With the increasing requirement for clean energy, the FOWT, which is often installed at the deep sea due to the high cost of the fix-bottom turbine in there, presents its bright prospect due to the high wind energy density in the deep sea. However, with the high energy generation, the FOWT also faces new challenges due to the complex surroundings in the deep sea, for example, the additional wave force due to the floating platform, which may cause the redistribution or higher level of the dynamic load on the FOWT and then the increased fatigue or failure risk. The active structural control may be an effective way to realize the load mitigation of the FOWT under the complex load conditions. The traditional active structural control design only considers one of the coupling effect to reduce the modeling complexity, that is, the aero-structural or hydro-structural coupling, which missing the coupling effect all these three physical disciplines. In this study, the load mitigation control of a FOWT is realized by the generalized H~∞~ structural controller by integrating these three physical domains. A passive tuned massed damper (TMD) is installed inside the floating platform, which includes a damper, spring and mass block. An active force is loaded on the mass block to adjust the dynamic response of the FOWT under the control module. The FOWT responses under the active control force, wind force, and wave load are simulated by the high-fidelity code, namely, OpenFAST. They are then applied as the input or output parameters in the reduced-order model (ROM) process for the controller design. A linear design model is identified in the state-space form and used as the representative of the FOWT dynamics. Based on this ROM, the H~∞~ controller design is implemented by design static output-feedback controllers with the feedback gain matrix obtained. The effectiveness of the designed H~∞~ under the multi-disciplines is verified by comparing with another two systems with H~∞~ controllers, which are designed only considering one of the aero- and hydro- domains. The results showed that by coupling different physical disciplines during the H~∞~ control design process, the load of the whole FOWT is mitigated greatly than these alternatives designed without considering the coupling of all physical disciplines, which suggests the great impact of their coupling effect to the FOWT tower dynamics and corresponding controller design. The designed H~∞~ controller will be helpful to extend the lives of the FOWT and also benefit its cost-reduction by decreasing the platform mass.

 


Control Co-Design for Rotor Blades of Floating Offshore Wind Turbines

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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