Dynamic Performance Of A Hybrid System Combing Wave Energy Converter And Wind Platform

Offshore wind and wave energy are the hot areas of new energy development.With the development of offshore wind energy,the size of offshore wind turbine and the water depth in the working sea area are larger.For the purpose of protecting the floating wind platform and increasing the power generation,it is theoretically feasible to integrate the wave energy converers(WECs)into the floating wind platform.At present,the research on the integrated system of WECs and wind platform under the combined action of wind and wave mostly focuses on the hydrodynamic aspect,while the aerodynamic aspect often adopts the empirical formula to simplify the external force treatment,which lacks accuracy,and the specific parameters of WECs also lacks basis.Based on the OC4 floating wind platform integrated with six oscillating WECs systems,the interaction between the platform and the float is numerically studied from two aspects of wind free and wind existent respectively.Firstly,based on the theory of viscous modified potential flow,the time-domain numerical model of the integrated system of WECs and floating platform without wind was established,and the selection and layout WECS were studied.The accuracy of the numerical model is verified by comparing with the published papers on double floating body.The size of WECs is obtained by dimensionless iterative method.Firstly,the variation rules of platform heave,heave and pitch motion response,wave power generation and mooring tension of integrated system with different diameters and draft ratios are studied.On this basis,by changing the key parameters of the WECs,such as power-take-off(PTO)damping,float spacing and resonance period,the influences of these parameters on the motion and power generation characteristics of the integrated system are studied.The design principles of WECs parameters are described from the perspectives of increasing power generation and reducing platform motion.And then set up a time domain numerical model under the action of wind integration system,from the regular wave and irregular wave is analyzed under the condition of two types of wave under the joint action of wind intergrated system on platform surge,heave,pitch three direction equilibrium position and the influence law of motion amplitudes,and the integrated system power and mooring tension change rule.The results show that the WECs can reduce the motion amplitude of large period wave droop and pitch,and the peak period of wave energy power generation lags behind the float resonance period.Increasing PTO damping,using larger spacing and increasing the resonant period of the float can increase the power generation of the wave energy float,but also increase the pitch motion of the platform.Considering the wind load,the addition of WECs reduces the balance position amplitude of the platform than the increased motion amplitude,and actually increases the safety of the platform under the combined action of wind and wave.The WECs has little influence on the wind turbine power generation,and can also provide additional wave power generation,and the total power generation of the integrated system is improved.The mooring tension of the integrated system decreases in the same direction as the wind and wave,while the tension of the other direction cables increases,and the increase is not high,which indicates the feasibility and engineering significance of the integrated system scheme.