Inversion Of Foundation Parameters And Dynamic Response Of Offshore Wind Turbine Structures By Bucket Foundation

With the emphasis on renewable energy,the development of offshore wind energy resources in our country has gradually entered a new stage.Compared with onshore wind power,offshore wind power has many advantages such as less land area,less impact on the environment,proximity to the southeast coastal area,stability and high efficiency.The bucket foundation has excellent anti-eccentric load,anti-sliding,and anti-overturning capabilities,which provides a new direction for the low-cost and high-efficiency development of offshore wind power.In the design stage of offshore wind turbines,the unclear conversion relationship between the foundation compressive modulus and elastic modulus will affect the design accuracy of the basic structure;whether the wind turbine is safe under the combined action of wind,waves,ocean currents and other complex environmental loads during the design service period Operation is one of the key considerations for offshore wind power designers.In response to the above problems,the thesis carried out research on the dynamic response characteristics of offshore wind turbine structure,the inversion of foundation soil parameters,and the dynamic response of the foundation structure under ultimate load.The main contents are as follows:(1)Based on the field prototype observation data,the dynamic response characteristics of offshore wind turbines under different operating conditions are analyzed.Calculate the observation data of an offshore wind turbine prototype,describe the structural vibration characteristics of the wind turbine under different working conditions,and clarify the influence of various operating factors such as ambient wind speed,start and stop operations,and impeller speed on the structural vibration of the offshore wind turbine under various working conditions.The vibration safety of wind turbines operating under different working conditions;the main frequencies of the first and second order structures of the single-tube multi-chamber foundation identified by the FFT method are 0.34 and 2.55 Hz,respectively.(2)Developed the MATLAB-ABAQUS joint simulation inversion program with multiple frequencies as the target,and realized the inversion of the foundation parameters of offshore wind turbines.First,the basic principles of PSO and MOPSO algorithms are introduced,the value range of the main parameters are determined,and the elastic modulus of the foundation is inverted;then the conversion coefficients obtained from the inversion are applied to the numerical model of offshore wind turbines,and the Kaimal wind spectrum pair is selected.The random wind load is simulated,and the structural dynamic response of the wind turbine under shutdown conditions is analyzed.The results show that the error of the conversion coefficient obtained by the MOPSO algorithm inversion is smaller and may be closer to the actual situation.The subsequent dynamic calculation will use the conversion coefficient obtained by the MOPSO algorithm inversion.(3)Research on the dynamic response of offshore wind turbine structure is carried out on the basis of the inversion results of foundation parameters.First,combined with the actual engineering,the wind,wave,and current loads on the wind turbine structure under extreme environments are analyzed and simulated.Secondly,the dynamic response of the wind turbine structure under different load combinations is compared.The results show that the combination of reduced wind speed and maximum wave height can be used as an offshore wind turbine extreme working condition control combination.Finally,it calculates and analyzes the degree of reduction of wind turbine structural safety performance under extreme environments by scour,and gives a prediction of offshore wind power foundation scour based on natural vibration frequency,which provides support for the basic safety analysis of offshore wind turbines.