Loading...

Modeling and Parametric Study of Tower Vibrations of Floating Offshore Wind Turbine and its Nonlinear Phenomena

Ghabraei, Soheil | 2023

0 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 57126 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Moradi, Hamed
  7. Abstract:
  8. Reliable electricity production is crucial for the prosperity and development of countries. Wind turbines (WTs) are the means of accessing a considerable amount of, renewable clean wind energy. In the deep offshore areas, wind is steadier, therefore many attempts have been made to innovate floating structures to implement Wind Turbines in the deep offshore areas. In this research, to investigate some of the technical challenges, the dynamics of the offshore wind turbine tower have been studied and investigated by developing three dynamic models focusing on the Tension Leg Floating Platform. The developed models are the concentrated mass model in the surge direction, the concentrated mass model in the heave direction, and finally a more accurate model in which coupling between surge and heave motions have been taken into account. Moreover, the wind turbine tower is modeled as a continuous beam using the Euler-Bernoulli beam theory. Afterward, the FAST code is utilized to verify the proposed models. Then, the dynamic analysis of the models has been done to investigate various dynamic phenomena, such as jump phenomenon, bifurcation phenomenon, etc., using existing nonlinear analysis methods. During the analysis of surge motion dynamics, it is observed that in the case of internal resonance, the oscillation amplitude of the wind turbine tower in the transverse direction is significantly higher in comparison to the floating platform. Any change increase in the mass of the wind turbine nacelle or floating platform as well as added mass of the floating, alters the frequency and amplitude of the oscillations. This issue may lead to an increase in the fatigue loads on the wind turbine tower and floating platform. Finally, the importance of considering the coupling of surge and heave motions for a more accurate modeling of the Tension Leg Platform has been shown. Finally, by utilizing numerical methods, the possibility of non-linear phenomena such as frequency doubling and chaos in the dynamics of the floating offshore wind turbine has been investigated
  9. Keywords:
  10. Wind Turbine ; Floating Platform ; Wave Loading ; Dynamic Model Development ; Validation ; Bifurcation ; Nonlinear Phenomenas

 Digital Object List

 Bookmark

No TOC