Experimental results of floating platform vibration control with mode change function using full-scale spar-type floating offshore wind turbine

2017 ◽  
Vol 42 (3) ◽  
pp. 230-242 ◽  
Author(s):  
Hiromu Kakuya ◽  
Takashi Shiraishi ◽  
Shigeo Yoshida ◽  
Tomoaki Utsunomiya ◽  
Iku Sato
Keyword(s):  
Vibration Control ◽  
Wind Turbine ◽  
Pitch Angle ◽  
Full Scale ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Blade Pitch Angle

Floating offshore wind turbines have great potential for harvesting renewable energy sources since offshore wind is stronger and more stable than onshore wind. The foundations of floating offshore wind turbines are not rigidly fixed and it leads to vibration of the floating platform pitch angle. This vibration is caused by fast blade pitch angle motions of variable speed control for controlling rotor speed at rated values. This study proposes a control method to address this vibration, floating platform vibration control. This method extracts a natural frequency component of the vibration from the floating platform pitch angle signal by a band pass filter and controls the blade pitch angle on the basis of proportional–derivative control. Its key characteristic is changing control modes in accordance with electrical power. Experiments using a full-scale spar-type floating offshore wind turbine were performed, and results show that the proposed floating platform vibration control can suppress the vibration of floating platform pitch angle.

A study on the platform-pitching vibration of floating offshore wind turbines based on classical control theory

2019 ◽  
Vol 44 (6) ◽  
pp. 610-630
Author(s):  
Hiromu Kakuya ◽  
Shigeo Yoshida ◽  
Iku Sato ◽  
Tomoaki Utsunomiya
Keyword(s):  
Transfer Function ◽  
Vibration Control ◽  
Pitch Angle ◽  
Offshore Wind ◽  
Floating Platform ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Classical Control ◽  
The Impact ◽  
Blade Pitch Angle

One of the issues of floating offshore wind turbines is the platform-pitching vibration generated by the blade pitch angle motion of the variable speed control. This study investigated the platform-pitching vibration based on the classical control theory using a transfer function between the generator speed and the nacelle pitch angle. This study also investigated the impact of the floating platform vibration control, which can suppress the vibration by adjusting the blade pitch angle according to the nacelle pitch angle, by using a transfer function to which floating platform vibration control is added. The stabilities of these transfer functions were determined using the Nyquist stability criterion, and the impact of the floating platform vibration control parameters was investigated using Bode diagrams.

Tank Testing of a New Concept of Floating Offshore Wind Turbine

2013 ◽  
Author(s):  
Marc Le Boulluec ◽  
Jérémy Ohana ◽  
Alexis Martin ◽  
Anne Houmard
Keyword(s):  
Numerical Modeling ◽  
Wind Turbine ◽  
Coupled System ◽  
Production Performance ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Full Scale Tests

The WINFLO project (Wind turbine with INnovative design for Floating Lightweight Offshore) aims at the development of competitive floating offshore wind turbines, by a consortium of 3 industrial partners (Nass&Wind Industrie, DCNS and Vergnet SA) and 2 scientific partners (IFREMER and ENSTA Bretagne). The design of the floater is an innovative semi-submersible free floating platform with particular aspects. Classical steps toward the assessment of the hydrodynamic and energy production performance include numerical modeling, model scale tank testing and intermediate or full scale tests at sea. The present study describes the wave tank tests including wind generation compared to some numerical modeling results of the coupled system composed of the support floater and the wind turbine.

Verification of Engineering Modeling Tools for Floating Offshore Wind Turbines

2013 ◽  
Author(s):  
Tiago Duarte ◽  
David Tomas ◽  
Denis Matha ◽  
António Sarmento ◽  
Frieder Schuon
Keyword(s):  
Wind Turbine ◽  
Physical Models ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Modeling Tools ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Engineering Modeling ◽  
Good Agreement

This paper presents a verification exercise with three different codes for floating offshore wind turbine modeling: FAST, S4WT and SIMPACK. The comparison showed good agreement in most of the results, and the main differences identified can largely be traced back to the different physical models used by the three simulation softwares. A detailed analysis of the wind turbine loads and motions is also included. FAST offered a greater computational efficiency compared with the other two softwares. Nevertheless, if one is interested in more detailed loads on blades, exact blade deflection predictions in bending and torsion, elastic effects of the floating platform etc., the more detailed codes S4WT and SIMPACK are beneficial.

