The Measurement and Analysis of Electromagnetic Environment of DC Transmission Line in High Altitude Areas

The electromagnetic environment of DC transmission lines has become the main restrictive factor for the design and operation. In order to further study the electromagnetic environment distribution in high altitude areas, this paper analyzes the ground-level composite field strength, Radio interference and audible noises of different lines which is the +/- 400kV Qaidam-Lhasa DC transmission project at altitudes over 4500m. Based on the measured data, the distribution law of the electromagnetic environment under the line was analyzed, and the changes of the electromagnetic environment with the increase of altitude were studied. The results show that the composite field strength, radio interference, and audible noise under the line are all within the standard limits, and with the increase of altitude, the overall trend is increasing. The research results can provide evaluation basic for electromagnetic environment problems in high-altitude DC transmission projects.