In UHV DC transmission projects, the selection of line conductor type must not only ensure the safe transmission of electricity over long distances but also meet environmental protection requirements. Among these requirements, the limits of the line’s electromagnetic environment become the most crucial factor in selecting conductors. Additionally, from an economic perspective, the choice of line conductor type is directly related to construction investment and operating costs.
Therefore, research on UHV DC wire cross-section and splitting types is conducted to meet the requirements of economic current density and long-term allowable current, as well as to comprehensively consider electromagnetic environmental limits, construction investment, and operating losses. This involves studying different structural methods and different altitudes to calculate the wire surface field strength and corona voltage. Analysis of electric field strength, ion flow density, audible noise, and radio interference is also conducted to determine the final conductor splitting type and sub-conductor cross-section.
For ±800 kV UHV DC projects, conductor structures of 6 x 720 mm2 and above should be used to meet environmental impact limits, particularly regarding audible noise.