Explore the vast range of titles available.

To enable the fast growth of the floating offshore wind industry, simulation models must be validated with experimental data. Floating wind model-scale experiments in wind–wave facilities have been performed over the last two decades with varying levels of fidelity and limitations. However, the turbine controls in these experiments have considered only limited control strategies and implementations. To allow for control co-design, this research focuses on implementing and experimentally validating more advanced turbine control actions and strategies in a wind–wave basin for a 1:70-scale model of the International Energy Agency’s wind 15 MW reference wind turbine. The control strategies analyzed include torque control, collective pitch control, and transition region control (setpoint smoothing). Our experimental and numerical results include the effects of varying rotor speeds, blade pitches, and wind environments on the turbine thrust and torque. Numerical models from three different software tools are presented and compared to the experimental results. Their ability to effectively represent the aero-dynamic response of the wind turbine to the control actions is successfully validated. Finally, turbine controller tuning parameters based on the derivatives of thrust and torque are derived to allow for improved offshore wind turbine dynamics and to validate the ability of modeling tools to model the dynamics of floating offshore wind turbines with control co-design.

This study investigates the elastic response characteristics of a floating wind turbine (FOWT) with two vertical-axis wind turbines (VAWTs), called double-rotor VAWTs. The model consists of two VAWTs mounted on a single semi-submersible floating structure and employs a single point mooring, which allows the FOWT to always self-align with the wind. Usually, a coupled analysis of the wind turbine and floating structure is used in the design of FOWTs; however, there is no coupled analysis available for VAWTs. In this study, we attempted to combine the wind turbine design software “QBlade” and the coupled wind turbine/floating body analysis code “UTWind” as one of the methods of coupled analysis of a VAWT and a floating body. Numerical simulation results were compared with experimental results using an elastic model scaled down to 1/100 of its actual model to determine the motion response and cross-sectional bending moments. The experimental results showed that the thrust of the VAWT had a particular influence on the cross-sectional forces and motion response between the two VAWTs. For cross-sectional forces, all results showed similar trends. Overall, the results of UTWind for double-rotor VAWTs are reasonable. It was also found that the pitch motion must be accurately reproduced to improve the accuracy.

Offshore wind energy is a renewable energy source that is developing fast. It is considered to be the most promising energy source in the next decade. Besides, the expanding trend for this technology requires the consideration of diversified seabeds. In deep seabeds, floating offshore wind technology (FOWT) is needed. For this latter technology, such as for conventional WT, we need to consider aspects related to performance, aerodynamic force, and forces during operation. In this paper, a two-bladed downwind wind turbine model is utilized to conduct experiments. The collective pitch and cyclic pitch angle are adjusted using swashplated equipment. The fluid forces and moments acting on the rotor surface are measured by a six-component balancing system. By changing the pitch angle of the wind turbine blades, attempts are made to manage the fluid forces generated on the rotor surface. Under varied uniform wind velocities of 7, 8, 9, and 10 m/s, the effect of collective pitch control and cyclic pitch control on the power coefficient and thrust coefficient of FOWT is then discussed. Furthermore, at a wind speed of 10 m/s, both the power coefficient and loads are investigated as the pitch angle and yaw angle change. Experimental results indicate that the combined moment magnitude can be controlled by changing the pitch-angle amplitude. The power coefficient is adjusted by the cyclic pitch-angle controller when the pitch-angle phase changes. In addition, the thrust coefficient fluctuated when the pitch angle changed in the oblique inflow wind condition.

Three models with different footing types were used to clarify the effect of heave plates on the hydrodynamic behavior of the elastic response of a flexible multicolumn floating offshore wind turbine (FOWT). The models were tested under regular waves, whose added mass, damping, and motion response results were compared with numerical simulations by NK-UTWind and WAMIT codes. As a whole, the attachment of heave plates was responsible for increasing the added mass and damping levels, consequently modifying the RAO of the models. Regarding the response in a sea condition, a decrease of 33% and 66% of the significant motion height (heave and pitch) was observed. Thus, the heave plate can be a good feature for the future design of FOWT.

Offshore wind energy is a rapidly maturing renewable energy technology that is poised to play an important role in future energy systems. The respective advances refer among others to the monopile foundation that is frequently used to support wind turbines in the marine environment. In the present research paper, the structural response of tall wind energy converters with various stiffening schemes is studied during the erection phase as the latter are manufactured in modules that are assembled in situ. Rings, vertical stiffeners, T-shaped stiffeners and orthogonal stiffeners are considered efficient stiffening schemes to strengthen the tower structures. The loading bearing capacity of offshore monopile wind turbine towers with the four types of stiffeners were modeled numerically by means of finite elements. Applying a nonlinear buckling analysis, the ultimate bearing capacity of wind turbine towers with four standard stiffening schemes were compared in order to obtain the optimum stiffening option.

