HOW WIND IS GENERATED?
• Wind is caused by the uneven energy
distribution and rotation of the Earth.
Then in China wind mills were used to raise water for
irrigation and sea water for production of salt.
In 1854 Daniel Halladay in US introduced a wind pump
and used for irrigation and industrial applications.
In 1880 P. La’cour used wind mill as a source of
In 1929 French engineer Darreius built an aero
In 1974 NASA constructed and operated a wind
generator of 100kW capacity.
In 1987 US firms generated a 2.5MW generator
CLASSIFICATION OF WIND TURBINES
1.Based on alignment of rotor axis
Horizontal axis turbine
Vertical axis turbine
2.Based on the force utilised
Lift type wind turbine
Drag type wind turbine
• Forces are transmitted from a moving fluid to
an object in the flow stream
Lift = the force component perpendicular to the
original flow direction
Drag = the force component in line with the original
α = low
α = medium
α = High
Low speed turbines
High speed turbines
Rotor shaft torque is
Rotor shaft torque is
Greater blade area is required
Aerofoil type blades are
required to minimize the
effect of drag forces
Blades are fabricated using
Blades are having high
thickness to chord ratio to
produce high lift
3. Based on generation
Small ( 10 kW)
• Remote Applications
(e.g. water pumping,
• Village Power
• Hybrid Systems
• Distributed Power
Large (250 kW - 2+MW)
• Central Station Wind Farms
• Distributed Power
DIFFERENT TYPES OF ROTORS
• Sheet metal blades.
• Width of blade increases
• Blade is fixed at inner and
• No. of blades 12-18.
• 2 or 3 aerodynamic blades.
• Blades made od fibre glass
• Diameter of rotor 2-25 m.
• It has 2 or more identical
hollow semi cylinders
fixed to vertical axis.
• Rotor rotates due to
• Driving torque is drag
type, so large starting
• Suitable for water
• 2 or 3 thin curved blades.
• Both end of blade attached to
• Operates for wind from any
• Driving force is lift torque.
• Used for electricity generation.
IMPORTANT TERMS RELATED TO WIND TURBINE
• Leading edge
• Trailing edge
• Chord line
Aerofoil shape of blade
• Mean line
• Angle of attack
• Pitch angle
WIND ENERGY EXTRACTION
Extract energy from wind stream by converting the
KE of wind to rotational motion required to operate
an electric generator.
On interaction of free wind on turbine rotor, the wind
transfers part of energy into rotor and speed of wind
AERODYNAMIC OPERATION OF WIND TURBINE
Airfoil:Cross section of wind turbine
Lift:Pressure difference between top
and the bottom surface of blade
in a force
aerodynamic lift that cause airfoil
to rise. This lift cause rotation of
blade about the hub
Drag:A Force perpendicular to lift force
also act on blades which impede
the blade rotation .this force is
called drag force.
Power in the Wind = ½ρAV3
Effect of air density,
Effect of swept area, A
Effect of wind speed, V
Swept Area: A = πR2 Area of the
circle swept by the rotor (m2).
• Wind power would increase four
times if rotor diameter is doubled.
• Wind power increases eight times
if wind speed is doubled.
More wind speeds
Less noise pollution
Less visual impact
Difficult to install and maintain
Energy losses due long distance transport
Important part that extract wind Energy
Light weight and good strength
Fabricated with aircraft industry technique.
Made of Fiberglass reinforced polyester
Structured for creating optimum lift.
Combination of blade and hub assembly
Pitch control of blades:
A system where the pitch angle of blade changes according
to the wind speed for efficient operation
Aerodynamic and Mechanical braking are used for over
speed protection , speed control , power control and
Low speed shaft:
shaft connected directly to rotor to the gear.
Mechanical power generated by rotor blade is
transmitted to the generator through two stage gear box
Provided for increasing shaft speed.
Used for converting mechanical power to electric
Commonly used generators are PMSG,SEIG,DFIG.
Microprocessor based controller monitor wind speed ,
direction of wind , power output and take proper yaw ,
Anemometer & wind wane:
Used for wind speed and direction monitoring.
Housing of generator, the gear box, yawing
High speed shaft:
Shaft connected between gear box and generator
Yaw drive and yaw motor :
Yawing is done using two yawing motors
meshed with big toothed wheel mounted on tower.
Yaw control continuously tracks and keep rotor axis in
At high wind machine is stopped by turning the rotor
axis right angle to wind direction.
Modern turbine are mounted on tubular towers
MODES OF WIND POWER
1) Standalone mode
2) Backup mode like wind diesel
3) Grid connected mode
Decentralized application of wind energy
Individual consumer install their own wind turbine
Used for powering domestic appliances battery
charging, water pump etc.
Capacity ranges between 2.5—5Kw
Most suited for remote mountainous areas.
BACK UP MODE LIKE WIND-DIESEL
DG is used for maintaining 24 hrs. power supply ,since wind
power is intermitted
Used in areas ina ccessible to grid,hosptals,miltary
GRID CONNECTED WIND TURBINE
Generated power is distributed among nearby customers
and excess power exported to grid.
Electric energy is purchased from grid when there is no
Cut in Speed: It is the wind speed(14m/s)
at which the turbine output begins.
Rated Speed: It is the Speed at which the
turbine is designed to generate rated
Cut out Speed: When the speed reaches
upper limit (25m/s) the turbine stops to
Renewable source of energy
Free of fuel cost
Supply power to remote areas
Public opinion is in favor of wind power generation
rather than nuclear generation
Economically competitive with other modes of
Reliable and has been used for ages
Low energy density.
Available at selected graphical location.
Wind speed being variable , wind energy is irregular.
Wind turbine design is complex.
Requires storage batteries which contribute
1. Renewable Energy Sources And Emerging