Experimental investigation into the dynamic behavior of a floating offshore wind turbine stabilized via a suspended counterweight

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.

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Reliability-based design optimization of a spar-type floating offshore wind turbine support structure

Reliability Engineering & System Safety ◽

10.1016/j.ress.2021.107666 ◽

2021 ◽

pp. 107666

Author(s):

Mareike Leimeister ◽

Athanasios Kolios

Keyword(s):

Wind Turbine ◽

Design Optimization ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Reliability Based Design Optimization ◽

Support Structure ◽

Floating Offshore Wind Turbine ◽

Reliability Based Design

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Coupled Dynamic Analysis for Multi-Unit Floating Offshore Wind Turbine in Maximum Operational and Survival Conditions

Volume 9: Ocean Renewable Energy ◽

10.1115/omae2015-42062 ◽

2015 ◽

Author(s):

H. K. Jang ◽

H. C. Kim ◽

M. H. Kim ◽

K. H. Kim

Keyword(s):

Wind Turbine ◽

Wind Turbines ◽

Time Domain ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Random Waves ◽

Mooring Lines ◽

Floating Offshore Wind Turbine ◽

Coupled Dynamic Analysis ◽

Floating Offshore Wind Turbines

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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