Repetitive Control of Wind Turbines
Translated title
Repetitive Kontrol af vindmøller
Authors
Tashkilot, Ayub ; Veress, Attila-Todor ; Pedersen, Kim Udengaard
Term
4. term
Education
Publication year
2013
Submitted on
2013-06-06
Pages
181
Abstract
Moderne vindmøller med stor rotordiameter oplever ofte et ujævnt vindfelt på tværs af rotoren, hvilket skaber varierende belastninger og træthed i vigtige komponenter. Mange af disse forstyrrelser gentager sig for hver omdrejning. Dette speciale undersøger, om individuel pitch-styring, hvor hvert blad justeres separat, kan dæmpe disse periodiske belastninger. Der opbygges en lineariseret tilstandsrum-model omkring en vindhastighed på 18 m/s og den påvirkes af en designet vindprofil. Modellen valideres mod den ikke-lineære NREL FAST 5 MW-simuleringsmodel for vindhastigheder fra 12 til 24 m/s (møllens tredje driftsområde), som er mål for reguleringsdesignet. Tre regulatorer udvikles: (1) en kollektiv pitch-regulator baseret på PI (proportional–integral); (2) en individuel pitch-regulator baseret på Multiblade Coordinate- (Coleman-) transformationen, som omsætter roterende bladmålinger til et fast referenceframe; og (3) en individuel pitch-regulator med en repetitiv reguleringsstrategi rettet mod periodiske forstyrrelser. Et Kalman-filter bruges til at estimere uobserverede tilstande. Alle regulatorer implementeres i NREL FAST 5 MW-modellen og sammenlignes med dens baseline-regulator. Resultaterne viser, at regulatoren baseret på Coleman-transformationen reducerer bladforskydning mere end baseline, mens den repetitive regulator reducerer træthed på tværs af komponenter endnu mere, dog med den ulempe at pitch-aktiveringen øges.
Modern wind turbines with very large rotors often face uneven wind across the rotor, which creates varying loads and fatigue in key components. Many of these disturbances repeat every rotor revolution. This thesis examines whether individual pitch control, which adjusts each blade angle separately, can reduce these periodic loads. A linearized state-space model is built around a wind speed of 18 m/s and driven by a designed wind profile. The model is validated against the nonlinear NREL FAST 5 MW simulation for wind speeds from 12 to 24 m/s (the turbine’s third operating region), which is the target for the control design. Three controllers are developed: (1) a collective pitch controller using PI (proportional–integral) control; (2) an individual pitch controller based on the Multiblade Coordinate (Coleman) transformation, which maps rotating blade signals into a fixed reference frame; and (3) an individual pitch controller using a repetitive control scheme aimed at periodic disturbances. A Kalman filter is used to estimate unmeasured states. All controllers are implemented in the NREL FAST 5 MW model and compared with its baseline controller. Results show that the Coleman-transformation-based controller reduces blade displacement more than the baseline, while the repetitive controller further reduces fatigue across components, with the drawback of increased pitch actuation.
[This abstract was generated with the help of AI]
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