Study on the limits of electromagnetic environment of ±800 kV DC transmission lines

Electromagnetic environment limits of ±800 kV DC transmission lines are the important basis to determine conductor bundle types and line structure. It is very important to determine reasonable electromagnetic environment limits for protecting environment and controlling construction investment. The electromagnetic environment limits of AC and DC EHV/ UHV transmission lines and the electromagnetic environment standards of relevant nations and international organizations were analyzed. Limits of the electric field strength, the ion current density, magnetic field, the radio interference and the audible noise of ±800 kV DC transmission lines in China were suggested. The structure of the conductor bundles, the least conductor height above the ground and the corridor width of ±800 kV DC transmission lines were determined on the basis of the electromagnetic environment limits and the forecast results of electromagnetic environment. The research results indicate that if the electromagnetic environment of ±800 kV DC transmission lines is controlled by the suggested limits, the electric field strength and the ion current density will be at the same level as that of the EHV DC transmission lines in China, the radio interference will be at the mid-level compared with other countries, the audible noise will accord with the national standards.