher than mechanical overspeed trip speed


119

Mechanical Over Speed Mechanical Over Speed PROTECTION SYSTEMPROTECTION SYSTEM Consists of

overspeed bolt assembly overspeed trip mechanism and position limit switch 12HA.

Overspeed bolt assembly, mounted inside the accessory gear shaft is used to sense the turbine speed

It is a spring loaded, eccentrically located bolt assembled in a cartridge and designed so that the adjustable spring force holds the bolt in the seated position until the trip speed is reached

As the turbine speed increases causes the centrifugal forces acting on the bolt to exceed the spring force and the bolt moves outward in less than one shaft revolution where it contacts and trips the overspeed mechanism

Overspeed trip mechanism is mounted on the accessory gear, adjacent to the overspeed bolt assembly

When actuated, the overspeed bolt assembly trips the latching trip finger of the OS trip mechanism, which causes to release the trip valve to dump hydraulic oil in the pilot dump valve cylinder of SRV/Stop Valve and close the SRV/Stop valve, shut off fuel flow and shut down the GT.

The OS trip mechanism may be tripped manually and must be reset manually.


120

Over Speed Over Speed PROTECTION SchematicPROTECTION Schematic

Mechanical Bolt Assembly


121

Over TemperatureOver TemperaturePROTECTION SYSTEMPROTECTION SYSTEM Protects the GT against possible damage caused by

overfiring In normal operation, the exhaust temp control system

reacts to regulate the fuel flow when the firing temperature limit is reached

In case of exhaust temperature (TTXM) or fuel low exceeds the control limit (TTRX), OT protection system initiates an alarm (L30TXA) prior to tripping the GT

If the temperature (TTXM) increase event higher than TTRXB + trip margin (TTKOT2), or,

It TTXM is higher than Isothermal trip set point (TTKOT1), the GT is tripped


122

Over TemperatureOver TemperaturePROTECTION SCHEMATICPROTECTION SCHEMATIC


123

VIBRATION VIBRATION PROTECTION SYSTEMPROTECTION SYSTEM Sensors (39V) are located on selected bearing housing of the GT, load

reduction gear and driven load Type of sensors:

Velocity Probes (EMF is generated in a coil if it is moved thorough a magnetic field)

Proximity Probes (non contact probe operating on the edy current principle)

Accelerometer Probes The controller will detect excessive vibration and sensor faults, annunciates

alarms and trips the GT Vibration protection software will display several alarm message such as:

Vibration Sensor disabled when input channel is disabled High Vibration Alarm when any vibration signal exceeds the alarm

setpoint for more than the specified time Vibration Transducer Fault when a short or open transducer Fault is

detected for more than the specified time. GT operation is not interrupted but indicates that maintenance or replacement is required


124

Vibration Protection System-2 High Vibration Trip or Shutdown when a group of vibration

signals are disabled If all GT sensors are disabled or faulty, or If all load reduction gear sensors are disabled or faulty If all generator sensors are disabled or faulty

Vibration Start Inhibit turbine start will be inhibited when: If 3 or more GT sensors are disables or faulty If 2 or more load reduction gear sensors are disabled or

faulty If 2 or more generator sensors are disabled or faulty

Vibration Differential Trouble


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Combustion Monitoring To reduce the likelihood of the extensive damage to the GT, if the

combustion system is deteriorated Monitor - Exhaust Thermocouples

- Compressor Discharge Temp Thermocouples Monitoring will effective to the extend

Incomplete mixing of gas pass through to the GT Uneven turbine inlet pattern could be caused by loss of fuel or loss of

flame in a combustors, - will cause uneven exhaust pattern Spread 1 (S1): Highest Lowest TC readings Spread 2 (S2): Highest 2nd Lowest TC readings Spread 3 (S3): Highest 3rd Lowest TC readings Limit : 16.7F 58.4F (TTKSPL7 and TTKSPL6)


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Display Messages Exhaust Thermocouple Trouble Alarm (L30SPTA): if any

Thermocouple value causes the largest spread > a constant for more than 4 sec.

Combustion Trouble Alarm (L30SPA) : if any Thermocouple value causes the largest spread > a constant for more than 3 Sec.

High Exhaust Temperature Spread trip (L30SPT), can occur if:


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128

Lesson 8GENERATOR

CONTROL & AVR


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Generator VentilationGenerator Ventilation

BASE

MAG. CORE

STATOR WDG

ROTOR

ROTOR wDG

EXCITER

RETAINING RINGFANS BEARING

REDUCTION GEAR

ENCLOSURE

MV PLATFORMEXHAUST

DUCT

FANS

MEASUREMENT RING

EARTH GRD PLUG

GEN HTRTC OIL OUTLETVibration

DetectorTC COLD AIR

TC HOT AIR


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Generator Air-cooled alternating current generator, speed 3000

rpm, coupled to a reducing gear by rigid flanges Stresses remain within acceptable limits at 120%

overspeed (3600 rpm) Generator is provided with semi direct internal cooling

fans which can flow fresh air through air inlet silencer from excitation compartment roof toward exhaust duct (above load reduction gear compartment

Open loop ventilation, ensured by 2 fans mounted on each end of the generator rotor body

Generator compartment are monitored by Thermocouples:

9 TC mounted at Stator winding (trip at 155 C) 2 TC in hot air circuit (alarm at 125 C, trip at 135 C) 2 TC in Cold air circuit (alarm at 95 C, trip at C) 1 TC at reduction gear oil outlet 1 TC at Bearing#3

Its construction cannot be damaged by 2 or phs faults due to short circuit external to the stator windings.

