Basic Knowledge of Electricity—What is an Ultra-High Voltage Power Grid

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UHV grids refer to transmission networks with AC voltages of 1000 kV and DC voltages of 800 kV positive or negative, or higher. Comparing it with our country’s existing power grid, which is primarily based on 500 kV AC and ±500 kV DC systems, the former is like an expressway while the latter is like a regular fast road; there is a huge difference between the two in terms of traffic volume, speed, and cost-effectiveness. At present, China’s ultra-high voltage transmission lines consist of 220 kV, 330 kV, and 500 kV AC transmission lines, as well as 500 kV DC transmission lines, which form the backbone of the grid. Five regional power grids and the Southern Power Grid have been established across the country. Among them, the regional power grids in East China, North China, Central China, and Northeast China, as well as the Southern Power Grid, have already established 500-kilovolt main grid structures; the Northwest Power Grid is building 750-kilovolt grid structures on top of its 330-kilovolt grid structure. However, since cross-regional power transmission in our country relies mainly on 500 kV AC and ±500 kV DC, there are various constraints in terms of technology, environmental protection, land resources, etc., that hinder the improvement of power transmission capacity. Ultra-high voltage power grids can meet the needs for long-distance, high-capacity power transmission over distances of 2,000 to 3,000 kilometers from east to west, and 800 to 2,000 kilometers from north to south; they are conducive to the development of large coal-fired power plants, large hydroelectric power stations, and large nuclear power plant complexes, as well as to the transmission of electricity over long distances. The 750 kV Guanting to Lanzhou East power transmission and transformation project, the design work for which was carried out by the Northwest Electric Power Design Institute of the group company, has been operating safely and stably up to this year, laying a solid foundation for the planned **ultra-high voltage power grid.