Multi-objective optimization of orthogonal TLCDs for reducing fatigue and extreme loads of a floating offshore wind turbine

2020 ◽  
Vol 209 ◽  
pp. 110260
Author(s):  
Semyung Park ◽  
Meghan Glade ◽  
Matthew A. Lackner
Author(s):  
Thanh Dam Pham ◽  
Junbae Kim ◽  
Byoungcheon Seo ◽  
Rupesh Kumar ◽  
Youngjae Yu ◽  
...  

Abstract A pilot floating offshore wind turbine project of Korea was proposed for installing in the East Sea of Korea. The prototype is a semisubmersible platform supporting a 750-kW wind turbine. A scaled model was tested in the basin tank of the University of Ulsan at scale ratio 1:40. The 750-kW floating offshore wind turbine was modeled by using the NREL-FAST code. Numerical results were validated by comparing with those of the test model. This paper analyzes dynamic responses and loads of the wind turbine system under extreme environmental conditions. Extreme environmental conditions based on metocean data of East Sea Korea. Extreme responses and extreme loads are important data for designing the structure of the 750 kW semi-submersible floating offshore wind turbine.


Author(s):  
Ajit C. Pillai ◽  
Philipp R. Thies ◽  
Lars Johanning

Abstract This paper uses a coupled FAST-OrcaFlex model in order to explore the impact of simulation duration on model convergence. The work analyses both operational and extreme cases, assessing the estimated fatigue and extreme loads experienced by a floating offshore wind turbine and its mooring system. Considering an OC4 semi-submersible deployed with the NREL 5 MW turbine, the case study performs a parametric sweep over a range of wind speeds, sea states, and simulation durations. Through this sweep, the paper establishes the impact of the simulation duration for this particular floating offshore wind turbine and characterizes the convergence properties of the loads and excursions as a function of the simulation duration. The results inform the selection of simulation durations to be used in coupled aero-hydro models and optimization frameworks for floating offshore wind applications and can be used to aid the development of guidance and standards for coupled floating offshore wind turbine models.


Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4138
Author(s):  
Kwansu Kim ◽  
Hyunjong Kim ◽  
Hyungyu Kim ◽  
Jaehoon Son ◽  
Jungtae Kim ◽  
...  

In this study, a resonance avoidance control algorithm was designed to address the tower resonance problem of a semi-submersible floating offshore wind turbine (FOWT) and the dynamic performance of the wind turbine, floater platform, and mooring lines at two exclusion zone ranges were evaluated. The simulations were performed using Bladed, a commercial software for wind turbine analysis. The length of simulation for the analysis of the dynamic response of the six degrees of freedom (DoF) motion of the floater platform under a specific load case was 3600 s. The simulation results are presented in terms of the time domain, frequency domain, and using statistical analysis. As a result of applying the resonance avoidance control algorithm, when the exclusion zone range was ±0.5 rpm from the resonance rpm, the overall performance of the wind turbine was negatively affected, and when the range was sufficiently wide at ±1 rpm, the mean power was reduced by 0.04%, and the damage equivalent load of the tower base side–side bending moment was reduced by 14.02%. The tower resonance problem of the FOWT caused by practical limitations in design and cost issues can be resolved by changing the torque control algorithm.


Author(s):  
H. K. Jang ◽  
H. C. Kim ◽  
M. H. Kim ◽  
K. H. Kim

Numerical tools for a single floating offshore wind turbine (FOWT) have been developed by a number of researchers, while the investigation of multi-unit floating offshore wind turbines (MUFOWT) has rarely been performed. Recently, a numerical simulator was developed by TAMU to analyze the coupled dynamics of MUFOWT including multi-rotor-floater-mooring coupled effects. In the present study, the behavior of MUFOWT in time domain is described through the comparison of two load cases in maximum operational and survival conditions. A semi-submersible floater with four 2MW wind turbines, moored by eight mooring lines is selected as an example. The combination of irregular random waves, steady currents and dynamic turbulent winds are applied as environmental loads. As a result, the global motion and kinetic responses of the system are assessed in time domain. Kane’s dynamic theory is employed to formulate the global coupled dynamic equation of the whole system. The coupling terms are carefully considered to address the interactions among multiple turbines. This newly developed tool will be helpful in the future to evaluate the performance of MUFOWT under diverse environmental scenarios. In the present study, the aerodynamic interactions among multiple turbines including wake/array effect are not considered due to the complexity and uncertainty.


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