technical session ii

8/3/2019 Technical Session II

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Overview of Wind Turbine Technology

S.ARULSELVANC-WET


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Wind Energy..

Wind turbines - a successful technology for

clean and safe production of electricity. Fastest growing renewable energy source.

Globally recognized as environment friendly and

sustainable.

Emerging as a economically competitive source

of energy.

Technology is matured.

Wind energy will never run out, is freely

available and causes no pollution.

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Wind as a source of energy

Wind is air in motion.

It has a mass.

A mass in motion has a momentum

Momentum is a form of energy that canbe harvested.

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Wind Wind energy relies on sun. Wind is

created by uneven heating of the earths

surface.

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Global creation of Winds

Uneven heating of the earth'ssurface. When sun hits one

part of the earth more

directly, it warms that partup. The warm air rises andcooler air rushes in, creatingwind.

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Turbine Evolution

Used for Pumping water

Grinding grain

Presently used for Generating Electricity

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Is it new technology?

9th Century Milling grain

13th Century

Post wind mill by Germans16th Century Dutch type wind mill by Holland

17th Century Euler conducted aerodynamic experiments

1890 Poul La Cour came with aerodynamic blade design

1891 First electricity producing wind turbine

1910

Wind mill becomes popular in Europe1980 Green energy decade for California

1986 First wind mill installed in India (Gujarat)


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Wind Energy

A wind energy system transforms the kineticenergy of the wind into mechanical orelectrical energy that can be harnessed forpractical use.

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Review of Power and Energy Relationships

Force= mass x acceleration F = ma

Typical Units Pounds, Newtons

Energy= Work (W) = Force (F) x Distance (d)

Typical units - kilowatt hours, Joules, BTU

Power= P = W / time (t)

Typical units kilowatts, Watts , Horsepower

Power= Torque(Q) x Rotational Speed()

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Kinetic Energy in the Wind

Kinetic Energy = Work = mV2

Where:

M= mass of moving object

V = velocity of moving object

What is the mass of moving air?

= density () x volume (Area x distance)

= x A x d

= (kg/m3) (m2) (m)

= kgV

A

d

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Power in the Wind

Power = Work / t

= Kinetic Energy / t

= mV2 / t

= (Ad)V2/t

= AV2(d/t)

= AV3

d/t = V

Power in the Wind = AV3

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A couple things to remember

Swept Area A = R2 (m2) Areaof the circle swept by the rotor.

= air density in India its

about 1.225-kg/m3

Power in the Wind = AV3

R

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Wind Turbine Power

Power from a Wind Turbine Rotor =CpAV

3

Cp is called the power coefficient. Cp is the percentage of power in the windthat is converted into mechanical energy.

What is the maximum amount of energythat can be extracted from the wind?

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The Betz Limit A maximum of 59.26% of the available

wind power can be converted tomechanical power at ideal conditions

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Wind Energy Conversion

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Power Conversion

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Axis of orientation- Vertical AxisAdvantages Omnidirectional

Accepts wind from any angle

Components can be mounted atground level Ease of service Lighter weight towers

Can theoretically use less materials tocapture the same amount of wind

Disadvantages Rotors generally near ground where

wind poorer Centrifugal force stresses blades Poor self-starting capabilities Requires support at top of turbine

rotor Requires entire rotor to be removed to

replace bearings Overall poor performance and

reliability Have never been commercially

successful

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Axis of orientation- Horizontal Axis

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Rotor Position

DOWN WIND TURBINEUPWIND TURBINE

WindWind

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Mechanical-electrical functional diagram

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COMPONENTS

1. ROTOR

2. DRIVE TRAIN

3. TOWER

4. CONTROL SYSTEM

5. YAW SYSTEM

6. MAIN FRAME

7. NACELLE Yaw system

Gearbox

Brake

Coupling

Generator

Cooler

Main shaft

Metrologicalinstruments

Mainbearing

Hub withspinner

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WIND TURBINE COMPONENTS

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Wi d T bi C


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Wind Turbine Components Rotor, or blades, which convert the wind's

energy into rotational shaft energy. Nacelle (enclosure) containing a drive train,

usually including a gearbox (Some turbinesoperate without a gearbox) and a generator.

