P. Thies, Magnus Harrold, L. Johanning, K. Grivas, G. Georgallis
Floating Offshore Wind turbine installations will require HV dynamic power cables to be connected to the of longer length static export power cables. Experience from offshore wind installations has highlighted the criticality of power cables, underlining the need for high integrity, yet cost effective cable solutions. This paper will assess the mechanical performance and load parameters for an Aluminum power conductor cable. Whilst copper is the conventional choice due to its lower resistive losses, Aluminum cores are increasingly used for static power cables, due to their benefits regarding overall cable weight and material cost. The work presented adopts a coupled aero-elastic and hydrodynamic modelling approach to simulate the behavior of the well-documented OC4 semi-sub platform, together with the 5MW NREL wind turbine. The model allows a direct comparison between the two cable types, maintaining the overall system and environmental conditions. The results inform the design envelope regarding the ultimate load conditions a for the two principle cable designs, providing global load estimates, such as effective tension and bending stresses, to inform the local stress analysis. Furthermore, the results will form the basis for future physical demonstration and validation tests. This paper will be of interest to technology developers and practitioners concerned with submarine dynamic power cables, offer a methodology to directly compare and evaluate different cable design options, and providing some design guidance for and aluminum conductor cables.
{"title":"Performance Evaluation of Dynamic HV Cables With Al Conductors for Floating Offshore Wind Turbines","authors":"P. Thies, Magnus Harrold, L. Johanning, K. Grivas, G. Georgallis","doi":"10.1115/IOWTC2019-7536","DOIUrl":"https://doi.org/10.1115/IOWTC2019-7536","url":null,"abstract":"\u0000 Floating Offshore Wind turbine installations will require HV dynamic power cables to be connected to the of longer length static export power cables. Experience from offshore wind installations has highlighted the criticality of power cables, underlining the need for high integrity, yet cost effective cable solutions. This paper will assess the mechanical performance and load parameters for an Aluminum power conductor cable. Whilst copper is the conventional choice due to its lower resistive losses, Aluminum cores are increasingly used for static power cables, due to their benefits regarding overall cable weight and material cost. The work presented adopts a coupled aero-elastic and hydrodynamic modelling approach to simulate the behavior of the well-documented OC4 semi-sub platform, together with the 5MW NREL wind turbine. The model allows a direct comparison between the two cable types, maintaining the overall system and environmental conditions.\u0000 The results inform the design envelope regarding the ultimate load conditions a for the two principle cable designs, providing global load estimates, such as effective tension and bending stresses, to inform the local stress analysis. Furthermore, the results will form the basis for future physical demonstration and validation tests.\u0000 This paper will be of interest to technology developers and practitioners concerned with submarine dynamic power cables, offer a methodology to directly compare and evaluate different cable design options, and providing some design guidance for and aluminum conductor cables.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125005390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper summarizes the results of the implementation and verification of a hydro-aero-servo-elastic load simulation model for a self-aligning floating offshore wind turbine (FOWT) combined with a structural analysis methodology of this FOWT structure. The main focus is a comparison of a rigid and a flexible support structure representation in the load simulation. This investigation is part of the multiparty project for the ‘Hydrodynamic and Structural Optimization of a Semi-submersible Offshore Wind Turbine’ (HyStOH), joining partners from science and industry and financially supported by the German Ministry of Economics Affairs and Energy, BMWi (Bundesministerium für Wirtschaft und Energie).
