Environmental Engineering Reference
In-Depth Information
Chapter 13
Jørgen Krogsgaard
Kastrup, Denmark
j.c.krogsgaard@gmail.com
13.1
Background
Almost all wind turbines in Denmark are producing electricity.
Electricity produced by an asynchronous generator is sent to
the public grid at 50 Hz with the related speed of rotation. The
windmill is, thereby, locked by the electricity grid. With constant
rotation speed, the blades will stall with increasing wind speed,
and thus reduce the rotor efect. With constant speed depending
on wind speed, the blade tip speed will remain constant. Average
tip speed of older windmills is about 40 m/s and with increasing
size of wind turbines the tip speed increases to about 70 m/s.
Usually most windmills have three blades. It is called the Danish
concept, and has its origins in the Gedser wind turbine that
was designed by Johannes Juul.
For information about Gedser wind turbine see chapter
History of Danish Wind
Power
by
Benny Christensen.
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