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General Wind Turbine Features: |
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- High efficiency at low wind speeds.
- Wind power output capacities from 300 Watts to 50 kW at 12/24/48vdc for off-grid Wind Power Generators and 120/240vac for Utility Grid Connected Wind Systems
- We offer both horizontal axis wind machines and vertical axis wind turbines.
Wind Turbine Basics
Essentially, a wind turbine is an alternator attached to a propeller or blade. When the wind blows, the propellers begin to move and the alternator produces electricity. The design details that determine which turbines are best suited for various wind speeds get more involved, but all wind turbines operate in the same manner.
Installing a wind turbine is a bit more involved than installing solar panels, but they are still relatively easy to incorporate into your alternative energy system. The turbine needs to be mounted in an area free from obstructions to wind flow (nearby buildings, trees, etc.).
Some smaller turbines can be mounted to the rooftop of your house, but vibrations from the turbine may be transferred to the frame of the building. Rooftop turbine mounts often come with rubber vibration dampers to minimize this problem. As a general rule however, the higher in the air you can get your wind turbine the more effective it will be, so independent, guyed towers are the recommended mounting system.
Types of Wind Generators
Wind turbines come in a range of output voltages, to match the overall voltage of your electrical system. While 12 volt is common for small to mid-sized systems, large systems can be designed in 24 or 48 volt configurations.
The primary consideration in a wind generator is the average wind speed at the installation site. A different turbine will give optimum performance at a site with average wind speeds below 15mph than one at a site with speeds in the low 20mph range. Generally, low speed generators will either have longer rotor blades or a larger number of short, wide blades to maximize power drawn from minimal wind. High speed generators may be built of more durable material, and will have narrow, relatively short blades to minimize potential rotor damage in extremely high winds. Before choosing which type of turbine is best for a particular site, some sort of wind speed measurement should be taken.
Benefits of Wind Energy
Like solar power, a wind energy system is an entirely clean source of renewable power. The only potentially hazardous materials involved are the storage batteries if installing an off-grid system. Wind turbines produce no emissions, use no traditional fuel, and can provide reliable year-round power given the right location and wind speeds.
Wind generators require relatively little maintenance, but it is recommended that the generator receives annual visual check-ups to ensure the propeller blades have not been damaged. If the turbine is located in a good spot, than it is very unlikely to be damaged by any flying debris, but a chipped or cracked blade can be a hazard should it break completely. A chipped or damaged blade will also negatively affect the turbine is performance.
For residential systems, wind power can be a wonderful source of power year-round, depending on the site. They can also be configured to power dedicated water pumping systems, which may be of particular interest to individuals currently without running water.
For commercial and industrial use, wind turbines are particularly useful in rugged remote locations such as mountaintop repeater stations or offshore oil platforms. High elevation and offshore or seaside remote sites often have fairly high year-round wind current that will make the most of wind generation systems. Industrial grade wind generators are available to withstand the worst storm winds present at such sites.
ESW Horizontal Axis Wind Turbine
Horizontal Axis wind generators (also called turbines) are usually used in standalone power systems and in some cases are also designed to charge a battery bank.
Wind generators are usually sized in the range of 300W to 5kW but are also available from 10kW or 20kW turbine or larger for domestic applications.
Conventional wind turbines have the turbine axis in the horizontal plane. The main body of the wind generator comprises of a set of blades, the alternator and the tail section. The power of the wind makes the blades turn. The blades are connected to the rotor inside the alternator which turns and generates electrical power. The tail ensures that the wind generator is facing directly into the wind.
Wind speed increases as the height above the ground increases. Output of a wind generator is dependent on the amount of wind but can also vary according to other circumstances.
As a rule of thumb, a wind generator should be installed no closer to an obstacle than at least ten times its height, and on the downwind side. The preferred distance is twenty times the height.
Wind speed increases as the height above the ground increases, so the wind generator should be installed on the highest tower that is practical and cost effective for your site. The typical tower used in domestic wind generator systems is between 10-20m tall.
SITING AND INSTALLATION
Wind generators need clean wind to operate. Clean wind is where the wind is constant from the one direction and is not being made turbulent from near-by obstacles. The clean wind is required to overcome the starting torque (that is the starting resistance) of the wind generator. Wind can be affected by terrain like hills, trees and nearby buildings or structures.
