This study delineates the development of the optimization framework for the preliminary design phase of Floating Offshore Wind Turbines(FOWTs),and the central challenge addressed is the optimization of the FOWT platfo...This study delineates the development of the optimization framework for the preliminary design phase of Floating Offshore Wind Turbines(FOWTs),and the central challenge addressed is the optimization of the FOWT platform dimensional parameters in relation to motion responses.Although the three-dimensional potential flow(TDPF)panel method is recognized for its precision in calculating FOWT motion responses,its computational intensity necessitates an alternative approach for efficiency.Herein,a novel application of varying fidelity frequency-domain computational strategies is introduced,which synthesizes the strip theory with the TDPF panel method to strike a balance between computational speed and accuracy.The Co-Kriging algorithm is employed to forge a surrogate model that amalgamates these computational strategies.Optimization objectives are centered on the platform’s motion response in heave and pitch directions under general sea conditions.The steel usage,the range of design variables,and geometric considerations are optimization constraints.The angle of the pontoons,the number of columns,the radius of the central column and the parameters of the mooring lines are optimization constants.This informed the structuring of a multi-objective optimization model utilizing the Non-dominated Sorting Genetic Algorithm Ⅱ(NSGA-Ⅱ)algorithm.For the case of the IEA UMaine VolturnUS-S Reference Platform,Pareto fronts are discerned based on the above framework and delineate the relationship between competing motion response objectives.The efficacy of final designs is substantiated through the time-domain calculation model,which ensures that the motion responses in extreme sea conditions are superior to those of the initial design.展开更多
考虑到海上浮式风机(floating offshore wind turbine,FOWT)因存在整体晃动导致背景响应强烈,在频域上有时表现为激励频率,且随激励频率的变化而变化,在使用传统调谐质量阻尼器(tuned mass damper,TMD)对其进行振动控制时出现频率失调...考虑到海上浮式风机(floating offshore wind turbine,FOWT)因存在整体晃动导致背景响应强烈,在频域上有时表现为激励频率,且随激励频率的变化而变化,在使用传统调谐质量阻尼器(tuned mass damper,TMD)对其进行振动控制时出现频率失调和效果不佳等现象,该研究设计并提出了一种带碰撞的磁流变弹性体变刚度调谐质量阻尼器(magnetorheological elastomer-pounding tuned mass damper,MRE-PTMD)对FOWT实施半主动控制。在该控制装置中,利用MRE的刚度可调特性,通过半主动控制技术实现阻尼器频率的实时调节,保持对FOWT的最优控制,同时引入限位挡板对MRE材料加以保护并实现碰撞耗能。以驳船型FOWT为例,建立了包含控制装置的17自由度动力方程,对其在风浪联合作用下的减振性能及参数影响进行了研究,并与传统TMD进行了对比。结果表明,所提控制装置能通过对结构响应的实时追踪适时调节阻尼器的控制参数,相比传统TMD有更佳的减振性能和适应性。参数分析表明,增大阻尼器质量比是提升MRE-PTMD工作性能的有效途径,通过对阻尼器质量比及碰撞参数的合理设计可在不过多影响减振效果的情况下实现对MRE的保护及控制装置小型化。展开更多
Complicated loads encountered by floating offshore wind turbines(FOWTs)in real sea conditions are crucial for future optimization of design,but obtaining data on them directly poses a challenge.To address this issue,w...Complicated loads encountered by floating offshore wind turbines(FOWTs)in real sea conditions are crucial for future optimization of design,but obtaining data on them directly poses a challenge.To address this issue,we applied machine learning techniques to obtain hydrodynamic and aerodynamic loads of FOWTs by measuring platform motion responses and wave-elevation sequences.First,a computational fluid dynamics(CFD)simulation model of the floating platform was established based on the dynamic fluid body interaction technique and overset grid technology.Then,a long short-term memory(LSTM)neural network model was constructed and trained to learn the nonlinear relationship between the waves,platform-motion inputs,and hydrodynamic-load outputs.The optimal model was determined after analyzing the sensitivity of parameters such as sample characteristics,network layers,and neuron numbers.Subsequently,the effectiveness of the hydrodynamic load model was validated under different simulation conditions,and the aerodynamic load calculation was completed based on the D'Alembert principle.Finally,we built a hybrid-scale FOWT model,based on the software in the loop strategy,in which the wind turbine was replaced by an actuation system.Model tests were carried out in a wave basin and the results demonstrated that the root mean square errors of the hydrodynamic and aerodynamic load measurements were 4.20%and 10.68%,respectively.展开更多
A floating offshore wind turbine (FOWT) has a great potential in producing renewable energy as offshore wind resource is rich in deep sea area (water deeper than 60 m) where fixed foundations are cost-effective or dep...A floating offshore wind turbine (FOWT) has a great potential in producing renewable energy as offshore wind resource is rich in deep sea area (water deeper than 60 m) where fixed foundations are cost-effective or deployable. However, compared with a fixed-bottom installation, FOWT has to suffer more extreme loads due to its extra degrees of freedom. Therefore, the stability of an FOWT is a key challenge in exploiting offshore deep-water wind. Focusing on the stability of barge-type FOWT, this paper is to investigate the effect of passive structural control by equipping a tuned mass damper (TMD) on the nacelle. The