On the 30th, at the 500 kV Yuxian Substation in Caidian District, Wuhan City, Hubei Province, power workers are urgently installing a new batch of green power equipment for operation. This "green heart," set to revitalize the old substation, is the world's first SF6-free 500 kV HGIS ultra-high voltage switchgear.
The 500 kV Yuxian Substation is a key hub in the Three Gorges power transmission corridor to Henan and Hubei provinces. Its first phase was completed and put into operation in 1996, and it has been operating safely for 30 years, ensuring stable power supply to Wuhan and surrounding areas. The existing HGIS bays each require 800 kg of sulfur hexafluoride gas, which needs regular maintenance and handling.
It is understood that sulfur hexafluoride gas has excellent insulation and arc-extinguishing properties and has been the mainstream gas for high-voltage switchgear since the 1950s. However, its greenhouse effect is 23,900 times that of carbon dioxide, placing significant carbon emission pressure on the power industry. Although strict controls are in place during use and recycling, it remains difficult to balance power supply reliability with the green and low-carbon requirements of the new era.
The world's first SF6-free 500 kV HGIS equipment installed this time uses C4-FN perfluoroisobutyronitrile eco-friendly mixed gas, reducing the gas charge to 360 kg. The greenhouse effect of C4-FN perfluoroisobutyronitrile eco-friendly gas is only one-tenth that of sulfur hexafluoride, while its insulation strength is 2.2 times that of sulfur hexafluoride, making it an internationally recognized ideal substitute for sulfur hexafluoride.
According to estimates, this equipment can achieve an equivalent carbon reduction of 800 tons over its full lifecycle, comparable to planting approximately 3,000 trees annually or taking about 150 fuel-powered vehicles off the road for a full year.
Previously, this eco-friendly technology had been maturely applied at 220 kV and 420 kV voltage levels. Its application at the 500 kV ultra-high voltage level this time sets a new global record for the voltage level application of this eco-friendly technology. After the project is put into operation, it will provide important practical experience for the maintenance and upgrade of ultra-high voltage eco-friendly gas switchgear and the low-carbon transformation of new power systems.