Tower, to support the rotor and drive train;and

Electronic equipment such as controls,electrical cables, ground support

equipment, and interconnection equipment

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Rotor -Comprises of all turning

parts of the unit outside the

nacelle

Rotor Blade

The hub

Blade pitch mechanism

ROTOR

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ROTOR AERODYNAMICS

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ROTORBLADE SECTION

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Turbine Power

(source: Manwell et. al Wind Energy Explained)

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How does the Turbine Rotate


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How does the Turbine Rotate

The pressure difference makes the turbine rotate

Low pressure

High pressureLift

Lift

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Airfoil Nomenclature


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Airfoil Nomenclature

wind turbines use the same aerodynamic principals as aircraft

VR = Relative Wind

= angle of attack = angle between the chord line and the direction of therelative wind, VR .

VR = wind speed seen by the airfoil vector sum of V (free stream wind) and R(tip speed).

V

R r

V

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Rotor Elemental Torque

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Lift & Drag Forces


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Lift & Drag Forces

The Lift Forceisperpendicular to thedirection of motion.We want to make this

force BIG.

The Drag Forceis

parallel to the directionof motion. We want tomake this force small.

= low

= medium


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POWER CONTROL

Power Control throughAerodynamic

(Angle of attack, Pitch angle, Lift & Drag)

Stall control

Pitch control

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PITCH CONTROL


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PITCH CONTROL

STALL CONTROL


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STALL CONTROL

Wind Turbines: Number of Blades


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Wind Turbines: Number of Blades

Most common design is the three-bladed turbine. The most

important reason is the stability of the turbine. A rotor with an oddnumber of rotor blades (and at least three blades) can be considered to

be similar to a disc when calculating the dynamic properties of the

machine.

A rotor with an even number of blades will give stability problems

for a machine with a stiff structure. The reason is that at the verymoment when the uppermost blade bends backwards, because it gets

the maximum power from the wind, the lowermost blade passes into

the wind shade in front of the tower.

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ROTOR BLADE-MATERIAL


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Materials - Al, Titanium, Steel, Fiber reinforced composite material

Fiber reinforced composite Material bladescurrently used in almost all WT structure

Types:

Glass fiber,

Carbon fiber,

Organic aramid fiber (Kevlar)Mostly use glass fiber -Strength properties are extraordinarily high

Carbon fibers

Has longest tearing strength

High modules of elasticity The stiffness of carbon fiber components is comparable to that of

steel

Fatigue properties are good

ROTOR BLADE MATERIAL

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THE HUB


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Rigid hub

all major parts fixed

relative to the main shaft

in which blade pitch can be

varied

no other blade motion is

allowed The main body of the rigid

hub casting or weldment to

which the blades are attached

THE HUB

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Pitching the blades individually


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Pitching the blades individually

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complete wind turbine drive train consist of all the

rotating components

1. Main shaft

2. Coupling

3. Gearbox

4. Brake

5. Generator

Drive Train

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SHAFT


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cylindrical element designed to rotate

transmit torque

attached to the gear pulley and couplings

wind turbine shafts are especially found in

gearboxes, generators and linkages

SHAFT

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MAIN SHAFT / LOW SPEED SHAFT /


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MAIN SHAFT / LOW SPEED SHAFT /

ROTOR SHAFT

transfer torque from the

rotor to the rest of the

drive train and transfer of

all other loads to the nacelle

structure supports the weight of the

rotor

made of steel

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Connecting shaft of the gearbox outlet to the

electric generator rotates with nominal speed of

1500 RPM

fitted with flexible coupling at each end to cater

for small misalignment between generator and gearbox

HIGH SPEED SHAFT

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GEARBOX

Increase the speed of the

input shaft to the

generator

Single heaviest and most

expensive component in a

wind turbine

Types:1) Parallel shaft gearboxes

2) Planetary gearboxes

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PARALLEL SHAFT GEARBOXES

Gears are carried on two or more parallel

shafts

shafts are supported by bearing

Limit to the speed up ratio

To achieve higher speed up ratio, multiple

stages are placed in series

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PLANETARY GEARBOXES

input and output shafts

are co- axial

There are multiple pairs of

gear teeth meshing at anytime

Loads on each gear reduced

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PLANETARY GEARBOXES

Ring wheel

Planet wheel

carrier arm Planet carrier rotates with the samerotational speed of the rotor

blades

Three planet wheel turn around inner

circumference of the ring wheel Increase the speed of the sun wheel

Advantageous:

Always three gear wheels supporting

each other and that all gear wheelsare engaged at the time

in principle it only needs to about a 1/3

of the size

sun wheel

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Classification of Generators


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Classification of Generators