turbulent wind with sharp fluctuations is established both in velocity and inflow direction based on standard Kaimal turbulence spectrum as suggested in the standard IEC61400-2. The irregular wave is generated according to the Pierson-Moskowitz spectrum. The dynamic structural characteristics of FOWT are calculated based on the fully coupled aero-hydro-servo-elastic solver FAST. Evidence has shown that the proposed method of the nacelle-based TMD is effective in controlling stability of an FOWT, as the sway and roll motions of barge and the side-side displacement of tower top decreased significantly. With the increase of mass, the side-side displacement of tower-top and the amplitude of roll motion of barge reveal a trend of increasing first and then decreasing. The stiffness and damping have little effect. Furthermore, the multi-island genetic optimization algorithm (MIGA) is employed to find globally optimum structural parameters (mass, stiffness and damping) of the TMD. The optimum structure parameters of TMD are achieved when the mass is 21393 kg, damping is 13635 N/(m/s) and stiffness is 6828 N/m. By adopting the optimized TMD, stability of roll motion of barge and side-side displacement of tower-top increase up to 53% and 50% respectively when compared with the normal TMD. The simulation results verify the validity and reliability of the proposed TMD control and the optimization methods.展开更多
A 6 MW spar-type floating offshore wind turbine （FOWT） model is put forward and a fully coupled aero-hydro-servo-elastic time domain model is established in the fatigue, aerodynamics, structures and turbulence （FAS...A 6 MW spar-type floating offshore wind turbine （FOWT） model is put forward and a fully coupled aero-hydro-servo-elastic time domain model is established in the fatigue, aerodynamics, structures and turbulence （FAST） code. Influence rules of wind 10ad and wave load on the characteristics of 6 MW spar-type FOWT are investigated. Firstly, validation of the model is carried out and a satisfactory result is obtained. The maximal deviations of rotor thrust and power between simulation results and reference values are 4.54% and -2.74%, respectively. Then the characteristics, including rotor thrust, rotor power, out-of-plane blade deflection, tower base fore-aft bending moment, and mooring line tension, are researched. The results illustrate that the mean value of dynamic response characteristics is mainly controlled by the wind-induced action. For characteristics of tower base fore-aft bending moment and platform pitch motion, the oscillation is dominated by the wave-induced action during all conditions considered. For characteristics of out-of-plane blade tip deflection and mooring line tension, the oscillation is commanded by combination effect of wave and wind loads when the wind speed is lower than the rated wind speed （hereinafter referred to as below rated wind speed） and is controlled by the wave-induced action when the wind speed is higher than the rated wind speed （hereinafter referred to as above rated wind speed）. As to the rotor thrust and power, the oscillation is dominated by the wind induced action at below rated wind speed and by the combination action of wind and wave loads at above rated wind speed. The results should be useful to the detailed design and model basin test of the 6 MW spar-type FOWT.展开更多
To simulate floating offshore wind turbine(FOWT)in coupled wind-wave domain via CFD method,the NREL 5MW wind turbine supported by the OC3-Hywind Spar platform is modeled in the STAR-CCM+ software.Based on the Reynolds...To simulate floating offshore wind turbine(FOWT)in coupled wind-wave domain via CFD method,the NREL 5MW wind turbine supported by the OC3-Hywind Spar platform is modeled in the STAR-CCM+ software.Based on the Reynolds-averaged Navier-Stokes(RANS)equations and re-normalisation group(RNG)k-εturbulence model,the rotor aerodynamic simulation for wind turbine is conducted.Numerical results agree well with the NREL data.Taking advantage with the volume of fluid(VOF)method and dynamic fluid body interaction(DFBI)technology,the dynamic responses of the floating system with mooring lines are simulated under the coupled wind-wave sea condition.The free-decay tests for rigid-body degrees of freedom(DOFs)in still water and hydrodynamic tests in a regular wave are performed to validate the numerical model by comparing its result with the results simulated by FAST.Finally,the simulations of the overall FOWT system in the coupled wind-wave flow field are carried out.The relationship between the power output and dynamic motion responses of the platform is investigated.The numerical results show that the dynamic response of wind turbine performance and platform motions all vary in the same frequency as the inlet wave.During platform motion,the power output of wind turbine is more sensitive than the thrust force.This study may provide some reference for further research in the coupled aero-hydro simulation of FOWT.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.52371261)the Science and Technology Projects of Liaoning Province(Grant No.2023011352-JH1/110).
