Journal of Marine Science and Engineering

Editorial

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4 pages, 159 KiB

Open AccessEditorial

Special Issue on Offshore Wind Energy

by E. Uzunoglu, A. Souto-Iglesias and C. Guedes Soares

J. Mar. Sci. Eng. 2024, 12(5), 816; https://doi.org/10.3390/jmse12050816 - 14 May 2024

Viewed by 1591

Abstract

As the impact of fossil fuels on the planet becomes clear, the world is increasingly focusing on renewable energy sources [...] Full article

(This article belongs to the Special Issue Offshore Wind Energy)

Research

Jump to: Editorial, Review

22 pages, 19256 KiB

Open AccessArticle

Dynamic Analysis of a Novel Installation Method of Floating Spar Wind Turbines

by Mohamed Hassan and C. Guedes Soares

J. Mar. Sci. Eng. 2023, 11(7), 1373; https://doi.org/10.3390/jmse11071373 - 5 Jul 2023

Cited by 6 | Viewed by 3293

Abstract

This paper presents the performance of a new, floating, mono-hull wind turbine installation vessel (Nordic Wind) in the installation process. The vessel can transport pre-assembled wind turbines from the marshalling port to the offshore installation site. Each assembled turbine will be positioned over [...] Read more.

This paper presents the performance of a new, floating, mono-hull wind turbine installation vessel (Nordic Wind) in the installation process. The vessel can transport pre-assembled wind turbines from the marshalling port to the offshore installation site. Each assembled turbine will be positioned over the pre-installed floating spar structure. The primary difficulty lies in examining the multibody system’s reactions when subjected to combined wind, current, and wave forces. Time-domain simulations are utilized to model the interconnected system, incorporating mechanical coupling between components, the mooring system for the spar, and the installation vessel. The primary objective is to focus on the monitoring and connection stages preceding the mating operations between the turbine and the floating spar. Additionally, it involves examining the impacts of wind, current, and wave conditions on the motion responses of the installation vessel and the spar, as well as the relative motions at the mating point, gripper forces, and mooring forces. The simulations show that the resulting gripper forces are reasonable to compensate. The relative motion at the mating point is not significantly affected by the orientations of the turbine blades, but it is influenced by the prevailing wave conditions. In addition, vessel heading optimization can minimize the relative motions at the mating point and gripper forces. Given the examined environmental conditions, the presented installation concept exhibits a commendable performance. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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19 pages, 8202 KiB

Open AccessArticle

Stress Distribution on the Preliminary Structural Design of the CENTEC-TLP under Still Water and Wave-Induced Loads

by Esmaeil Zavvar, Hossam S. Abdelwahab, Emre Uzunoglu, Bai-Qiao Chen and C. Guedes Soares

J. Mar. Sci. Eng. 2023, 11(5), 951; https://doi.org/10.3390/jmse11050951 - 28 Apr 2023

Cited by 16 | Viewed by 2698

Abstract

An assessment is made of the stress distribution and the hydrodynamic response of the preliminary structural design of the tension leg platform of a 10 MW wind turbine. The platform supporting a 10 MW turbine is modelled and analysed by the finite element [...] Read more.

An assessment is made of the stress distribution and the hydrodynamic response of the preliminary structural design of the tension leg platform of a 10 MW wind turbine. The platform supporting a 10 MW turbine is modelled and analysed by the finite element method. The stress distribution of the platform is determined in still water with the turbine at above-rated conditions, and the response of the tension leg platform is estimated in the time domain. The results of the time domain analysis show reasonable agreement between the present results and the available data. To check the design stiffener dimensions, span, and spacing against stress distribution, classification societies’ recommendations are used. The results of the stress distribution analysis indicate that the critical locations of the platform are the interaction of the lower columns with the upper columns and the connection of the tower of the turbine. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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15 pages, 1182 KiB

Open AccessArticle

Service Operation Vessels Fleet Size and Mix Location Routing for the Maintenance of an Offshore Floating Wind Farm

by Lis M. R. Silva, He Li and C. Guedes Soares

J. Mar. Sci. Eng. 2023, 11(3), 664; https://doi.org/10.3390/jmse11030664 - 21 Mar 2023

Cited by 8 | Viewed by 3220

Abstract

Mixed-integer linear programming is adopted to translate the routing of service operation vessels that support the logistic aspects of the maintenance of offshore floating wind farms into mathematical language. The models attempt to help the decision-makers by providing quantified tools to screen out [...] Read more.

