two or three moving parts. Most feature three blades of 2-15 feet in length, a generator
located at the hub, and a tail y los component of system: controllers, inverters and
batteries.
MATERIAL COMPOSITION OF THE BLADES
Most small wind turbines use blades made of plated metal: polyester reinforced with
fiberglass or a lesser extent, carbon fiber, wood rarely. It has stopped using aluminum
for its tendency to deform under stress.
ORIENTATION
The small size of mini-wind turbines cannot put motors with orientation of rotor facing
the wind direction or other metal components that it has the turbines of size medium:
almost all small wind turbines have directional arms to guide the rotor into the wind.
The tail keeps the turbine facing into the wind
ROBUSTNESS
For best performance, the turbines have to be in places with influence by winds
consistent: for small wind turbines machines, given their small size, robustness is
essential.
The heavier wind turbines have proved to be more robust and reliable than the lighter
ones. The weight of a turbine mini wind compared with area swept by its rotor-called
specific mass, measured in kg/mq- is therefore a good indicator of choice between
different machines. Typically, a higher specific mass carries a higher price
POWER CONTROL
In strong wind regime, the turbines have to have a passive positioning system that
deflects the rotor about the rotational axis of the blade. Most micro and mini-turbines
was bends a hinge so that the rotor turns to the arm directional: some vertical, others
horizontal. The wind speed at which the misalignment is performed and how that which
takes place depends on the hinge placed between the directional arm and the gondola.
GENERATORS
Most wind turbines use permanent magnet alternators: the configuration is simple and
robust. Turbines for domestic use, the alternator configurations can be: permanent
magnet alternator field winding conventional and induction generator.
TOWER
Because wind speeds increase with height, the turbine is mounted on a tower. In
general, the higher the tower, the more power the wind system can produce. The tower
also raises the turbine above the air turbulence that can exist close to the ground
because of obstructions such as hills, buildings, and trees. A general rule of thumb is to
install a wind turbine on a tower with the bottom of the rotor blades at least 30 feet (9
meters) above any obstacle that is within 300 feet (90 meters) of the tower. Relatively
small investments in increased tower height can yield very high rates of return in power
production. For instance, to raise a 10-kW generator from a 60-foot tower height to a
100-foot tower involves a 10% increase in overall system cost, but it can produce 29%
more power.
There are two basic types of towers: self-supporting (free standing) and guyed. Most
home wind power systems use a guyed tower. Guyed towers, which are the least
expensive, can consist of lattice sections, pipe, or tubing (depending on the design),
and supporting guy wires. They are easier to install than self-supporting towers.
However, because the guy radius must be one-half to three-quarters of the tower
height, guyed towers require enough space to accommodate them. Although tilt-down
towers are more expensive, they offer the consumer an easy way to perform
maintenance on smaller light-weight turbines, usually 5 kW or less.