文摘This study delineates the development of the optimization framework for the preliminary design phase of Floating Offshore Wind Turbines(FOWTs),and the central challenge addressed is the optimization of the FOWT platform dimensional parameters in relation to motion responses.Although the three-dimensional potential flow(TDPF)panel method is recognized for its precision in calculating FOWT motion responses,its computational intensity necessitates an alternative approach for efficiency.Herein,a novel application of varying fidelity frequency-domain computational strategies is introduced,which synthesizes the strip theory with the TDPF panel method to strike a balance between computational speed and accuracy.The Co-Kriging algorithm is employed to forge a surrogate model that amalgamates these computational strategies.Optimization objectives are centered on the platform’s motion response in heave and pitch directions under general sea conditions.The steel usage,the range of design variables,and geometric considerations are optimization constraints.The angle of the pontoons,the number of columns,the radius of the central column and the parameters of the mooring lines are optimization constants.This informed the structuring of a multi-objective optimization model utilizing the Non-dominated Sorting Genetic Algorithm Ⅱ(NSGA-Ⅱ)algorithm.For the case of the IEA UMaine VolturnUS-S Reference Platform,Pareto fronts are discerned based on the above framework and delineate the relationship between competing motion response objectives.The efficacy of final designs is substantiated through the time-domain calculation model,which ensures that the motion responses in extreme sea conditions are superior to those of the initial design.
文摘考虑到海上浮式风机(floating offshore wind turbine,FOWT)因存在整体晃动导致背景响应强烈,在频域上有时表现为激励频率,且随激励频率的变化而变化,在使用传统调谐质量阻尼器(tuned mass damper,TMD)对其进行振动控制时出现频率失调和效果不佳等现象,该研究设计并提出了一种带碰撞的磁流变弹性体变刚度调谐质量阻尼器(magnetorheological elastomer-pounding tuned mass damper,MRE-PTMD)对FOWT实施半主动控制。在该控制装置中,利用MRE的刚度可调特性,通过半主动控制技术实现阻尼器频率的实时调节,保持对FOWT的最优控制,同时引入限位挡板对MRE材料加以保护并实现碰撞耗能。以驳船型FOWT为例,建立了包含控制装置的17自由度动力方程,对其在风浪联合作用下的减振性能及参数影响进行了研究,并与传统TMD进行了对比。结果表明,所提控制装置能通过对结构响应的实时追踪适时调节阻尼器的控制参数,相比传统TMD有更佳的减振性能和适应性。参数分析表明,增大阻尼器质量比是提升MRE-PTMD工作性能的有效途径,通过对阻尼器质量比及碰撞参数的合理设计可在不过多影响减振效果的情况下实现对MRE的保护及控制装置小型化。
基金This work is supported by the National Key Research and Development Program of China(No.2023YFB4203000)the National Natural Science Foundation of China(No.U22A20178)
文摘Complicated loads encountered by floating offshore wind turbines(FOWTs)in real sea conditions are crucial for future optimization of design,but obtaining data on them directly poses a challenge.To address this issue,we applied machine learning techniques to obtain hydrodynamic and aerodynamic loads of FOWTs by measuring platform motion responses and wave-elevation sequences.First,a computational fluid dynamics(CFD)simulation model of the floating platform was established based on the dynamic fluid body interaction technique and overset grid technology.Then,a long short-term memory(LSTM)neural network model was constructed and trained to learn the nonlinear relationship between the waves,platform-motion inputs,and hydrodynamic-load outputs.The optimal model was determined after analyzing the sensitivity of parameters such as sample characteristics,network layers,and neuron numbers.Subsequently,the effectiveness of the hydrodynamic load model was validated under different simulation conditions,and the aerodynamic load calculation was completed based on the D'Alembert principle.Finally,we built a hybrid-scale FOWT model,based on the software in the loop strategy,in which the wind turbine was replaced by an actuation system.Model tests were carried out in a wave basin and the results demonstrated that the root mean square errors of the hydrodynamic and aerodynamic load measurements were 4.20%and 10.68%,respectively.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51676131 and 51176129)the Innovation Key Program of Shanghai Municipal Education Commission(Grant Nos.13YZ066 and 13ZZ120)the Doctoral Fund of Ministry of Education of China(Grant No.20123120110008)
