gas tubine generator

5/21/2018 Gas Tubine Generator

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Document Type:Procedure/Work Plan Title:

Gas Turbine Generator

Document Number:

ENGRO ENERGY LIMITEDPage1of 14

Revision:0 Date:June 05,2009

Change: Date:


OPERATING PROCEDURE

EEL Qadir Pur Power Project217 MW Combined Cycle Power Plant

Qadir Pur, District GhotkiSindh, Pakistan


(QFR 35 2

)


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1.0 DESCRIPTION OF THE SYSTEM

The Purpose of Gas turbine generator is to convert mechanical energy of gasturbine into electrical power. The technical data of gas turbine generator is

1. Cold air temperature 40C

2. Active Power 135MW3. Voltage 13.8KV4. Current 6644.7A5. Power Factor (Cos) 0.85

6. Frequency 50Hz7. Speed 3000 rpm8. Number of phases 39. Excitation current 890A

The Generating Units main components are the generator (stator + rotor), theExciter system (a three phase ac machine + single phase PMG + rotating diodes),thecooler and two bearings. Generator operates on Faradays Law of Electromagneticinduction.DC Excitation is supplied to the rotor through brushless excitation system consisting of

rotating diodes to generate the magnetic field. The rotating magnetic field is cut by thestator conductors and emf (voltage) is induced.

STATOR: Consists of three major components Stator Frame, Stator Core and Statorwindings.Stator frame is a tough and rigid structure and hold the magnetic core andwindings.The core is built into a fabricated steel frame and consists of low loss siliconsteel segmental stampings insulated by a layer of varnish on both sides. The statorwinding is of the two layer diamond type with coils held in open slots by epoxy resinbake fabric wedges and the insulation is synthetic resin bonded mica glass tapethroughout. The laminations of the stator winding are transposed in a regular pattern toMinimize circulating currents and losses.

Technical data for the stator is as under1. Number of slots 662. Number of conductors per slot 23. Voltage 13.8kV4. Current 6644.7A5. Number of terminal outputs 66. Temperature rise


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ROTOR: The rotor main components are the solid rotor shaft, the field winding, theretaining ring and the fans.The field winding conductors are made of silver-bearing copper strips. They areConsolidated together with their insulating material. The rotor windings coil-ends aresecured under the retaining rings to protect the windings against centrifugal forces bymeans of laminated glass sheaths insulation.To detect a rotor ground fault in thegenerator, a system formed by a brush actuated by a solenoid comes into contact with acontact ring inside the excitation winding. Rotor is provided with shaft grounding brushto direct any induced voltages in the rotor shaft to ground.Technical data for the rotor is as under

1. Number of poles 22. Number of slots 28

3. Excitation voltage 400V4. Excitation current 891A5. Temperature rise


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- Number of poles 6 No. of poles 16- Voltage (DC) 108 V Number of slots 96

- Current (DC) 7.5 A Voltage 270 V- Resistance at 75 C 12.197 Ohms Current 18.5A- Number of slots 54 Number of phases single- No of conductors per slot 2- Voltage 435 V- Current 1055 A- Number of phases 3- Number of diodes 12

Exciter cooling is carried out with air circulation by the shaft mounted fan on the exciter

side. The heated air meets the main generator hot air and is get cooled through the

water to air heat exchangers.

GENERATOR COOLING

Gas turbine Generator is air cooled consisting of two axial flow fans mounted on theshaft , rotating at 3000 rpm and delivering an air flow of 41m

3/s. Four water to air cooler

are installed to carry out the cooling of hot air when it leaves the generator. The waterused in the coolers is the cooling tower water.

While taking the coolers in service, proper venting and draining should be carried out toflush out the metal particles and air trapped in the cooler by opening the drains andvents of the coolers and also visual inspection of water boxes sealing should be carriedout to check for any leakage. Two Coolers water leakage detectors (level detectorstype) are provided to detect any leakage in the coolers at the earliest and to initiate thealarm accordingly.

