Influence of altitude on radio interference level of AC power lines based on corona cage

To investigate the effect of altitude on radio interference (RI) of AC power lines, a corona cage test system was used to measure the RI excitation function values of different bundle conductors in different altitude locations, such as Wuhan 23 m, Jingyuan 1408 m, Xining 2261 m, Gonghe 2943 m and Yangbajain 4300 m. Then, the RI curves with different altitudes, bundle numbers and subconductor diameters were obtained. The analysis and comparison show that the actual RI altitude correction values fall in between the range of 1 dB/300 m and 40(1 - σ/σ₀) when the altitude below 3200 m, which is widely used as Italian correction term and Westinghouse correction term, respectively. Above this altitude, they are not applicable to predict the correction values. In this study, an RI correction term is proposed from the test results, which are fitted well for different altitude regions <;4300 m.