文摘A floating offshore wind turbine (FOWT) has a great potential in producing renewable energy as offshore wind resource is rich in deep sea area (water deeper than 60 m) where fixed foundations are cost-effective or deployable. However, compared with a fixed-bottom installation, FOWT has to suffer more extreme loads due to its extra degrees of freedom. Therefore, the stability of an FOWT is a key challenge in exploiting offshore deep-water wind. Focusing on the stability of barge-type FOWT, this paper is to investigate the effect of passive structural control by equipping a tuned mass damper (TMD) on the nacelle. The turbulent wind with sharp fluctuations is established both in velocity and inflow direction based on standard Kaimal turbulence spectrum as suggested in the standard IEC61400-2. The irregular wave is generated according to the Pierson-Moskowitz spectrum. The dynamic structural characteristics of FOWT are calculated based on the fully coupled aero-hydro-servo-elastic solver FAST. Evidence has shown that the proposed method of the nacelle-based TMD is effective in controlling stability of an FOWT, as the sway and roll motions of barge and the side-side displacement of tower top decreased significantly. With the increase of mass, the side-side displacement of tower-top and the amplitude of roll motion of barge reveal a trend of increasing first and then decreasing. The stiffness and damping have little effect. Furthermore, the multi-island genetic optimization algorithm (MIGA) is employed to find globally optimum structural parameters (mass, stiffness and damping) of the TMD. The optimum structure parameters of TMD are achieved when the mass is 21393 kg, damping is 13635 N/(m/s) and stiffness is 6828 N/m. By adopting the optimized TMD, stability of roll motion of barge and side-side displacement of tower-top increase up to 53% and 50% respectively when compared with the normal TMD. The simulation results verify the validity and reliability of the proposed TMD control and the optimization methods.
基金the National Basic Research Program(973) of China(No.2014CB046205)
文摘A 6 MW spar-type floating offshore wind turbine （FOWT） model is put forward and a fully coupled aero-hydro-servo-elastic time domain model is established in the fatigue, aerodynamics, structures and turbulence （FAST） code. Influence rules of wind 10ad and wave load on the characteristics of 6 MW spar-type FOWT are investigated. Firstly, validation of the model is carried out and a satisfactory result is obtained. The maximal deviations of rotor thrust and power between simulation results and reference values are 4.54% and -2.74%, respectively. Then the characteristics, including rotor thrust, rotor power, out-of-plane blade deflection, tower base fore-aft bending moment, and mooring line tension, are researched. The results illustrate that the mean value of dynamic response characteristics is mainly controlled by the wind-induced action. For characteristics of tower base fore-aft bending moment and platform pitch motion, the oscillation is dominated by the wave-induced action during all conditions considered. For characteristics of out-of-plane blade tip deflection and mooring line tension, the oscillation is commanded by combination effect of wave and wind loads when the wind speed is lower than the rated wind speed （hereinafter referred to as below rated wind speed） and is controlled by the wave-induced action when the wind speed is higher than the rated wind speed （hereinafter referred to as above rated wind speed）. As to the rotor thrust and power, the oscillation is dominated by the wind induced action at below rated wind speed and by the combination action of wind and wave loads at above rated wind speed. The results should be useful to the detailed design and model basin test of the 6 MW spar-type FOWT.
基金supported by the National Basic Research Program of China(″973″Program)(No.2014CB046200)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120073120014)
文摘To simulate floating offshore wind turbine(FOWT)in coupled wind-wave domain via CFD method,the NREL 5MW wind turbine supported by the OC3-Hywind Spar platform is modeled in the STAR-CCM+ software.Based on the Reynolds-averaged Navier-Stokes(RANS)equations and re-normalisation group(RNG)k-εturbulence model,the rotor aerodynamic simulation for wind turbine is conducted.Numerical results agree well with the NREL data.Taking advantage with the volume of fluid(VOF)method and dynamic fluid body interaction(DFBI)technology,the dynamic responses of the floating system with mooring lines are simulated under the coupled wind-wave sea condition.The free-decay tests for rigid-body degrees of freedom(DOFs)in still water and hydrodynamic tests in a regular wave are performed to validate the numerical model by comparing its result with the results simulated by FAST.Finally,the simulations of the overall FOWT system in the coupled wind-wave flow field are carried out.The relationship between the power output and dynamic motion responses of the platform is investigated.The numerical results show that the dynamic response of wind turbine performance and platform motions all vary in the same frequency as the inlet wave.During platform motion,the power output of wind turbine is more sensitive than the thrust force.This study may provide some reference for further research in the coupled aero-hydro simulation of FOWT.
