More information about Wind Turbines

When you are thinking about a wind turbine as a possible solution for your rising energy needs, there here is some interesting information about them.

Most of us know wind turbines only as a different type of power generator or plant.
The similarity more or less ends there because the concept, design, installation and operation all are different to a conventional plant.

Take for example the concept.

It is based on the principle of converting the energy imbibed in a flowing air stream (kinetic energy) to electrical energy by using a wind turbine (rotor) a mechanical device.

There are 2 basic designs, namely;

• Horizontal Axis wind turbines (this is the most familiar image used to represent the wind turbine!)
• Vertical axis wind turbines (where the hub and the rotor shaft along with the rotor blades are in vertical axis).

The fuel?
There is no fuel as such because the wind is already in motion unlike the shaft of a diesel engine which has to overcome the inertia, friction and the load all the way.
A best recommended velocity for wind is 4.5 m/s to 6.5 m/s. The higher the velocity more will be the power generated. However there will be a limit to this due to the limitations in mechanical strength of components and also gear box designs.
Therefore a speed governor and control system will ensure the Turbine rotors won’t spin out of control!

The conversion of the kinetic energy is of course by an electrical power generator of more or less conventional design.

The installation?
Being dependent on power of wind flow, the Turbine, the shaft, the coupling and the generator (alternator) have to be installed at an elevation as high as possible.
This is because the air velocity is high and unidirectional at higher elevations than at ground level.

How is this done?

There are two basic types of towers used, namely;

• The Free Standing design –This will have a single pole like structure with a base plate. (Again a familiar image!)
• The Free standing Unit with the base plate and 3 or 4 Guy wires (Stay wires)
• The lattice design tower (a conical lattice) –This is the least familiar but best suited for industrial applications and the Vertical Axis wind turbines.

The electrical power distribution?
Here the differences end and the wind turbine joins the conventional electrical power distribution process. Whether the system is Grid Tied or Off Grid will play a big part.
As the current applications in Ireland are for supplementing the existing utility power while complimenting the supply of each other (when the other needs maintenance, low wind velocity shut downs etc.) standard power grid coupling techniques would be adopted.

The Control System?
Thyristor type control devices are used for gentler handling of the moving components and the Power Grid when cutting in and out. This is monitored by a micro computer based system generally with a lot of data inputs. To provide the owner with a fail safe system several electronic, electrical and mechanical strategies are employed one system monitoring the other at times. When the wind speed is low or high (generally around 25 m/s) the control system would cut of the wind turbine

An interesting possibility to think over is the possibility of the asynchronous generator operating as motor when the wind speed is very low. The wind turbine would draw the power from the grid and operate as a huge fan! This may damage both the grid and the wind turbine. Fortunately the manufacturers incorporate safety devices in the control system of the wind turbine to prevent this happening.

Thanks the Techstore Team


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