Wind mills are also known as Wind turbines. Wind turbines have been helping the humans to effectively convert the energy of the wind to many useful energy forms from the last three thousand years. The conversion of energy began at that time. Not comparing the past workings, the present day wind turbines are really capable of converting the great amount of energy in the wind to electric power. The working and design of blades is the only reason for the generation of electricity. This is also due to the aerodynamic analysis done on the blades of the wind turbine.
The basic knowledge we all have about the wind turbine is that the blades rotate due to the movement of air, but how does the blades rotate?
The air foil technology is used in the blades of wind turbine. It looks like a leaf turned to a half and tuned to a point at the bottom. This produces an air lift which moves the blade. This is the main reason for its rotation. Inertia and relativity are considered for an in depth knowledge.
When a moving train must come to rest position, it will take some time and eventually come to the rest position. So once the train gets started, the movement of the train will become easier further. The same way, when the blade starts to rotate, it will become easy for the blade to move continuously.
Relativity is another concept behind the movement of blades. Relative velocity is equal to subtraction of Wind velocity and Blade velocity. Once the blade velocity gets accustomed to relative velocity, there generates a continuous twist from the bottom of the blade to the top. This is the concept behind the movement of the blades of wind turbine.
But How does this generate power with very low movement??
Even though the wind speeds are very low, the power gets generated. This is only by using a separate gear box which increases the speed to achieve a very high speed ratio. The speed ratio may vary from 1:60 to 1:90. This is when the wind speed is very low. But when the wind speed is too high some times. During that time, when there is no equipment used, the wind turbine will be damaged. So a brake pad is also used which helps to limit the speed to a maximum speed. In most cases, the maximum speed is limited to 90 kilometers per hour. In this way the mechanical system is directly connected to a step up transformer and is converted to power.
When the wind blows from any other direction, a velocity sensor is used to detect the direction of wind. It detects the direction and send the signals to the electronic controller which controls the facing of the wind turbine. This equipment is known as Yawing Mechanism. A gear arrangement in the blades provides the proper alignment if blades with relative velocity. The maximum efficiency that can be obtained by a wind turbine is known as Betz’s limit. The maximum efficiency is approximately 60%. If the efficiency crosses the 60%, the wind turbine will come to stop working as no movement takes place in the air molecules.
