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electrical generator
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Generator Generator ConstructionConstruction
ByBy Ms. Soh Ley BauMs. Soh Ley Bau
Generation Section--Electrical Unit Generation Section--Electrical Unit (ILSAS),TNB(ILSAS),TNB
System OverviewSystem OverviewPrinciple of Thermal Power Plant
System OverviewSystem Overview Principle of Thermal Power PlantPrinciple of Thermal Power Plant
System OverviewSystem Overview
Furnace The chemical energy from fuel is converted to
heat
Back
System Overview System Overview
The heat from the burning fuel causes The heat from the burning fuel causes water in the boiler change to steamwater in the boiler change to steam
Boiler
Back
System OverviewSystem Overview
The steam is sent to the turbine, where it causes the turbine blades to
rotate. The turbine converts the energy
in the steam into mechanical energy.
Steam Turbine
Back
System OverviewSystem Overview
Generator
The turbine shaft connects the turbine to the generator through a coupling and as the turbine rotates,
the generator rotor shaft also rotates.
NextCoupling?Coupling?
Ask meAsk me
System OverviewSystem Overview
GeneratorThen, the generator converts the
mechanical(rotating) energy into electrical energy
NEXT-DEMO
Turbine
Coupling
System OverviewSystem Overview
Generator
Side Turbine side
I get it !!
How the electrical generator How the electrical generator work?work?
How AC How AC generator generator
work?work?
AC AC GeneratorGenerator
Prepared by @ Ms.Soh Ley Bau 13
Single Phase Generator/ Single Phase Generator/ AlternatorAlternator
Types of GeneratorsTypes of Generators
Turbo Generator (Turbo Generator (Cylindrical Cylindrical Rotors)Rotors)
Turbine GeneratorTurbine Generator
Salient pole GeneratorSalient pole GeneratorHydro GeneratorHydro GeneratorDiesel GeneratorDiesel Generator
Salient Pole GeneratorSalient Pole Generator
Salient Pole Generator Salient Pole Generator Hydroelectric PlantHydroelectric Plant
(Chenderoh, Sg Perak)(Chenderoh, Sg Perak)
Salient Pole GeneratorSalient Pole GeneratorStator WindingsStator Windings~ Cameron Highland~ Cameron Highland
Salient Pole Rotor Salient Pole Rotor
A 4 Pole rotor starts as a solid rough forging
The shaft, spider and the 4 poles and pole tips are created by machining away part of the forging.
The strip wound fielding winding is added to complete the rotor
Solid 6 pole machine with Solid 6 pole machine with brushless exciterbrushless exciter
Salient Pole GeneratorSalient Pole GeneratorRotor Pole Rotating Type Exciter
Salient Pole RotorSalient Pole RotorCameron Highland Cameron Highland
Salient Pole Rotor Salient Pole Rotor Kenyir (112MVA, 24 poles)Kenyir (112MVA, 24 poles)
Salient Pole GeneratorSalient Pole GeneratorDiesel Generator
Salient Pole GeneratorSalient Pole Generator6.6kV Black Start Diesel Generator (PD1)
Salient Pole GeneratorSalient Pole GeneratorDiesel Generator,12 poles Diesel Generator,12 poles
WWhat are the hat are the
functions of functions of generator in generator in the Power the Power
Utility Utility Industry?Industry?
