Wedoany.com Report-Oct. 30, During the 14th Five-Year Plan period (2021–2025), China has made significant progress in ultra-high-voltage (UHV) alternating current (AC) and direct current (DC) transmission projects, with 45 UHV projects now in operation nationwide. By the end of 2025, the west-to-east power transmission program is expected to reach over 340 million kilowatts of capacity, a 25 percent increase from 270 million kilowatts at the end of the 13th Five-Year Plan period (2016–2020).

A key project is the ±800 kV UHV DC transmission line from Baihetan in southwest China to Jiangsu Province in east China. Stretching 2,080 kilometers across Sichuan, Chongqing, Hubei, Anhui, and Jiangsu, the line transmits hydropower from Baihetan to Jiangsu in just 7 milliseconds, forming a central part of the west-to-east transmission program.

China has accelerated construction of interprovincial and cross-regional UHV DC corridors. According to an executive from the UHV division of State Grid Corporation of China (SGCC), eight UHV DC projects, including Baihetan-Jiangsu, have been launched during the period, covering 13,600 kilometers and providing more than 50 million kilowatts of cross-regional transmission capacity.

Data from the National Energy Administration (NEA) indicate that UHV DC line length has increased from 28,000 kilometers to over 40,000 kilometers. China now operates one ±1,100 kV UHV line, 23 ±800 kV lines, and 21 1,000 kV lines, forming the world’s largest and technologically advanced ultra-long-distance power transmission network.

The grid structure has also been optimized. Building on UHV main grids established in north and east China during the 13th Five-Year Plan, four central provinces and the Sichuan-Chongqing region established UHV AC main grids during the 14th Five-Year Plan.

Several notable projects have entered operation, including the Longdong-Shandong ±800 kV UHV DC line, China’s first “wind-solar-thermal-storage integration” project. The 915-kilometer line from Qingyang, Gansu, to Tai’an, Shandong, delivers 36 billion kilowatt-hours annually, with more than half from clean energy. The Ningxia-Hunan ±800 kV UHV DC line, launched in October 2025, transmits over 36 billion kilowatt-hours annually from wind and photovoltaic bases in northwest China to Hunan, with at least 50 percent of the power sourced from renewable energy.

In 2024, cross-regional UHV DC channels transmitted around 420 billion kilowatt-hours of clean energy, a 70 percent increase from the end of the 13th Five-Year Plan, accounting for nearly 60 percent of total transmitted power. SGCC’s Sichuan–Chongqing 1,000 kV UHV AC project achieved 26 “world firsts,” demonstrating China’s advanced technological capabilities.

Technological innovations during the period include breakthroughs in topology, flexible transmission, and high-altitude construction. SGCC has standardized ±800 kV, 8 million kilowatt UHV DC technology and developed over 500 technical documents, enhancing the power transmission and transformation equipment industry. Projects such as Longdong-Shandong applied domestically produced tap changers and DC control systems, while Zhangbei deployed domestic DC dry capacitors, improving China’s manufacturing strength in electrical equipment.

These developments collectively support large-scale renewable energy transmission, safe operation of multi-infeed DC grids, and strengthen China’s position in advanced power equipment technology.

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