Wind turbines are the machines used to convert wind (Kinetic energy) to electrical energy. On contrary to fans where electrical energy is converted to wind, in wind turbines winds are made to rotate fans and energy is produced.
Wind is one of the most common energy available in the earth and developed because of atmospheric difference of earth atmosphere.
Major factor for generation of wind includes:-
1. Rotation of earth,
2. Irregularity of earth surface
3. Uneven heating of earth by sun.
Bacause of iragularity of earth surface and uneven heating, wind flow pattern and intensity differs from place to place. Higher windy areas are the best suitable places for harvesting wind energy, Wind turbine installation shall be economical in these places. Wind turbines can be installed in almost all areas including sea and water bodies.
Wind energy has been harvested from long time by humans for transport industry like ship sailing and irrigation work like pumping of ground water.
Now a days wind turbine comes as a very sophisticated machine with aerodynamic fan blades, Rotors, gear box and generator.
When wind strikes at fan blades due to pressure difference it starts rotating blade and rotor, gearbox transmit energy to required rotational rpm and rotational energy is converted into electrical energy by generator installed.
In wind farms, Power is generated by no of wind turbines; power generated is collected and is transmitted to grid by stepping up voltage through transformer
Types of wind turbine:-
- Horizontal wind turbine
- Vertical wind turbine
Wind energy can be harvested through both horizontal and vertical type wind turbine, The difference between horizontal and vertical turbine is based on the axis of rotation as shown below.
Horizontal turbine being most energy efficient is commonly used for power generation and most of the large capacity turbines are manufactured in horizontal axis. In horizontal turbine base tower needs to be extremely strong as it has to support complete fan assembly, gearbox and generator at the top of tower which is exposed to high wind. The rotation of blade can produce more power while construction of horizontal axis turbine requires precision and heavy duty load calculation. Structure failure due to metal fatigue is major challenge in case of horizontal turbine therefore wind turbines are designed with upwind design.
Yaw drive are important part of horizontal turbine To ensure Production of maximum power all the time, Yow drive is used to keep rotor facing into the wind direction for max power output.
Yaw drive can be hydraulic or electric driven, while in recent times electric drives are popular due to higher flexibility and low maintenance design
Vertical wind turbines are more stable turbines and are less affected by wind direction. Being vertical rotor gearbox and generator can be installed at ground to make structure light. Maintenance of these turbines are easy. Limitation with this turbine is its lower efficiency because to air drag due to lower elevation.