Power from wind in india

WIND ENERGY ENGINEERING Wind Electric Conversion Systems

* Wind Energy Availability

• Energy in wind, speed

• Wind Turbine, Design

• Variables – wind power density

• Generator and power output

• PV-Wind, Diesel-set-Wind Hybrid System

• Tower design

• Wind Electric Conversion System

economics

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Wind Energy Engineering Syllabus-1

Wind energy Assessment by Measurement and instrumentation – Beaufort number -Gust parameters – Wind type – power law index -Betz constant -Terrain value.

Energy in wind– study of wind data and applicable Indian standards – Steel Tables, Structural Engineering for tower design- Wind farms–– fatigue stress – Tower design.

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Wind Energy Engineering Syllabus-2

Wind Energy Conversion Systems: Variables – wind power density – power in a wind stream – Wind turbine efficiency – Forces on the blades of a propeller –Solidity and selection curves.

Horizontal Axis –WT and Vertical Axis -WT-Power duration curves- wind rose diagrams -study of characteristics - actuator theory- Controls and instrumentations.

Grid-Connected WECS and Independent WECS- Combination of WECS and diesel generator, Battery storage – Wind Turbine Circuits.

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CL 716 WIND ENERGY

ENGINEERING: Text & Reference Books

1. S. Rao & B. B. Parulekar, “Energy Technology”, 3rd Edition, Khanna publishers, 1995.

2. Wind and Solar Power Systems, Mukund. R. Patel, 2nd Edition, Taylor & Francis, 2001

3. Wind Energy Handbook, Edited by T. Burton, D. Sharpe N. Jenkins and E . Bossanyi, John Wiley & Sons, N.Y. 2001

4. . L .L. Freris, Wind Energy Conversion Systems, Prentice Hall, 1990.

5. D. A. Spera, Wind Turbine Technology: Fundamental concepts of Wind Turbine Engineering, ASME Press

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From wind to electricity.

The first wind powered electricity was produced in

1888. It had a rated power of 12 kW (direct current - dc).

In the 1930's the first large scale AC turbine was constructed

in the USA.

In the 1970's the fuel crises sparked a revival in R & D

work in America (USA and Canada) and Europe (Denmark,

Germany, the Netherlands,Sweden and the UK) and

modern wind turbine-generators were developed. This was

achieved due to improvements in aerodynamic and

structural design, materials technology and mechanical,

electrical and control engineering and led to capablilty to

produce several megawatts of electricity.

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Wind power is

economically viable.

Over the last two decades, there has been a tremendous amount of technical improvement in wind turbines. Their costs have increased by about a factor of 9, due to more advanced controls, materials, and engineering, but at the same time their energy production has increased by a factor of 56, leading to a net decline in the cost per watt of a factor of more than six. Wind power is thus rapidly becoming economically viable.

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Kinetic energy >

Mechanical

[Rotational] >

Electrical energy

Wind turbines convert the

kinetic energy in wind into

mechanical power that runs a

generator to produce

electricity.

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horizontal-axis vs vertical-axis

There are two basic designs of wind electric

turbines: vertical-axis, or "egg-beater" style,

and horizontal-axis (propeller-style)

machines.

Horizontal-axis wind turbines are most

common today, constituting nearly all of the

"utility-scale" (100 kilowatts, kW, capacity and

larger) turbines in the global market.

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Wind power for developing countries

Large-scale grid connected wind turbines are common with wind farm; This can be the main national network, in which case electricity can be sold to the electricity utility.

Micro-grids distribute electricity to smaller areas, typically a village or town. When wind is used for supplying electricity to such a grid, a diesel generator set is often used as a backup for the periods when windspeeds are low.

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Figure: The Practical Action small

wind turbine ©Practical Action

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Performance of WECS

The availability of wind resources are

governed by the climatic conditions of the

region concerned- for which wind survey is

extremely important to exploit wind energy.