本文总结了自调心浮式海上风力机(FOWT)液压-气动-伺服-弹性载荷仿真模型的实现与验证结果，并结合该浮式海上风力机结构分析方法。重点比较了刚性和柔性支撑结构在载荷模拟中的表现形式。这项研究是“半潜式海上风力涡轮机的流体动力学和结构优化”(HyStOH)多方项目的一部分，由德国经济事务和能源部BMWi (bundesministium fr Wirtschaft und Energy)资助，由科学和工业合作伙伴参与。
{"title":"Loading and Structural Analysis of the Self-Aligning HyStOH Floating Wind Turbine Concept","authors":"A. Manjock, Markus S. Starr","doi":"10.1115/iowtc2019-7551","DOIUrl":"https://doi.org/10.1115/iowtc2019-7551","url":null,"abstract":"\u0000 This paper summarizes the results of the implementation and verification of a hydro-aero-servo-elastic load simulation model for a self-aligning floating offshore wind turbine (FOWT) combined with a structural analysis methodology of this FOWT structure. The main focus is a comparison of a rigid and a flexible support structure representation in the load simulation. This investigation is part of the multiparty project for the ‘Hydrodynamic and Structural Optimization of a Semi-submersible Offshore Wind Turbine’ (HyStOH), joining partners from science and industry and financially supported by the German Ministry of Economics Affairs and Energy, BMWi (Bundesministerium für Wirtschaft und Energie).","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"2014 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131271113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Ikoma, Mitsuru Nakamura, Satsuya Moritsu, Y. Aida, K. Masuda, H. Eto
This paper describes characteristics of motion responses and tether tensions of a floating structure with four moon pools, on which one or two vertical axis wind turbine models are installed. Effects of several moon pools founded in a floating structure on motion characteristics have been unclear. In this study, the authors proposed a twin-VAWT installed floating system, which was a pontoon based structure. However four moon pools were set on. The study conducted model experiments in a wave tank using regular waves with 0.6 to 2.0 seconds in wave periods and 0.02 and 0.04 m in wave height. The model had four moon pools and was installed with one or two vertical axis turbine models. From it, gyroscopic moment effects were investigated. Besides, the study performed numerical calculations with the linear potential theory based method which were a Green function method. As a results, responses of the twin-turbine model are not affected by gyroscopic moment. The study discusses motion responses and tether tensions with nonlinear behaviours from mainly the experimental results. Also the effect of moon pools were investigated from the calculations. From comparisons of motion results on calculation models with same displacement but different draft, the results suggested that not only heave motion but also roll motion could be reduced because of the moon pools if the size of the moon pools were optimized.
{"title":"Effects of Four Moon Pools on a Floating System Installed With Twin-VAWTs","authors":"T. Ikoma, Mitsuru Nakamura, Satsuya Moritsu, Y. Aida, K. Masuda, H. Eto","doi":"10.1115/iowtc2019-7598","DOIUrl":"https://doi.org/10.1115/iowtc2019-7598","url":null,"abstract":"\u0000 This paper describes characteristics of motion responses and tether tensions of a floating structure with four moon pools, on which one or two vertical axis wind turbine models are installed. Effects of several moon pools founded in a floating structure on motion characteristics have been unclear.\u0000 In this study, the authors proposed a twin-VAWT installed floating system, which was a pontoon based structure. However four moon pools were set on. The study conducted model experiments in a wave tank using regular waves with 0.6 to 2.0 seconds in wave periods and 0.02 and 0.04 m in wave height. The model had four moon pools and was installed with one or two vertical axis turbine models. From it, gyroscopic moment effects were investigated. Besides, the study performed numerical calculations with the linear potential theory based method which were a Green function method.\u0000 As a results, responses of the twin-turbine model are not affected by gyroscopic moment. The study discusses motion responses and tether tensions with nonlinear behaviours from mainly the experimental results. Also the effect of moon pools were investigated from the calculations. From comparisons of motion results on calculation models with same displacement but different draft, the results suggested that not only heave motion but also roll motion could be reduced because of the moon pools if the size of the moon pools were optimized.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122251418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Guyot, Cyrille De Mourgues, G. L. Bihan, Pierre Parenthoine, Julien Templai, Aengus Connolly, M. Boulluec
EOLINK have developed an innovative floating wind turbine in which the single tower is replaced by a set of legs providing a pyramidal architecture. A 1/10th scale prototype of EOLINK’s 12MW concept has been connected to the grid in April 2018 in France. Firstly, the paper describes the technical specifications of this device. Both the turbine and the floater have been designed using Froude scaling, in order to properly represent the EOLINK full scale 12MW concept. The device has been devised from scratch and deploys a Permanent Magnet Synchronous Generator (PMSG) and an individual electric blade pitch system. The patented mooring system comprises a single point mooring (SPM) system able to withstand very high tide ranges in shallow waters. Regarding monitoring, motions have been recorded using both an Inertial Measurement Unit (IMU) and high precision Global Positioning System (GPS) sensors. Mooring lines tensions have also been monitored. Wind is recorded using both an embedded anemometer on the floating turbine and onshore anemometers installed by IFREMER. This Institute has also measured wave height using a wave recorder. Secondly, experimental results during production and storm events are presented. The encountered environmental conditions highlight the capability of the EOLINK design to withstand harsh wind events, and its ability to produce 12MW using a small sized semi-submersible floater. Then, numerical analysis using FAST and Flexcom is compared with experimental results. Static analysis, decay-tests, Response Amplitude Operators (RAOs) and Power Spectral Densities (PSDs) results are detailed. Power production and the embedded control command capabilities are also presented.