Mixed-integer linear programming is adopted to translate the routing of service operation vessels that support the logistic aspects of the maintenance of offshore floating wind farms into mathematical language. The models attempt to help the decision-makers by providing quantified tools to screen out the optimal planning for preventive maintenance. The models search for the optimal offshore base location, vessel’s routing per day, vessel’s capacity, and vessel fleet composition that minimize the total fixed and variable infrastructure cost. The integration of the vehicle fleet size and mix problem, facility location–allocation problem, and vehicle-routing problem with time window advances the state of the art. A realistic case study is shown, and the results and discussions demonstrated that the practical insights of the solutions, as well as the identification of the route patterns through a navigation route table, may improve the decision planning of preventive maintenance. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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24 pages, 5059 KiB

Open AccessArticle

Adaptive Backstepping Integral Sliding Mode Control for 5DOF Barge-Type OFWT under Output Constraint

by Syed Awais Ali Shah, Bingtuan Gao, Irfan Ahmad, Hameed Ullah, Nigar Ahmed and Anjum Saeed

J. Mar. Sci. Eng. 2023, 11(3), 492; https://doi.org/10.3390/jmse11030492 - 24 Feb 2023

Cited by 6 | Viewed by 1996

Abstract

This article presents a new control solution for a dynamical model of a translational oscillator with a rotational actuator (TORA) based on multi-body dynamics for a barge-type offshore floating wind turbine (OFWT). TORA has been employed as an active structural control strategy. The [...] Read more.

This article presents a new control solution for a dynamical model of a translational oscillator with a rotational actuator (TORA) based on multi-body dynamics for a barge-type offshore floating wind turbine (OFWT). TORA has been employed as an active structural control strategy. The solution of bounding the output movements of platform pitch and tower bending angle to a certain limit, along with mitigating the OFWT vibrations due to environmental disturbances and uncertainties, is presented in this novel control framework. This new control algorithm consists of a high-gain observer (HGO)-based adaptive backstepping integral sliding mode control (ISMC) and a barrier Lyapunov function (BLF). This guarantees satisfying the constraints on the states and effectively resolves the problem of the unavailability of the system states. The proposed control law based on the BLF has been compared with an adaptive backstepping ISMC to show the efficiency of the output-constraint control scheme. Through MATLAB/SIMULINK numerical simulations and their numeric error table, the effectiveness of the proposed control scheme has been examined. The results confirm the validity and efficiency of the proposed control approaches. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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26 pages, 3444 KiB

Open AccessArticle

Impact of Limited Degree of Freedom Drag Coefficients on a Floating Offshore Wind Turbine Simulation

by Arjun Srinivas, Bryson Robertson, Jonah Benjamin Gadasi, Barbara Gwynne Simpson, Pedro Lomónaco and Jesús María Blanco Ilzarbe

J. Mar. Sci. Eng. 2023, 11(1), 139; https://doi.org/10.3390/jmse11010139 - 7 Jan 2023

Cited by 6 | Viewed by 3442

Abstract

The worldwide effort to design and commission floating offshore wind turbines (FOWT) is motivating the need for reliable numerical models that adequately represent their physical behavior under realistic sea states. However, properly representing the hydrodynamic quadratic damping for FOWT remains uncertain, because of [...] Read more.

The worldwide effort to design and commission floating offshore wind turbines (FOWT) is motivating the need for reliable numerical models that adequately represent their physical behavior under realistic sea states. However, properly representing the hydrodynamic quadratic damping for FOWT remains uncertain, because of its dependency on the choice of drag coefficients (dimensionless or not). It is hypothesized that the limited degree of freedom (DoF) drag coefficient formulation that uses only translational drag coefficients causes mischaracterization of the rotational DoF drag, leading to underestimation of FOWT global loads, such as tower base fore-aft shear. To address these hydrodynamic modeling uncertainties, different quadratic drag models implemented in the open-source mid-fidelity simulation tool, OpenFAST, were investigated and compared with the experimental data from the Offshore Code Comparison Collaboration, Continued, with Correlation (OC5) project. The tower base fore-aft shear and up-wave mooring line tension were compared under an irregular wave loading condition to demonstrate the effects of the different damping models. Two types of hydrodynamic quadratic drag formulations were considered: (1) member-based dimensionless drag coefficients applied only at the translational DoF (namely limited-DoF drag model) and (2) quadratic drag matrix model (in dimensional form). Based on the results, the former consistently underestimated the 95th percentile peak loads and spectral responses when compared to the OC5 experimental data. In contrast, the drag matrix models reduced errors in estimates of the tower base shear peak load by 7–10% compared to the limited-DoF drag model. The underestimation in the tower base fore-aft shear was thus inferred be related to mischaracterization of the rotational pitch drag and the heave motion/drag by the limited-DoF model. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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27 pages, 1562 KiB