According to the Principle of operation

ASYNCHRONOUS TYPE

SYNCHRONOUS TYPE

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INDUCTION GENERATOR


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INDUCTION GENERATOR

Construction Stator

Rotor

i. slip ringii. Squirrel cage

Working PrincipleNs=120.f/P

Ns-Synchronous speed

% of slip = (Ns-N/Ns)*100

N-Rotor speed

N= Ns (1+s) for generator

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Slip-Torque Characteristic of Induction Machine


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Slip-Torque Characteristic of Induction Machine

P = (2NT / 60)

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CONDITION FOR MAXIMUM TORQUE


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CONDITION FOR MAXIMUM TORQUE

R2=sX2

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Direct grid connected SCIG

Soft

starter

Gearbox

SCIG

Transformer GridCapacitor

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CONVENTIONAL METHOD


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P P P

CONVENTIONAL METHOD

Q

Directly Grid connected SGIG

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NOV 20 2010

Various wind turbine concepts usingasynchronous (induction) generators

Induction generator (WRIG) with slip control

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Directly Grid Connected


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Directly Grid Connected

ADVANTAGES&

DISADVANTAGES

Main advantages

Simple and low cost

Cheap, low maintenance

Main Drawbacks

Low wind energy conversion efficiency

Poor power factor

Power fluctuation output

High mechanical stress on turbine components

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Doubly fed induction generator

Reduced-capacity

converter Transformer GridGearbox

DFIG

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Doubly FED Induction generator-Sub synchronous Operation


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50 Hz

60 x frequency

number of pole pairsrpm =

Rotational speed6-poled stator

Stator field = 1000 rpm

Synchronizing with frequency


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50 Hz

AC

DC AC

DC


Rotor mechanically = 900 rpm

Rotor field = +100 rpm

Doubly FED Induction generator-Super synchronous Operation


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50 Hz

60 x frequency

number of pole pairsrpm =

Rotational speed6-poled stator




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50 Hz

AC

DC AC

DC


Rotor mechanically = 1100 rpm

Rotor field = -100 rpm


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Doubly fed induction generator

The configuration known as DFIG (Double fed induction

generator) correspond to the WRIG (Wound rotor induction

generator) with partial scale frequency converter

The partial scale frequency converter performs the reactive

power compensation and ensures smoother grid connection The generator has a wider range of speed control, e.g.,

(-40% to +30%) around the synchronous speed (wider than

OptiSlip)

The use of slip rings and protection in case of grid faults is

a major drawback

Variable speed operation is obtained by injecting a

controllable voltage into the rotor at the desired frequency

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Doubly fed I.G


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Doubly fed I.G

Advantages and disadvantages

Advantages

Reduced-capacity converter (cost, efficiency)

Decoupled control of active/reactive power

Smooth grid connection

Disadvantages Regular maintenance of slip ring and gearbox

Limited fault ride-through capability

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ync ronous enerator-


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yConstruction

Rotor

Salient Cylindrical

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Types of Synchronous


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Types of Synchronous

Generator

Electrically excited synchronousgenerator

Permanent magnet synchronousgenerator

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Variable Speed Generator

Direct Rotor Driven Generators

Gearbox

G

Transformer Grid

Fullpower

converter


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Variable Speed Turbines with Full Converter

Parallel VSC converters

High power applications with low voltage (e.g. 690V)

Redundancy

Loss optimized (slave converter disabled at low wind speeds

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COMPARISON BETWEEN DIFFERENT WIND GENERATOR

CONCEPTS

World share of yearly installed wind power

for different wind turbine concepts.

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Control and Protection systems


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y

Generator,

converter and

power control

Pitch system

Start, stop and

sequencing Surveillance

Increasing use of advanced electronics for

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Why do we need a control!

the primary energy source is non linear andunpredictable.

Increase in wind speed develops an enormouspower in rotor To be optimized

To transfer the electrical power to the grid at animposed level, for wide range of wind velocities.