IntroductionIntroduction To convert the rotational To convert the rotational
mechanical energy (steam mechanical energy (steam turbine) into electrical energyturbine) into electrical energy
Steam Steam TurbineTurbine
GeneratorGeneratorMain Main exciterexciter
IntroductionIntroduction
To supply energy to the power To supply energy to the power grid and route some power to grid and route some power to
machine auxiliaries (via the machine auxiliaries (via the Unit Transformer)Unit Transformer)
One-line diagram for generator and One-line diagram for generator and generator transformergenerator transformer
Layout of Power PlantLayout of Power Plant
Pressure Rise in a TransformerPressure Rise in a Transformer
Transformer-Phase to Earth Transformer-Phase to Earth FaultFault
Transformer-Phase to Earth Transformer-Phase to Earth FaultFault
Transformer-Phase to Earth Transformer-Phase to Earth FaultFault
Split Generator ShaftSplit Generator Shaft
Generator Main Circuit Generator Main Circuit Breaker (SFBreaker (SF66))
Generator Main Circuit Generator Main Circuit Breaker (SFBreaker (SF66))
Components of GMCBComponents of GMCB
Generator ConstructionGenerator Construction
Stator
Rotor
Bracket
Generator ConstructionGenerator ConstructionMain Components:
– a.)Stator (stationary part)– b.)Rotor (rotating part)– c.)Rotor Bearing– d.)Pilot AC Exciter– e.)Main Exciter– f.)Automatic Voltage Regulator (AVR)– g.) Rotating rectifier– h.)Stator Output Leads and Isolated Phase Bus– i.)Generator Neutral Earthing– j.)Hydrogen Cooling system
StatorStatorStator consists of stator core,stator frame,
slot wedges and etc.Function:-Armature- produce output of the generator
Stator ConstructionStator Construction
-Special explosion proof design- In case any gas explosion inside, it provides a safe tight housing
-MaterialMaterial :No.1 SM41 AP, of JIS G 3106 Rolled Steel for welded Construction and is tested to be free from cracks etc. by a supersonic test
•Stator Frame
Stator ConstructionStator Construction
Stator Stator corecore
WedgeWedge
End winding
Stator ConstructionStator ConstructionStator Core
The functions of stator core are :
a) Concentrate the lines of magnetic flux around the stator windings
b) Support and hold the windings in position around the rotor as the rotor turns.
Stator coreStator core
Figure : Side view of the stator core
*Note : Air-cooled generator in Serdang power station
Stator ConstructionStator Construction Slot Wedge
Function:
The stator windings or stator coils are simply long insulated bars which are assembled and wedged-locked into the stator core slots running length wise through the generator.
Stator ConstructionStator Construction Slot Wedge
Wedge is located on the top of each slot
End winding
Stator ConstructionStator ConstructionStator Lamination
-To form a stator core, high quality silicon steel plates of little core loss are used and punch them with a die in such segments as shown in the illustration.
-After giving them varnish treatment, pile them up on a stator frame.
Stator LaminationStator Lamination
*Stator Core
Stator LaminationStator Lamination
Stator ConstructionStator ConstructionStator core end
Stator ConstructionStator Construction Stator core end Functions: -The coil end is rigidly tied with a glass cord to the micarta
coil support which is bolted to the stator core and laminated core.
(Reason: withstand the immense power at the time of short circuit )
-At the extreme end is placed a resin ring made of epoxy impregnated glass fiber, and molding mixtures are stuffed in the space between the said ring and coil in order to support them.
Effect of the Flexible MountingEffect of the Flexible Mounting
Flexible MountingFlexible Mounting
~ To prevent high level vibration (two-pole machines) from being transmitted to the frame and foundation, the stator core is supported from the frame by a flexible mounting.
~ To support the weight of the core and to withstand short circuit torque.
Flexible MountingFlexible Mounting
Rotor ConstructionRotor Construction
Rotor shaft of an inner cooled Rotor shaft of an inner cooled generatorgenerator
Pole face
Prepared by @ Ms.Soh Ley Bau 65
Rotor ForgingRotor Forging
@soh-Serdang GT5
Rotor ConstructionRotor ConstructionRotor coil
Example of rotor end windingExample of rotor end winding*Serdang Power Station Nov.2003,Unit 2
Rotor ConstructionRotor ConstructionRotor CoilMaterial : cold worked silver bearing
copper
Function: Field coil of the generator
Rotor ConstructionRotor Construction
Coupling at turbine side
Rotor
@Unit 1 SJSSAA,kapar(Oct 03)
Rotor ConstructionRotor Construction
Retaining ring
@Unit 1 SJSSAA,kapar(Oct 03)
Retaining RingRetaining Ring
Function:
~To support the rotor coil end, thin cylindrical coil retaining rings are force fitted to both ends of the rotor body
@Sohlb Serdang GT5
Rotor ConstructionRotor Construction
End windings of the rotor coil
@Unit 1 SJSSAA,kapar(Oct 03)
Generator PartsGenerator Parts
NEXTNEXT
Generator’s Journal BearingGenerator’s Journal Bearing Bearing # 5 (Turbine side)
Bearing # 6
(Excitation side)
NEXTNEXT
@Unit 1 SJSSAA,kapar(Oct 03)
Generator’s Journal BearingGenerator’s Journal Bearing
Function:To support the generator rotor.