Open AccessArticle

Approach for Installation and Logistics of a Floating Offshore Wind Farm

by Hugo Díaz and C. Guedes Soares

J. Mar. Sci. Eng. 2023, 11(1), 53; https://doi.org/10.3390/jmse11010053 - 30 Dec 2022

Cited by 16 | Viewed by 6456

Abstract

An approach is developed for floating wind farm installation by creating a model that allows the planning of the main logistics and installation aspects of a floating wind farm. The method aims to preserve the coherency between logistic methods and project performance, as [...] Read more.

An approach is developed for floating wind farm installation by creating a model that allows the planning of the main logistics and installation aspects of a floating wind farm. The method aims to preserve the coherency between logistic methods and project performance, as floating wind farm installation is a complex problem, due to the number of components that impose specific constraints in areas such as transportation and manufacturing. The planning tool is developed based on the knowledge about how to use the various approaches and on the analysis of different logistical solutions. A techno-economic view of the logistics and installation involved in the floating wind farm design is the main objective of this study. A case study for the CENTEC TLP concept implemented in Spanish and Irish waters is performed. Case study findings reveal the major aspects that affect the design and logistics factors. The tool is developed for the main types of floating wind platforms and is applicable for the preliminary design of wind farms worldwide. The tool suggests a strategy of design and logistic aspects dependent on a few inputs such as the number of components for installation, distances and the maximum number of turbines. These findings are especially important for the new floating wind farms being positioned further offshore. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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26 pages, 4513 KiB

Open AccessArticle

Failure Rate Assessment for Onshore and Floating Offshore Wind Turbines

by He Li, Weiwen Peng, Cheng-Geng Huang and C. Guedes Soares

J. Mar. Sci. Eng. 2022, 10(12), 1965; https://doi.org/10.3390/jmse10121965 - 10 Dec 2022

Cited by 36 | Viewed by 16271

Abstract

A detailed analysis is performed on a dataset of failure and maintenance records from various onshore wind farms located in different geographical areas for the safety, risk, reliability, availability, and maintainability characterization of wind turbines. Specifically, characteristics related to failures, including the criticality [...] Read more.

A detailed analysis is performed on a dataset of failure and maintenance records from various onshore wind farms located in different geographical areas for the safety, risk, reliability, availability, and maintainability characterization of wind turbines. Specifically, characteristics related to failures, including the criticality of failure modes, failure frequencies, failure rates, and lifetime distributions of components, are analyzed to support the failure identification and failure prevention of wind turbines. Additionally, characteristics of maintenance, including typical maintenance measures of failures, policies for spare components, delayed maintenance, as well as related times such as reaction time, travelling time, and mean time to repair, are provided to support the maintenance management of wind farms. Based on the operational data analysis results, a reliability influence factor-based failure data correction approach is presented to transfer the onshore data to floating offshore turbines by modeling the differences in failure occurrences based on experts’ judgment. A comprehensive comparison with existing studies validates the performance of the proposed approach. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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23 pages, 7630 KiB

Open AccessArticle

Experimental Analysis of CENTEC-TLP Self-Stable Platform with a 10 MW Turbine

by Mohamad Hmedi, Emre Uzunoglu, Antonio Medina-Manuel, Jordi Mas-Soler, Felipe Vittori, Oscar Pires, José Azcona, Antonio Souto-Iglesias and C. Guedes Soares

J. Mar. Sci. Eng. 2022, 10(12), 1910; https://doi.org/10.3390/jmse10121910 - 5 Dec 2022

Cited by 10 | Viewed by 3304

Abstract

This work evaluates the experimental test results regarding the operational performance of a free-float capable tension leg platform with a 10 MW wind turbine. It covers the platform dynamics in the selected installation area: Ribadeo, Spain. The model and the facility are initially [...] Read more.

