Wind Power Generators:
Turbines Technology
Wind has become the fastest
growing sector of the renewable energy, and the cost of wind turbines is falling due to mass production and
active technological innovation. One of our hopes to surpass
global warming and today's energy crisis is in wind turbine
technology.
Designs vary significantly, and the possibilities of
technological innovation are still immense. Wind turbines
technology is much more than just the basic horizontal-axis three blades
wind turbines, operating with the blades facing into the wind,
with a power ranging from a few hundred kilowatts to several
megawatts...
See for more details on the power of wind turbines:
Wind Generators: Power and Size
See also for some tips on
experimental urban wind turbines: Urban Wind
Generators
Constant and variable wind turbine speed control
Traditional wind turbines use constant speed control
technology, but advanced electronics allow the adjustment of the blade pitch angle in order to achieve
optimum rotational speed and higher levels of efficiency.
Constant speed rotors are designed to deflect high wind
gust loads, while variable wind turbine technology controls strong and gusty
winds, enabling the gust peaks to be converted to electric
power.
In contrast with constant speed wind turbines, variable speed
ones may attain peak efficiency at any wind speed, and not only
at one specific speed, which means comparatively greater annual
energy production.
GE,
Suzlon and other big manufacturers are actively exploring
variable speed systems.
Wind power technologies: stall and pitch control
Controlling the power output from the turbines blades is a major
issue in any wind turbine, and it can be accomplished by two
main technologies.
One, known as the pitch control technology, is based on the
adjustment of the blades by a control system, intimately
connected to the brake system.
The other technology, the stall (or passive) control technology
is purely based in the aerodynamic properties of the blade,
without any control system or moving parts to adjust. It’s a
technology based in the twist and thickness of the blade along
its length.
Wind Turbine Parts
Typical wind turbines involve a set (usually three) of rotor
blades rotating around a hub. The hub is connected to a gearbox
and a generator, located inside the nacelle, which houses the
electrical components.
See, diagram below (source: BWEA).
The nacelle
The nacelle sits atop the tower and contains the electrical
components, namely the gearbox, the brake, the wind speed and
director monitor, the yaw mechanism and the generator.
Rotor blades
The diameter of the blades is a crucial element in the turbine
power: typically, the longer they are, the greater the energy produced. But
their design and the materials incorporated by them are also key
elements.
Blades are often made of fiberglass reinforced with polyester
or wood-epoxy. Vacuum resin infusion is a new material connected
to a technology
presented by large manufacturers as
Suzlon.
Typically blades rotate at 10-30 revolutions per minute, either
at a constant speed (the more traditional
solution) or at a variable speed.
Gearboxes and direct drives
Most wind turbines use gearboxes, whose function is to increase
the rotational speed required by the generators to produce
electricity. Some new technologies are exploring direct drives
generators in order to dispense the expensive gears.
Brake
The brake is a disk used to stop the rotor blades in emergencies
and to ensure the safety of the turbine (in the case of very
high damaging winds, for instance).
Controller
The controller is a set of electrical components. It controls
the starting, the stopping and the turbine rotor blade speed.
Typically the controller starts up the turbine at wind speeds
around 8 to 14 miles per hour and stops the machine at around 55
miles per hour (to avoid the damages caused by turbulent
high winds).
Generator
The generator is the device responsible for the production of
60-cycle AC electricity.
The yaw mechanism of wind power
generators
In more typical wind turbines, the yaw mechanism is connected to
sensors (anemometers…) that monitor wind direction, in order to
turn the tower head to line up the blades with the wind.
Wind Turbines
Towers
See, for details: Wind Turbines Towers
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