No abstract

Abstract:The audible noise (AN) induced by corona discharge of AC transmission lines is more severe at high altitudes than at low altitudes; this has become a crucial limiting factor for the structural design of power lines and their environmental impact assessment. To determine the altitude effect and correction of AN level for AC power lines, a corona cage test system was used to measure the acoustic power level of four bundled conductors at five elevations, namely Wuhan (23 m), Tianshui (1100 m), Xining (2261 m), Gonghe (2943 m), and Yangbajain (4300 m). We obtained the AN characteristics for different altitudes, bundle numbers, and subconductor diameters through a statistical analysis of measured data. The analysis and comparison results indicate that the actual AN correction values are slightly less than the Bonneville Power Administration term of 1 dB/300 m at altitudes below 3200 m. Above 3200 m, the difference increases gradually. A correction term 2.85 dB/1000 m is recommended for more accurate evaluation.

No abstract

Abstract:A reasonable acoustic power formula is vital to precisely evaluate the audible noise (AN) level of ultra-high-voltage (UHV) AC power lines. This study derived a formula by taking several AN measurements under heavy rain conditions, using multiple conductor bundles in a UHV corona cage, and then subjecting these measured values to least squares fitting. The validity of the proposed formula was subsequently verified with statistical data obtained from two long-term stations at Henan and Hubei Province, which are located under the Jindongnan-Nanyang-Jingmen UHV AC transmission lines operating at 1000 kV. The deviation between the prediction and the long-term (L50) value was 0.76 dB for the Henan station and 0.17 dB for the Hubei station. It shows that the acoustic power formula derived in this paper is more accurate than the widely used Bonneville Power Administration formula, in which the corresponding deviations are much larger (3.07 and 2.53 dB).

No abstract