This work evaluates the experimental test results regarding the operational performance of a free-float capable tension leg platform with a 10 MW wind turbine. It covers the platform dynamics in the selected installation area: Ribadeo, Spain. The model and the facility are initially presented, along with the experimental setup and the load cases. The testing campaign includes a software-in-the-loop method to emulate the rotor thrust and the aerodynamic and gyroscopic moments in pitch and yaw. The result sets are structured to start from basic information from system identification cases and continue with responses against regular and irregular waves accompanied by steady and stochastic wind scenarios. The performance in operational and extreme conditions is assessed as well as fault scenarios. The experiments demonstrate auspicious motion dynamics and mooring line behavior when examined against class society rules. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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19 pages, 4888 KiB

Open AccessArticle

Data-Driven Damage Quantification of Floating Offshore Wind Turbine Platforms Based on Multi-Scale Encoder–Decoder with Self-Attention Mechanism

by Musa Bashir, Zifei Xu, Jin Wang and C. Guedes Soares

J. Mar. Sci. Eng. 2022, 10(12), 1830; https://doi.org/10.3390/jmse10121830 - 29 Nov 2022

Cited by 3 | Viewed by 2489

Abstract

A Multi-Scale Convolutional Neural Network with Self Attention-based Auto Encoder–Decoder (MSCSA-AED), is a novel high-performance framework, presented here for the quantification of damage on a multibody floating offshore wind turbine (FOWT) structure. The model is equipped with similarity measurement to enhance its capability [...] Read more.

A Multi-Scale Convolutional Neural Network with Self Attention-based Auto Encoder–Decoder (MSCSA-AED), is a novel high-performance framework, presented here for the quantification of damage on a multibody floating offshore wind turbine (FOWT) structure. The model is equipped with similarity measurement to enhance its capability to accurately quantify damage effects from different scales of coded features using raw platform responses and without human intervention. Case studies using different damage magnitudes on tendons of a 10 MW multibody FOWT were used to examine the accuracy and reliability of the proposed model. The results showed that addition of Square Euclidean (SE) distance enhanced the MSCSA-AED model’s capability to suitably estimate the damage in structures operating in complex environments using only raw responses. Comparison of the model’s performance with other variants (DCN-AED and MSCNN-AED) used in the industry to extract the coded features from FOWT responses further demonstrated the superiority of MSCSA-AED in complex operating conditions, especially in low magnitude damage quantification, which is the hardest to quantify. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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22 pages, 7966 KiB

Open AccessArticle

Hydrodynamic Analysis of the WIND-Bos Spar Floating Offshore Wind Turbine

by Thiago S. Hallak, C. Guedes Soares, Oscar Sainz, Sergio Hernández and Alfonso Arévalo

J. Mar. Sci. Eng. 2022, 10(12), 1824; https://doi.org/10.3390/jmse10121824 - 28 Nov 2022

Cited by 9 | Viewed by 3613

Abstract

The WIND-bos spar Floating Offshore Wind Turbine is studied both experimentally and numerically. The experimental model of the moored WIND-bos platform is presented, and the different numerical models that have been developed to analyze the hydrodynamics of the platform are described. The results [...] Read more.

The WIND-bos spar Floating Offshore Wind Turbine is studied both experimentally and numerically. The experimental model of the moored WIND-bos platform is presented, and the different numerical models that have been developed to analyze the hydrodynamics of the platform are described. The results provide a detailed comparison of numerical and experimental motion responses of the floating structure in regular and irregular waves. The numerical study includes frequency domain results from spectral analysis, weakly nonlinear time-domain results from a validated in-house code, and coupled time-domain results from commercial software. The importance of damping calibration is put in evidence, whereas damping ratios are calculated iteratively in the coupled time-domain simulations, and nonlinear damping force is considered within the developed numerical scheme. The results compare well and also show that the novel concept has a good motion performance in general. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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17 pages, 3444 KiB

Open AccessArticle

Research on Structural Failure Analysis and Strengthening Design of Offshore Wind Turbine Blades

by Xiaohan Fu and Meiping Sheng

J. Mar. Sci. Eng. 2022, 10(11), 1661; https://doi.org/10.3390/jmse10111661 - 4 Nov 2022

Cited by 8 | Viewed by 3046

Abstract

The existing blade protection mechanisms are highly dependent on the control system and its power supply. Safety of offshore wind turbines cannot be guaranteed under extreme weather when the control protection mechanisms fail. So far, not enough consideration has been given to the [...] Read more.

