Breakthrough In Small
Wind Technology
The main work of wind turbines is to utilize
the energy of wind and convert it into electricity; stronger wind is considered
good for electricity production. But the speed of wind should not be too strong
because it makes turbines spin too fast and in this process it commits suicide!
Why is it so? Because turbine blades get ripped off by stronger winds –
excessive heat damages the alternator. Turbine tower too can’t remain
unaffected by the strong wind. To prevent all this damage a mechanical breaking
system furling is generally used. This method prevents wind turbine from
spinning too quickly by turning the blades away from the direction of the wind.
Furling can be manual or automatic with same goal i.e. turning the turbine
blade edges into the wind when the wind is dangerously strong and stormy.
Furling acts by decreasing the angle of
attack, which lessens the induced drag from the lift of the rotor, as well as
the cross-section. One major problem in designing wind turbines is getting the
blades to stall or furl quickly enough when hit by a gust of wind. A fully
furled turbine blade, when stopped, has the edge of the blade facing into the
wind. But True North Power NG has launched a small wind turbine without a
mechanical furling system at their test site in
Senior
The AFCTM manipulates the WIND ARROW turbine
and slows the speed when it approaches the power limit at around 30mph
(~50km/hr) and 1200 watts. The AFCTM pulls strings or here, blades of turbines
at optimal speed, until the wind gusts subside. The AFCTM releases the turbine
once the wind gusts subside, so that it quickly regains its equilibrium in
terms of speed and power. This AFCTM achieves all this tasks incessantly
without putting additional burden on the system. If a wind speeds above 40 or
even 50mph (~80km/hr) is experienced for a prolonged period, the turbine is
controlled against over speeding while continuing to produce as much as 30% or
more of its stated power. The controller has excellent mechanism when a storm
approaches. It switches on its SOS mode or prefers Storm-Otto-Shutdown. The SOS
mode is equipped with an electromagnetic braking system. The breaks remain
operational till the storm subsides or waits for an operator to restart the
system (controller RESET).
Intelligent controllers like the AFCTM are the need of the hour and they have an advantage over eco-friendly energy solutions.
Article Courtesy of http://www.alternative-energy-news.info/breakthrough-small-wind-technology/#more-543
Laser
Sensors for Wind Turbines
A system that detects gusts before they
arrive reduces wear, boosts output.
By Tyler Hamilton
A new fiber-optic laser system can measure
wind speed and direction up to 1000 meters in front of a wind turbine, giving
the massive machines enough precious seconds to proactively adapt to gusts and
sudden changes in wind direction. The device, developed by Catch the Wind, a
startup based in
The device could help lower the cost of
renewable electricity from wind. Wind turbines lose roughly 1 percent of their
operating efficiency for every degree their blades are out of alignment with
the oncoming wind. Catch the Wind claims that its laser system can boost
turbine power output by 10 percent by improving orientation accuracy. The pitch
of the blades can also be adjusted in advance of the wind to reduce wear and
tear on turbine gearbox components and blades, lowering repair and maintenance
costs by up to 10 percent and extending the operating life of a wind farm, the
company says.
John Kourtoff, chief executive officer of
offshore wind developer Trillium Power, calls Catch the Wind's approach
"conceptually intriguing" if it can both reduce wind-farm costs and
increase revenues. "On the face of it, it makes sense. It would be
advantageous for us," he says. "But I'd have to see real field
data."
Current wind-energy measurement systems--both
mechanical anemometers and more advanced LIDAR (light detecting and ranging)
devices--are used primarily to determine if a location is suitable for a wind
farm. The systems are also kept as part of on-site weather stations used for
longer-term wind forecasting. Real-time data can also be gathered by mounting a
small anemometer on the back of a turbine's nacelle, Kourtoff says. The problem
with this setup is that the air is so disturbed after passing by the turbine
blades that measurements are often skewed and unreliable. Also, the turbine can
only respond to wind changes after its blades have been hit, leaving them
vulnerable for a few seconds to a range of punishing forces caused by wind
shear, gusts, and turbulence.
Catch the Wind has adapted LIDAR so that it can be mounted on wind turbines
and used to measure wind changes in time to make adjustments to the turbine. It
pulses three invisible laser beams in front of the turbine that can
simultaneously measure both vertical and horizontal wind speeds at different
distances, as well as sudden changes in direction. Like conventional LIDAR, it
does this using the Doppler principle: when the laser bounces off small dust
particles carried in the wind, it changes color. The color of the laser is
directly proportional to the speed of the particle. The device uses proprietary
algorithms to convert this data into measurements of wind speed and direction
before communicating a course of action to the turbine's control system. The device
provides 20 seconds' advance notice--enough to turn the nacelle and angle the
blades so that the turbine can catch more of the wind energy while reducing
strain on its parts.
Conventional LIDAR isn't suited for mounting on wind turbines because these
devices rely on mirrors, which must be precisely positioned, to project a
single beam as a three-dimensional cone, says company president Philip Rogers.
Changes in temperature or sudden movement can knock the mirrors out of
alignment.
Catch the Wind's system is currently being field-tested at the Wind Energy
Institute of Canada on the windy shoreline of