(In order to keep the shaft free from undue stress because of deflection of shaft and misalignment, the bearings are of spherical surface which are machined to have a high pressure oil-line,lubricating oil line, etc.
BACKBACK
Bearing BracketBearing BracketTop half of bearing bracket
Bottom half of bearing bracket
Main Exciter side
Rotating Rectifier
NEXTNEXT
@Unit 1 SJSSAA,kapar(Oct 03)
Bearing BracketBearing Bracket
Dismantle the top half bearing bracket using overhead crane
NEXTNEXT
@Unit 1 SJSSAA,kapar(Oct 03)
Bearing BracketBearing Bracket- Welded construction & is directly fixed to the stator frame
- It is divided into two parts both at the turbine side & the exciter side.
- Having sufficient mechanical strength by means of many ribs.
- In the bracket are included bearings, gland seal ring and oil seal and the lower section of the lower bracket constitutes a deforming tank.
- To fix the stator frame, gasket and sealing compounds are used and the construction is such that gas leakage is kept to the minimum.
BACKBACK
Gland seal Gland seal Gas tight enclosure for hydrogen cooled generator
Function:
-To prevent hydrogen gas leakage along the shaft
NEXTNEXT
@Unit 1 SJSSAA,kapar(Oct 03)
Gland sealGland seal
BACKBACK
Seal ringSeal ring
Position of seal ring
Seal ring (Bottom half)
Gland seal
Seal ringSeal ring
BACKBACK
Air Gap BaffleAir Gap Baffle
Air Gap BaffleAir Gap Baffle
Function:Function:
-To separate the -To separate the high pressure and high pressure and the low pressure the low pressure ventilation zones at ventilation zones at the exciter end of the exciter end of the rotor & stator.the rotor & stator.
BACKBACK
BlowerBlower
- Multi-stage axial blower is installed only at turbine side (inner cooled machine)
Function:
-To feed the cooling gas(cold gas) into a long and narrow vent duct in the axial direction ventilation.
NextNext
BlowerBlowerBlower Blade
Material:
Ni-Cr-Mo steel
Cooling Fan/blowerCooling Fan/blower**Unit 5 Port Dickson Power Station****Unit 5 Port Dickson Power Station**
BACKBACK
Blower ShroudBlower Shroud
BACKBACK
Gas cooler/Hydrogen CoolerGas cooler/Hydrogen Cooler
NEXTNEXT
Gas Cooler Hydrogen CoolerGas Cooler Hydrogen Cooler-Two gas coolers are each arranged vertically both on the right side and the left side of the turbine side in the generator.
-Cooling tubes with spiral copper fins are used as shown (b).
-The cold gas temperature is designed to maintain below 45C when the cooling water temperature is 40 C .
(a)
(b)
NEXT
Gas Cooler Hydrogen CoolerGas Cooler Hydrogen Cooler
1. During generator operation, electrical resistance heating in the gen.windings-creates large amount of heat
2. This heat is removed from gen.windings-circulating hydrogen gas through windings
3. Circulation is accomplished by cooling fan.
4. The heat from hydrogen gas is then removed by cooling water flowing through hydrogen coolers
BACKBACK
Generator Generator Exciter System Exciter System Fundamentals Fundamentals
Excitation SystemExcitation System
Functions a.) Supply, control and regulate the amount of field
current applied to the generator field winding, so that the generator output voltage kept constant, at predetermined levels, under varying load conditions.
b.) Allow the operator to change the reactive loading of the machine
Basic Exciter PrinciplesBasic Exciter Principles
Three factorsThree factors which affect the output of a generator.