The existing blade protection mechanisms are highly dependent on the control system and its power supply. Safety of offshore wind turbines cannot be guaranteed under extreme weather when the control protection mechanisms fail. So far, not enough consideration has been given to the above problems in mechanical design for protecting wind turbine blades. In this paper, a reinforcing cable component (RCC) is proposed to improve the resistance ability of offshore wind turbine blades. The static model of the blades with reinforcing cable component was presented. The Finite Element (FE) simulation was performed for a 5 MW offshore wind turbine and load reduction effect of connection location for RCC was discussed according to the FE results. A static strain verification test was carried out. Simulation and test results indicate that the proposed reinforcing cable component effectively reduces the strain as well as the tip displacement of the blades. The proposed mechanical structure will help to enhance the survival ability of offshore wind turbine blades when the control protection system fails. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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21 pages, 3440 KiB

Open AccessFeature PaperArticle

An Improved Failure Mode and Effect Analysis of Floating Offshore Wind Turbines

by He Li, A. P. Teixeira and C. Guedes Soares

J. Mar. Sci. Eng. 2022, 10(11), 1616; https://doi.org/10.3390/jmse10111616 - 1 Nov 2022

Cited by 19 | Viewed by 5212

Abstract

This paper proposes an improved failure mode and effect analysis method for a comprehensive failure analysis that provides a holistic perspective of actions on the potential failures of floating offshore wind turbines. A new way of constructing risk priority numbers was developed by [...] Read more.

This paper proposes an improved failure mode and effect analysis method for a comprehensive failure analysis that provides a holistic perspective of actions on the potential failures of floating offshore wind turbines. A new way of constructing risk priority numbers was developed by considering the background knowledge of the specialists involved in the failure analysis. The failure analysis was conducted based on an extensive dataset from multiple specialists that covers five floating offshore wind turbine systems, 15 main components, 42 failure modes, and 104 failure causes. Consequently, 21 recommendations are suggested for designers and operators to prevent and mitigate the risk of unexpected failures of floating offshore wind turbines. Furthermore, a comparison analysis was conducted to illustrate the similarities and differences between the proposed failure mode and effect analysis and the conventional method. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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22 pages, 3606 KiB

Open AccessArticle

Mooring System Transport and Installation Logistics for a Floating Offshore Wind Farm in Lannion, France

by Jorge Altuzarra, Alberto Herrera, Onintze Matías, Joaquín Urbano, Cristina Romero, Shan Wang and C. Guedes Soares

J. Mar. Sci. Eng. 2022, 10(10), 1354; https://doi.org/10.3390/jmse10101354 - 22 Sep 2022

Cited by 12 | Viewed by 5740

Abstract

This study addresses the planning procedures for the installation of the mooring systems that support the floating offshore wind turbines in a wind farm. It considers the logistics of the installation process and discusses the important role of the weather windows in the [...] Read more.

This study addresses the planning procedures for the installation of the mooring systems that support the floating offshore wind turbines in a wind farm. It considers the logistics of the installation process and discusses the important role of the weather windows in the planning of those operations at a preliminary stage of the project. The case study is based on a wind farm array of 47 Telwind floating wind turbine platforms, to be located in Lannion (France), with a potential of 470 MW. The study includes the transport and logistics requirements of different mooring components, such as chains, connectors and drag anchors; the description of the installation operations considering the typology of vessels that are necessary in these manoeuvres; as well as the planning and costs associated with the transport and installation. Given the diversity of elements and operations involved in the installation procedure, it is demonstrated that the research results of duration and costs of this type of operations are only possible to obtain using a simulation tool. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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Graphical abstract

20 pages, 2241 KiB

Open AccessArticle

The Technical and Economic Feasibility of the CENTEC Floating Offshore Wind Platform

by Almudena Filgueira-Vizoso, Laura Castro-Santos, David Cordal Iglesias, Félix Puime-Guillén, Isabel Lamas-Galdo, Ana Isabel García-Diez, Emre Uzunoglu, Hugo Díaz and C. Guedes Soares

J. Mar. Sci. Eng. 2022, 10(10), 1344; https://doi.org/10.3390/jmse10101344 - 21 Sep 2022

Cited by 8 | Viewed by 2945

Abstract

This paper defines a methodology for the economic feasibility analysis of a floating offshore wind farm composed of tensioned leg platforms, which are part of the EU ARCWIND research project. In this context, the phases and subphases of its life-cycle process are considered [...] Read more.