However, the duration of these faults must be limited in time to avoid causing detrimental overheating

REDUCTION GEAR SIDE

GENERATOR BEARING NO.3 SIDE


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Generator MeasurementStator ThermocouplesBearing Vibration sensor Lube oil pressure switch Thermocouple ThermometersReduction Gear Vibration Sensors Thermocouples ThermometersMiscellaneous Rotor Grounding Rotor Ground detection Space Heater


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Excitation System Rotating Main function of the Exciter is to control generator output voltage by

controlling DC excitation current Use a voltage sensor (transformer TP1) and current sensor (transformer TI3) to

provides feedback of generator output back to the AVR Use an excitation transformer to provide excitation voltage to exciter field. The excitation voltage and current are controlled by AVR through firing angle of

thyristor 3Phases, High Frequency AC output from rotating armature is rectified and

applied to the main generator field Controlled DC current is fed to the stationary field of the rotating exciter as a

result of comparison between feedback signals and a ref. point established by the setting of voltage regulator

Field excitation is provided by a standard brushless excitation system which consists of a rotating armature, diode bridge and stationary field.


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Excitation System & AVRGenerator Values Stator Voltage - U Stator Current - I Power Factor - Q Active Power - P Reactive power - Q Apparent Power - S Energy - Frequency - F Temperature - T

Bar Temp T1 T6 Hot Air Temp T7-T8 Cold Air Temp T9 T10


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Excitation System & AVR 2 Transfer switch 43S provides for selection of Auto or Manual (back up) AVR

Automatic Excitation is a close loop system controlled by AVR, regulates generator output at rated voltage 11KV according to change of the load

Manual Excitation is controlled by separate source As the load increase, generator voltage tends to decrease, AVR will

increase excitation current to allow generator voltage back to the rated voltage

Stator side of the exciter is fed by regulated DC current from AVR It induces rotated rotor of the exciter to produce AC current and then

rectified to be 236 volts and 0 481 Amp, to generate 11KV, 50Hz, 38MVA


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Generator CP SystemTP1

TI3

V,I Sensor

PPT Exc. TrafoG2

Exc. Voltage


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Brush Vs Brushless ExcitationWITH BRUSHLESS EXCITATION Eliminate the need for brushes, commutator

& slip-ring as well as maintenance of them It uses bridge rectifier circuit consists of SCR

& diode. The bridge rectifier circuit placed on the rotor. The bridge rectifier circuit rotates with the

speed of the rotor. The A.C supply given to the bridge rectifier by

the principle of Electromagnetic Induction. Bridge rectifier being represented by a

transformation from A.C voltage to D.C voltage.

The D.C output of the rotating rectifier is applied to the D.C rotating field of the motor

ADVANTAGES Life of motor using brushless excitation

significantlylonger compared to a motor using brushes.

It reduces noise. Loss should be reduced, i.e brush drop. It reduces the maintenance and replacement. Less maintenance cost. It reduces spark, wear & tear.

WITH BRUSH EXCITATION Requires collector ring, brushes or commutator. The function of the brush is to collect current from

Commutator. Usually made of carbon or graphite and are in

the shape of rectangular block.

DISADVANTAGES Requires maintenance, adjustment & inspections. Produces brush drop, spark, noise & friction loss. Limits maximum speed of the machine. Brushes assembly on a large machine is a costly

element.


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Generator & Excitation FaultsEXCITATION FAULTS Excitation Transformer

Overheating 1st step Excitation Transformer

Overheating 2nd step Excitation rectifier Fuse Flashing too long Excitation Over current 1st step Excitation Over current 2nd step Voltage regulator power supply Voltage regulator measuring Excitation Rotating Diode Loss of excitation

GENERATOR FAULTS Rotor Earth Fault Stator Earth Fault Reverse power Fault Negative phase sequence Stator over current 1st & 2nd steps Generator Differential Protection Stator Over voltage Generator Overheating 1st & 2nd

step


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Brushless Exciter Rotor Rotating Diodes of field exciter


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Exciter - Specification V 236 volt I 481 Amp PF 0.9 Speed - 3000 rpm No, of pole - 10 No. of Phase - 5

Armature V - 236 V I - 481 A

Filed V - 35V I - 55A No. of Pole - 8 No. of Coil - 3 / pole


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Reactive Power Capability Real power (P=MW)

is used to drive load Generator output

(Apparent Power S) should be maintained within the capability curve

Higher Power Factor, will increase P(MW) to handle load or decrease Q (VAR) with the same S.

S Volt Amp

Q - VAR

P - Watt


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Generator Capability vsAmbient Temp

In simplified way, Exhaust temperature is Firing temp + Ambient

Exhaust temp is controlled by Exhaust temp set point, (constant), so

Higher Ambient Temp, will reduce allowable firing temperature, which may cause to reduce MW output generated by generator.

T1

P1

P2


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Brushless Exciter Rotor


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QUESTION &

ANSWER


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FOR

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Please do not hesitate to contact me at 0813 140 78900

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Documents

2GTG - Know How Training 14 March 2013 - Participants 2pg_2