Performance of W E C S depends upon:

Subsystems like

wind turbine (aerodynamic),

gears (mechanical),

generator (electrical) and Control (electronic)

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Wind Electric Potential in India

Gross Potential: 45,000 MW

Technical Potential:13,000 MW

Sites with Annual Average Wind

Power Density > 200 watts/m2

generally viable, 208 such sites

in 13 states identified

States with high potential :

Gujarat, Andhra Pradesh,

Tamil Nadu, Karnataka,

Kerala, Madhya Pradesh,

and Maharashtra.

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India’s Installed Wind Power

Gen Capacity at end of 2001

State Installed capacity, MW

Tamil Nadu 828

Maharashtra 236

Gujarat 167

Andhra 92

Karnataka 50

M.P. 23

All Others 111

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Wind resources

Apart from having a good wind turbine, the

most critical aspects for the success of

investment in the wind energy sector are

having a good site and

an accurate assessment of the wind

resource at the site.

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Wind Resource Monitoring

Site selection

Wind Monitoring

Wind Resource Mapping

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Choosing an exact location for the

monitoring tower:

Place the tower as far away as possible

from local obstructions to the wind

Select a location that is representative of

the majority of the site.

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anemometer

An instrument for measuring the force or velocity of wind. There are various types:

A cup anemometer, is used to measure

the wind speed from the speed of rotation

of a windmill which consist of 3 or 4

hemispherical or conical cups, each fixed

to the ends of horizontal arms attached to

a vertical axis.

A Byram anemometer is a variety of cup

anemometer.

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A counting anemometer has cups or a fan whose

rotation is transmitted to a counter which integrates

directly the air movement speed.

A hand anemometer is small portable anemometer

held at arm's length by an observer making a wind

speed measurement.

A pressure tube anemometer (Dines anemometer)

is an instrument that derives wind speed from

measurements of the dynamic wind pressures. Wind

blowing into a tube develops a pressure greater

than the static pressure, while wind blowing across

a tube develops a pressure less than the static. This

pressure difference is proportional to the square of

the wind speed.

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WIND

Wind Speed at 10 m height

SPEED

Beaufort scale

SCALE

Wind

0.0-0.4 m/s (0.0-0.9 knots) 0 Calm

0.4-1.8 m/s (0.9-3.5 knots) 1 Light

1.8-3.6 m/s (3.5-7.0 knots) 2 Light

3.6-5.8 m/s (7-11 knots) 3 Light

5.8-8.5 m/s (11-17 knots) 4 Moderate

8.5-11 m/s (17-22 knots) 5 Fresh

11-14 m/s (22-28 knots) 6 Strong

14-17 m/s (28-34 knots) 7 Strong

17-21 m/s (34-41 knots) 8 Gale

21-25 m/s (41-48 knots) 9 Gale

25-29 m/s (48-56 knots) 10 Strong Gale

29-34 m/s (56-65 knots) 11

>34 m/s (>65 knots) 12 Hurricane

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For wind data from selected stations,

essential attributes are:

Station location

Local topography

Anemometer height and exposure

Type of observation (instantaneous or

average)

Duration of record.

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Topographic maps

provide the analyst with a preliminary look

at other site attributes, including:

Available land area

Positions of existing roads and dwellings

Land cover (e.g., forests)

Political boundaries

Parks

Proximity to transmission lines.

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For verifying site conditions items of

importance include:

Available land area

Land use

Location of obstructions

Trees deformed by persistent strong winds (flagged

trees)

Accessibility into the site

Potential impact on local aesthetics

Cellular phone service reliability for data transfers

Possible wind monitoring locations.

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Cost – economics-1

The cost of producing electricity form the wind is

heavily dependent on the local wind regime.

The power output from the wind machine is

proportional to cube of the windspeed and so a

slight increase in windspeed will mean a

significant increase in power and a subsequent

reduction in unit costs.

Capital costs for windpower are high, but running

costs are low and so access to initial funds,

subsidies or low interest loans are an obvious

advantage when considering a wind-electric

system.

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Cost – economics-2

If a hybrid system is used a careful cost-

benefit analysis needs to be carried out.

A careful matching of the load and

energy supply options should be made to

maximise the use of the power from the

wind - a load which accepts a variable

input is ideally matched to the intermittent

nature of windpower.

