The 110-kilovolt Qiuchuan Substation in Quzhou, Zhejiang province, resumed power transmission on Tuesday, following efforts by State Grid Quzhou Power Supply Company to replace the gas used in its GIS (gas insulated switchgear) equipment.

It was the company’s first attempt at installing new gases for GIS, with the aim of promoting low-carbon development within the substation to contribute to the national dual carbon goals.

Sulfur hexafluoride, a common insulation and arc-quenching medium in substation equipment, is widely used in GIS equipment. However, sulfur hexafluoride is a potent greenhouse gas, with greenhouse effects amounting to 23,000 times more than carbon dioxide.

Research by environmental experts at the State Grid Electric Power Research Institute revealed that using a mixture of sulfur hexafluoride and nitrogen gas in a 3:7 ratio instead of pure sulfur hexafluoride gas can effectively reduce emissions while ensuring the insulation performance of electrical equipment.

In line with green development, energy conservation and emission reduction in power grid equipment, State Grid Quzhou Power Supply Company initiated a "fluorine reduction" project at the Qiuchuan Substation.

According to the project, during the outage of the GIS equipment, all sulfur hexafluoride gas adopted in a total of eight air chambers, including the 110-kV bus bars and lines at the Qiuchuan Substation, was replaced with a mixture of sulfur hexafluoride and nitrogen gas.

Throughout the construction process, standardized operating procedures were strictly formulated based on on-site surveys and technical standards. Professional equipment was used for the collection of the original sulfur hexafluoride gas, with strict control over key steps such as pressure relief, vacuuming and gas injection, to ensure the safety of personnel and equipment.

Additionally, the staff members conducted refurbishments and upgrades on the GIS equipment's inflation joints, density relays, rapid grounding switches and other devices. This not only enhanced energy efficiency and emission reduction but also significantly improved the safety and reliability of the equipment.

Following the gas transformation, after estimating the impact of the greenhouse effect, the annual reduction in sulfur hexafluoride emissions will be equivalent to reducing carbon dioxide emissions by 34.66 metric tons.

In the future, State Grid Quzhou Power Supply Company will uphold the principles of green development, promote the low-carbon upgrade of substations and contribute to the construction of a green power grid through practical actions.