Audible noise spectral characteristics of high‐voltage ac bundled conductors at high altitude

Abstract

At high altitudes, the corona discharge around a conductor surface is severe, and the induced audible noise (AN) is irritating; this is due to the low air density at high altitudes. Therefore, AN has become a crucial limiting factor in the design of ac power lines of 500 kV or higher at high altitudes. An investigation of the spectral characteristics of AN should help provide a greater understanding of corona noise; however, only a few studies have investigated the spectral characteristics of AN in practical bundled conductors at high altitude. Therefore, it is difficult for power utility companies to select suitable conductors. In this study, the AN spectral characteristics of 6 × LGJ400, 6 × LGJ720, and 8 × LGJ500 bundled conductors were investigated using an ultra-high-voltage corona cage (8 × 8 × 35 m) in Xining, Qinghai Province (altitude: 2261 m). The AN equivalent A-weighted level and the 1/3-octave frequency characteristics of these three conductors were obtained, and the influence of the electric field (E-field) on these characteristics was analysed. Subsequently, the relationship between the AN A-weighted level and the 8-kHz level was examined. We found that, with the increase of the E-field, the low-frequency components of AN level did not exhibit an obvious trend, but in the high-frequency band (1.6–20 kHz), a clear positive correlation was observed between the spectrum level and E-field strength. Among these three conductors, the 8 × LGJ500 conductor was the optimal conductor for reducing the AN levels at high altitude. The results obtained in this study can provide a data reference for the construction of high-altitude ac power lines.