wind energy

WIND ENERGY

Energy available in the wind over the earth’s surface is estimated to be

1.6x107 K.W

The problems associated with Utilizing wind energy

(i) The energy is available in dilute form

(ii) (ii) The availability of the energy varies

Means of storage have to be devised if a continuous supply of power is required

Wind millKinetic

energy of movi

ng air

Mechanical

energy

Machine

/Generator

Classification of wind mills

Wind mills

Horizontal Windmills

Single Bladed

Double Bladed

Multi Bladed

Vertical Windmills

Darrieus rotor

Savonius rotor.

Horizontal Axis single blade Wind mills

Wind Turbine Cost Breakdown

1 propeller type Wind Mill

2 propellers type Wind Mill

3 propellers type

Holland type

Sail type

Multi-blade

Vertical axis wind turbines

Straight wing type

Darrieus type

Cup type

S- paddle type

Savonius type

Crossflow type

Lift and drag

Stalling effect

Pitch angle

Wind Surveys

1. Instrumentation – Wind direction sensors

2. Data recording systems- Strip chart

3. Type of data- Wind speed and directional-hourly averages

4. Data reporting – Wind Frequency curves, Daily, Weekly,

Monthly

Wind direction sensors

Strip chart

Strip chart

Site Selection Consideration

1. High annual average wind speed

2. Availability of anemometry

3. Availability of Wind V(t) curve at proposed site

4. Wind Structure at the proposed site

5. Altitude of the proposed site

6. Distance to Roads and Railways

7. Nearness of site to local center/user

8. Nature of ground

9. Favorable Land cost

Anemometer

Methods of Generating Synchronous Power from WTGs

Rotor Generator The conversion systems

Constant Speed Variable pitch Fixed Ratio gear

AC Generator

Constant Speed Variable pitch Two stage ratio gear

AC Generator

Rotor Generator The conversion systems

Constant Speed Fixed pitch Variable Ratio gear

AC Generator

Variable Speed Fixed pitch DC Generator/DC Motor /AC generator

Rotor Generator The conversion systems

Variable Speed Fixed pitch AC Generator/ Rectifier/DC motor/ AC generator

Variable Speed Fixed pitch AC Generator/ Rectifier/ Inverter

Rotor Generator The conversion systems

Variable Speed Fixed pitch Direct Converter (Matrix Converter)

Variable Speed Fixed pitch Wound Rotor Induction Generator

Rotor Generator The conversion systems

Variable Speed Fixed pitch Wound Rotor Induction Generator and Cycloconverter circuit in the rotor circuit

Induction Generator

Two Types of Induction Generator

1. Normal Type (Non-Isolated)

2. Isolated Type (Self Excited)

Normal Type (Non-Isolated)

Normal Type (Non-Isolated)

Isolated Type (Self Excited)

Controls

1. Orientation of the rotor

2. Start up and cut-in

3. Varying Pitch of the blades

4. Generator output monitoring

5. Shutdown and cut out owing to malfunction or very high winds

6. Maintenance Mode

Controls

Controls

Power in the Wind :

Po = 0.5*ρ *A* Cp*v3

Where

ρ = density of air

v= wind speed

Cp= efficiency factor or Power Coefficient

A= Cross-sectional area of turbine disc

Maximum wind turbine efficiency - the Betz limit

The power developed by the wind turbine is

Power =(P1 - P2 ) * At *Ut

where At is the turbine disc area

Volume flow continuity

Au *Uu = Ad *Ud = At *Ut

Force on the turbine

F = m*Uu -m*Ud

Power extracted by the Turbine:

PT = F*Ut =m(Uu –Ud )*Ut