The wind generator is a fan-like device placed inside the wind turbine and it converts the rotational energy produced by the wind into electrical power. Therefore, the generator plays the central part in a wind turbine. Wind energy is a renewable source of energy, which in itself is produced because of solar energy.
Slow speed generators are usually driven by rotors. A generator requires a rotational speed of at least 1,800 rpm to produce electricity, whereas a rotor turns at not more than 800 rpm. A wind turbine with a high-speed generator requires a gear system that can increase the rotational speed of the main shaft to drive a generator.
Generation of Electricity
The conversion of mechanical energy into electrical energy takes place because of the interaction between the magnetic field and coils. The rotor turns to generate the rotational motion required for drawing electrons through the magnetic field and transmits them through coils and takes them away using fixed terminals. Additional power is generated by a number of methods including amplifying the magnetic field, or increasing the speed of the rotor or the length of the wire in coils.
The variation in the speed, the continuity and the direction of wind creates problems for the generation of electricity. The fluctuations make it difficult to produce a regular stream of electric current. Therefore, an inverter is connected to the generator to produce a constant stream of electricity, with the right voltage.
As the wind energy generators work constantly, they require regular cooling. Usually, the generator would be encapsulated inside a duct and a large fan would perform air cooling. However, in some generators, even water cooling is used. This type of generators are more compact and thus increase the overall efficiency. However, such generators require a radiator so as to take away the heat through the cooling system.
Designs and Grid Connection
A wind turbine can have either a synchronous or an asynchronous generator. The connection between the generator and the grid can be either direct or indirect. A direct connection means that the generator is directly connected to the 3-phase AC grid. An indirect connection means that the electric current generated by the turbine is passed through several electrical devices that adjust the current so as to match the frequency and voltage of the grid. In the case of asynchronous generators, the process takes place automatically.