Reaserch On Coupled Dynamic And Damage Identification Of Mooring System Of Ultra Large Wind Turbine Novel Floating Platform

Wind power generation plays an important role in global clean energy.Floating wind turbines(FOWTs)have many advantages,such as wide application depth,large scale,easy to move and dismantle.China has abundant offshore wind power resources with huge potential.Most wind farms are close to the load centers mainly in the economically developed eastern regions,which are convenient for local consumption.The FOWTs are undergoing the process of extra large(XL),and is constantly developing to the open sea,in order to reduce the cost of power generation.With the increase of offshore distance and water depth,the interference of wave action on XL-FOWTs are intensified,and the high speed offshore wind load makes the safe and stable operation of XL-FOWTs face great challenges.Floating platform is an important guarantee for the safety,stability and efficient operation of offshore wind turbines.Its motion form in the Marine environment is extremely complex and affected by many factors such as wave,wind load,structure and mooring,and its dynamic behavior has strong nonlinear characteristics.This paper studied the nonlinear coupled dynamic characteristics of the floating platform of XL-FOWTs and the failure of mooring system.The main work of this paper is as follows:1.Based on the blade element momentum theory,modal method,potential flow theory and catenary theory,a fully coupled aero-servo-elastic – hydro-mooring multi-physical field model suitable for the typical nonlinear dynamic system of XL-FOWTs was established.2.In order to enhance simulation capabilities of existing numerical tools for the design of XL-FOWTs,this study has developed and implemented a coupling framework that is capable of predicting nonlinear dynamics of FOWTs subjected to wind,wave and current loadings.The coupling framework F2 A based on FAST and AQWA makes use of the advantages of FAST in efficiently examining aero-servo-elastic effects and the capabilities of AQWA in modelling nonlinear hydrodynamics and mooring dynamics of a FOWT.The verification of F2 A was carried out by comparing with Open FAST.The results show excellent agreements between F2 A and Open FAST.This implies that the simulation capabilities of FAST are well implemented within AQWA.3.A new type of dual-body floating platform for 13 MW or above XL-FOWTs was designed.Full-coupling simulation calculation was carried by the F2 A coupling module,and time-frequency analysis was conducted to study the dynamic characteristics of the new dualbody floating platform under different ocean load cases.4.The influence of the structure configuration and mooring system parameters on the dynamic characteristics of the dual-body platform was studied.The porous structure of the upper tank was proposed to optimize the platform stability of the platform.Based on fractal theory,the fractal characteristics of porous structure were analyzed to verify the optimization effect of fractal structure on platform stability.The influence of the position and number of tendon moorings on the dynamic response of the platform and change of the mooring forces was studied.5.For the mooring system,a new fault diagnosis method PS-DBN based on deep convolutional neural network was proposed.The feasibility of the method was verified by analyzing the nonlinear characteristics of the mooring system.