Environmental Engineering Reference
In-Depth Information
Figure 3.19
The maximal annual production for the 20 Aeromotors.
Numbers 1-13 are of the 2-bladed type, 14-20 are the 3-bladed
version.
3.8
From DC to AC: Juul's First Experiments
ater the War
In order to get the full benefits of wind power, it was obvious
that wind turbines should be connected to a high voltage AC-
grid—as already demonstrated with the Agricco turbine in 1921.
After the war, this development was taken up again by Johannes
Juul. As mentioned earlier in this chapter, he had as a young man
attended the electricity course of Poul la Cour in 1904. Since then,
he had worked with electricity and in 1926 was employed in the
utility SEAS in Southern Zealand. Beside his work, he was allowed
to make independent research and development work and it
resulted in several inventions and products for the Danish
industry [12].
In 1947, at the age of 60, he decided to take up again the
wind tunnel experiments made by Poul la Cour in 1891-1903, but
this time concentrated on diferent types of aerodynamic blade
profiles. In 1948, a wind tunnel was built from plywood at the
SEAS facilities in Haslev and in 1950, the first experimental wind
turbine was built by SEAS to make practical tests, based on Juul's
research. Originally it had a downwind rotor with two 4 m blades,
but it was soon changed to an upwind rotor, where the blades
were supported by wires and stays. The 15 kW AC-generator was
an ordinary asynchronous motor, coupled to the grid. It started
as a motor, driving the rotor (at under-synchronous speed), but
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