Built-in Double Pendulum Active Resonance Wave Energy Technology

At present,wave energy technology is not yet mature and has not been commercialized.Now the research mainly focuses on the layout,operation and maintenance of the devices and transmission systems.These technologies have become mature and is approaching to commercialization.But,the low conversion efficiency of existing wave technologies has become a bottleneck hindering the development of wave energy technology.Improving the conversion efficiency has become a key issue.The conversion efficiency of wave energy devices working in resonance is very high,which has been confirmed by theory and experiment.Researchers have done a lot of research on the mechanism of wave energy conversion.However,the existing wave energy devices are difficult to achieve resonance in actual wave conditions.Obviously,some of the mechanisms have not been clarified.Active Resonance Wave Energy technology has studied the mechanism and formed a set of theories.Based on this theory,a built-in double pendulum active resonance wave energy technology(BDPARWET)and concomitant prototype(BDPARWEP)are proposed.The optimal hydrodynamic configuration of the device is put forward.The rigidity regulation model for controlling the frequency of the wave energy system is derived.The optimal control model for PTO(Power Take off)damping and the optimal operation mode of the device are given.The device is discussed by analytic solution and numerical simulation.It is proved that the conversion efficiency of BDPARWEP is much higher than that of the existing wave energy devices,which provides a theoretical and technical basis for the commercialization of wave energy technology.The main results are as follows:(1)Combined with NS equation and multi-rigid-body dynamics theory,the equilibrium equation of wave energy device is established.The coupling relationship between flow field and device is established by the boundary conditions of wave energy device.The algorithm is programmed and loaded into FLUENT software by UDF technology.The numerical simulation platform of the built-in double pendulum active resonance wave energy technology is formed.(2)Based on the theories of multi-rigid-body dynamics and potential flow,the equilibrium equation of wave energy system(device & water)is established.Through the linearized equation,the rigidity-adjusting model of the device is derived.The sensitivity of the rigidityadjusting model to hydrodynamic parameters and the deviation rate of natural vibration period caused by swing rotation are analyzed.Free attenuation experiment and regular wave excitation experiment are used to verify the rigidity-adjusting model.(3)By solving the analytical solution of linear system,the influence of PTO damping on conversion efficiency of wave energy device is obtained,and the theoretical solution of optimal PTO is given.Considering the designed maximum allowable amplitude of device,the practical control strategy of optimal PTO damping of wave energy device is given.(4)The numerical experiments prove that the single point mooring system can effectively control the slow drift motion,without affecting the stability and conversion efficiency of the device.It is a feasible mooring scheme.(5)Fixed-point mode is the most efficient operation mode.Under fixed-point operation mode,the wave energy devices can maintain high conversion efficiency under different sea conditions.Considering the installation technology is relatively mature,it is a realizable wave energy utilization scheme.(6)The energy capture efficiency of the device under irregular waves is studied.Based on the half-power bandwidth method,a more reasonable calculation method of conversion efficiency is proposed.By this method,the energy capture capability of the device under irregular waves can be evaluated more objectively.