Journal of Marine Science and Engineering

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42 pages, 10326 KiB

Open AccessArticle

Analysis, Forecasting, and System Identification of a Floating Offshore Wind Turbine Using Dynamic Mode Decomposition

by Giorgio Palma, Andrea Bardazzi, Alessia Lucarelli, Chiara Pilloton, Andrea Serani, Claudio Lugni and Matteo Diez

J. Mar. Sci. Eng. 2025, 13(4), 656; https://doi.org/10.3390/jmse13040656 - 25 Mar 2025

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Abstract

This article presents the data-driven equation-free modeling of the dynamics of a hexafloat floating offshore wind turbine based on the application of dynamic mode decomposition (DMD). The DMD has here been used (i) to extract knowledge from the dynamic system through its modal [...] Read more.

This article presents the data-driven equation-free modeling of the dynamics of a hexafloat floating offshore wind turbine based on the application of dynamic mode decomposition (DMD). The DMD has here been used (i) to extract knowledge from the dynamic system through its modal analysis, (ii) for short-term forecasting (nowcasting) from the knowledge of the immediate past of the system state, and (iii) for system identification and reduced-order modeling. All the analyses are performed on experimental data collected from an operating prototype. The nowcasting method for motions, accelerations, and forces acting on the floating system applies Hankel-DMD, a methodological extension that includes time-delayed copies of the states in an augmented state vector. The system identification task is performed by using Hankel-DMD with a control (Hankel-DMDc), which models the system as externally forced. The influence of the main hyperparameters of the methods is investigated with a full factorial analysis using error metrics analyzing complementary aspects of the prediction. A Bayesian extension of the Hankel-DMD and Hankel-DMDc is introduced by considering the hyperparameters as stochastic variables, enriching the predictions with uncertainty quantification. The results show the capability of the approaches for data-lean nowcasting and system identification, with computational costs being compatible with real-time applications. Accurate predictions are obtained up to 4 wave encounters for nowcasting and 20 wave encounters for system identification, suggesting the potential of the methods for real-time continuous-learning digital twinning and surrogate data-driven reduced-order modeling. Full article

(This article belongs to the Special Issue Advances in Offshore Wind and Wave Energies—2nd Edition)

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13 pages, 5927 KiB

Open AccessArticle

Long-Term (1979–2024) Variation Trend in Wave Power in the South China Sea

by Yifeng Tong, Junmin Li, Wuyang Chen and Bo Li

J. Mar. Sci. Eng. 2025, 13(3), 524; https://doi.org/10.3390/jmse13030524 - 9 Mar 2025

Viewed by 708

Abstract

Wave power (WP) is a strategic oceanic resource. Previous studies have extensively researched the long-term variations in WP in the South China Sea (SCS) for energy planning and utilization. This study extends the analysis of long-term trends to the last year based on [...] Read more.

Wave power (WP) is a strategic oceanic resource. Previous studies have extensively researched the long-term variations in WP in the South China Sea (SCS) for energy planning and utilization. This study extends the analysis of long-term trends to the last year based on ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5) reanalysis data from 1979 to 2024. Our results mainly indicate that the trends in WP after 2011 are significantly different from those before 2011. Before 2011, the WP in the SCS primarily showed an increasing trend, but, after 2011, it shifted to a decreasing trend. This trend has seasonal differences, manifested as being consistent with the annual trend in winter and spring while being inconsistent with the annual trend in summer and autumn. It indicates that the opposite trend in WP before and after 2011 was mainly the result of WP variations in winter and spring. To illustrate the driving factor for the WP’s variations, the contemporary long-term trend of the wind fields is systematically analyzed. Analysis results reveal that, regardless of seasonal differences or spatial distribution, the two trends are consistent in most situations, indicating that wind fields are the dominant factor for the long-term variations in WP. Meanwhile, the effects of the wind fields on the WP variations can also be modulated by environmental factors such as oceanic swell propagation and local topography. This study contributes to the knowledge of the latest trends and driving factors regarding the WP in the SCS. Full article

(This article belongs to the Special Issue Advances in Offshore Wind and Wave Energies—2nd Edition)