1. The number of conductorsnumber of conductors (fixed for a particular generator)
2. The speed of rotation of the rotorspeed of rotation of the rotor( fixed at 3000RPM for 2 pole machines operating on a 50Hz system)
3. The strength or density of the magnetic fluxstrength or density of the magnetic flux or field( varied by increasing or decreasing field current)
Types of ExcitersTypes of Exciters
1. Static Type System1. Static Type System AC power directly from the main generator
leads The power taken from the generator leads
is first stepped down through a special transformer and then fed to rectifiers for conversion to dc.
Types of ExcitersTypes of Exciters
2. A-C Generator (Alternator)/PMG 2. A-C Generator (Alternator)/PMG Excited SystemExcited System
The main generator drives an alternator to produce ac power, which is then converted to dc by means of rectifiers.
Static ExcitationStatic Excitation
Static Excitation Static Excitation
If generator voltage not reaches to 60% within 20 sec, initial excitation failure alarm is raised.
30sec20 sec 0 sec
Excitation TransformerExcitation TransformerDry type Excitation Transformer Dry type Excitation Transformer
( 3.44MVA 15/0.88kV)( 3.44MVA 15/0.88kV)
Core Type TransformerCore Type Transformer
PMG Excited SystemPMG Excited System
PhotoPhoto
AC
Advantage of Brushless Excitation Advantage of Brushless Excitation SystemSystem
1. Reliability. “ AC Exciter-Rotating Rectifier” mounted on a common shaft
2. Maintenance cost is reduced because there is no brush, commutator and slip ring
3. There is no troubles of insulation resistance since the adhesion of carbon duct is varnish.
4. All devices are placed in closed housing and not exposed to the atmospheric conditions.
Advantage of Brushless Excitation Advantage of Brushless Excitation SystemSystem
5. Change of brush is needless during operation so that with an increase of safety, the operation can continue for the long term.
6.Generator field breaker,field regulator and exciter bus or cable become unnecessary.
(not required any DC bus duct from excitation transformer to IPB for static excitation)
Advantage of Brushless Excitation Advantage of Brushless Excitation SystemSystem
7. Foundation cost will also reduces since air ducts and exciter bus (Excitation Transformer) are not needed in foundation.
8. It permits continuous conservative operation and tolerates transitory over loads to ceiling voltages.
9. Spare exciter is also unnecessary
GeneratorGenerator
AVR card
Rotating
Rectifier
PMGPMG
Main generator
NEXTNEXT
Brushless Excitation System-Main ExciterBrushless Excitation System-Main Exciter
PMG Rotating Armature
Rotating Rectifier
BackBack
Brushless Excitation System-PMGBrushless Excitation System-PMG
Rotating armature PMG or Pilot Exciter
NEXTNEXT
Permanent Magnet GeneratorPermanent Magnet Generator
PMG StatorPMG Stator
PMG RotorPMG Rotor
NEXTNEXT
Pilot Exciter/PMG/High Pilot Exciter/PMG/High Frequency GeneratorFrequency Generator
PMG= Permanent Magnet GeneratorFunction: To provide a constant source of excitation power
for exciter field via the Automatic Voltage Regulator(AVR) which is the controlling device governing the level of excitation provided to the exciter field
BackBack
Automatic Voltage regulator Automatic Voltage regulator (AVR) Panel (AVR) Panel
Function:
-AVR responds to a voltage sensing signal derived, via an isolating transformer (Potential Transformer) from the main stator winding.
NEXTNEXT
Automatic Voltage Automatic Voltage Regulator (AVR) PanelRegulator (AVR) PanelFunctions:Control the field current in order to
maintain the generator output voltage at a predetermined level, with minimal changes over a wide range of load demand.
Adjusting the Q(Mvar) reactive power
Automatic Voltage Automatic Voltage Regulator (AVR) PanelRegulator (AVR) Panel
Improve the power system stability (transient stability)
Suppress the over generator voltage on the load rejection
BackBack
Exciter Stator & Exciter RotorExciter Stator & Exciter Rotor
Field coil on the stator of main exciter
(Rotating Armature)
NextNext
Exciter Stator & Exciter RotorExciter Stator & Exciter Rotor
Function:-As an AC Generator (Rotating Armature)-Exciter Stator-Create magnetic field-Exciter Rotor-Induced current
BackBack
Rotating RectifierRotating Rectifier
Function:AC to DC Converter-To provide excitation
(DC supply) into the main rotor
BackBack
?? ????
