A Comprehensive Study On The Dynamic Response Of Serbuoys-offshore Wind Tension Leg Platform

Beacuse of the exploitation of deep-sea wind energy resources and relatively weak surge performance in plane of TLP,a new type tension leg platform wind turbine connected with a series buoy(Serbuoys-TLP)was proposed by the scholars.It is preliminarily confirmed that the buoys can effectively suppress the surge of TLP wind turbine.However,the performance of Serbuoys-TLP is not ideal in some conditions,and even the motions of Serbuoys-TLP increase.Based on the diffraction and radiation wave theory,a coupled time domain model of wind turbine,tension leg and multiple series buoy are established to solve the above-mentioned problem.The suppression effect of series buoys to surge motion response of TLP wind turbine are analysed.The specific parameters of buoys adapted to the actual sea conditions are given according to the relevant results.Firstly,the hydrodynamic model of the wind turbine foundation and the buoys are established based on the three-dimensional potential flow theory.The hydrodynamic characteristics of the model are analyzed by using the boundary element method(BEM).The hydrodynamic information of the wind turbine foundation and buoys are obtained in frequency domain,such as the additional mass,the radiation damping and the wave force corresponding to different frequencies.At the same time,the mooring stiffness of TLP and Serbuoys-TLP is added to the AQWA-LINE,and the frequency domain RAO in surge has been calculated.The results accord with the characteristics of typical TLP.In AQWA-NAUT,the buoy is taken as the tendon with enlarged diameter and the decay tests of TLP and Serbuoys-TLP are carried out.The results of the decay tests are agreed with the results of frequency domain analysis.Secondly,a time-domain simulation program(DUTMST 1.0)for the TLP and SerbuoysTLP based on MATLAB is provided,with consideration of the multi-body coupling effect between the body,tension leg and buoy.That is,each buoy can be analysed as a separate mass structure connected on the tension leg.The dynamic responses of TLP and Serbuoys-TLP are presented under different wave conditions.The results show that the Serbuoys-TLP can significantly reduce the horizontal response of the TLP.In addition,the horizontal response suppression effects of Serbuoys-TLP are investigated by varying the wave period and parameters of buoys.Additionally,the parameters of buoys adapted to the East China Sea are given by the analysis of suppression efficiency.Finally,an improved time-domain simulation program(DUTMST 2.0)is developed based on the DUTMST 1.0,with consideration of the dynamic response of tendons.Combined with the parameters of buoys obtained before,the coupled dynamic responses of TLP and SerbuoysTLP are presented.The horizontal response suppression effects of Serbuoys-TLP are investigated when considering the dynamic response of the tendons.At the same time,the function of calculating the current force of tendons is developed in the DUTMST 2.0,and the suppression effects of Serbuoys-TLP are analyzed when current act on the tendons.