GENERATOR BEARINGS

The generator is equipped with two journal bearings to support the shaft.Bearings are lubricated with lube oil ( pressure 0.8~ 1.5 bars, temperature 40C-55 Cand flow rate is 180 l/min) and at low speeds jacking oil is introduced to the bearings tolift the shaft in order to provide sufficient clearance between the bearing and the

journals.

Both the bearings are equipped with resistance temperature detectors (RTDs) tomonitor the bearing metal temperature and to initiate an alarm and trip in case ofbearing damage. One Resistance Temperature Detector is installed on the lube oil drainline to monitor the drain oil temperature.Generator bearing turbine end is also equipped with two seismic detectors whichmonitor the bearing vibration and two proximity detectors to monitor the shaft vibration.


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Generator bearing exciter end is equipped with one seismic vibration detector to monitorthe bearing vibration and two proximity type vibration detectors to monitor the shaft

vibration.The vibration detectors initiates alarm and trip in case vibrations exceeds the limitvalues.

SPACE HEATERSWhen the machine shuts down the heating resistors are activated when temperatureinside the generator falls below 25C. The role of the heating resistors is to preventinternal condensation.Six sets of three 200 W resistors are mounted on the lower part on each side of themachine.

SOUND PROOF ENCOSURE AND LIGHTINGThe enclosure provides a complete protection for the generator against weatherconditions and thermally and acoustically insulates it.Four doors with safety locks are provided for access to the enclosure.The enclosure of the generator unit is lighted by standard 230V A.C incandescent lamps.Emergency lighting is ensured by protected incandescent lamps supplied with 125V D.C locatedin the enclosure.

GENERATOR JACKING OIL SYSTEMJacking oil system is provided to lift the generator bearings at low speed (turning gearoperation) in order to maintain a sufficient clearance between the journal and bearings toprevent metal to metal contact. The system mainly consists of hydraulic oil pump-motor set,pressure regulation unit, filtration unit, pressure acquisition and control unit.The system is capable of providing working pressure at max. 20 MPa (200 bars)and flow rate

at max. 36 L/min. Filtration unit of filtration accuracy up to 10m is provided.System technical data is as under1. Power supply: three-phase, four-wire, 380V10%V2. Maximum Working Pressure: 20 MPa3. Maximum flow rate: 36 L/min24. Motor power: 15 kW25. Pressure transmitter contact: DC24V4mA~20mA6. Electric space heater contact: AC220V40 W

The inlet of jacking oil pumps is from the main lubrication system so lubrication system shouldbe in service before the jacking oil system is taken in operation.

start up of jacking Oil system for flushing and jacking oil pressure adjustment:

1. Check for correct and firm component installation, electric connection and pipeConnection of the device, e.g. conformity of oil inlet/outlet and blow down portof valves and pumps with indications.

2. Check that monitoring instruments are installed in easily visible positions.

3. Check and confirm that system valves (#7#10#16 and #31) are fully open;

handle of valve (#14) is fully released (turn anticlockwise to the end position).4. Loose oil pump blow down pipe connector and fill clean hydraulic oil into pump


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cavity through pump blow down port until it is filled up.5. Quality of the oil shall be checked and it should be as per OEM recommendations to

ensure the performance and service life of the equipments (Viscosity 20~46 mm2/s).6. Check and confirm the pressure value at the Pressure gauge # 32 is less than 0.15Mpa.

If itshigher adjust valve #16 till the pressure value is below 0.15Mpa.7. The main lubricating system shall be started before the high pressure shaft raising oil

pump device is started. Operation of pump is forbidden when main lubrication systemis under no flow status. Otherwise, the pump will be damaged.

8. Check for correct motor rotation direction. Correct motor rotation direction shall beclockwise (viewing from motor tail end).

9. Perform flushing to remove any foreign matters inside before the operation of thesystem. For flushing, close main oil outlet stop valves (#12 and #13) to the generatorbearings, run the pump to circulate the oil within the pipeline to perform self circulatedflushing with the two pumps in alternative operation. After flushing, check and replace

filter candle of oil filter (#8) before proceeding further to test run procedure.10. To carry out the pressure adjustment, start motor and run idly (with overflow valve fully

loose) for 1 minute and observe pressure values (values indicated by three pressuregages).

