25-08-2017, 09:32 PM
WIND ENERGY
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WIND MILL
A Windmill is a machine which converts the energy of wind into rotational energy by means of vanes called sails or blades.
Originally windmills were developed for milling grain for food production .
Windmills used for generating electricity are commonly known as wind turbines.
WIND TURBINE
A windmill used to generate electricity is commonly called a WIND TURBINE.
The first windmills for electricity production were built by the end of the 19th century by prof.james Blyth in Scotland.
By 1908 there were 72 wind driven electric generators in Denmark from 5kw to 25kw.
By the 1930 s windmills were widely used to generate electricity on farms in the U.S.
As the 21st century began,rising concerns over energy security ,global warming & eventual fossil fuel depletion led to an expansion of interest in all available forms of renewable energy.
POWER CONTROL
A Wind turbine is designed a maximum of power at wide spectrum of wind speeds.
All wind turbines are designed for a maximum wind speed,called the survival speed,above which they do not survive.
The survival speed of commercial wind turbines is in the range of 40 m/s.
The wind turbines have three models of operation.
1.Below rated wind speed operation
2.Around rated wind speed operation
3.Above rated wind speed operation.
Connection to the electric grid
The wind turbine is connected to the grid through an inverter which takes the direct current (DC) produced by the generator of the turbine & converts it to alternating current (AC) which can be directly exported to the electricity grid network.