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25 pages, 12921 KiB

Open AccessArticle

Quantum-Inspired MoE-Based Optimal Operation of a Wave Hydrogen Microgrid for Integrated Water, Hydrogen, and Electricity Supply and Trade

by Hady H. Fayek, Fady H. Fayek and Eugen Rusu

J. Mar. Sci. Eng. 2025, 13(3), 461; https://doi.org/10.3390/jmse13030461 - 27 Feb 2025

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Abstract

This research explores the optimal operation of an offshore wave-powered hydrogen system, specifically designed to supply electricity and water to a bay in Humboldt, California, USA, and also sell it with hydrogen. The system incorporates a desalination unit to provide the island with [...] Read more.

This research explores the optimal operation of an offshore wave-powered hydrogen system, specifically designed to supply electricity and water to a bay in Humboldt, California, USA, and also sell it with hydrogen. The system incorporates a desalination unit to provide the island with fresh water and feed the electrolyzer to produce hydrogen. The optimization process utilizes a mixture of experts in conjunction with the Quantitative Structure-Activity Relationship (QSAR) algorithm traditionally used in drug design, to achieve two main objectives: minimizing operational costs and maximizing revenue from the sale of water, hydrogen, and electricity. Many case studies are examined, representing typical electricity demand and wave conditions during typical summer, winter, spring, and fall days. The simulation, optimization, and results are carried out using MATLAB 2018 and SAM 2024 software applications. The findings demonstrate that the combination of the QSAR algorithm and quantum-inspired MoE results in higher revenue and lower costs compared to other current techniques, with hydrogen sales being the primary contributor to increased income. Full article

(This article belongs to the Special Issue Advances in Offshore Wind and Wave Energies—2nd Edition)

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24 pages, 9412 KiB

Open AccessArticle

Research on Decoupling Duty Cycle Optimization Control Method of a Multiport Converter for Dual-Port Direct Drive Wave Power Generation System

by Lei Huang, Shixiang Wang, Baoyi Pan, Haitao Liu, Jiyu Zhang and Shiquan Wu

J. Mar. Sci. Eng. 2024, 12(10), 1811; https://doi.org/10.3390/jmse12101811 - 11 Oct 2024

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Abstract

Dual-port direct drive wave energy power generation systems (DP-DDWEPGS) have received widespread attention due to their smooth and zero-free output power, compared to single-port direct drive wave energy power generation systems (SP-DDWEPGS) which have the disadvantage of large out-put power fluctuations. To further [...] Read more.

Dual-port direct drive wave energy power generation systems (DP-DDWEPGS) have received widespread attention due to their smooth and zero-free output power, compared to single-port direct drive wave energy power generation systems (SP-DDWEPGS) which have the disadvantage of large out-put power fluctuations. To further enhance the performance of the DP-DDWEPGS, optimal power capture control is proposed to achieve maximum power point tracking. Meanwhile, a multiport converter is applied to the DP-DDWEPGS to solve the problem caused by an excessive number of switching devices in the overall system converter. The multiport converter fulfills all the functional requirements of the DP-DDWEPGS while reducing the number of switching devices. However, switch multiplexing of the multiport converter also introduces coupling relationships between each port and the wave force exhibits time-varying characteristics, necessitating advanced control methods with superior fast-tracking capability. Therefore, in this paper, a decoupling duty cycle optimization model predictive control for DP-DDWEPGS is proposed. Based on the characteristics of switching multiplexing, NSC finite control set model predictive control (FCS-MPC) decouples the current prediction and the cost function, reduces the number of candidate voltage vectors in each operation, and shortens the operation time by 70%. To address the issues of high ripple value and increased error due to decoupling in FCS-MPC, duty cycle optimization control is added, greatly reducing the fluctuations in electromagnetic force and power of the permanent magnet linear generator (PMLG). Based on the established simulation model, the feasibility and superiority of the multiport converter and decoupling duty cycle optimization model predictive current control method are verified. Full article

(This article belongs to the Special Issue Advances in Offshore Wind and Wave Energies—2nd Edition)