11. Adjust overflow valve (#14) to step up pressure by increment of 3~5 MPa/step untiloverflow valve reaches preset pressure value, which is preset working pressure of thedevice. Working pressure shall be strictly controlled below 20 MPa.

13. After running continuously for a period of time under set working pressure, oil warmup shall be within allowable range (below 65C).

14. Check the temperature of pump case .Normally it should be 10C~20C higher than oiltemperature at pump inlet.

15. After the device runs for a period of time, adjust overflow valve (#14) to depressurize

the system to no-load operation status, and then stop the motor.16. Jacking oil system shall be started and stopped under no-load conditions at low speeds.

2. PREREQUISITES FOR START UP OF GENERATOR ANDNO LOAD TESTS

2.1 Lube oil system is in operation and lube oil pressure is normal on pressuregauges on both generator bearings.

2.2 Pressure switches on generator bearings (63QT-2A & 63QT-2B) are calibrated at

proper value to initiate the trip on low bearing lube oil pressure.

2.3 Site glasses on the lube oil drain lines of each bearing are clear and transparentand lube oil drain flow is proper.

2.4 Jacking oil system is in operation and jacking oil pressure for each bearing isnormal.

2.5 T/G is in operation.


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2.6 Generator cooling water system is properly ventilated, flushed and cooling waterpressure is normal.

2.7 Water leak detection system installed, checked and normal.

2.8 Proper lighting system in the generator compartment installed and is operational.

2.9 Air filters installed and are clean.

2.10 Hot air and cold air temperature sensors are normal and alarm and trip settingsadjusted, tested and are intact.

2.11 Stator winding temperature and magnetic core temperature sensors are normaland alarm/trip settings adjusted, tested and are in intact.

2.12 Vibration transducer and normal and alarm and trip settings adjusted, tested and

are intact.

2.13 Generator bearings metal temperatures sensors are normal andalarm/protections settings adjusted, tested and are intact.

2.14 Operations of the space heaters tested and are normal.

2.15 Rotor ground detection brushes are in proper contact with the slip rings.

2.16 Generator earth switch is in open position.

2.17 Generator 13.8KV isolator is in open position.

2.18 Generator 13.8 KV synchronizing circuit breaker (GCB) is in open position.

2.19 Excitation circuit breaker is on manual mode.

2.20 AVR system installed, contains the diode failure signaling facility, its functioningtested and is on manual mode.

2.21 Insulation resistance of stator winding (between phases and phases to ground)measured and is normal (> 11.9M using 2500V megger).

2.22 Insulation resistance of the rotor winding measured and is normal (>1M using500V megger).

2.23 Insulation resistance of the exciter winding and rectifier rings measured and is

normal ( ).

2.24 Measurement of exciter rotor and stator windings resistance and it is normal.

2.25 Excitation circuit protections like under excitation and over excitation are intactand are tested.

2.26 All the CTs and PTs for monitoring control and protections are intact and theircircuits are checked.


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2.27 Generator neutral is properly grounded through grounding transformer.

2.28 Shaft grounding brushes are installed on the shaft to drain out the rotor induction.2.29 Rotating diode fault detection fuses are installed and are of proper rating.

2.30 Generator protections stator earth fault, rotor earth fault, differential protection,overvoltage, under voltage, unbalance load are intact and are tested.

2.31 Alarms and protections panels are ready to annunciate any alarm andeach alarm/trip indication tested.

2.32 Start up and shut down control panel is ready and tested.

2.33 Emergency trip buttons are installed checked and are normal.

2.34 Sight glasses on drain oil lines should be clear and transparent.

2.35 Both Black Start Diesel Generators are in operation and GT auxiliary busbars of 11KV, 415V, DC (110V) power supply and UPS are energized.

