|Topic : paper:
an Alternative Concept for a High-Altitude Wind-Power Generator
- May 2018Journal of Physics Conference Series 1037(4):042023
LicenseCC BY 3.0
- Abstract. To generate power
from high-altitude winds, concepts using kites or planeslinked
to the ground with tether are in development. The most popular
high-altitude wind generation concept is one using a flying wing
attached to a single tether whose movement generates power by turning a
winch. The usual trajectories for power generation consist of a
period where the kite distance is increased, and the pulling
force enlarged by figure-of-eight movements, interrupted by a
pull-back phase where power is consumed. We comparethat with a new
concept we introduce here. It uses a triplet of tethers whose length
sum is kept more or less constant using differential gears, resulting
in a trajectory surface. It does not have a pull-back phase and allows
to have similar power output in a closed trajectory. Moreover, starting
and landing can be achieved without additional equipment when using a
soft kite as wing, and keeping the wing flying without any wind is
easier. Also the control can be easier, as one has more degrees of
freedom in the force direction and the movement of the kite. Its
disadvantages are an increased effort for the ground stations and more
restrictions on the location. Also the tether’s air drag is
increased. Optimal power generation is compared using an example
configuration and state with given wind speed under the assumption of
an optimal steering of the generators and the kites. This
is done for state snapshots, for example trajectories, wind
speeds, and kites.
(PDF) Assessment of an Alternative Concept for a High-Altitude
Wind-Power Generator. Available from: HERE
[accessed Feb 12 2020].
For convenience, I quote the paper for its use of the following symbols:
1r one-tether, angle of attack optimized, distance is allowed to increase,
3r. three tethers, angle of attack fixed, distance (tether length sum) fixed,
3r three tethers, angle of attack optimized, distance (tether length sum) fixed.
“4. Discussion & Outlook
It has been shown that:
3r is comparable in terms of power output.
3r makes it possible to have a kite with constant angle of attack.
3r makes it possible to land and start the kites without additional equipment.
3r makes it possible to keep the kite airborne when no wind is present.
A key feature of 3r could
be a constant power production which could be achieved by steering the
distance motor-generator accordingly while keeping a closed trajectory.
An optimization achieving this would proof the value of this new
concept. To increase the precision of the evaluation, acceleration
forces based on the trajectory should be included and whole trajectory
optimizations should be done.”