Design Of Direct-drive Wave Power Generation System Driven By Mass-adjustable Float

In the floating wave power system,when the natural frequency of the float coincides with the wave frequency,the system would theoretically work in the resonance state,which makes the efficiency of wave energy capture system reach the maximum.The natural frequency of the float is related to various parameters,including the float size,float shape,float stiffness,float mass,float additional mass,and so on.In order to achieve higher efficiency of wave energy capture system,different scholars have done a lot of research about how these parameters impose influence on the wave energy conversion device.However,there is still no efficient and accurate method for mass adjustment,and also no verification of the capture efficiency of mass-adjustable floats.The reason might come from the fact that changes of float mass can lead to variation of more than one parameter,like draught,additional mass,hydrodynamic coefficients,and etc.In order to solve these problems,a simple design of a mass-adjustable float was given,and a new optimization calculation method based on the high-order polynomial fitting theory was proposed in ths paper.This optimized method combines the advantages of boundary element analysis and numerical calculation,introduces an additional coefficient K related to the wave frequency and the draught of the float,which optimizes Hooft's approximate equation between the additional mass and the float size.This optimized method can improve the computational efficiency without losing calculation accuracy.In this paper,the design and adjustment methods of wave power generation system based on the mass-adjustable float are deeply studied,and the work is mainly carried out from the following aspects:1.The research status of wave energy capture and power generation system is analyzed.The basic working principle,merits and demerits of wave power generation system is summarized.The advantages and significance of floating wave power generation system in the whole ocean wave energy utilization field are analyzed.2.A simple mass-adjustable float model is designed.Based on this,a new type wave energy capture system is established.In the power generation system,a linear generator was selected as the power output device,and the design of the system fully considered the seawater corrosion problem.3.A new optimization calculation method is proposed,which combines the merits between boundary element analysis and numerical calculation.An additional coefficient K is introduced,which is related to the wave frequency and the draft depth of the float.The approximate expression between the additional mass and the float size is optimized by using the high-order polynomial fitting to introduce.It improves calculation efficiency of the algorithm without losing accuracy.4.In the simulation,the AQWA was used to calculate the response of the mass-adjustable float and the ordinary float at different wave frequencies.The output was used as an input for the electrical simulation and Maxwell linear generator model.Finally,it is verified that the mass-adjustable float has higher wave capturing efficiency than that of the ordinary float.