wind Flashcards
Effect of solidity on performance
Solidity is a geometric parameter that describes the ratio of total blade area to the rotor’s swept area.
- low solidity produces a broad and flat curve which means that cp will change very little over wide tip speed ration range
High solidity producess narrow perfomance curve with a sharp peak making the turbine very sensitive to tip speed ratio
optimum solidity appears to be achieved with three blades
Pitch control
most imp application is for power regulation
blade to be “feathered” when its 90 degree of positive pitch
Power regulation can be achieved either by pitching to promote stalling or pitching to feather,
Stall regulation
control method used in wind turbines to limit power output in high wind speeds. Instead of actively adjusting blade pitch.
VAWT
They do not require high winds for generating power
they can be
easily maintained, are less likely to kill birds, and do not
obstruct helicopter operations or radar
Their noise levels are very low
They can be arranged close to each other (unlike horizontal
turbines), thereby saving more space.
wind measurement
Cup anemometer
Ultrasonic anemometer
anemometer towers needs anenometer pole and supporting cables and data aquisition system
Measurment points needs to account for average hub hieght , blade length
micro-siting
The micro-siting is used to calculate the productivity of a region, taking into account
the roughness of the terrain and topography
Array losses
Turbulence intensity also increases through the wind farm due to
the interaction of the wind with the turning rotors.
wind turbine spacing (both downwind and crosswind)
➢ wind turbine operating characteristics;
➢ number of turbines and size of the wind farm;
➢ turbulence intensity;
➢. frequency distribution of the wind direction (the wind rose).
array efficiency = annual energy of whole array / anual enery of one isolated turbine * total no of turbines