Excitation with carbon brushExcitation with carbon brushSJTJ,Unit 5~2003SJTJ,Unit 5~2003
Cartridge TypeCartridge TypeSJTJ,PD1 2004SJTJ,PD1 2004
Slip Ring BrushGearSlip Ring BrushGear
Slip RingSlip Ring
Prepared by Ms.Soh
Stator Terminal Box and Stator Terminal Box and BushingBushing
Terminal BoxTerminal Box
Stator TerminalStator Terminal
Bushings
Function:
- To route the electricity produced in the stator windings
Isolated Phase systemIsolated Phase system
Function:
-The output of the stator is connected to the generator transformer via an isolated Phase Bus (IPB) system
Isolated Phase systemIsolated Phase system
•Required high reliability
•Made of high quality materials and welded constructions are adopted.
•Dry air is constantly feed into IPB bus through the air supply equipment
•Prevent external air from flowing into IPB
•Prevent the inside of IPB from dewing
Generator Neutral EarthingGenerator Neutral Earthing
Function:Function:• To limit the stator To limit the stator
earth fault current earth fault current that can flowthat can flow
• (to prevent the earth fault (to prevent the earth fault current flow through the core of current flow through the core of the generator)the generator)
Generator Transformer & Generator Transformer & TransmissionTransmission
Generator Transformer (11kV/275kV)
Transmission side (switchgear) 275kV
Note:*PD power station
Seal Oil SystemSeal Oil System
Seal Oil SystemSeal Oil System
Function:-To lubricate the seals and prevent
hydrogen from escaping from the generator without introducing an excessive amount of air and moisture into the generator
Hydrogen cooling systemHydrogen cooling system(Inner Cooling)(Inner Cooling)
Figure :Longitudinal sectional view of generator
Characteristics of Hydrogen CoolingCharacteristics of Hydrogen Cooling Table 1:
Air
Hydrogen
Density
1.00 0.07
Thermal conductivity
1.00 7.00
Heat Transfer coefficient from surface gas
1.00 1.35
Specific heat 1.00 0.98
Support of combustion Yes
No
Oxidizing agent
Yes No
Prepared by @ Ms.Soh Ley Bau 132
Serdang GT5
Siemen
Prepared by Ms. SOh
Prepared by Ms.Soh
Prepared by Ms.Soh
Prepared by @ Ms.Soh Ley Bau 133
Serdang GT5
Siemen
Prepared by Soh
Prepared by @ Ms.Soh Ley Bau 134
Characteristics of Hydrogen CoolingCharacteristics of Hydrogen Cooling
An ideal cooling mediumAn ideal cooling mediumThe combination of low density and high specific heat of hydrogen
Lower effectiveness of air as a cooling mediumLower effectiveness of air as a cooling medium (requires a 20% to 30% size increases over a hydrogen cooled machine a similar rating).
Design for higher electrical loadingDesign for higher electrical loading compared to the air –cooled machine due to better cooling.
Hydrogen Inner-cooling Hydrogen Inner-cooling systemsystem
To remove heat directly from the stator and rotor conductors by hollowing them and flowing a high velocity gas through these hollows
Advantages:– Sharply increase output in similar size– Possible to employ higher hydrogen gas pressures
than a conventional hydrogen cooled unit
AcknowledgementAcknowledgement
Mr. Low Siew Wooi,JPSMr. Low Siew Wooi,JPSMr. Foo Hi Kium, ILSASMr. Foo Hi Kium, ILSASMr. Mok Kin Wah,ILSASMr. Mok Kin Wah,ILSASMr. Lew Kar Wong, SJTJMr. Lew Kar Wong, SJTJMr. Thong Lit Yen, TNBHMr. Thong Lit Yen, TNBH