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WIND RESOURCE ASSESSMENT-

India- Implemented through :

(i) State Nodal Agencies

(ii) Centre for Wind Energy Technology (C-

WET)

Financial Assistance :

(i) Full establishment costs of Wind Resource

Assessment Project (WRAP) of C-WET by

the Central Government.

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WIND RESOURCE ASSESSMENT

Implemented through…. :

(ii) The cost of setting up the wind monitoring

stations would be shared between MNRE

and State Nodal agencies in 80:20 ratio,

except for North-eastern and hilly States,

where it would be in 90:10 ratio.

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Resource Survey in India

Centre for Wind Energy Technology (C-WET)

Chennai.

6 Volumes of “Wind Energy –Resource Survey in

India” , containing wind data have been published

Master Plans for 87 sites prepared and available

from C-WET at nominal cost.

Wind data available from C-WET on CD ROM.

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Government of India

Ministry of New and Renewable Energy

(Wind Power Division)

Block No.14, CGO Complex,

Lodhi Road, New Delhi – 110003

•C-WET would evaluate the eligibility of manufacturer, who approaches for Type. Certification, as per the evaluation criteria in vogue, which is being followed by C-WET. •Validity of Self-Certification facility for models specified in the List of Models and Manufacturers thereof issued by C-WET is extended up to 30th September, 2007. •Self-Certification facility would be available for a maximum period of 18 months from the date of signing of the agreement with C-WET for the models hereinafter including in the category "Model under Testing and Certification at C-WET" in the List to be issued by C-WET.

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Wind Turbine, tail, support tower

The amount of power a turbine will

produce depends primarily on the

diameter of its rotor.

The diameter of the rotor defines its

“swept area,” or the quantity of wind

intercepted by the turbine.

The turbine‟s frame is the structure onto

which the rotor, generator, and tail are

attached. The tail keeps the turbine

facing into the wind.

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Wind Turbine, tail, support tower

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Horizontal Axis upwind

Wind Turbine

Most turbines today are Horizontal Axis

upwind machines with two or three

blades, made of a composite material like

fiberglass.

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Some definitions: Solidity: In reference to a wind energy

conversion device, the ratio of rotor blade surface area to the frontal, swept area that the rotor passes through.

wind rose: A diagram that indicates the average percentage of time that the wind blows from different directions, on a monthly or annual basis.

power curve: A plot of a wind energy conversion device's power output versus wind speed.

power coefficient: The ratio of power produced by a wind energy conversion device to the power in a reference area of the free wind stream.

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CEESAT NITT NOTES 46

The formula for calculating the

power from a wind turbine is:

CEESAT NITT NOTES 47

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Some definitions….

1 m/s = 3.6 km/h = 2.237 mph = 1.944 knots

1 knot = 1 nautical mile per hour = 0.5144 m/s =

1.852 km/h = 1.125 mph

average wind speed: The mean wind speed over a

specified period of time.

PITCH CONROL: A method of controlling the

speed of a wind turbine by varying the orientation,

or pitch, of the blades, and thereby altering its

aerodynamics and efficiency.

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Tip Speed Ratio

The tip-speed is the ratio of the rotational speed

of the blade to the wind speed. The larger this

ratio, the faster the rotation of the wind turbine

rotor at a given wind speed. Generation requires

high rotational speeds. Lift-type wind turbines

have maximum tip-speed ratios of around 10.The

tip speed ratio (λ = ΩR/v), R Wind turbine blade

radius (m), Ω Wind turbine rotor angular speed

(rpm), v Wind speed [m/s].

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Operating Characteristics

All wind machines share certain operating

characteristics, such as cut-in, rated and cut-out wind speeds.

Cut-in Speed Cut-in speed is the minimum wind speed at which the wind turbine will generate usable power. This wind speed is typically between 7 and 10 mph.

Rated Speed The rated speed is the minimum wind speed at which the wind turbine will generate its designated rated power. For example, a "10 kilowatt" wind turbine may not generate 10 kilowatts until wind speeds reach 25 mph. Rated speed for most machines is in the range of 25 to 35 mph.