scholarly journals Impact of Typhoons on Floating Offshore Wind Turbines: A Case Study of Typhoon Mangkhut

2021 ◽  
Vol 9 (5) ◽  
pp. 543
Author(s):  
Jiawen Li ◽  
Jingyu Bian ◽  
Yuxiang Ma ◽  
Yichen Jiang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Safety Evaluation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Coupling Motion

A typhoon is a restrictive factor in the development of floating wind power in China. However, the influences of multistage typhoon wind and waves on offshore wind turbines have not yet been studied. Based on Typhoon Mangkhut, in this study, the characteristics of the motion response and structural loads of an offshore wind turbine are investigated during the travel process. For this purpose, a framework is established and verified for investigating the typhoon-induced effects of offshore wind turbines, including a multistage typhoon wave field and a coupled dynamic model of offshore wind turbines. On this basis, the motion response and structural loads of different stages are calculated and analyzed systematically. The results show that the maximum response does not exactly correspond to the maximum wave or wind stage. Considering only the maximum wave height or wind speed may underestimate the motion response during the traveling process of the typhoon, which has problems in guiding the anti-typhoon design of offshore wind turbines. In addition, the coupling motion between the floating foundation and turbine should be considered in the safety evaluation of the floating offshore wind turbine under typhoon conditions.

scholarly journals Proposal and Performance Study of a Novel Mooring System with Six Mooring Lines for Spar-Type Offshore Wind Turbines

2021 ◽  
Vol 11 (24) ◽  
pp. 11665
Author(s):  
Shi Liu ◽  
Yi Yang ◽  
Chao Wang ◽  
Yuangang Tu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Mooring Lines ◽  
Included Angle ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Spar-type floating offshore wind turbines commonly vibrate excessively when under the coupling impact of wind and wave. The wind turbine vibration can be controlled by developing its mooring system. Thus, this study proposes a novel mooring system for the spar-type floating offshore wind turbine. The proposed mooring system has six mooring lines, which are divided into three groups, with two mooring lines in the same group being connected to the same fairlead. Subsequently, the effects of the included angle between the two mooring lines on the mooring-system’s performance are investigated. Then, these six mooring lines are connected to six independent fairleads for comparison. FAST is utilized to calculate wind turbine dynamic response. Wind turbine surge, pitch, and yaw movements are presented and analyzed in time and frequency domains to quantitatively evaluate the performances of the proposed mooring systems. Compared with the mooring system with six fairleads, the mooring system with three fairleads performed better. When the included angle was 40°, surge, pitch, and yaw movement amplitudes of the wind turbine reduced by 39.51%, 6.8%, and 12.34%, respectively, when under regular waves; they reduced by 56.08%, 25.00%, and 47.5%, respectively, when under irregular waves. Thus, the mooring system with three fairleads and 40° included angle is recommended.

scholarly journals The Effect of the Second-Order Wave Loads on Drift Motion of a Semi-Submersible Floating Offshore Wind Turbine

2020 ◽  
Vol 8 (11) ◽  
pp. 859
Author(s):  
Thanh-Dam Pham ◽  
Hyunkyoung Shin
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Second Order ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Hydrodynamic Loads ◽  
Drift Motion ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Floating offshore wind turbines (FOWTs) have been installed in Europe and Japan with relatively modern technology. The installation of floating wind farms in deep water is recommended because the wind speed is stronger and more stable. The design of the FOWT must ensure it is able to withstand complex environmental conditions including wind, wave, current, and performance of the wind turbine. It needs simulation tools with fully integrated hydrodynamic-servo-elastic modeling capabilities for the floating offshore wind turbines. Most of the numerical simulation approaches consider only first-order hydrodynamic loads; however, the second-order hydrodynamic loads have an effect on a floating platform which is moored by a catenary mooring system. At the difference-frequencies of the incident wave components, the drift motion of a FOWT system is able to have large oscillation around its natural frequency. This paper presents the effects of second-order wave loads to the drift motion of a semi-submersible type. This work also aimed to validate the hydrodynamic model of Ulsan University (UOU) in-house codes through numerical simulations and model tests. The NREL FAST code was used for the fully coupled simulation, and in-house codes of UOU generates hydrodynamic coefficients as the input for the FAST code. The model test was performed in the water tank of UOU.

