The stability of platform structure is the paramount guarantee of the safe operation of the offshore floating wind turbine. The NREL 5MW floating wind turbine is established based on the OC3-Hywind Spar Buoy platform ...The stability of platform structure is the paramount guarantee of the safe operation of the offshore floating wind turbine. The NREL 5MW floating wind turbine is established based on the OC3-Hywind Spar Buoy platform with the supplement of helical strakes for the purpose to analyze the impact of helical strakes on the dynamic response of the floating wind turbine Spar platform. The dynamic response of floating wind turbine Spar platform under wind, wave and current loading from the impact of number, height and pitch ratio of the helical strakes is analysed by the radiation and diffraction theory, the finite element method and orthogonal design method. The result reveals that the helical strakes can effectively inhibit the dynamic response of the platform but enlarge the wave exciting force; the best parameter combination is two pieces of helical strakes with the height of 15%D （D is the diameter of the platform） and the pitch ratio of 5; the height of the helical strake and its pitch ratio have significant influence on pitch response.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
基金financially supported by the National Natural Science Foundation of China(Grant No.51176129)the Innovation Key Program of Shanghai Municipal Education Commission(Grant No.13YZ066)the Doctoral Fund of the Ministry of Education of China(Grant No.20123120110008)
文摘The stability of platform structure is the paramount guarantee of the safe operation of the offshore floating wind turbine. The NREL 5MW floating wind turbine is established based on the OC3-Hywind Spar Buoy platform with the supplement of helical strakes for the purpose to analyze the impact of helical strakes on the dynamic response of the floating wind turbine Spar platform. The dynamic response of floating wind turbine Spar platform under wind, wave and current loading from the impact of number, height and pitch ratio of the helical strakes is analysed by the radiation and diffraction theory, the finite element method and orthogonal design method. The result reveals that the helical strakes can effectively inhibit the dynamic response of the platform but enlarge the wave exciting force; the best parameter combination is two pieces of helical strakes with the height of 15%D （D is the diameter of the platform） and the pitch ratio of 5; the height of the helical strake and its pitch ratio have significant influence on pitch response.
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.
