A wind turbine converts the kinetic energy in the wind into mechanical power. We use a generator to convert mechanical energy in electricity.
- Depending on the technology, the blades of the wind turbine turns revolution per minute.,at a variable velocity of the rotor.
- whereas, velocity varies due to the velocity of wind in order to reach greater efficiency
Blowing air can turn the wings of turbine and electricity will generate from generator.
How does the blowing wind turns the wings?
- The blade has a lots of airfoil cross section consisting of different size and shape from root to tip.
- Airfoil technology make the wind turbine blades turn.
- That means the lift force is produced when a fluid moves over an airfoil.
- In this way wind turbine receive a basic rotation .
- The turning of wind turbine blade experience the wind relatively.(CONCEPT OF RELATIVE VELOCITY)
i.e V relative=V wind – V blade
- Therefore,the wind turbine blade is position in a tilted mannered in order to align with the relative wind speed .
- As the blade velocity increases to the tip the relative wind speed become more inclined towards the tip .
- This means that a continous twist is given to the blade from root to tip.
- However this rotation cannot be directly coupled to a generator.
- because the wind turbine blades typically turns at a very low rate at rpm due to issue of noise and mechanical strength.
- Considering this low speed rotation we cannot produce any meaningful electricity frequency from a generator .the speed is increases in gear box .
- The gearbox use a planetary gear set arrangement to achive the high speed ratio.
- A break also sits in a nacelle the function of brake is to arrested the wind blade rotation during excessively windy condition.
- cut off speed≈ 80km/hr.
- Consequently the electricity is passed through the cable towards the base of step up transformer .
- The wind turbine should face the wind normally for max. power extraction .
- but wind direction can change at any time.
- A velocity sensor on the top of the nacelle measure the wind speed and direction .
- The deviation in the wind direction is sent to an electronic controller .Further, to correct the error ,the appropriate signal is send to yawing mechanism.
- The yaw motor turn the nacelle
- thus the turbine will always be align with the blow direction.
- according to wind speed the relative velocity angle of the wind also changes
- a blade tilting mechanism tilt the blade and guarantee a proper alignment of the blade with the relative velocity.
- thus the blade are always at the optimum angle to attack with the relative wind flow.