To meet power quality requirements

To detect the abnormal conditions and preventing

the wind turbine from possible dangeroussituations

Achieve desired function and Safe Operation

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Control system


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Control system consists of

Various sensors, Transducers and Limit

switches (input) PLC (Process)

Circuit breakers, Converters, contactorsand relays (output)

Set point list

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Important functions of Controlsystem

Alignment to the wind by YawingStart-up and shutdown procedure

Connection of the electrical load

Rotor speed Control

Power limitation

Cable twist limits

Temperature control

Control system

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Transition states Steady State

SYSTEM CHECK

START

Grid Connection

Grid Disconnection

Shutdown

Ready To start

Power Production

Freewheeling

Emergency Shutdown

General Sequence

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What is a protection system

Priority

Fail safe

Single failure and non-safe-life components Two or more failure interdependent

PROTECTION SYSTEM

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PROTECTION SYSTEM

The protection system shall beactivated in such cases as,

Over-speed

Generator overload or fault

Excessive vibration

Abnormal cable Twist

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BRAKING SYSTEM

The braking system shall beclassified into

Aerodynamic braking

Mechanical braking

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BRAKE


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minimum requirement to act as a parking brake

Used for parking the rotor for maintenance purpose

during high wind it bring the rotor to stand still

calipers gripping a brake

brake pads are generally made from sintered metal orresin based material

BRAKE

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BRAKE


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BRAKE

PARTIAL SPAN PITCH CONTROL

Inner part of the blade is fixed relative

to the hub

outer part is mounted on bearings,and

can be rotated about the radial

axis of the blade

Advantageous;

Pitching mechanism need not be aspassive as it must be full span pitch

control

AERODYNAMIC BRAKING SYSTEM

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BRAKE


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TIP BRAKE: function as air brakes

blade tip is fixed on a carbon fiber shaftmounted on a bearing inside the main bodyof the blade

during operation the tip is held fast

against the main blade by a hydrauliccylinder.

effectively stop the diving force of theblades

BRAKE

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BRAKE


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SPOILERS:

Intentionally deployed to create a

carefully controlled stall over part of

a

blade in order to lift it generate.

BRAKE

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NACELLE


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The nacelle cover is the wind

turbine housing Protects turbine

components from weather

Reduces emitted mechanical soundMaterial

G-FRC glass-fiber reinforced

composite materials

On larger Machines it has a holethat it can be entered personal for

inspector (or) maintains the

internal components.

NACELLE

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MAIN FRAME


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Transfer the rotor loading to the yaw bearing and to

provide mountings for the gearbox and generator

either welded beam or casted

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Yaw Control


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Rotate the nacelle with respect to the tower

on its slew bearing

keep the turbine facing in the wind

unwind the power and other cables

Wind Vane on nacelle tells controller

which way to point rotor into the wind

Yaw drive turns gears to point rotor intowind

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YAW DRIVE


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Rotate the nacelle with respect to the tower on its slew bearing

keep the turbine facing in the wind

unwind the power and other cables

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TOWER


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One of the main components ofthe HAWT

Raises turbine up in the air

Ensures blade clearance

Types

Free standing lattice (truss)

Cantilever pipe (tubular

tower)

Guyed lattice or pole

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TOWER


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STEEL LATTICE TOWERS:

Usually assembled from angle section towers are square in plan with tower legs

facilitating the attachment of the bracing

members

Advantageous:

Material saving can be obtained

CONCRETE TOWERS:

In the thirties steel reinforced concrete

towers were used Aerometers

concrete towers are built either conventionalre-inforced concrete towers or pre stressed

concrete towers

Tower should have

Maximum strength ,fatigue

strength,stiffness,buckling criterion

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FOUNDATION


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TOWER FOUNDATION:

The foundation of a Wind turbine must be sufficient to keep the turbine

upright and stable under the most extreme design conditions

at most sites ,the foundation is constructed as a reinforced concrete pad

Installation on rock: rods grouted into holes drilled deep in to the rock

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Types of Foundations

Gravity Based raft foundations Square / Rectangle

Hexagonal

Gravity type pile foundations Inclined pile foundation

Vertical pile foundation

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RCC for Raft Foundation Mounting Part

(FMP)Part CuM Mix Ratio Bags of cementPoured

PCC 16 1:2:4 91

Raft 258 1 : 1.483 : 2.285 2080

Pedestal 40 320

Total Bags of cement 2491 Bags

Top dia. of Tower 2.968 mtrs Qty. of Steel 34.7 Tons

Total wt. of Nacelle 65 Tons Volume of Raft 258.67 CuM

Total wt of Tower 132 Tons Volume of 40 CuM11.02.2011


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OFFSHORE FOUNDATIONMonopile

Monopile

Tripod

Gravity base

Advantages: Fast and highlyautomatedinstallation

No prior

preparation of seabed is required

Simple fabrication

Consist of three basicparts:

Bare pile

Conical transitionthe the Tower that itsupports

Boat landing Planto the pile andprovides a basis forthe J-tube that carriesthe power cable tothe sea bed of thewind turbine.

