Lo F.CCHAO-NAN WANG2021-08-052021-08-05201710234535https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037809712&partnerID=40&md5=707379c1bca395947a5d0ba058bb2c92https://scholars.lib.ntu.edu.tw/handle/123456789/576821The main purpose of this study is to establish a complete wind turbine blade surface damage diagnosis system. The noise characteristics of the blades are generated by the operation of the wind turbines. In this article, the method of time-frequency signal is analyzed by a short-time Fourier transform. In order to establish the normal module, first, we measure the sound signal of a normal wind turbine, and analyze sound signal by a short-time Fourier transform. Second, we use marginal frequency, decibel transformation polynomial regression, and so on. Regarding the normal module as a reference, we can compare it with other wind turbines to calculate the index. After calculating the index, we use the ROC curve theory to determine the optimal threshold. The optimal threshold can estimate the situation of surface damage on the wind turbine blade. We can detect damage while turbines are operating. The final result of the paper is verified by photo, and we look forward to applying it on the health detection system of wind turbine.Acoustic noise; Fourier transforms; Turbomachine blades; Wind turbines; Blade noise; Marginal frequencies; Polynomial regression; ROC curves; Short time Fourier transforms; Turbine components[SDGs]SDG7journal article2-s2.0-85037809712