Hydro Generator

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1 HYDRO GENERATOR TYPE , CONSTRUCTIONAL DETAILS & EXCITATION SYSYTEM

Transcript of Hydro Generator

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HYDRO GENERATOR TYPE , CONSTRUCTIONAL

DETAILS &

EXCITATION SYSYTEM

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HYDRO GENERATOR

These are low speed machine of the salient Pole type. They have large no. of poles. Rotor is characterized by large diameter and short axial length. Capacity of such generator varies from 500 KW to 300 MW. Power factor are usually 0.90 to 0.95 lagging.

Available head is a limitation in the choice of speed of hydro generator.

Standard generation voltage in our country is 3.3KV, 6.6KV, 11 KV ,13.8 KV, & 16KV at 50 Hz.

Short Circuit Ratio varies from 1 to 1.4.

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DIFFERENCES FROM TURBO- GENERATOR

TURBO GENERATOR

DRIVEN BY STEAM TURBINE

RUN AT HIGH SPEED CYLLINDRICAL ROTOR UNIFORM AIR GAP LOWER AIR GAP LOWER SCR (0.5 TO 0.8) SINUSOIDAL P- CURVE MAXIMUM POWER AT

=90O

HYDRO- GENERATOR

WATER TURBINE LOW SPEED SALIENT POLE NON UNIFORM AIR GAP HIGHER AIR GAP HIGHER SCR (1 TO 1.4) DISTORTED SINUSOIDAL

P- CURVE FOR < 90O

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POWER -ANGLE CURVE OF SYNCHRONOUS M/C.

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SHORT CIRCUIT RATIO

DEFINED AS THE RATIO OF FIELD CURRENT REQUIRED TO GENERATE RATED OPEN CIRCUIT VOLTAGE TO THE FIELD CURRENT REQUIRED TO CIRCULATE RATED ARMATURE CURRENT ON 3 SHORT CIRCUIT AT STATOR TERMINAL

SCR = SCR AFFECTS BOTH THE PHYSICAL SIZE AND

OPERATING CHARACTERISTICS

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LOW SCR MEANS GREATER Xd LARGE VOLTAGE VARIATION POOR VOLTAGE REGULATION LESS SYNCHRONOUS POWER LOWER STABILITY LIMIT LOWER ARMATURE SHORT CKT CURRENT

SHORT CIRCUIT RATIO

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HIGH SCR LOWER VALUE OF Xd HIGH ARMATURE SHORT CKT CURRENT GREATER STABILITY LIMIT GOOD VOLTAGE REGULATION

SHORT CIRCUIT RATIO

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CLASSIFICATIONS

WITH RESPECT TO POSITION OF ROTOR ( i) HORIZONTAL (ii) VERTICAL 1) SUSPENSION TYPE 2) UMBRELLA TYPE SUSPENSION TYPE THRUST BEARING IN UPPER BRACKET

ABOVE ROTOR UMBRELLA TYPE THRUST BEARING IN LOWER BRACKET

BELOW ROTOR

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DESIGNATION

TYPE OF HYDROGENRATOR IS DESIGNATED AS FOLLOWS FOR AN EXAMPLE

SV 505 - 16

190 SV SYNCHRONOUS VERTICAL NUMERATOR 505 OUTER DIAMETER OF

STATOR CORE IN cm

DENOMINATOR 190 ACTIVE LENGTH AT STATOR CORE IN cm

16 NO. OF POLES

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SELECTION OF NO. OF POLE Nsyn (Sync. Speed) = 120 F P Synchronous Speed Of The Generator Depends

Upon The Specific Speed Of The Turbine Nsyn = Ns X Hn 1.25 / Pt

0.5

SPECIFIC SPEED IS THE SPEED AT WHICH A HOMOLOGUS TURBINE WOULD RUN WHEN DEVELOPING 1 METRIC KW UNDER 1 M HEAD

Type of Turbine Sp. Speed (rpm , in m-Kw )

Head (m)

PELTON 12 - 60 > 400

FRANSIS 60 - 400 30- 650

KAPLAN 220 -1000 3-75

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CONSTRUCTION STATOR CONSTRUCTION

