Subject:- Renewable Energy Sources

Topic:- Wind Energy

Difficulty:- Low

Wind turbines are designed to yield Maximum output at a wind speed of 15M/S if the wind speed is more the excess energy is wasted. But the rotor is to be protected from damage . This done by power control mechanism.

The important method use in power control is as follows:

Pitch Control :-

• The power output of the turbine is constantly checked by an electronic measuring unit.
• When the power output become to high, it a actuate the blade pitch mechanism Which turns the rotor blades out of the wind this reduce the power output.
• When the wind velocity reduce and the power output falls, the blade is turned back to the original position &the power again increases.

Passive Stall control :

• In this control blade fixed at a fixed angle. When the wind speed increases, it creates turbulence on the side opposite to the facing wind reduce the angle of attack.
• This will reduce the lift force developed & hence reduce the power output.
• It is much sampler method than the pitch control method but it less accurate.

Yaw Control :-

• This is another method in which the turbine is rotated about a vertical axis facing or away from the wind.
• This method is used only in small wind turbines power plant 1 KW or less.