A Study Of Wind Powered Turbine Generation

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Gear Box: Gear box connect low-speed shaft to the high-speed shaft from about 30 to 60 rotations per minute (rpm) to 1200 to 1500 rpm, the rotational speed required by most generators to produce electricity. This gear box is a costly and heavy part of the wind turbine.
Low-Speed Shaft: This is the connecting pipe between the rotor and the gear box. Rotor: This is made up of the blade and the hub. It is a portion of the wind turbine that collects energy from the wind and rotates about an axis (horizontally or vertically) at a rate determined by the wind speed and shape of the blade. The blade is attached to the hub, which in turn is attached to the main shaft.
Brake: A disc brake which can be applied mechanically, electrically or hydraulically to stop the rotor in emergencies is used.
Yaw Drive: This is an equipment that is used to keep the rotor facing into the wind as the wind direction changes. It is only found in the upwind turbine.
Yaw Motor: This powers the yaw driver.
High Speed Shaft: This drives the generator.
Wind Vane: This is an instrument that measures or decodes the wind direction and communicate with the yaw drive to channel the turbine rotor properly with respect to the wind.
Nacelle: This is the housing or casing which sits on-top of the tower and includes the gear box, low and high speed shafts, generator, controller and brakes. The rotor is being attached to it
Tower: This is being made of steel lattice and is very high because wind speed increase with height and taller towers enable turbines to capture more energy and generate more electricity.
2.1    BASIC PRINCIPLES OF WIND POWER GENERATION
Wind power is a measure of the energy available in the wind. It is a function of the cube (third power) of the wind speed, if the wind speed is doubled, power in the wind is increased by a factor of eight (i.e. 23) this relationship means that the small difference in wind speed leads to a large difference in power.
Wind speed is therefore defined as the rate at which airflow past a point above the earth’s surface.
The output of a wind turbine varies with the wind speed through the motor. The “rated wind speed” is the speed at which the “rated power” is
achieved. This corresponds to the point at which the conversion efficiency is near its maximum. In most system, the power output above the “rated wind speed” is mechanically or electrically maintained at a constant level allowing more stale system control.
The power output drops sharply at wind speed. This is better explained by the cubic power law, which states that the power available in the wind increases eight times from every doubling of the wind speed and decreases eight times for every halving of the wind speed.
In a particular wind site, the power output expected at the average wind speed can be determined by the power curve.

Just like the weather, the wind can be unpredictable. It varies from place to place and from moment to moment. It is invisible and as such can only be measured with a special instrument. While wind turbines are mostly commonly classified by their “rated power” at certain “rated wind speed”, energy output is also greatly influenced by some subtle features of a wind turbine’s design.
These include:
1)    Cut-in-Speed: This is the minimum wind speed at which the blade will turn and generate useable power. This wind speed is typically between 7mph and 10mph.
2)    Blade Air Foil Shape: This determines the power produced at moderate speed.
When air flows past the blade a wind speed and pressure differential created between the upper and lower surface is greater and thus acts to “lift” the blade.