Analysis of non-stationary characteristics of measured wind speed in mountains based on TVF-EMD

Abstract The time-varying average wind speed is extracted by using time-varying filtering EMD (TVF-EMD), and the non-stationary characteristics of the measured wind speed in mountainous areas are analyzed. A non-stationary wind speed model is established, and compared with the traditional stationary model. The results show that TVF-EMD is more accurate and reliable in extracting time-varying average wind speed than traditional wavelet transform. The stationary model overestimates the turbulent characteristics of wind, and the turbulence intensity and gust factor are higher than those of the non-stationary model. In the non-stationary model, the turbulent energy of fluctuating wind is reduced because the time-varying trend term is eliminated. In the whole frequency band, the power spectral density is lower than that of the steady-state model. Kaimal PSD with along-wind and Von Karman PSD with cross-wind are suitable for non-stationary wind fields in mountainous areas.