tower. And like many others they experienced vibration problems
due to the blades passing in the “wind shadow” behind the tower.
This was a contributing cause to the fact that the wind turbine
was
not able to reach the projected maximum of 40 rpm. In this
case, vibration problems were avoided by limiting the speed of the
turbine to a lower level. As the turbine was running at variable
speeds and the electricity from the AC-generator had to pass
a con
verter to obtain grid frequency of 50 Hz, it gave no extra
technical problems. But the production was of course reduced, ...