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33 pages, 12159 KiB

Open AccessArticle

Advancing Offshore Renewable Energy: Integrative Approaches in Floating Offshore Wind Turbine-Oscillating Water Column Systems Using Artificial Intelligence-Driven Regressive Modeling and Proportional-Integral-Derivative Control

by Irfan Ahmad, Fares M’zoughi, Payam Aboutalebi, Aitor J. Garrido and Izaskun Garrido

J. Mar. Sci. Eng. 2024, 12(8), 1292; https://doi.org/10.3390/jmse12081292 - 31 Jul 2024

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Abstract

This research investigates the integration of Floating Offshore Wind Turbines (FOWTs) with Oscillating Water Columns (OWCs) to enhance sustainable energy generation, focusing on addressing dynamic complexities and uncertainties inherent in such systems. The novelty of this study lies in its dual approach, which [...] Read more.

This research investigates the integration of Floating Offshore Wind Turbines (FOWTs) with Oscillating Water Columns (OWCs) to enhance sustainable energy generation, focusing on addressing dynamic complexities and uncertainties inherent in such systems. The novelty of this study lies in its dual approach, which integrates regressive modeling with an aero-hydro-elasto-servo-mooring coupled system with a deep data-driven network and implements a proportional-integral-derivative (PID) control mechanism to improve system stability. By employing Artificial Neural Networks (ANNs), the study circumvents the challenges of real-time closed-loop control on FOWT structures using the OpenFAST simulation tool. Data-driven models, trained on OpenFAST datasets, facilitate real-time predictive behavior analysis and decision-making. Advanced computational learning techniques, particularly ANNs, accurately replicate the dynamics of FOWT-OWC numerical models. An intelligent PID control mechanism is subsequently applied to mitigate structural vibrations, ensuring effective control. A comparative analysis with traditional barge-based FOWT systems underscores the enhanced modeling and control methodologies’ effectiveness. In this sense, the experimental results demonstrate substantial reductions in the mean oscillation amplitude, with reductions from 5% to 35% observed across various scenarios. Specifically, at a wave period from 20 s and a wind speed of 5 m/s, the fore-aft displacement was reduced by 35%, exemplifying the PID control system’s robustness and efficacy under diverse conditions. This study highlights the potential of ANN-driven modeling as an alternative to managing the complex non-linear dynamics of NREL 5 MW FOWT models and underscores the significant improvements in system stability through tailored PID gain scheduling across various operational scenarios. Full article

(This article belongs to the Special Issue Advances in Offshore Wind and Wave Energies—2nd Edition)

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16 pages, 5004 KiB

Open AccessArticle

A Jacket-Frame Mounted Oscillating Water Column with a Variable Aperture Skirt

by Carlos Pérez-Collazo, Deborah M. Greaves and Gregorio Iglesias

J. Mar. Sci. Eng. 2023, 11(12), 2383; https://doi.org/10.3390/jmse11122383 - 18 Dec 2023

Cited by 3 | Viewed by 1823

Abstract

During the last decade jacket-frames have emerged as the main kind of substructure for bottom-mounted offshore wind farms in intermediate water depths. With the offshore wind industry moving towards deeper waters, the predominance of jacket-frames is expected to increase in future years. Multipurpose [...] Read more.

During the last decade jacket-frames have emerged as the main kind of substructure for bottom-mounted offshore wind farms in intermediate water depths. With the offshore wind industry moving towards deeper waters, the predominance of jacket-frames is expected to increase in future years. Multipurpose platforms combining wind and wave energy are proposed as an innovative solution to enhance the sustainability of offshore wind energy. In this research, a multipurpose platform is investigated with a novel feature in its oscillating water column (OWC) wave energy converter—a variable geometry skirt. A comprehensive physical modelling campaign was carried out using a 1:50 scale model. The performance of the OWC and its interaction with the wave field were investigated under four different skirt aperture angles. It was found that the skirt aperture angle plays a significant role in the capture-width ratio and the pneumatic mean power of the OWC. The best performance was obtained with a skirt aperture angle of 140 deg. More generally, these results prove that the variable-geometry skirt is a promising innovation for hybrid wave-wind systems mounted on jacket-frame substructures. Full article

