Author: dr.sc. Mate Jelavić
Title: Wind turbine control for structural dynamic loads reduction
Category: PhD thesis
Date: May 29th 2009
Mentor: prof.dr.sc. Nedjeljko Perić
- prof.dr.sc. Ivan Petrović (Faculty of Electrical Engineering and Computing, chairman)
- prof.dr.sc. Nedjeljko Perić (Faculty of Electrical Engineering and Computing, mentor)
- prof.dr.sc. Joško Deur (Faculty of Mechanical Engineering and Naval Architecture, member)
- prof.dr.sc. Stjepan Car (Končar - Electrical Engineering Institute, member)
- prof.dr.sc. Željko Jakopović (Faculty of Electrical Engineering and Computing, member)
In this thesis a systematic approach to wind turbine control problem is
presented. The state-of-the art in wind turbine control is analyzed by
examining the controller structure as well as methods for their
parameterization, based on derived process models. Investigation of
state-of-the-art control algorithms through extensive simulations showed some
of their drawbacks. One of them is wind turbine behavior in the event of sudden
wind gusts that often results in unacceptable rotor overspeed. Other is well
known problem of periodic loading of the structure due to ununiform wind field
that classic control algorithms can not deal with. To improve the wind turbine
behavior in the event of large wind gusts use of short-term increase of
generator torque is proposed. The proposed concept proved to be good solution
to this problem while improving the wind turbine energy yield at the same time.
For alleviation of periodic loading of the structure well known individual
pitch control concept is explored. In this thesis use of estimated structural
loads instead of loads measurement is proposed. Two concepts are examined - use
of Kalman filter and estimation based on other, easy-to-measure process values.
Both concepts demonstrated abilities of loads estimation that can be used for
individual pitch control. The proposed approach that doesn't require any loads
measurements is especially appealing because of its easy implementation on an
running wind turbines.
All obtained results were additionally verified by carrying complete simulation
test defined according to IEC standards.