Dynamic Response Analysis For Offshore Wind Turbine Structures

Offshore wind power, as a kind of clean and renewable energy scource, has far-reaching significance for protecting the ecological environment. Compared with onshore wind turbine structures, offshore wind turbine structures installed in severe marine environment suffer variety random loads including wind, waves, currents, sea ice and tidal, and earthquake. Currently, some challenges have to be faced such as design technology and practical experience of the offshore wind turbine in complex and poor marine environment. Therefore, it is of significance to study dynamic response analysis of the offshore wind turbine structures in stochastic marine environment and ensure safety of wind turbine structures.The study on dynamic analysis for the offshore wind turbine structures associated with lots of subjects such as Aerodynamics, Dynamics of Structures, Soil Dynamics and so on, is an important subject on failure mechanism of the offshore structure engineering topics. Based on the state of arts of offshore wind turbine, vibration characteristics and structural dynamic response of the offshore wind turbine structures under varying load combinations are conducted in the paper. The contents of the research include:(1) Based on dynamic characteristics of wind and aerodynamic performance of the wind turbine, harmony superposition method (HSM) is employed to synthesize wind speed time series. According to momentum theory and blade element theory, random aerodynamic loads of the offshore wind turbine structures is simulated, which is helpful to futher study for dynamic analysis of the offshore wind turbine structures in fluctuating wind field.(2) Stochastic environmental loads such as wind turbine loads, wave loads, currents loads and seismic loads, acting on the offshore wind turbine structures, has been specially analysis. Pile and soil interaction models considering p-y, t-z and Q-z curves are established. ANSYS software is selected to calculate offshore wind turbine structure and corresponding ANSYS elements are described in detail.(3) Dynamic characteristics of the offshore wind turbine structure are obtained due to modal analysis. Transient dynamic response of the wind turbine structure and foundation under separate dynamic loading, such as wind load, wave load and seism load, is analyzed. Combining cases of the stochastic environmental loads, design control condition of the offshore wind turbine structures is validated. The study of structural dynamic response for the offshore wind turbine structures under the stochastic dynamic loads containing wind load, wave load and seism load is achieved. Meanwhile, some conclusions have been drawn for practical engineering.