Dynamic Responses of a Spar Type Floating Offshore Wind Turbine With Failed Moorings

2020 ◽  
Author(s):  
Yajun Ren ◽  
Vengatesan Venugopal
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Floating Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Platform Motions

Abstract The complex dynamic characteristics of Floating Offshore Wind Turbines (FOWTs) have raised wider consideration, as they are likely to experience harsher environments and higher instabilities than the bottom fixed offshore wind turbines. Safer design of a mooring system is critical for floating offshore wind turbine structures for station keeping. Failure of mooring lines may lead to further destruction, such as significant changes to the platform’s location and possible collisions with a neighbouring platform and eventually complete loss of the turbine structure may occur. The present study focuses on the dynamic responses of the National Renewable Energy Laboratory (NREL)’s OC3-Hywind spar type floating platform with a NREL offshore 5-MW baseline wind turbine under failed mooring conditions using the fully coupled numerical simulation tool FAST. The platform motions in surge, heave and pitch under multiple scenarios are calculated in time-domain. The results describing the FOWT motions in the form of response amplitude operators (RAOs) and spectral densities are presented and discussed in detail. The results indicate that the loss of the mooring system firstly leads to longdistance drift and changes in platform motions. The natural frequencies and the energy contents of the platform motion, the RAOs of the floating structures are affected by the mooring failure to different degrees.

scholarly journals Numerical Study of a Proposed Semi-Submersible Floating Platform with Different Numbers of Offset Columns Based on the DeepCwind Prototype for Improving the Wave-Resistance Ability

2019 ◽  
Vol 9 (6) ◽  
pp. 1255
Author(s):  
Zhenqing Liu ◽  
Yicheng Fan ◽  
Wei Wang ◽  
Guowei Qian
Keyword(s):  
Wind Turbines ◽  
Numerical Study ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Offshore Wind Turbines ◽  
Irregular Wave ◽  
Decay Test ◽  
Floating Offshore Wind Turbines

DeepCwind semi-submersible floating offshore wind turbines have been widely examined, and in some countries this type of floating offshore wind turbine has been adopted in the construction of floating wind farms. However, the DeepCwind semi-submersible floating offshore wind turbines still experience large surge motion that limits their operational time. Therefore, in this study, a semi-submersible floating platform with different numbers of offset columns, but with the same total weight, based on the DeepCwind prototype is proposed. From the free-decay test, it was found that the number of the floating columns will affect the natural frequency of the platform. Furthermore, the regular wave test in the time domain and the irregular wave test in the frequency domain show that increasing the number of the floating columns will reduce the surge motion greatly, while the effects in the heave and pitch motions are not obvious.

Design Requirements for Floating Offshore Wind Turbines

2013 ◽  
Author(s):  
Xiaohong Chen ◽  
Qing Yu
Keyword(s):  
Wind Turbine ◽  
Case Studies ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Design Parameters ◽  
Offshore Wind Turbine ◽  
Support Structure ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Design Requirements

This paper presents the research in support of the development of design requirements for floating offshore wind turbines (FOWTs). An overview of technical challenges in the design of FOWTs is discussed, followed by a summary of the case studies using representative FOWT concepts. Three design concepts, including a Spar-type, a TLP-type and a Semisubmersible-type floating support structure carrying a 5-MW offshore wind turbine, are selected for the case studies. Both operational and extreme storm conditions on the US Outer Continental Shelf (OCS) are considered. A state-of-the-art simulation technique is employed to perform fully coupled aero-hydro-servo-elastic analysis using the integrated FOWT model. This technique can take into account dynamic interactions among the turbine Rotor-Nacelle Assembly (RNA), turbine control system, floating support structure and stationkeeping system. The relative importance of various design parameters and their impact on the development of design criteria are evaluated through parametric analyses. The paper also introduces the design requirements put forward in the recently published ABS Guide for Building and Classing Floating Offshore Wind Turbine Installations (ABS, 2013).

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