Audible noise analysis of 750-kV AC transmission line in high-altitude area under different weather

In order to build UHV AC transmission lines at high altitudes, it is necessary to analyze the audible noise (AN) characteristics of the existing EHV transmission lines at high-altitude areas to guide the design. The typical test data of AN for 750-kV single-circuit transmission lines measured at the Guanting long-term observation station, located at an altitude of 1854 m, were collected. Two methods of sorting the test data of AN and extracting valid data were given. Then the levels of AN under different weather conditions were analyzed, which showed that AN was raised with the increase of instantaneous rainfall and snowfall. Typical frequency spectrums of AN under different weather were also obtained, the pure tone at 100 Hz was more prominent under rainy and snowy weather, and the pure-tone oscillation attenuated at different positions. The statistical results and the calculated difference of AN over 5.5 h with continuous rainfall were obtained. For the 750-kV transmission line in the quiet plateau areas, the calculated difference between AN during rainy days and fair weather can be taken as 25 dB, and the calculated value of the altitude correction coefficient of 2.85 dB/1000 m is better consistent with the measured value.