Wind Turbine Generators (WTGs)

The Wind Turbine Generator (WTG) can be roughly divided into 3 parts: The Tower, The Nacelle and The Rotor

1.   The Tower: The structure of the WTG tower can be of two types- the lattice type or the conical tubular type. The lattice tower is made of steel shaped into a lattice structure. The tubular tower is again made of steel and slightly conical in shape with a broader base which gets narrower with height.The height of the tower is optimized such that it would enable the blades to capture maximum amount of energy from the wind and hence generate more electricity.

2.   The Nacelle: This part of the WTG holds the Gear- Box, the Generator, the  Control System, the Brake, the Yawing System, the Cooling System, the Anemometer and the Wind Vane.

• The Gear –Box is connected to the hub and rotor. The gears help attain the required rotations per minute for electricity generation.
• The gear box is connected to the Generator. The movement of the gear sets the generator coils in motion and helps produces electricity.
• The Control System monitors the functioning of the WTG. It is made of computers that examine the proper functioning of each part of the WTG.
• The Brakes fall into place to control the motion of the gear box, and in turn, the generator.
• The Yawing System ensures that the WTG is always facing the wind. It is the yawing motor coupled with the yaw bearings which turns the nacelle to face the direction of the wind to generate electricity.
• The Cooling System ensures that the generator does not get overly heated.
• The Anemometer measures the wind speed and sends the data to the control system which initiates or prevents the functioning of the machine based on the wind speed data received.
• Wind vane collects data on the direction of the wind. This data is then sent to the control system which ensures that the machine is yawed in the direction of the wind.

3.   The Rotor: The rotating part of the WTG which includes the Blades and the Hub are together called the rotor. The blades are aerodynamically designed to capture the wind. The pitching system of the blades exposes the blades adequately to the winds and sets them in motion or stops them in case of excessive wind speeds.

A site, to install a wind turbine, is selected after a careful study of the terrain, the wind condition and the overall climatic conditions of the geographical location. 

A foundation is laid at the selected site to facilitate the installation of the WTG. This foundation has to be strong to withhold in case of heavy winds so as to reduce vibration. Provisions are also made to conduct lightening so the WTG does not get affected.

The nacelle, the rotor and the tower are transported to this site for the installation process.

The tower is erected on the foundation. The height of the tower is specified as per the design of the machine being used, the terrain on which the machine is installed and the wind conditions prevailing in the area.

The nacelle is subsequently placed on the tower.

The rotor is assembled and attached to the nacelle. Sometimes the hub is attached to the nacelle following which the blades are attached one by one to the hub instead of assembling the entire hub and rotor and attaching it to the nacelle.

After the WTG is completely assembled and ready, it is connected to the grid so that the electricity generated can be supplied for transmission and distribution. 

The anemometer and the wind vane send in the wind velocity and wind direction data to the control system which yaw the nacelle against the wind.

The blades of the WTG are so designed that once they are pitched in, they capture the wind and are set in motion when wind speeds adequate to generate power exist. The blades are set in motion and they in turn rotate the shaft which is connected to the gear box. The gears speed up the motion attained from the rotor. The function of the gear is to increase the speed so that the rotations per minute required to generate electricity is reached

The rotational motion of the gear is then translated to the generator by means of another shaft. This motion induces an electro motive force or voltage within the generator.

The voltage thus generated is then fed into the Power Electronic Circuit for stabilization. The power generated from the turbine is stepped up by a transformer placed at the bottom of the tower and is connected to the external grid which feeds it for transmission and distribution