{"title":"Experimental Offshore Floating Wind Turbine Prototype and Numerical Analysis During Harsh and Production Events","authors":"M. Guyot, Cyrille De Mourgues, G. L. Bihan, Pierre Parenthoine, Julien Templai, Aengus Connolly, M. Boulluec","doi":"10.1115/iowtc2019-7602","DOIUrl":"https://doi.org/10.1115/iowtc2019-7602","url":null,"abstract":"\u0000 EOLINK have developed an innovative floating wind turbine in which the single tower is replaced by a set of legs providing a pyramidal architecture. A 1/10th scale prototype of EOLINK’s 12MW concept has been connected to the grid in April 2018 in France. Firstly, the paper describes the technical specifications of this device. Both the turbine and the floater have been designed using Froude scaling, in order to properly represent the EOLINK full scale 12MW concept. The device has been devised from scratch and deploys a Permanent Magnet Synchronous Generator (PMSG) and an individual electric blade pitch system. The patented mooring system comprises a single point mooring (SPM) system able to withstand very high tide ranges in shallow waters. Regarding monitoring, motions have been recorded using both an Inertial Measurement Unit (IMU) and high precision Global Positioning System (GPS) sensors. Mooring lines tensions have also been monitored. Wind is recorded using both an embedded anemometer on the floating turbine and onshore anemometers installed by IFREMER. This Institute has also measured wave height using a wave recorder. Secondly, experimental results during production and storm events are presented. The encountered environmental conditions highlight the capability of the EOLINK design to withstand harsh wind events, and its ability to produce 12MW using a small sized semi-submersible floater. Then, numerical analysis using FAST and Flexcom is compared with experimental results. Static analysis, decay-tests, Response Amplitude Operators (RAOs) and Power Spectral Densities (PSDs) results are detailed. Power production and the embedded control command capabilities are also presented.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128642418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recent studies have shown that the intermittency of wind energy can be mitigated by means of an energy storage system (ESS). Energy can be stored during periods of low energy demand and high wind availability to then be utilised during periods of high energy demand. Measure-Correlate-Predict (MCP) methodologies are used to predict the wind speed and direction at a wind farm candidate site, hence enabling the estimation of the power output from the wind farm. Once energy storage is integrated with the wind farm, it is no longer only a matter of estimating the power output from the windfarm, but it is also important to model the behaviour of the ESS in conjunction with the energy demand. The latter is expected to depend, amongst other factors, on the reliability of the MCP methodology used. This paper investigates how different MCP methodologies influence the projected time series behaviour and the capacity requirements of ESS systems coupled to offshore wind farms. The analysis is based on wind data captured by a LiDAR system installed at a coastal location and from the Meteorological Office at Malta International Airport in the Maltese Islands. Different MCP methodologies are used to generate wind speed and direction time series at a candidate offshore wind farm site for various array layouts. The latter are then used in WindPRO® to estimate the time series power production for each MCP methodology and wind farm layout. This is repeated with actual wind data, such that the percentage error in energy yield from each MCP methodology is quantified, and the more reliable methodology could be identified. While it is evident that the integration of storage will reduce the need for wind energy curtailment, the reliability of the MCP methodology used is found to be crucial for proper estimation of the behaviour of the ESS.