This paper defines a methodology for the economic feasibility analysis of a floating offshore wind farm composed of tensioned leg platforms, which are part of the EU ARCWIND research project. In this context, the phases and subphases of its life-cycle process are considered to deal with aspects such as bathymetry, characteristics of the platforms, distance from the farm to shore, distance from the farm to port and offshore wind speed. All the costs and other external parameters such as capital cost, electric tariff, interest rate, percentage of financing and corporate tax have been analysed to calculate the internal rate of return, net present value, discounted pay-back period and levelized cost of energy of the farm. This work studies a farm composed of TLP offshore wind platforms designed by CENTEC and located at Ribadeo in Spain. Results indicate the costs and the economic feasibility of this platform for deep waters. They indicate that the platform is economically feasible for the location selected. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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24 pages, 2470 KiB

Open AccessArticle

Availability Analysis of an Offshore Wind Turbine Subjected to Age-Based Preventive Maintenance by Petri Nets

by Eduard Lotovskyi, Angelo P. Teixeira and C. Guedes Soares

J. Mar. Sci. Eng. 2022, 10(7), 1000; https://doi.org/10.3390/jmse10071000 - 21 Jul 2022

Cited by 9 | Viewed by 2907

Abstract

This paper analyses the production availability and the associated maintenance costs of an offshore wind turbine with a horizontal axis configuration using Petri Nets modelling with Monte Carlo Simulation. For this purpose, different features are implemented: the reliability and maintainability characteristics of the [...] Read more.

This paper analyses the production availability and the associated maintenance costs of an offshore wind turbine with a horizontal axis configuration using Petri Nets modelling with Monte Carlo Simulation. For this purpose, different features are implemented: the reliability and maintainability characteristics of the components; the logistics of the production and maintenance operations, including different types of vessels, the mobilization time, costs and weather window. The maintenance strategies consist of corrective maintenance and age-based imperfect preventive maintenance that depends on the components’ age and age reduction ratio. Thereby, to increase the operating income and to reduce the costs associated with the operation and maintenance activities, the optimal parameters of the age-based preventive maintenance are estimated. As a case study, a generic offshore wind turbine that operates at the Viana do Castelo wind farm in Portugal is adopted. The wind farm is located 18 km off the shore. The turbine’s total exploration life is 25 years. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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25 pages, 5792 KiB

Open AccessArticle

Hydrodynamic Responses of a Barge-Type Floating Offshore Wind Turbine Integrated with an Aquaculture Cage

by Yuting Zhai, Haisheng Zhao, Xin Li and Wei Shi

J. Mar. Sci. Eng. 2022, 10(7), 854; https://doi.org/10.3390/jmse10070854 - 22 Jun 2022

Cited by 13 | Viewed by 4153

Abstract

The dynamic responses of a new structure combining a barge-type floating offshore wind turbine and an aquaculture cage is investigated numerically. First, a 5 MW barge-type floating offshore wind turbine with an aquaculture cage (FOWT-AC) is designed and the numerical model is established [...] Read more.

The dynamic responses of a new structure combining a barge-type floating offshore wind turbine and an aquaculture cage is investigated numerically. First, a 5 MW barge-type floating offshore wind turbine with an aquaculture cage (FOWT-AC) is designed and the numerical model is established in ANSYS-AQWA. The numerical model of the barge-type FOWT-AC is then checked, and the natural periods of the six degrees of freedom motion satisfy the recommendations of the DNV specification. Based on the reasonable model, the comparison study of dynamic responses between the barge-type FOWT-AC and FOWT under the environmental conditions of the South China Sea is carried out, and it is observed that the FOWT-AC produces a basically lower standard deviation of the motion responses. To investigate the new structure of the barge-type FOWT-AC deeply, the analyses of second-order hydrodynamic response, typical environmental conditions and the mooring line breaking scenario are carried out. The simulation results show that the second-order wave loads increase the dynamic response of the barge-type FOWT-AC slightly unless it causes resonance for the structure. In addition, the motion responses of the floating structures increase significantly when the currents are applied, especially when the aquaculture cage is integrated into the barge-type FOWT. When one of the mooring lines connected to the offshore or onshore side of the platform breaks, the presence of the aquaculture cage results in a smaller standard deviation in the motion responses of the coupled structure, which means that the barge-type FOWT-AC structure is more stable. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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34 pages, 27285 KiB