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OFFSHORE FOUNDATION

Tripod

Tripod foundation threelegged steel jacket

light in weight and cost

efficient 3 piles are driven 10 to 20 Mt.in to the sea bed depending onsoil conditions and ice loads.

Advantages:

3 legged model is suitable forlarger water depths

Minimum preparations arerequired at site before

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OFFSHORE FOUNDATION

Tripod with Suction Buckets

As an alternative to use threepiles to support the tripodstructure and transfer loads to

the soil suction buckets can beused.

One suction bucket thensupport each of three tripodlegs.

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CENTRE FOR WIND ENERGY TECHNOLOGY


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CHENNAI

OFFSHORE FOUNDATION

Floating Foundation

Typical view of the buoyant floatingfoundation of wind turbine

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The worlds largest wind turbine 7.5 MW
http://www.freepatentsonline.com/7156586-0-large.jpg


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Now Enercon E-126.rotor diameter - 126 meters (413 feet)135 m hub height

20 million kilowatt hours per year

Swayand Enova, NorwayGoing to build a 10MW wind-turbineblade diameter at 145m (476ft)Hub height 162.5m (533ft).

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Grid Parameters
http://www.metaefficient.com/goto/AmazonWindEnergy/


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VOLTAGE :+10%

FREQUENCY :-3HZ

+1HZ

ASYMMETRYCURRENT :+12.5%

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Indian Power Scenario


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India's total installed capacity

as on July 31, 2010

1,63,669.80 MW

Thermal power - 105646.98 MW

Hydro power plants - 37,033.40 MW

Renewable energy - 16,429.42 MW

Nuclear energy - 4,560.00 MWWind Energy 12000 MW

Source : CEA

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Total Installed Capacity in India


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Fuel MW Percentage

Total Thermal 1,05,646.98 64.6 %

Coal 87,093.38 53.3 %

Gas 17,353.85 10.5 %

Oil 1,199.75 0.9 %

Hydro (Renewable) 37,033.40 24.7 %

Nuclear 4,560.00 2.9 %

RES** (MNRE) 16,429.42 7.7 %

Total 1,63,669.80

Coal,87093.38

Gas, 17353.85

Oil, 1199.75 Hydro(Renewable),

37033.40

Nuclear,4560.00

RES**(MNRE),16429.42

Total 163669.80

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Wind Installed capacity - Top 5


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U.S.A 36220 MW

China 25805 MW

Germany 25704 MWSpain 19450 MW

India 11807 MW

U.S.A, 36220

China, 25805

Germany,25704

Spain, 19450

India, 11807

Total 162,545 as on 31.07.2010

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Wind Power Installed Capacity in India


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Sl.No State Capacity in MW

1 Tamil Nadu 4906.74

2 Karnataka 1472.75

3 Maharashtra 2077.74 Rajasthan 1088.37

5 Andhra Pradesh 136.05

6 Madhya Pradesh 229.39

7 Kerala 27.75

8 Gujarat 1863.64

9 West Bengal 1.1

10 Others 3.2

Total 11806.69

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Total 11806.69 as on 31.03.2010

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IPP

TNEB Wind 17MW

Gas

ThermalHydro

214 MW

CGS

CPP

1180 MW

3130 MW

2187 MW 2970MW

517 MW

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Size revolution


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Size revolution

1985 1995 2005

?2020

55 kW

600 kW

4-5 MW

20-40 MW ?

2011

7.5 MW

Essential requirements


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- High Wind Resources at particular site- Adequate land availability

- Suitable terrain and good soil

conditions

- Proper approach to site

- Suitable power grid nearby

- Techno-economic selection of WEG

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Advantages of Wind Energy


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No fuel cost

Environment friendly and pollution free Potential exists to harness wind energy

Lowest gestation period and capacity addition can be

in modular form

Cost of generation reduces over a period of time Low of O&M Costs

Limited use of land

Accommodation of other land uses

Employment

New market

Local Infrastructure development

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Social Benefits


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Increase in land price

Roads in rural areas

Better employment potential

More number of schools, colleges and

hospitals Improvement in standard of living

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Limitations of Wind Energy


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Located only where strong and dependable

winds are available.

Wind is intermittent and hence infirm power.

Wind towers and blades subject to damage

from very high wind and lightning.

Environmental disadvantages on a local orneighborhood level, include:

Visual impact on landscape Noise emission Moving shadows

Impact on birds Interference with electromagnetic

communication Personal safety

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technical session ii

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