{"title":"Investigating the Influence of MCP Uncertainties on the Energy Storage Capacity Requirements for Offshore Windfarms","authors":"M. Mifsud, R. Farrugia, T. Sant","doi":"10.1115/iowtc2019-7504","DOIUrl":"https://doi.org/10.1115/iowtc2019-7504","url":null,"abstract":"\u0000 Recent studies have shown that the intermittency of wind energy can be mitigated by means of an energy storage system (ESS). Energy can be stored during periods of low energy demand and high wind availability to then be utilised during periods of high energy demand. Measure-Correlate-Predict (MCP) methodologies are used to predict the wind speed and direction at a wind farm candidate site, hence enabling the estimation of the power output from the wind farm. Once energy storage is integrated with the wind farm, it is no longer only a matter of estimating the power output from the windfarm, but it is also important to model the behaviour of the ESS in conjunction with the energy demand. The latter is expected to depend, amongst other factors, on the reliability of the MCP methodology used.\u0000 This paper investigates how different MCP methodologies influence the projected time series behaviour and the capacity requirements of ESS systems coupled to offshore wind farms. The analysis is based on wind data captured by a LiDAR system installed at a coastal location and from the Meteorological Office at Malta International Airport in the Maltese Islands. Different MCP methodologies are used to generate wind speed and direction time series at a candidate offshore wind farm site for various array layouts. The latter are then used in WindPRO® to estimate the time series power production for each MCP methodology and wind farm layout. This is repeated with actual wind data, such that the percentage error in energy yield from each MCP methodology is quantified, and the more reliable methodology could be identified. While it is evident that the integration of storage will reduce the need for wind energy curtailment, the reliability of the MCP methodology used is found to be crucial for proper estimation of the behaviour of the ESS.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121857878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To effectively use the resources of marine environments, it is necessary to consider the deep and remote parts of the ocean. Stationkeeping of floating offshore wind turbines (FOWTs) mainly relies on mooring lines[1][2]. However, current mooring lines have structural and economical limitations for applications in extreme sea environments. The University of Ulsan is conducting ongoing research to develop a new economical stationkeeping system that can maintain the position of a FOWT in the deep sea using passive flapping foils. This paper describes an experimental study of the stationkeeping of actual structures based on the above-mentioned investigations and suggested directions to supplement the deficiencies in stationkeeping systems using passive flapping foils. This experiment was carried out in the three-dimensional “Widetank” and in actual sea conditions, focusing on the drift of a floater in the surge direction.
{"title":"Experimental Study of the Stationkeeping of a Floater Using Passive Flapping Flat Plates in Waves","authors":"Woo-lim Sim, Hyunkyoung Shin, Rupesh Kumar","doi":"10.1115/iowtc2019-7527","DOIUrl":"https://doi.org/10.1115/iowtc2019-7527","url":null,"abstract":"\u0000 To effectively use the resources of marine environments, it is necessary to consider the deep and remote parts of the ocean. Stationkeeping of floating offshore wind turbines (FOWTs) mainly relies on mooring lines[1][2]. However, current mooring lines have structural and economical limitations for applications in extreme sea environments. The University of Ulsan is conducting ongoing research to develop a new economical stationkeeping system that can maintain the position of a FOWT in the deep sea using passive flapping foils. This paper describes an experimental study of the stationkeeping of actual structures based on the above-mentioned investigations and suggested directions to supplement the deficiencies in stationkeeping systems using passive flapping foils. This experiment was carried out in the three-dimensional “Widetank” and in actual sea conditions, focusing on the drift of a floater in the surge direction.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128850363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The application of a computational fluid dynamics (CFD) code to simulate the response of a semi-submersible floating wind turbine under pitch decay motion was investigated in this study. Estimation of the natural period, the hydrodynamic damping and the flow characteristics were the main focus of this study. An extensive verification study of the simulation results was conducted to improve the confidence and reliability of the numerical simulation by the estimation of the numerical errors and uncertainties. The time series of pitch motion was plotted against model test data. In addition, the pitch period and hydrodynamic damping were calculated and compared to experimental data. Detailed flow characteristics as vorticity field and hydrodynamic pressure field on the floater surface were illustrated after post processing of the computational data. The results of the flow characteristics suggest that the heave damping plates were a major contributor to the hydrodynamic damping of this floater in pitch decay.