For the design of floating offshore wind turbines (FOWT), all the load cases need to be calculated by using a coupled model of wind turbine and platform, while the uncoupled approach will help to reduce the number of simulations for the design and optimization of floating offshore wind turbines. In this study, the effects of the wind and wave actions on the tower loading of a FOWT were investigated and an uncoupled approach for the load calculation was proposed and verified by comparing with the result of coupled simulation. First, the effect of elastic platform was considered by tuning the Young’s modulus of the tower material when rigid platform model was used in the analysis. The effect of wind and wave actions on the loading of the tower was then investigated. It was found that the difference of the wind load between fixed and floating wind turbines is observed only in the mean component and can be predicted by considering the hydrostatic stiffness of the platform and mooring stiffness. The standard deviation of the fore-aft tower moment increased as the significant wave heights increased when the mean wind speeds and peak wave periods were fixed. This is caused by the increase of the inertia force induced by the pitch and surge motions of the platform and the increase of the fluctuating pitch angle. On the other hand, the standard deviation of the fore-aft tower moment decreased as the peak periods increased when the mean wind speeds and significant wave heights were fixed. The increase of the peak period caused the decrease of the pitch and surge accelerations of the platform and results in the decrease of the inertia force. Finally, the tower loading in extreme sea states during power production was carried out by using the proposed uncoupled approach and the results showed good agreement with those by the coupled approach, and the simulation time was reduced to 1/40.

In this study, advanced hydrodynamic models are proposed to predict dynamic response of a floating offshore wind turbine (FOWT) in combined wave and current conditions and validated by laboratory and full-scale semi-submersible platforms. Firstly, hydrodynamic coefficient models are introduced to evaluate the added mass and drag coefficients in a wide range of Reynolds numbers. An advanced hydrodynamic model is then proposed to calculate the drag force of cylinder in combined wave and current conditions. The proposed model is validated by the water tank tests in the current-only, wave-only and current-wave conditions and is used to investigate the effect of current on the dynamic response of FOWT. Finally, the full-scale semi-submersible platform used in the Fukushima demonstration project is investigated. It is found that the predicted dynamic responses of platform by the proposed hydrodynamic models are improved by the directional spreading function of the sea wave spectrum and show favorable agreement with the field measurement.

The full exploitation of offshore wind resources can essentially satisfy the massive energy demand. The realization and application of ultra-high-power offshore wind turbines are crucial to achieving full use of deep-sea wind energy and reducing the cost of wind power. For the VolturnUS-S semi-submersible floating foundation of a 15 megawatt (MW) offshore wind turbine, the effect of structural parameters on hydrodynamic performance was investigated by controlling the variables described in this paper. Accordingly, the floating foundation was optimized and coupled to the 15 MW offshore wind turbine. The dynamic performance of the integrated 15 MW offshore wind turbine was analyzed under different operating conditions, by applying the aero-hydro-servo-elastic coupled method. The results show that for a wave in a 0-degree direction, a 5% increase of column spacing will reduce the peak value of the pitch transfer function by 33.61%, and that a 5% decrease of the outer column diameter will further reduce the peak value by 26.27%. The standard deviation of the time-domain surge responses was reduced by 19.78% for the optimized offshore wind turbine, and the maximum value of the mooring line tension was reduced by 13.55% under normal operating conditions.

When wind turbines work in a cold and humid environment, especially offshore condition, ice accretion on the blade surfaces has a negative effect on the aerodynamic performance. In order to remove the ice from the wind turbine blade, the adhesive characteristics of atmospheric icing on the blade surface should be mastered under various conditions. The objective of this study is to evaluate the effects of offshore atmospheric conditions, including wind speeds, ambient temperatures and, especially, the salt contents on ice adhesion strength for wind turbine blades. The experiments were conducted on a NACA0018 blade airfoil under conditions including an ambient temperature of −3 °C~−15 °C, wind speed of 6 m/s~15 m/s and salt content of 1~20 mg/m3. The results showed that salt content was the most important factor affecting the ice adhesion strength, followed by ambient temperature and wind speed. The interactive effect of wind speed and salt content, ambient temperature and salt content were extremely significant. The research can provide a reference for the anti-icing for offshore wind turbines.

An Offshore Wind joint venture between Ukraine and Taiwan is proposed to exchange Ukrainian welding experience for Taiwan's offshore wind technology, notably floating. The first Black Sea offshore wind farm is envisioned as the first economic driver of the project, with the production of the later joint fixed and floating offshore wind turbine foundations envisioned. The dangers and benefits of this project from technical and board socio-political aspects were analysed using the SPEED framework. The analysis indicates that leveraging Ukrainian welding expertise could significantly enhance Taiwan's offshore wind capacity, leading to potential economic and technological gains for both countries. As Ukraine and Taiwan governments search for possible post-war cooperation directions, this paper provides a promising idea in Offshore Wind. The goal is to support the establishment of friendly relations between Taiwan and Ukraine.