The 33rd China International Exhibition on Electric Power Equipment and Technology
Shanghai International Energy Storage Technology Application Expo / Hydrogen Energy Expo
Ultra-High Voltage (UHV) transmission refers to power lines operating at 1,000 kV AC or ±800 kV DC and above, enabling the transmission of gigawatts of electricity over distances of 1,000–5,000 km with transmission losses of only 3–7%. China is the global leader in UHV technology, having built the world's first commercial UHV AC line (1,000 kV Jindongnan–Nanyang–Jingmen, 2009) and the world's first ±800 kV UHV DC line (Yunnan–Guangdong, 2010). UHV transmission is central to China's strategy of transmitting hydropower from the southwest and wind/solar power from the northwest to load centres in the east, addressing the geographic mismatch between renewable energy resources and electricity demand. State Grid Corporation has invested hundreds of billions of RMB in UHV infrastructure.
5 Key Questions About UHV Transmission
China's energy resources are concentrated in the west (hydropower in Sichuan and Yunnan, wind and solar in Xinjiang, Inner Mongolia, and Gansu) while electricity demand is concentrated in the east (Beijing-Tianjin-Hebei, Yangtze River Delta, Pearl River Delta). UHV transmission bridges this geographic gap, enabling clean energy generated thousands of kilometres away to power China's industrial and urban centres. Without UHV, these remote renewable resources could not be economically exploited, and eastern cities would remain dependent on local coal-fired generation.
UHV AC (1,000 kV) is used for shorter-distance bulk transmission within regional grids, where the synchronous AC connection provides frequency regulation support and the infrastructure can be tapped at intermediate points. UHV DC (±800 kV or ±1,100 kV) is used for longer-distance point-to-point transmission, offering lower losses over very long distances, no reactive power limitations, and the ability to connect asynchronous grids. China operates both UHV AC and UHV DC systems, with DC preferred for the longest routes (2,000+ km) and AC for regional backbone transmission.
UHV transmission requires specialised equipment including: UHV transformers and autotransformers (the largest and most technically demanding transformers in the world); UHV circuit breakers and disconnectors; UHV surge arresters; UHV shunt reactors for reactive power compensation; UHV insulator strings and hardware; UHV conductor bundles (multiple conductors per phase to manage electric field and corona); and for DC systems, converter stations with thyristor or IGBT valve halls, converter transformers, and smoothing reactors. Chinese manufacturers including TBEA, CHINT, and Pinggao have developed domestic UHV equipment capability, reducing dependence on international suppliers.
UHV transmission lines require wide right-of-way corridors (typically 80–100 m for ±800 kV DC lines) and tall towers (50–100 m), creating visual and land use impacts. Electric and magnetic fields near UHV lines are regulated by national standards. Corona discharge from UHV conductors generates audible noise and radio interference that must be managed through conductor bundle design and minimum ground clearance requirements. However, UHV transmission enables the replacement of local coal-fired generation with remote clean energy, delivering substantial air quality and carbon emission benefits that far outweigh the localised environmental impacts of the transmission infrastructure.
China's UHV network is expected to continue expanding through the 2020s and 2030s, with additional DC lines connecting large wind and solar bases in the northwest and northeast to eastern load centres, and AC backbone reinforcements strengthening regional grid interconnections. The development of ±1,100 kV UHV DC technology (the world's highest voltage DC system, commissioned in 2019 on the Changji–Guquan line) demonstrates China's continued technology leadership. Future UHV development will increasingly focus on integrating large-scale offshore wind and desert solar projects into the national grid.
Key Takeaways
Surge arresters protect power equipment from voltage spikes caused by lightning strikes and switching operations. As China's grid expands into regions with severe lightning activity, demand for advanced surge protection continues to grow. EP Shanghai connects surge arrester manufacturers with utility specification engineers and equipment buyers.
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