STATOR FRAME - CYLLINDRICAL OR POLYGONAL IN FORM

TO SUPPORT THE STATOR CORE STATOR CORE PROVIDES HOUSE FOR STATOR

WINDINGS BUILT UP OF THIN VARNISHED STAMPINGS

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STATOR WINDINGS

DOUBLE LAYER BAR TYPE WAVE CONNECTED OR COIL TYPE LAP CONNECTED

STATOR TEMPERATURE INDICATOR RTD ARE INSERTED INTO THE SLOTS OF THE

CORE AT DIFFERENT STRATERGIC LOCATION FOR MEASURING THE TEMPERATURE OF STATOR WINDING AND STATOR CORE

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STATOR HEATERS

FOR AVOIDING CONDENSATION INSIDE THE GENERATOR BARREL DURING SHUT DOWN TO PROTECT THE INSULATION OF THE GENERATOR WINDING

AIR COOLERS

PROVIDED AROUND THE STATOR FRAME FOR COOLING THE GENERATOR WINDING

BEARING COOLERS H S LUBRICATION BRAKE DUST COLLECTOR SYSTEM

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ROTOR CONSTRUCTION

TYPES OF ROROR Disc type Disc are directly shrink

fitted on the shaft Rotor with spider and rim Shaftless Instead of shrinking the

spider on shaft it is coupled to the shaft by means at flange coupling

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ROTOR COMPONENTS

ROTOR SPIDER ROTOR RIM ROTOR SHAFT SLIP RINGS FANS

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BRACKETS

Provided for housing thrust and guide bearing

Two brackets: Upper bracket Lower bracket

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BRAKING AND JACKING SYSTEM Brake shoes are pressed against the brake

tracks on the rotor to bring the machine to the rest.

Used as jacks for lifting of the rotor for which the oil under pressure (about 100 kg/cm2) is fed from high pressure pump unit. After jacking the rotor can be maintained in lifted position by turning the locking net and releasing oil pressure

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BRAKING AND JACKING SYSTEM

On normal shutdown brakes are applied to bring the rotor quickly to standstill to reduce wear in the thrust pad .

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DAMPER WINDINGS

For preventing hunting Consists at low resistance copper, bars

embedded in slots in the pole face of salient pole machine.

Copper bars are short circulated at both ends by heavy copper rings.

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EXCITATION SYSTEMEXCITATION SYSTEM

1.1. EXCITATION TRANSFORMER EXCITATION TRANSFORMER (DRY TYPE )(DRY TYPE )

2.2. RECTIFIER SYSTEMRECTIFIER SYSTEM3.3. AUTOMATIC VOLTAGE AUTOMATIC VOLTAGE

REGULATOR REGULATOR 4.4. POWER SUPPLY UNITSPOWER SUPPLY UNITS5.5. FIELD FLASHING UNITSFIELD FLASHING UNITS

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TYPES OF EXCITATION SYSTEM

DC MAIN EXCITER AND AMPLIDYNE + MAGNETIC AMPLIFIER AVR

DC MAIN EXCITER + PILOT EXCITER + MAGNETIC AMPLIFIER AVR

DC MAIN EXCITER +THYRISTORISED AVR

FULLY STATIC EXCITER WITH THYRISTORISED AVR

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6.6. FIELD CIRCUIT BREAKERFIELD CIRCUIT BREAKER

7.7. DISCHARGE RESISTORDISCHARGE RESISTOR

8.8. DIGITAL CONTROL, PROTECTION DIGITAL CONTROL, PROTECTION & METERING EQUIPMENT& METERING EQUIPMENT

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WITH LARGE ALTERNATORS IN WITH LARGE ALTERNATORS IN POWER SYSTEM, EXCITATION POWER SYSTEM, EXCITATION CONTROL PLAYS A VITAL ROLE.CONTROL PLAYS A VITAL ROLE.

SYSTEM PERFORMANCE IS TAKEN SYSTEM PERFORMANCE IS TAKEN CARE OF BY EXCITATION SYSTEM.CARE OF BY EXCITATION SYSTEM.

IN ORDER TO MAINTAIN SYSTEM IN ORDER TO MAINTAIN SYSTEM STABILITY IT IS NECESSARY TO STABILITY IT IS NECESSARY TO HAVE VERY FAST RESPONSEHAVE VERY FAST RESPONSE

FEATURES OF FEATURES OF EXCITATION SYSTEMEXCITATION SYSTEM

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EXCITATION SYSTEM FOR LARGE EXCITATION SYSTEM FOR LARGE SYNCHRONOUS MACHINE SYNCHRONOUS MACHINE OPERATING WITH THE GRID.OPERATING WITH THE GRID.

