Study on Field Measurements of Strong Wind Characteristics Near the Typhoon Mekkhala" Landing Place and Design Wind Loads of Transmission Lines

In order to obtain features of strong wind near typhoon landing places around transmission lines and improve the wind-resisting design reliability, full-scale field measurements of strong wind at the height of 30 m near the typhoon 'Mekkhala' landing place close to a transmission line were performed. The characteristics of wind load parameters, including mean wind velocities, wind directions, turbulence intensities, turbulence integral scales, gust factors and power spectra, were comprehensively studied. Moreover, the design parameter values of wire wind loads were examined. Results show that during the typhoon landfalling, the horizontal mean wind velocities rose rapidly from a low base less than 20 m/s to 41.1 m/s with sudden wind direction changes around 160°. In the strong wind phase after typhoon landing, the turbulence intensities and gust factors decreased from 0.35 to 0.15 and 2.25 to 1.25, respectively, with the increase of mean wind velocities. The relationships of gust factors corresponding to turbulence intensities and peak factors were progressive increases. The Ishizaki model was examined to be good to represent the changing pattern between gust factors and turbulence intensities. The dispersion of turbulence length scales was considerable. The power spectra calculated by field measurement data matched the Von-Karman empirical spectrum. The span factors and gust response factors of conductors and ground wires computed by DL/T 5551-2018 could moderately cover the most unfavourable results corresponding to the maximum mean wind velocity of 41.1m/s. © 2021 Chin. Soc. for Elec. Eng.