Most manufacturers will provide figures on the cut-in wind speed. This is the speed of the wind (generally measured in meters/second) at which the starting torque is overcome and the wind generator begins to turn and generate power. In areas with frequent light winds, a low cut-in speed is an important feature for maximum output. Manufacturers provide a rated output of a wind generator at a specified wind speed. Not all manufacturers rate their units at the same wind speed.
In some areas of the world where there is very little wind monitoring undertaken, the system designer will have very limited wind data to use to design the system. Designers will use their own experience, knowledge and relevant information obtained from the manufacturer when determining the anticipated output of the wind generator system.
If a user is installing an off-grid system, than to overcome the power loss in the cables, the wind generator needs to be located as close as possible to the battery bank. If the preferred site is distant from the house or building, the batteries and inverter could be located near the wind generator and the power transmitted as 240V AC to minimize cable losses. Alternatively the generation voltage can be higher and then transformed down to battery voltage if the batteries are installed near the house. Higher voltage transmission means lower losses.
Wind generators can produce some running noise in high winds. The noise can come from the blades, gear-box, brush gear or wind whistling past the tower, pole or guy wires. The noise may not be loud but may be noticeable to you or close neighbors. The background noise of the wind itself usually covers the sound of the blades. Always ensure that there are no objections to the low level noise produced.
TURBINE CONTROLS
As the wind speed increases, the wind generator will spin faster. If wind speed continues to increase, the generator may ultimately be destroyed. All wind generators therefore have a wind cut out speed at which the unit will employ some form of over-speed control to either stop the unit generating power or govern the rotational speed to produce constant power.
The two most common forms of over-speed control are mechanical braking and feathering.
In mechanical braking, a brake is applied as a result of the centrifugal forces developed when the unit approaches the cut out speed. If the unit is operating in an area where the average speed is close to the cut out speed, braking might happen frequently and the brakes will wear out rapidly.
Feathering can occur in two ways: either by rotating the individual blades to reduce their angle into the wind, thereby reducing rotor speed; or turning the whole unit out of the wind.
Wind generators are always producing power when turning. If the batteries are fully charged the excess power is redirected into a dummy load, usually an electrical element. The dummy load can get very hot and should be positioned where it will not be touched accidentally.
Wind generators and the accompanying system, being mounted on top of metal towers, are very susceptible to lightning strikes. Lightning arresters should be installed in the system to protect electronic components from the effects of lightning strikes.
ESW Vertical Axis Wind Turbine
The Vertical Axis Wind Turbine (VAWT) converts wind energy to electrical power. Wind pressure (wind speed) on the cage blades cause the cage structure to rotate producing current flow and the associated voltage
Vertical Axis Wind Generators may be easily installed in almost any location with good wind exposure. Connecting the VAWT to a power grid provides the option of selling power back to the utility company. Rebates are also offered in some countries / states.
With the changes in the economy, the rising costs of fuel oil, and the rising prices of energy in general, there is an increasing demand for home generated power, be it from solar-electric, solar thermal heating, or wind generated power. Of those three options, wind generated power is by far and away the most mature option, with the best odds for getting a reasonable payback for a typical home with sufficient wind.
For wind power generators, there are two general types to consider: Horizontal blade generators and vertical axis wind generators.
Vertical wind generators have the advantage of being suitable for a ground level installation. They can be installed in the middle of the back yard, or on top of the roof of your garage. They also do not need a yaw element (the tail of a conventional turbine blade) to steer them into the wind direction, as they can generate energy from any wind direction the breeze is blowing in from. Depending on where you are setting your vertical wind generator up, your local utility company may offer credits for doing so, and nearly 90% of the utility companies in the United States offer some form of net metering, where excess electricity you produce from your vertical wind generator is sold back to them and credited against your bill. Look seriously into the options your utility company provides before investing in a vertical wind generator, and consider it an investment in cheaper power down the road.
Vertical Axis Wind Turbine
Advantages:
- Lower construction costs because there is no need to build a higher tower structure as compared to other wind turbine systems.
- Reduced costs as rotor blades are vertical, eliminating "yaw" drives.
- Easier to maintain as moving parts are located nearer to the ground.
- Improved aerodynamics as VAWT have a higher airfoil pitch angle, while decreasing drag at low and high pressures.
- Lower wind startup speeds than other wind turbine systems.
- Usually have a lower "Tip-Speed" ratio so less likely to break in high winds.
- Low height is useful where laws do not permit high structures.
- Does not need to turn to face the wind due to wind direction changes making them ideal in turbulent wind conditions.
- Vertical Axis wind Turbine blades are easily seen by birds.
- Wind generators can operate 24 hours a day.
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