HIGH CONTROL SPEED IS HIGH CONTROL SPEED IS ACHIEVED BY USING INERTIAL ACHIEVED BY USING INERTIAL FREE CONTROL AND POWER FREE CONTROL AND POWER ELECTRONICS.ELECTRONICS.

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BUS-1CB

BUS-2

GCB

GENERATOR TRANSFORMER

UAT

AVR

REF. VOL.

GGENERATOR

R

EXC.TR.

PT

GATECONTROL

NGTDR

FB

G

F.F

A.C

D.C

CT

CONTAINS FIELD BREAKER CONTROL CONTAINS FIELD BREAKER CONTROL LOGIC, THYRISTOR PANELS AND AVRLOGIC, THYRISTOR PANELS AND AVR

EXCITATION PANELEXCITATION PANEL

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CONSTANT EXCITATION : WATER CONSTANT EXCITATION : WATER FLOW INCREASEFLOW INCREASE

When water flow is increased When water flow is increased advances to advances to ’ along ’ along the the arc of radius ‘E’ and centre ‘O’.arc of radius ‘E’ and centre ‘O’.

This results in increase in power from the original This results in increase in power from the original value value due to increase in due to increase in ..

I’x shifts in phase and magnitude pf. Increases.I’x shifts in phase and magnitude pf. Increases.

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CONSTANT POWER : CONSTANT POWER : VARYING EXCITATIONVARYING EXCITATION

I cos ?

V

I 'X

E

IX

Constant power line will be a straight line parallel to x-Constant power line will be a straight line parallel to x-axis axis (I cos op = Constant)(I cos op = Constant)

• If excitation is varied E moves on constant power If excitation is varied E moves on constant power line, varying the phase position and magnitude of line, varying the phase position and magnitude of current.current.

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EXCITATION CONTROLEXCITATION CONTROL

POWER-ANGLE CURVE FOR VARYING EXCITATION LEVELSFIG.3(b)

d30° d2 d1

Pe.

P

90°180°

d2 d3d1> >d

EXCITATIONINCREASES

It is not advisable under any It is not advisable under any circumstances to operate large unit on circumstances to operate large unit on Manual control.Manual control.

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If unavoidable, keep highest If unavoidable, keep highest permissible permissible terminal voltage and terminal voltage and lagging Power factor.lagging Power factor.

If the machine is synchronized with If the machine is synchronized with the the AVR set point to match the rated AVR set point to match the rated terminal terminal voltage and in Auto control then voltage and in Auto control then during during loading no operator intervention loading no operator intervention is is necessary.necessary.

The excitation change occurs The excitation change occurs automatically.automatically.

Continued-----Continued-----

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VIxt

E

VtVt'

EN

P1

Ixd

I 'X

E

P2

Continued-----Continued-----

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When water flow is increased from When water flow is increased from level level P1 to P2. E shifts in phase to P1 to P2. E shifts in phase to increase the increase the load angle.load angle.

This causes a drop in terminal This causes a drop in terminal voltage Vt.voltage Vt.

AVR acts to increase E so that V’AVR acts to increase E so that V’tt = V= Vt t ..

This results in increase in E, I and This results in increase in E, I and phase phase advancements of E and Eadvancements of E and ENN to to the new the new operating point.operating point.

Continued-----Continued-----

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OBJECTIVESOBJECTIVES GOOD RESPONSE IN VOLTAGE AND GOOD RESPONSE IN VOLTAGE AND

REACTIVE POWER CONTROL.REACTIVE POWER CONTROL. SATISFACTORY STEADY STATE SATISFACTORY STEADY STATE

STABILITY i.e. SUFFICIENT CLAMPING STABILITY i.e. SUFFICIENT CLAMPING OF ELECTRO - MAGNETIC & OF ELECTRO - MAGNETIC &

ELECTRO - MECHANICAL TRANSIENT. ELECTRO - MECHANICAL TRANSIENT. TRANSIENT STABILITY FOR ALL STATED TRANSIENT STABILITY FOR ALL STATED

CONDITIONS.CONDITIONS. QUICK VOLTAGE RECOVERY AFTER QUICK VOLTAGE RECOVERY AFTER

FAULT CLEARANCE.FAULT CLEARANCE.

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CAPABILITY CURVECAPABILITY CURVE

CURVE-1 : STATOR CURRENT LIMIT

CURVE-2 : ROTOR CURRENT LIMIT

CURVE-3 : STABILITY LIMIT

UNDER EXCITED : (- Q) OVER EXCITED : (+ Q)

Pn

M1/Xs Qn

I

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THANKS