{"title":"CFD Simulation of Semi-Submersible Floating Offshore Wind Turbine Under Pitch Decay Motion","authors":"Yu Wang, Hamn-Ching Chen, G. Vaz, S. Burmester","doi":"10.1115/iowtc2019-7515","DOIUrl":"https://doi.org/10.1115/iowtc2019-7515","url":null,"abstract":"\u0000 The application of a computational fluid dynamics (CFD) code to simulate the response of a semi-submersible floating wind turbine under pitch decay motion was investigated in this study. Estimation of the natural period, the hydrodynamic damping and the flow characteristics were the main focus of this study. An extensive verification study of the simulation results was conducted to improve the confidence and reliability of the numerical simulation by the estimation of the numerical errors and uncertainties. The time series of pitch motion was plotted against model test data. In addition, the pitch period and hydrodynamic damping were calculated and compared to experimental data. Detailed flow characteristics as vorticity field and hydrodynamic pressure field on the floater surface were illustrated after post processing of the computational data. The results of the flow characteristics suggest that the heave damping plates were a major contributor to the hydrodynamic damping of this floater in pitch decay.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129899768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With their light weights, small components like braces and heave plates and steady trim angle caused by the wind loads acting on the rotor, semisubmersible foundations used as support platform for wind turbines exhibit a complex behaviour where viscous loading play an important role. The work done by the Offshore Code Comparison Collaboration Continued with Correlation (OC5) project has shown that standard engineering tools were not always able to predict accurately the motions of the DeepCwind semisubmersible that were measured in a basin. The correct amplitude of the motions at the natural periods of this system appeared to be difficult to obtain with simulations (especially the low frequency surge, and the pitch resonant motion). In view of the complexity of the system, it was not possible to clearly identify the causes of the differences between the simulations and the model-test results. A follow-on validation campaign was therefore performed at the Maritime Research Institute Netherlands (MARIN) under the MARINET2 project with the same floating substructure, with a focus on better understanding the hydrodynamic loads and reducing uncertainty in the tests by minimizing the system complexity. The wind turbine was replaced by a stiff tower with resembling inertia properties. The mooring system was simplified by using taut-spring lines with equivalent linear stiffness in surge. This paper reviews the new tests done with the simplified set-up and examines the differences with previous tests done with more complex test set-ups. The main motivation of this work is to study how variations of an experimental set-up can affect the outcome of tests in a wave basin. To start with, the main parameters of the systems (inertia, hydrostatics, and mooring stiffness) for all set-ups are characterized to check how similar they are. Then the level of damping in all systems is compared. Finally, the paper looks at how well the motion responses of this semisubmersible in waves correlate between all these campaigns.
{"title":"Effects of Variations on the Experimental Set-Up on the Motion Response of a Floating Wind Semisubmersible (OC4 Type)","authors":"S. Gueydon","doi":"10.1115/iowtc2019-7543","DOIUrl":"https://doi.org/10.1115/iowtc2019-7543","url":null,"abstract":"\u0000 With their light weights, small components like braces and heave plates and steady trim angle caused by the wind loads acting on the rotor, semisubmersible foundations used as support platform for wind turbines exhibit a complex behaviour where viscous loading play an important role. The work done by the Offshore Code Comparison Collaboration Continued with Correlation (OC5) project has shown that standard engineering tools were not always able to predict accurately the motions of the DeepCwind semisubmersible that were measured in a basin. The correct amplitude of the motions at the natural periods of this system appeared to be difficult to obtain with simulations (especially the low frequency surge, and the pitch resonant motion). In view of the complexity of the system, it was not possible to clearly identify the causes of the differences between the simulations and the model-test results. A follow-on validation campaign was therefore performed at the Maritime Research Institute Netherlands (MARIN) under the MARINET2 project with the same floating substructure, with a focus on better understanding the hydrodynamic loads and reducing uncertainty in the tests by minimizing the system complexity.\u0000 The wind turbine was replaced by a stiff tower with resembling inertia properties. The mooring system was simplified by using taut-spring lines with equivalent linear stiffness in surge. This paper reviews the new tests done with the simplified set-up and examines the differences with previous tests done with more complex test set-ups. The main motivation of this work is to study how variations of an experimental set-up can affect the outcome of tests in a wave basin. To start with, the main parameters of the systems (inertia, hydrostatics, and mooring stiffness) for all set-ups are characterized to check how similar they are. Then the level of damping in all systems is compared. Finally, the paper looks at how well the motion responses of this semisubmersible in waves correlate between all these campaigns.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117181960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Offshore wind technology is at the forefront of exploiting renewable energy at sea. The latest innovations in the field comprise floating wind turbines deployed in deep waters that are capable of intercepting the stronger, less turbulent winds farther away from the landmass. Despite being able to augment the power harnessed, wind resources remain intermittent in nature, and so unable to satisfy the energy demand at all times. Energy storage systems (ESS) are therefore being considered a key component to smoothen out the supply-demand mismatch when wind penetration into electricity grids increases. Yet, multiple issues pertaining to the integration of ESSs on large-scale projects arise, including economic, environmental and safety considerations. This paper presents a novel concept for integrating a hydro-pneumatic energy storage (HPES) system within a spar-type floating offshore wind turbine (FOWT) platform. It aims to assess the technical feasibility of integrating the storage unit within the floater. A preliminary investigation on the influence of integrated storage on the static stability and hydrostatic response of a conventional ballast-stabilised FOWT is conducted, followed by numerical simulations for the dynamic response using ANSYS® AQWA™. Based on the results presented, several conclusions are drawn on the implications of integrating energy storage with floating wind turbine structures. Finally, a preliminary assessment of the thermal efficiency of the storage system based on this specific embodiment is also presented and discussed.
