Study On Motion Response And Energy Capture Of Multi-section Raft Wave Energy Converter

Wave energy is a kind of clean renewable energy,which has a high energy density.The utilization and development of wave energy are highly valued in the world.Especially,in the United Kingdom,Norway,the United States and other countries,wave energy development and utilization technology has been advanced.The wave energy development and utilization technology of our country is still in the initial stage,so it is necessary to carry out related technology research and development work for China Sea.In this paper,a multi section raft type wave energy converter(WEC)is used as the research object.The floating body element is connected by a biaxial hinge.On the basis of the initial layout scheme of a hydraulic cylinder,equivalent stiffness and damping model of the energy conversion system in the wave energy converter is established.With China's South Sea conditions,numerical simulation for WEC is carried out by utilizing AQWA hydrodynamic calculation module.First of all,the hydrodynamic model of wave energy converter is established,and the frequency domain analysis is carried out by using three-dimensional potential flow theory.The RAO,additional mass and radiation damping of the floating body element can be obtained.Then,through the time domain calculation,the overall movement of the WEC,mooring force,the relative rotation of the floating body element and the joint reaction force are statistically analyzed.Finally,through a large number of simulation calculation,the influence of equivalent rotation damping and equivalent rotational stiffness on the energy absorption is analyzed,and then the optimization suggestion of the layout scheme of the hydraulic cylinder is put forward.The results showed that: the hydrodynamic interaction among the multi floating bodies has a significant effect on the additional mass and radiation damping parameter of the floating body element.The influence on the heave and pitch directions is small,and it has little effect on other degrees.In the frequency spectrum and the directional spectrum,energy absorption power of WEC is different.Especially,the power on yaw motion is very different.In different sea conditions,the equivalent damping and the equivalent stiffness corresponding to the maximum power are different.And the stiffness and damping coefficients is different in pitch and yaw direction.