| Nowadays,sustainable development has become an important trend.Simultaneously,searching for novel clean energy has become a hot topic dueto the coming of energy crisis.Offshore wind power,with its advantages,has become one of the most remarkable renewable energy in the world.Considering the natural correlation,ocean wave energy is also considerable where the offshore wind energy resource is rich.Therefore,this paper proposes a kind of a novel combined mono-pile offshore wind turbine and an heave-type wave energy converter system.This kind of novel combined system is able to share the supporting platform and power transmission system,which can not only improve the utilization of the marine renewable energy and save space,but also effectively reduce the cost of unit power generation.The concept of the combined system is to achieve the major strategy of constructing a renewable energy system in China which meets the China's maritime power strategy.Major content and results are the following:(1)Firstly,the preliminary conceptual design of the novel combined monopile wind turbine and a heave-type wave energy converter system has been proposed,in which the relative information of wind turbine has been based on the National Renewable Energy Laboratory(NREL)5MW offshore wind turbine model.Moreover,the optimized displacements and power-take-off parameters of the WEC also has been investigated,to further study its hydrodynamic performance.In this paper,the hydraulic transmission system--PTO system(Power-take-off)has been proposed to utilize the vertical motion of the wave energy converter to generate power.The numerical simulations indicate that the wave energy production is considerable.(2)Secondly,based on the potential fluid theory and multi-body dynamics analysis method,the hydrodynamic model of the combined system has been investigated,the characteristics of the hydrodynamic model under the typical sea cases has been further studied.The characteristics of the vertical motion of the wave energy converter(WEC)is an important factor to evaluate the power production efficiency of the heave-type WEC.Besides,the hydrodynamic interaction effect and the mechanical coupling effect between the WEC and the monopile foundation are investigated,the obtained loads history will be applied to the dynamic response analysis of the combined system in the following sections.(3)The characteristics of the energy production has been investigated and compared with that of the TWWC(TLP-WT-WEC-combination)which was proposed by our team.The results show that the wave energy production efficiencies of them are very similar,while the one with fixed monopile foundation is slightly larger.Considering the lower cost of the monopile foundation,the scheme of the combined system with fixed monopile foundation is more feasible.(4)The coupled wind-wave load and multi-body coupling force time history have been input to the finite element model under the typical sea cases to analyse the dynamic responses of the combined system(stress of the key nodes have been further analysed).The possibility of the resonance between the combined system and the wave can be excluded by the modal analysis.Finally,the level of safety of the combined system has been verified and the optimal design has been proposed accordingly. |
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