Master forsvar Apostolos Doris

Supervisor: Gunner Chr. Larsen, DTU Wind Energy

Alan Wai Hou Lio, DTU Wind Energy

Examiner: Mohsen Soltani, AAU

The defence is a part of the Online Wind Energy Master

About the Online Wind Energy Master

The part-time master programme is scheduled to take two to four years, making it possible for participants to study while working. The participants come from all over the world and in August, the first participants graduate.

On Friday August 30, 2019, there will be a reception in B118 for the eight graduates. 

Abstract: Individual Pitch Control for Wind Turbine Load Reduction in a Wind Farm

In this thesis the concept of individual pitch control is tried in a DTU10MW reference wind turbine (WT) with overall objective the reduction of the fatigue loads of the wind turbine blades. This WT is a large scale benchmark system that has been developed in a collaboration between Vestas and DTU. It is an upwind, three bladed structure with a rated power of 10MW and it is designed for offshore applications.

The controller is designed using loop-shaping techniques and a transfer function that describes the dynamics of each blade in the frequency domain. To obtain the load reduction the controller attenuates the amplitude of the flap-wise bending moment perturbations at the blade roots. The controller is constructed by targeting the first two harmonics of the blade rotational frequencies of the WT. The input of the controller is the pitch angle of each blade and the output is the flap-wise bending moment at the blade roots. By using the so called ‘black-box’ system identification technique and the aforementioned input/output configuration the transfer function of the blade dynamics is derived. The derived controller is implemented in a WT model in aero-elastic code Hawc2. For this implementation the controller transfer function is being transformed from the continuous Laplace domain to the discrete Z-domain and from there to a time domain polynomial expression that relates the output with the time history of the output and the input.

By using Hawc2 simulations open- and close-loop responses of the flap-wise bending moment are derived and compared in the time and frequency domain. The outcome of this comparison is that the close-loop system exhibits a high degree of perturbation attenuation. Last but not least the concept of equivalent fatigue loading is used to assess the performance of the controller in terms of fatigue. The outcome of this comparison is that the close-loop system achieves a high degree of fatigue load reduction with respect to the open-loop system.


tir 27 aug 19
10:00 - 12:00



DTU Risø Campus
Frederiksborgvej 399, bld. 118, meeting room Poul la Cour
4000 Roskilde