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Rated Speed…

At wind speeds between cut-in and rated, the

power output from a wind turbine increases

as the wind increases. The output of most

machines levels off above the rated speed.

Most manufacturers provide graphs, called

"power curves," showing how their wind

turbine output varies with wind speed.

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Cut-out Speed

At very high wind speeds, typically between

45 and 80 mph, most wind turbines cease

power generation and shut down. The wind

speed at which shut down occurs is called

the cut-out speed. Having a cut-out speed is

a safety feature which protects the wind

turbine from damage. Shut down may occur

in one of several ways. In some machines an

automatic brake is activated by a wind speed

sensor.

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Cut out speed & yaw

Some machines twist or "pitch" the blades to

spill the wind. Still others use "spoilers," drag

flaps mounted on the blades or the hub which

are automatically activated by high rotor

rpm's, or mechanically activated by a spring

loaded device which turns the machine

sideways to the wind stream. Normal wind

turbine operation usually resumes when the

wind drops back to a safe level.

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number of blades

The number of rotor blades and the total area they

cover affect wind turbine performance. For a lift-

type rotor to function effectively, the wind must flow

smoothly over the blades.

To avoid turbulence, spacing between blades

should be great enough so that one blade will not

encounter the disturbed, weaker air flow caused by

the blade which passed before it.

It is because of this requirement that most wind

turbines have only two or three blades on their

rotors

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Transmission- Gear box

The number of revolutions per minute (rpm)

of a wind turbine rotor can range between

40 rpm and 400 rpm, depending on the

model and the wind speed.

Generators typically require rpm's of 1,200

to 1,800. As a result, most wind turbines

require a gear-box transmission to increase

the rotation of the generator to the speeds

necessary for efficient electricity production.

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Electrical Generators

It converts the turning motion of a wind

turbine's blades into electricity. Inside

this component, coils of wire are rotated

in a magnetic field to produce electricity.

Different generator designs produce

either alternating current (AC) or direct

current (DC),

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generators for wind turbines

At the present time and for the near future,

generators for wind turbines will be

synchronous generators,

permanent magnet synchronous

generators, and

induction generators, including the squirrel-

cage type and wound rotor type.

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Squirrel cage induction generator

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Doubly Fed Wounded Rotor

Asynchronous Generator.

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Grid Connected Permanent Magnets

Synchronous Generator in full converter

topology

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generators for SMALL wind

turbines

For small to medium power wind turbines,

permanent magnet generators and squirrel-cage

induction generators are often used because of

their reliability and cost advantages. Induction

generators, permanent magnet synchronous

generators, and wound field synchronous

generators are currently used in various high

power wind turbines.

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Induction generator

Induction generator offers many advantages over a

conventional synchronous generator as a source of

isolated power supply.

Reduced unit cost, ruggedness, brush less (in

squirrel cage construction), reduced size, absence

of separate DC source and ease of maintenance,

self-protection against severe overloads and short

circuits, are the main advantages

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induction generator…

Further induction generators are loosely

coupled devices, i.e. they are heavily damped

and therefore have the ability to absorb slight

change in rotor speed and drive train

transient to some extent can therefore be

absorbed.

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drawback of the induction

generator

Reactive power consumption and poor

voltage regulation under varying speed are

the major drawback of the induction

generators, but the development of static

power converters has facilitated the control of

induction generator, regarding output voltage

and frequency.

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Synchronous generator

Synchronous generators are closely coupled

devices and when they are used in wind

turbines which is subjected to turbulence and

requires additional damping devices such as

flexible couplings in the drive train or to

mount gearbox assembly on springs and

dampers.

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range of output power ratings.

Generators are available in a large

range of output power ratings.

The generator's rating, or size, is

dependent on the length of the wind

turbine's blades because more energy is

captured by longer blades.

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Range of power

<100 kW

101 kW - 250 kW

251 kW - 500 kW

501 kW - 750 kW

750 kW - 1000 kW

1001 kW - 2000 kW

>2000 kW

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Applications adapted to run on

DC.

• Storage systems using batteries store DC

and usually are configured at voltages of

between 12 volts and 120 volts in USA.

