Study on vibration of offshore wind turbine supporting system under the wind-wave coupling effect

For offshore wind turbines, the wind and wave loads are the main actions exerted on the offshore structures during the operational process. In order to reasonably simulate the wind-wave coupling effect and the dynamic characteristics of the structure under the coupling effect, the Davenport horizontal fluctuating wind speed spectrum is processed according to the Fourier transform and the harmonic superposition method, thus the fluctuating wind spectrum which coincided well with the target power spectrum is acquired. On the basis of the random wave theory, the calculation equation of wave load for offshore wind turbine structures are put forward. Besides, the wind and wave coupling mechanism analysis is carried out by Turkstra method. In numerical analysis, the integrated finite element model of the offshore wind turbine structure is established considering the interaction between the wind turbine foundation and the soil. Meanwhile, based on the frequency domain method, the in-site measured acceleration signals of an offshore wind turbine are processed and analyzed and the dynamic characteristics of each part of the wind turbine supporting system are obtained. Comparing the measured values with the numerical simulation results, it shows that the calculation method of the wind-wave coupling effect has a preferable accuracy as well as a certain amount of safety coefficient, which can ensure the safety of the structure in actual operation process.