Chinese Gas-Insulated Switchgear Enables Commissioning of Longdong-Shandong ±800kV UHV DC Transmission Project

On May 7, China's first large-scale integrated wind-solar-thermal-storage comprehensive energy base UHV transmission project—the Longdong~Shandong ±800kV UHV DC transmission project—was officially energized and put into operation. The project has an annual transmission capacity exceeding 36 billion kilowatt-hours, with new energy sources accounting for more than 50% of the total. After commissioning, it will reduce carbon dioxide emissions by approximately 14.9 million tons annually, contributing to the nation's dual carbon goals.

The 550kV AC gas-insulated switchgear (GIS) at the receiving-end Dongping converter station was supplied by Chinese manufacturers. Among this equipment, the 550kV fast circuit breakers connected to converter transformers can rapidly clear main transformer short-circuit faults, significantly enhancing substation operational safety. This successful application of the product represents the first such implementation internationally.

As a State Grid UHV DC project with significant technical challenges and tight construction schedules, a specialized project team was established by the High Voltage Company to provide comprehensive lifecycle services from design optimization and manufacturing to on-site installation, ensuring the successful completion of the Dongping converter station.

The 550kV GIS fast circuit breaker, independently developed by the High Voltage Company, features a total breaking time of less than 25ms and an opening time of 8ms. Its design incorporates separate tanks for the closing resistor and arc extinguishing chamber, effectively preventing mutual interference between the resistor plates and the arc chamber's opening/closing movements while maintaining interruption capability. This design significantly improves equipment reliability and establishes a solid defense line for stable UHV grid operation.

The successful commissioning of this project represents another powerful demonstration of technical capabilities in the high-end power equipment field, and marks the company's achievement of internationally leading technical standards in fast circuit breaker technology.