{"title":"Assessing the Impact of Integrating Energy Storage on the Dynamic Response of a Spar-Type Floating Wind Turbine","authors":"C. Cutajar, T. Sant, R. Farrugia, D. Buhagiar","doi":"10.1115/iowtc2019-7577","DOIUrl":"https://doi.org/10.1115/iowtc2019-7577","url":null,"abstract":"\u0000 Offshore wind technology is at the forefront of exploiting renewable energy at sea. The latest innovations in the field comprise floating wind turbines deployed in deep waters that are capable of intercepting the stronger, less turbulent winds farther away from the landmass. Despite being able to augment the power harnessed, wind resources remain intermittent in nature, and so unable to satisfy the energy demand at all times. Energy storage systems (ESS) are therefore being considered a key component to smoothen out the supply-demand mismatch when wind penetration into electricity grids increases. Yet, multiple issues pertaining to the integration of ESSs on large-scale projects arise, including economic, environmental and safety considerations.\u0000 This paper presents a novel concept for integrating a hydro-pneumatic energy storage (HPES) system within a spar-type floating offshore wind turbine (FOWT) platform. It aims to assess the technical feasibility of integrating the storage unit within the floater. A preliminary investigation on the influence of integrated storage on the static stability and hydrostatic response of a conventional ballast-stabilised FOWT is conducted, followed by numerical simulations for the dynamic response using ANSYS® AQWA™. Based on the results presented, several conclusions are drawn on the implications of integrating energy storage with floating wind turbine structures. Finally, a preliminary assessment of the thermal efficiency of the storage system based on this specific embodiment is also presented and discussed.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"433 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116007791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most of the existing floating offshore wind turbines (FOWT), whether in concept or built, host a single turbine. Structures that can host multiple turbines have received attention in recent years, mainly with the aim of reducing the overall cost of energy production and maintenance. A concept challenge of placing multiple wind turbines on a single floating platform is that under variable wind directions, the leading turbines may block the wind against the trailing turbines. In this work, concept design of a wind-tracing floating structure accommodating three wind turbines is presented. The triangular-shapefloating platform is made of pre-stressed concrete, and the turbines are located on the corners. The floating structure uses a single-point mooring system which allows for the entire structure to rotate in response to the change of wind direction. Due to the particular configuration of the floating structure, it is essential to consider the wind, wave and current loads, along with the response of the structure, simultaneously. Response of the FOWT to simultaneous environmental loads from different directions is studied by use of the constant panel approach of the Green function method, subject to constant wind loads on the turbines and linear mooring loads. We also consider the elasticity of the structure by use of finite element analysis, coupled with the hydro- and aero-dynamic loads and responses.
{"title":"Concept Design and Analysis of Wind-Tracing Floating Offshore Wind Turbines","authors":"Shuijin Li, A. Lamei, M. Hayatdavoodi, C. Wong","doi":"10.1115/iowtc2019-7580","DOIUrl":"https://doi.org/10.1115/iowtc2019-7580","url":null,"abstract":"\u0000 Most of the existing floating offshore wind turbines (FOWT), whether in concept or built, host a single turbine. Structures that can host multiple turbines have received attention in recent years, mainly with the aim of reducing the overall cost of energy production and maintenance. A concept challenge of placing multiple wind turbines on a single floating platform is that under variable wind directions, the leading turbines may block the wind against the trailing turbines. In this work, concept design of a wind-tracing floating structure accommodating three wind turbines is presented. The triangular-shapefloating platform is made of pre-stressed concrete, and the turbines are located on the corners. The floating structure uses a single-point mooring system which allows for the entire structure to rotate in response to the change of wind direction. Due to the particular configuration of the floating structure, it is essential to consider the wind, wave and current loads, along with the response of the structure, simultaneously. Response of the FOWT to simultaneous environmental loads from different directions is studied by use of the constant panel approach of the Green function method, subject to constant wind loads on the turbines and linear mooring loads. We also consider the elasticity of the structure by use of finite element analysis, coupled with the hydro- and aero-dynamic loads and responses.","PeriodicalId":131294,"journal":{"name":"ASME 2019 2nd International Offshore Wind Technical Conference","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116920611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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