Design of ±500kV 2Bi-Pole Overhead Transmission Line with Metalic Return in the Republic of Korea

South Korea has many mountains and a high population density, which makes it difficult to construct overhead transmission lines. Also, due to the increase in power demand in the metropolitan area, large-capacity long-distance transmission from remote power generation complexes is necessary. However, due to complaints about the construction of ultra-high voltage AC transmission lines which may cause a concern of health problems through electromagnetic waves, it is not easy to build new HVAC transmission networks. This paper introduces the design method of the 500kV East Coast-Metropolitan Area transmission line that transmits power from the East Coast power plants to the metropolitan area in the Republic of Korea. It explains the background of adopting the world's first HVDC 2Bi-Pole metallic return system instead of existing HVAC system, as well as related design factors such as the selection of conductors, insulation design, and tower shape determination.