2.36 DC batteries of proper rating are installed and are charged properly.

2.37 DC lube oil pump is healthy and is tested normally.

2.38 Starting motor circuit breaker protections for over current, earth fault, shortcircuit fault are tested, normal and are intact.

2.39 Starting motor transformer (11KV/6.3KV) ready and its protections areintact and tested.

2.40 Start/stop push buttons for manual operation of the DC lube oil pump andAuxiliary lube oil pump provided and tested.

2.41 Emergency Diesel Generator is commissioned and is ready to cut inoperation to energize the emergency bus bar for safe lubrication andturning gear operation.

2.42 Generator stator voltage monitoring between three lines meters installedand tested.

2.43 Generator stator current monitoring between the phases installed andtested.

2.44 Generator excitation voltage and current monitoring meters installed andtested.

2.45 Generator active power and reactive power monitoring and recordingmeters installed and tested.


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2.46 Generator power factor meter installed.

3. INSTRUCTIONS FOR GENERATOR START UP AND NOLOAD

After fulfilling all the requirements mentioned above, generator can be startedwith turbine. During start up following observations should be made verycarefully.

3.1 Vibrations of bearings and shaft displacement.

3.2 Generator bearing metal temperatures.

3.3 Generator bearings drain oil flow should be observed through the sight glass anddrain temperatures should be monitored vigilantly.

3.4 Continuous local monitoring of generator area should be carried out to observeany abnormal sound, lube oil leakage and drain oil flow from the sight glass.

3.5 Cooling water pressures/ temperatures at the inlet and outlet of generator coolersshould be monitored locally.

3.6 Hot air and cold air temperatures for generator cooling and exciter cooling shouldbe monitored.

4. TESTS AT FSNL

4.1 Measurement of short-circuit characteristic (Procedure awaited)A short circuit is placed at the generator terminals. The test consists ofmeasuring the short-circuit current as a function of the excitation current.Equipment used:Adjustable power supply deviceA8000/5 A CT and a mill voltmeter class 0.55 A AC ammeter class 0.5

4.2 Measurement of no-load characteristic (Procedure awaited)The test consists of measuring the voltage at the generator terminals as afunction of the excitation current.

Equipments used:an adjustable power supply devicea 15000/100 A CT or 20000/100 A CT and a mill voltmeter class 0.5a 150 V AC voltmeter class 0.2


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5. SYNCHRONISATION AND LOADING

In addition to all above requirements following additional measures are requiredto be taken to ensure the error free synchronization of the generator.

5.1 Pressure of Hydraulic Oil for the actuation of the Generator circuit breakeris normal.

5.2 Pressure of SF6 Gas for the Generator circuit breaker is normal.

5.3 Operation of the Generator circuit breaker is checked and is normal.

5.4 Emergency trip of Generator circuit breaker is provided and tested.

5.5 Generator isolator is closed.

5.6 Open/ close status of the circuit breaker provided, checked and is normal.

5.7 Circuit breaker failure for the GCB is intact and tested.

5.8 Main unit step up transformer and auxiliary transformer are in energizedposition (if not their Energization tested and all their protections are intact).

5.9 220KV GIS is ready (either energized if dead then its testing would havecompleted before the synchronization of the GT generator.

5.10 Operations of the synchronization relays should be checked by manualinjections of electrical signals.

5.11 Following protections for the generators are tested, normal and are intact

Differential protection, Unbalanced load protection, loss of excitation/ overexcitation, overvoltage/under voltage, Reverse power, over frequency/under frequency, stator earth fault (100%), Rotor earth fault, underimpedance and voltage restrained over current relay.

6. NORMAL OPERATIONS

During normal operations of the generators following parameters should be monitored,logged, analyzed and controlled within the permissible operating limits to ensure thesafe operation of the unit.- Stator winding temperatures-Cooling air, hot air temperatures-Exciter hot air temperatures- drive end bearing metal temperatures


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- Non-driven end bearing metal temperatures- Generator bearings vibrations (seismic and shaft displacement).