Open AccessArticle

Experimental and Numerical Study of the Influence of Clumped Weights on a Scaled Mooring Line

by Tomas Lopez-Olocco, Leo M. González-Gutiérrez, Javier Calderon-Sanchez, Adolfo Marón Loureiro, Leandro Saavedra Ynocente, Ana Bezunartea Barrio and Nicolás Vivar Valdés

J. Mar. Sci. Eng. 2022, 10(5), 676; https://doi.org/10.3390/jmse10050676 - 16 May 2022

Cited by 6 | Viewed by 2692

Abstract

Recently, several experimental and numerical studies have underlined the advantages of adding clumped weights at discrete positions of mooring lines. To confirm the influence of these weights, an experimental study was performed for a 1:30 scale model of a mooring line. In this [...] Read more.

Recently, several experimental and numerical studies have underlined the advantages of adding clumped weights at discrete positions of mooring lines. To confirm the influence of these weights, an experimental study was performed for a 1:30 scale model of a mooring line. In this study, the clumped weight is modeled as a scaled disc placed at different positions along the mooring line. The series of experiments has been carried out at the CEHIPAR towing tank using a submerged studless chain both with and without clumped weights. The experiments consist of the excitation of the suspension point with horizontal periodic motions using different amplitudes and periods, where the mooring line’s tension at the fairlead is measured using a load cell and a dynamometer, and the motion of a part of the line is recorded using low-cost submerged cameras. Similarly to previous experiments, the fairlead tensions increase with higher amplitudes and lower periods, and a clear pattern in the motions of the line at different depths is found. The dissipated energy and the fairlead tension is also increased by the addition of the clumped weight, and the variation of this energy with its position along the line is monitored. The presence of clumped weights is also implemented into a finite element numerical code, previously validated without clumped weights, where all the previous experiments with clumped weights are replicated with remarkable accuracy. This double experimental and computational approach to the problem provides an important dataset for numerical code validations and opens future discussions about the impact of clumped weights on floating platforms. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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18 pages, 13030 KiB

Open AccessArticle

Integrated Dynamics Response Analysis for IEA 10-MW Spar Floating Offshore Wind Turbine

by Xiaojiang Guo, Yu Zhang, Jiatao Yan, Yiming Zhou, Shu Yan, Wei Shi and Xin Li

J. Mar. Sci. Eng. 2022, 10(4), 542; https://doi.org/10.3390/jmse10040542 - 14 Apr 2022

Cited by 12 | Viewed by 4588

Abstract

Wind energy in the deep-sea area is more abundant and the capacity of wind turbines can be made larger. Therefore, the research on deep-sea floating offshore wind turbines will be the primary strategy for wind energy exploitation in the future. The spar-type platform [...] Read more.

Wind energy in the deep-sea area is more abundant and the capacity of wind turbines can be made larger. Therefore, the research on deep-sea floating offshore wind turbines will be the primary strategy for wind energy exploitation in the future. The spar-type platform depends on the characteristics of a small water plane, deep draft, and good stability, which has been applied to the commercial development of deep-sea wind energy. In the next ten years, the 10-MW wind turbine will become the mainstream class installed in the floating offshore wind turbine farm. Thus, it is very necessary to conduct a comprehensive and in-depth study on the 10-MW spar type floating offshore wind turbine. The direct-drive 10-MW offshore wind turbine was proposed by the International Energy Agency (IEA) in Wind Task 37 in 2019. In this paper, a spar-type platform is designed to support the IEA 10-MW reference wind turbines, and a nonlinear aero-hydro-servo-elastic numerical model is established using the FAST tool (which is developed by the National Renewable Energy Laboratory, NREL). Then, the accuracy of the wind turbine and the sensitivity of the controller are verified, and the natural periods of the floating offshore wind turbine are obtained by free-decay tests. The natural periods of the platform in six degrees-of-freedom are found to be within the range recommended by the design standard. The measured wind and wave data of the target site close to Fujian Province of China are used to evaluate the performance of the floating offshore wind turbine under the 100-, 50-, 5-, and 2-year-return stochastic weather conditions. The results indicate that the design of the spar platform is reasonable and has excellent hydrodynamic performance. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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13 pages, 3030 KiB

Open AccessFeature PaperArticle

Fostering Offshore Wind Integration in Europe through Grid Connection Impact Assessment

by Nuno Amaro, Aleksandr Egorov and Gonçalo Glória

J. Mar. Sci. Eng. 2022, 10(4), 463; https://doi.org/10.3390/jmse10040463 - 24 Mar 2022

Cited by 8 | Viewed by 2875

Abstract

Floating offshore wind energy is one of the solutions that can foster the ongoing climate transition in Europe. The ARCWIND project aims to contribute to this topic by considering multiple research activities designed to contribute to the development of multiple floating technologies, identifying [...] Read more.

