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There are many types of wind turbines which are divided into two basic categories:
 Horizontal axis, where the rotor is propeller type and is continuously parallel to the wind direction and the ground.
Vertical axis, which is stable and is vertical to the surface of the ground.
The power output of a wind turbine depends on the its size and the wind speed. The size is related to the energy needs that the turbine is expected to meet and varies from a few hundred to several million Watts.
The typical dimensions of a 500KW wind turbine are: Rotor diameter 40 metres and height between 40 and 50 metres, and the dimensions of a 3 MW turbine are 80 metres and 80 to 100 meters, respectively.
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While there is no definitive reason, except perhaps for aesthetic reasons, the market is dominated exclusively by horizontal axis wind turbines, with two or three blades. A typical horizontal axis wind turbine consists of the following parts:
The rotor, which is composed of two or three blades made of reinforced polyester. The blades are attached to a nacelle which is able to rotate around vertical axis.
The transmission system, which consists of the main shaft, its bearings and the gear box which adjusts the rotation speed of the rotor to the synchronous speed of the electrical generator. The rotation speed remains constant during the normal operation of the machine.
The electrical generator, synchronous or induction with 4 to 6 poles which is connected to the gear box by a flexible coupling and converts the mechanical energy into electrical energy. It is located in the nacelle. Also located there is the braking system which is a regular disc brake which is placed on the main shaft or on the generator axis.
The steering system maintains the rotation axis of the rotor constantly parallel to the direction of the wind.
The tower, which supports all of the above electromechanical equipment. The tower is metallic tubular type and rarely, of reinforced concrete.
The electronic controller is located at the base of the tower. The control system monitors, coordinates and controls all the functions of the wind turbine, ensuring its uninterrupted operation. |
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