| | | Wind Electric Generators

From WikiVerde

Wind electric generators are widely used as a source of electricity although the generation can be intermittent at times due to the nature of wind. It is impossible to store wind energy if batteries are not employed for this purpose. Most of the primary wind locations are far away from major cities where primary electricity demands lie. Nevertheless, the usage of wind electric generators is still very common and growing.

1 Parts of a Generator
2 Generation of Tension
3 Small Sized Turbines
4 Starting the Generator
5 Soft Starting
6 Cooling the Generator
7 Costs on Par with Conventional Sources
8 Power Issues
9 Weak Grids
10 What is Islanding?
11 Health Hazard
12 Shipping Risks
13 References

Parts of a Generator

The wind electric generator comprises a nacelle, tower, braking system, gearbox, rotor, controllers, generator, sensors and yaw system. It is essential that sufficient amount of wind source be present at the site. There should be a good power grid located near to the wind electric generator. Land should be adequate and the layout should be scientifically laid.

Generation of Tension

The wind electric generator or turbine firstly needs to generate voltage or tension in order to successfully manufacture electricity. Large turbines can generate as much as 690 Volts of AC which alternates in three phases. This voltage is raised through a transformer to reach levels between 10000 to 30000 volts.

Small Sized Turbines

Residential usage demands a much smaller wind electricity generator and for such purposes a small turbine is perfect. Their capacity can be as little as 400 watts and operate using DC current as opposed to AC in the larger ones. They also comprise aeroelastic blades and have a vane that points in the direction of the wind. Installation over the roof of the house is possible and factors such as vibration, roof durability as well as ledge turbulence contribute to installation feasibility. Power generation can meet as much as 10 to even 25% of the home’s electricity needs.

Starting the Generator

When the speed of the wind is lesser the turbine controller is programmed to allow the turbine to continue running idle. This does not necessitate any grid connection. If it had a grid connection it would function like any motor. At higher wind speeds the grid connection is critical and the right moment of grid connection is also crucial. If the grid is not connected at the right time it can lead to resistance from the generator gearbox. This restricts acceleration in the rotor which in turn results in over speeding. Safety methods such as usage of brakes like fail-safe are used in emergency situations as a corrective measure.

Soft Starting

Hard switching a wind electric generator can often result in power peaks which result in flickering lamps and other side effects. It also places undue strain on the gearbox of the turbine. This is why a soft start in a wind electric generator is usually recommended. The usage of thyristors helps to gradually increase connection to the grid. The thyristor is a semi-conductor switch which is regulated electronically. Thyristors often an energy waste ranging from 1-2% which is why modern turbines have a bypass switch. This gets activated once soft start has been achieved. This minimizes the energy wastage.

Cooling the Generator

Cooling is essential while using the wind electric generator. The generator is typically encapsulated inside a duct with the aid of a fan. Some manufacturers even employ usage of water cooling systems to cool the wind electric generator. Such generators have a more compact design which in turn provides more efficiency in electricity manufacture. However, a nacelle is needed to be placed in the radiator to exude excess heat.

Costs on Par with Conventional Sources

Today modern technology and usage of new techniques has made it possible to manufacture electricity from wind sources that can compete with fossil fuels. The subsequent decade is expected to see a further drop in the prices of electricity generated from wind sources at which time it will be cheaper than conventional sources of electricity.

Power Issues

Aspects such as stability of voltage, harmonic distortion as well as frequency all contribute in combination to the overall quality of the power. Sinusoidal shaped ACs are best preferred by manufacturers of wind electric generators.

Weak Grids

In cases where the turbine is connected to a weak grid it can result in power surges as typical of a hard start. This necessitates reinforcement of the grid which can be performed by a local electrical company.

What is Islanding?

This refers to a condition where a portion of the grid gets removed from the primary power grid. When left to its devices in such a state the disconnected and main grid will cease to be in the same phase after sometime. Re-establishing the connection can cause overloading power surges. It also releases a large volume of energy inside the drive train and it produces results similar to any hard switching mechanism. It is therefore critical that the turbine controller checks the frequency and voltage of the grid’s AC. If the current is found to be outside the set standards the turbine is disconnected from this grid. It will also instantly stop later.

Health Hazard

It has been found by researcher Nina Pierpont that there is a health hazard emanating from the usage of the wind electric generator. It goes by the name of wind turbine syndrome. It usually impacts those people who stay near the vicinity of the turbines. Sleeping disorders, fatigue, frequent headaches, dizziness as well as irritable behavior are some of the common symptoms. The cause could be the continuous sound of the wind turbines. It is recommended as per standards that turbines having loud noise levels should be installed at least one mile away from residential locations. Till now not much research has been done on the subject of wind turbine syndrome and results are fairly inconclusive.

Shipping Risks

It has been found that the presence of off-shore wind turbines, also known as wind farms, can have a harmful impact on ships and in many cases has been known to cause shipwrecks as well. Wind turbines have been known to cause a disturbance to the communications and radar of ships which could cause an unwanted collision.