Analysis And Research Of Loads Considering The Joint Effects Of Wind And Wave For Offshore Wind Turbine

Considering the joint effects of wind and wave, the simulation and calculation of waveloads acting on the monotower of an offshore wind turbine and the loads response and loadresponse spectrum analysis of the tower base have been studied in this thesis, which includesfive sections: the summarization of the offshore wind turbine technology, the simulation andcalculation of wave loads, the analysis and calculation of aerodynamic loads of wind turbine, theanalysis and calculation of loads from wind and wave acting on a monotower and the responsespectrum analysis of offshore wind turbine with the joint effects of wind and wave.In the first section, the offshore wind conditions, the supporting technology of offshorewind farm and the comparative advantage according to the differences between the offshorewind farm and the onshore wind farm are discussed. Based on the differences of designs betweenthe onshore wind turbine and the offshore wind turbine, the characteristics of offshore windturbine and the optimum design of the offshore wind turbine are introduced.In the second section, the mathematic models of irregular linear wave simulation andregular wave simulation are established at first. According to the models, water particlekinematic parameters are solved and the wave loads acting on the monotower tower arecalculated. After that, the irregular linear wave loads calculating program and regular wave loadscalculating program using C++/Fortran mixed-program method are developed. This sectionincludes two aspects: firstly, the water particle velocity and acceleration of an irregular linearwave are obtained according to the simulation and calculation of irregular linear wave based onlinear wave theory; the water particle velocity and acceleration of an extreme wave are obtainedaccording to the simulation and calculation of a regular wave based on stream function theory.Secondly, according to the wave kinematic parameters the horizontal wave loads are calculatedusing Morison equation. The results of extreme wave simulation and calculation are inagreement with those obtained by the foreign ECN program used in the calculation of the waveloads for the offshore wind turbine. This validates the simulation and calculation model of thewave loads simulation and calculation.In the third section, the aerodynamic performance calculation model of the horizontal wind turbine and the method of aerodynamic loads are introduced.In the forth section the extreme and fatigue loads of tower base of a monotower offshorewind turbine are calculated in two conditions which account for wave loads action or not and theloads characteristics with the joint effects of wind and wave are derived from the results ofcalculation and analysis of extreme and fatigue loads.In the last section a simple load model of offshore wind turbine system is set up and theresponse characteristics of the loads of tower base are obtained according to the dynamicresponse analysis of offshore wind turbine based on this model.