- Generator stator voltage- Generator stator current- Generator Active power- Generative reactive power- Excitation voltage- Excitation current.- Power factor.Operation of the generator should always be carried out within the limits specified by theCapability curve.If Generator trips due to any of its protection, then the fault should be thoroughlyinvestigated in cooperation with the maintenance section and get rectified before

restarting it.

7. SHUT DOWN OF GENERATORDuring deloading and shut down all above parameters should be monitoredcarefully for their variation with reference to the load.During shut down if generator circuit breaker does not open at the set reversepower load it means that the breaker trip circuit is open. Restart the generatorshould be restarted reloaded to minimum load value (~5MW) and manually openthe Generator circuit breaker. If the breaker still refuses to open then attemptshould be made to open the breaker from the local. If there is any problem withregard to SF6 Gas pressure or Hydraulic Oil pressure then the breaker should beisolated by opening the relevant 220KV circuit breakers in the GIS.Under this situation the manual emergency tripping of the m/c is strictlyprohibited as it will result in high levels of reverse power currents while generatorwill stay connected to the system.( Reference : GT operation and Maintenancemanual from NSRD).Monitor and note the run down vibration on generator bearings and also checkfor the cut in of jacking oil pump at set low speed ( ). If it did not starton auto then start it manually.During shutdown check the correct operation of the space heaters which shall beswitched on when the temperature within generator is below 25C.The spaceheaters are used for preventing condensation detrimental to the generator

winding insulation.If the machine has to be stopped in a cold weather, it is important to empty thecoolers and make sure that they are empty-particularly for the lower tube (openthe air vent-valves and the water drain-valves).if it is possible, blast withCompressed air to eliminate the eventual water pockets.


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8. INSTRUMENTATION

Measurement Type of sensor Alarm Setting Trip Setting

Stator winding RTD 120C 130C










Stator winding RTD 120C 130CStator winding RTD 120C 130C

Magnetic Core RTD 120C 130C












Cold air RTD 60C 65C

Cold air RTD 60C 65C

Hot Air RTD 105C 110C

Hot Air RTD 105C 110C

Exciter Hot air RTD 105C 110C


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Water leakage at DE Water leakagedetector n1

Contact closed Contact closed

Water leakage at NDE Water leakagedetector n2

Contact closed Contact closed

Bearing metal temperature

n1 at DERTD 85C 90C


n2 at DERTD 85C 90C

Bearing metal temperaturen1 at NDE

RTD 85C 90C


n2 at NDERTD 85C 90C

Oil outlet temperature at

DE

RTD 70C 75C

Oil outlet temperature atNDE

RTD 70C 75C

Lube Oil Low pressure Pressure switch 63QT-2A

/ 0.0396Mpa

0.069Mpa

Lube Oil Pressure Pressure Switch63QT-2B

/ 0.0396Mpa

0.069Mpa

Jacking oil pressure low atinlet of pumps

Pressure switch 0.0396Mpa

0.069Mpa

/

Jacking Oil Pressure low

at the outlet of the pumpsPressure Switch 8Mpa (turbine not

allowed to start)

/

DE Bearing vibration Seismic sensor 39V-A 7.5mm/s 11.8mm/s

DE Bearing vibration Seismic sensor 39V-B 7.5mm/s 11.8mm/s

NDE Bearing vibration Seismic sensor 39V-5A 7.5mm/s 11.8mm/s

Shaft displacement at DE Sensor 165m (peak to peak) 260m (peak to peak)

Shaft displacement at DE Sensor 165m (peak to peak) 260m (peak to peak)

Shaft displacement at NDE Sensor 165m (peak to peak) 260m (peak to peak)

Shaft displacement at NDE Sensor 165m (peak to peak) 260m (peak to peak)


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9. REFRENCESGenerator manual Operations and maintenance instructions for QFR-135-213.8KV Gas turbo generators.

(CONQ.140.409)

gas tubine generator

Documents

generator stator rotor

gas turbine generatorrotor

gas turbine generator1

gas tubine generator

number of conductors

number of slots

stator winding

stator core