(This article belongs to the Special Issue Advances in Offshore Wind and Wave Energies—2nd Edition)

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23 pages, 8364 KiB

Open AccessArticle

A Novel Composite Pitch Control Scheme for Floating Offshore Wind Turbines with Actuator Fault Consideration

by Shuang Liu, Yaozhen Han, Ronglin Ma, Mingdong Hou and Chao Kang

J. Mar. Sci. Eng. 2023, 11(12), 2272; https://doi.org/10.3390/jmse11122272 - 30 Nov 2023

Cited by 2 | Viewed by 1530

Abstract

It is of great importance to simultaneously stabilize output power and suppress platform motion and fatigue loads in floating offshore wind turbine control systems. In this paper, a novel composite blade pitch control scheme considering actuator fault is proposed based on an augmented [...] Read more.

It is of great importance to simultaneously stabilize output power and suppress platform motion and fatigue loads in floating offshore wind turbine control systems. In this paper, a novel composite blade pitch control scheme considering actuator fault is proposed based on an augmented linear quadratic regulator (LQR), a fuzzy proportional integral (PI) and an adaptive second-order sliding-mode observer. Collective pitch control was achieved via the fuzzy PI, while individual pitch control was based on the augmented LQR. In the case of actuator fault, an adaptive second-order sliding-mode observer was constructed to effectively eliminate the need for the upper bound of unknown fault derivatives and suppress the chattering effect. This paper conducted co-simulations based on FAST (Fatigue, Aerodynamics, Structures, and Turbulence) and MATLAB/Simulink to verify the effectiveness and superiority of the proposed scheme under different environmental conditions. It is shown that platform roll was reduced by approximately 54% compared to that under PI control. For the tower fore–aft moment, load reductions of 45% or more were achievable. The proposed scheme can greatly reduce the pitch and roll of the floating platform and loads in the windward direction of the wind turbine. Full article

(This article belongs to the Special Issue Advances in Offshore Wind and Wave Energies—2nd Edition)

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Review

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34 pages, 11771 KiB

Open AccessReview

A Review and Design Principle of Fixed-Bottom Foundation Scour Protection Schemes for Offshore Wind Energy

by Dongyue Gao, Xinying Pan, Bingchen Liang, Bo Yang, Guoxiang Wu and Zhenlu Wang

J. Mar. Sci. Eng. 2024, 12(4), 660; https://doi.org/10.3390/jmse12040660 - 16 Apr 2024

Cited by 4 | Viewed by 3771

Abstract

Foundation scour is the erosion of sediments around pile foundations by wave and current in offshore wind energy. This phenomenon destabilizes foundations and poses a threat to pile safety. Therefore, scour protection becomes a crucial challenge in offshore wind projects. This paper reviews [...] Read more.

Foundation scour is the erosion of sediments around pile foundations by wave and current in offshore wind energy. This phenomenon destabilizes foundations and poses a threat to pile safety. Therefore, scour protection becomes a crucial challenge in offshore wind projects. This paper reviews and synthesizes recent publications and patented technologies related to scour protection. Considering the primary engineering concerns, the paper proposes design principles for effective scour protection schemes to standardize evaluation criteria. These principles prioritize efficacy, independence, and cost-efficiency, enabling the analysis of scour protection scheme applicability. In addition, this paper summarizes and describes common protection schemes in the literature. The effectiveness of their protection is analyzed and summarized, and their economic and performance independence is evaluated. This paper categorizes flow-altering scour protection schemes found in the literature. Based on a comprehensive understanding of the mechanisms and engineering requirements of scour protection, the paper proposes a focus on determining the erosion reduction rate curve (

E p - U / U_{c}

curve) as a key criterion for evaluating the effectiveness of protection schemes under varying flow velocities and the erosion reduction rate of scour protection schemes under extreme conditions. The study highlights the necessity of establishing a comprehensive design evaluation methodology, which is crucial for addressing the significant challenges related to scour encountered in offshore wind power projects. Full article

(This article belongs to the Special Issue Advances in Offshore Wind and Wave Energies—2nd Edition)

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