The Dynamic Coupling Effects of a MUFOWT (Multiple Unit Floating Offshore Wind Turbine) with Partially Broken Blade

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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Seakeeping Tests of a FOWT in Wind and Waves: An Analysis of Dynamic Coupling Effects and Their Impact on the Predictions of Pitch Motion Response

Journal of Marine Science and Engineering ◽

10.3390/jmse9020179 ◽

2021 ◽

Vol 9 (2) ◽

pp. 179

Author(s):

Giovanni Amaral ◽

Pedro Mello ◽

Lucas do Carmo ◽

Izabela Alberto ◽

Edgard Malta ◽

...

Keyword(s):

Frequency Domain ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Dynamic Coupling ◽

Coupling Effects ◽

Mooring Lines ◽

Scaled Model ◽

Wave Basin ◽

Domain Models ◽

Catenary System

The present work highlights some of the dynamic couplings observed in a series of tests performed in a wave basin with a scaled-model of a Floating Offshore Wind Turbine (FOWT) with semi-submersible substructure. The model was moored by means of a conventional chain catenary system and an actively controlled fan was used for emulating the thrust loads during the tests. A set of wave tests was performed for concomitant effects of not aligned wave and wind. The experimental measurements illustrate the main coupling effects involved and how they affect the FOWT motions in waves, especially when the floater presents a non-negligible tilt angle. In addition, a frequency domain numerical analysis was performed in order to evaluate its ability to capture these effects properly. The influence of different modes of fan response, floater trim angles (changeable with ballast compensation) and variations in the mooring stiffness with the offsets were investigated in the analysis. Results attest that significant changes in the FOWT responses may indeed arise from coupling effects, thus indicating that caution must be taken when simplifying the hydrodynamic frequency-domain models often used as a basis for the simulation of FOWTs in waves and in optimization procedures for the design of the floater and mooring lines.

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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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