• A typical 100 W battery-charging machine

has a shipping weight of only 15 kg.

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A .C. Generators…..

• Generators that produce AC are

generally equipped with features to

produce the correct voltage (120 or 240

V) and

• constant frequency (60 / 50 cycles) of

electricity, even when the wind speed is

fluctuating.

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Advantages of Induction

generator over synchronous

Induction generator offers many advantages over a

conventional synchronous generator as a source of

isolated [A .C] power supply.

Reduced unit cost, ruggedness, brush less (in

squirrel cage construction), reduced size, absence

of separate DC source and ease of maintenance,

self-protection against severe overloads and short

circuits, are the main advantages

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Environmental Aspects of

Power Generation Using WECs

Wind turbines are most environment friendly method

of producing electricity.

They do not pose any adverse effect on the global

environment, unlike the conventional coal or oil-fired

power plants. The pollution that can be saved per

year from a typical 200 kW wind turbine, involving of

substitution of 120 - 200 tonnes of coal which

contain pollution contents as, Sulphur dioxide

(SO2): 2 –3 tonnes, Nitrogen oxide (NOX): 1.2 to

2.4 tonnes, and other particulates of 150-300 kg. .

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Audible noise

The wind turbine is generally quiet. The wind turbine

manufacturers generally supply the noise level data

in dB versus the distance from the tower.

A typical 600 kW wind turbine may produce 55 dB

noise at 50 meter distance from the turbine and 40

dB at a 250 meter distance [4, 22] comparable with

the noise level in motor car which may be

approximately 75 dB.

This noise is, however, is a steady state noise. The

wind turbine makes loud noise while yawing under

the changing wind direction. Local noise ordinance

must be compiled with.

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Towers

Tower on which a wind turbine is mounted is not just a support structure. It also raises the wind turbine so that its blades safely clear the ground and so it can reach the stronger winds at higher elevations.

Maximum tower height is optional in most cases, except where zoning restrictions apply. The decision of what height tower to use will be based on the cost of taller towers versus the value of the increase in energy production resulting from their use.

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Towers….

Studies have shown that the added

cost of increasing tower height is often

justified by the added power generated

from the stronger winds.

Larger wind turbines are usually

mounted on towers ranging from 40 to 70

meters tall.

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The tower must be strong enough to

support the wind turbine and to sustain

vibration, wind loading and the overall

weather elements for the lifetime of the

wind turbine.

Tower costs will vary widely as a function

of design and height.

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Research and development

Research and development is going on to make wind power competitive with fossil fuel and nuclear power in strict sense, without taking into account of wind power‟s social factors such as environment benefits.

Efforts are being made to reduce the cost of wind power by: design improvement, better manufacturing technology, finding new sites for wind systems, development of better control strategies (for output and power quality control), development of policy and instruments, human resource development, etc

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About Enercon - E-30-230 kW-

Gearless type--1

Variable speed drive, Continuous pitch regulation,

Starts gen. at low speed of 2.5 m/s,

Gearless construction, no transmission loss,

Synchronous gen., draws < one % reactive power from grid,

By using AC_DC_AC conversion, pumps the power at „grid frequency‟,

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About Enercon - E-30-230 kW-

Gearless type--2

Produces power at all loads at near unity

power factor without using capacitors

Supply reactive power to the grid to improve

grid power factor

Slow speed generator of maximum 50 rpm

Three independent air breaks, no

mechanical breaks

Lightning protection

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Wind Turbine Design

Design efforts benefit from

knowledge of the wind speed distribution and

wind energy content corresponding to the

different speeds and

the comparative costs of different systems to

arrive at the optimal rotor/generator combination.

Optimizing for the lowest overall cost considers

design factors such as relative sizes of rotor,

generator, and tower height.

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Thanks to extensive R&D efforts during the

past 30 years, wind energy conversion has

become a reliable and competitive means for

electric power generation.

The life span of modern wind turbines is

now 20-25 years, which is comparable to many

other conventional power generation

technologies.

The average availability of commercial wind

power plants is now around 98%.

Thank You