Floating offshore wind energy is one of the solutions that can foster the ongoing climate transition in Europe. The ARCWIND project aims to contribute to this topic by considering multiple research activities designed to contribute to the development of multiple floating technologies, identifying high-potential deployment areas while considering their economic viability and the impact that these would have in existing power systems. Regarding the latter activity, a two-step methodology was implemented to first calculate the nodal capacity that existing electricity networks have to absorb energy from these potential new wind farms and secondly to assess the impact at the point of connection. This assessment is performed by identifying grid reinforcement needs, verifying the impact on short circuit current levels and measuring the impact on the existing energy mix at countrywide level. This article includes the description of this methodology as well as its application to six different use cases covering five European countries: Portugal, Spain, France, the United Kingdom, and Ireland. Results obtained seem to indicate that, in most cases, the current power systems have enough capacity for the possible connection of new floating offshore wind farms without major reinforcement needs and that these wind farms can have a major contribution to the countries’ energy mix and to the achievement of established climate targets. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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25 pages, 3141 KiB

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Experimental Challenges and Modelling Approaches of Floating Wind Turbines

by Mohamad Hmedi, Emre Uzunoglu, Chen Zeng, J. F. Gaspar and C. Guedes Soares

J. Mar. Sci. Eng. 2023, 11(11), 2048; https://doi.org/10.3390/jmse11112048 - 25 Oct 2023

Cited by 3 | Viewed by 3306

Abstract

This paper reviews experimental methods for testing floating wind turbines. The techniques covered include early-stage and up-to-date approaches such as a porous disc method and hybrid model testing. First, the challenges induced by Froude and Reynolds similitudes and the importance of the various [...] Read more.

This paper reviews experimental methods for testing floating wind turbines. The techniques covered include early-stage and up-to-date approaches such as a porous disc method and hybrid model testing. First, the challenges induced by Froude and Reynolds similitudes and the importance of the various aerodynamic phenomena are discussed. The experimental methods are evaluated based on their cost, versatility, requirements, and limitations. The work primarily focuses on representing aerodynamic loads via hybrid and physical rotor testing, and a preliminary classification is proposed to facilitate the selection of the approaches. The work does not aim to identify an optimal method, but it provides insights into each method’s distinctive features, serving as a roadmap for selecting the most appropriate methodology based on the specific testing goals and level of accuracy. Overall, this study offers a comprehensive resource for testing the coupled hydrodynamic and aerodynamic performance of floating wind turbines. The conclusions offer guidance for selecting an appropriate methodology based on the desired testing outcome. Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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17 pages, 1404 KiB

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Market Needs, Opportunities and Barriers for the Floating Wind Industry

by Hugo Díaz, José Serna, Javier Nieto and C. Guedes Soares

J. Mar. Sci. Eng. 2022, 10(7), 934; https://doi.org/10.3390/jmse10070934 - 7 Jul 2022

Cited by 56 | Viewed by 6711

Abstract

This paper reviews the status of floating wind energy expansion, market needs, opportunities, and barriers. Even more expensive than many other generation technologies currently, the floating wind will contribute to the decarbonization of Europe. This document assesses the market strategies available to develop [...] Read more.

This paper reviews the status of floating wind energy expansion, market needs, opportunities, and barriers. Even more expensive than many other generation technologies currently, the floating wind will contribute to the decarbonization of Europe. This document assesses the market strategies available to develop floating wind farms in Europe. The study includes four main phases in addition to the overview of the current state-of-the-art: a technology review, market outlook, opportunities, and commercialization barriers. During its development, the offshore wind has moved from experimentation to a final design (Semisubmersible/barge, Tension Leg Platform, and Spar). Full article

(This article belongs to the Special Issue Offshore Wind Energy)

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