Vibration Mechanism and Noise Characterization of Offshore Wind Turbines

This study used accelerometers and hydrophones to measure the vibration and underwater noise from two different types of offshore wind turbine installed near the East China Sea Bridge (Shanghai). Wind speed and rotor speed were also monitored synchronously. The spectrograms of the vibration and underwater noise signals display well-defined spectral lines that are easily distinguishable. Line-component spectra of both vibration and underwater noise signals were synchronously extracted through filtering and correlation analysis. On this basis, relationships between the intensity and frequency of wind turbine vibration and underwater noise line-component spectra, rotor speed, and wind speed were analyzed. Results indicate that rotor speed is positively correlated with wind speed, and that the peak vibration frequencies and intensities of both types of turbine are positively correlated with rotor speed. Consequently, it can be concluded that the frequency and intensity of turbine-generated underwater noise are closely related to wind speed. Additionally, the vibration mechanism and the characterization of underwater noise of the wind turbines have been revealed.