The Gansu-Hunan ultra-high-voltage (UHV) direct current transmission project had delivered 247.14 TWh of electricity as of September 14, including 23.61 TWh so far this year, according to State Grid Gansu Electric Power Co., Ltd.

The project is China's first UHV DC line to bundle large-scale wind and solar power with thermal power for inter-provincial transmission. With a rated voltage of ±800 kV and a transmission capacity of 8 GW, the line spans five provincial-level regions — Gansu, Shaanxi, Chongqing, Hubei and Hunan — and serves as a key channel in China's west-to-east power transmission strategy, supporting cross-provincial allocation of renewable energy and regional power supply security.

The operational status of core equipment at the ±800 kV Qilian converter station, including the valve cooling system, converter transformers and circuit breakers, directly affects the safety and stability of the transmission channel. During the summer peak-load period this year, maintenance staff at the station used drones and rail-mounted robots in valve halls to conduct special inspections.

The Qilian converter station has built a comprehensive equipment maintenance system focused on preemptive hazard control and rapid risk response, using digital and intelligent technologies to support stable UHV transmission. In May, the station completed its ninth annual maintenance, dividing work into 59 operation areas and covering 1,198 AC and DC inspection items, six targeted maintenance tasks and 16 differentiated maintenance tasks, along with multiple software upgrades and 22 equipment defect elimination tasks.

Since the Qilian converter station began operation, State Grid Gansu EHV Company has continued to optimize its maintenance model in response to harsh weather such as strong winds and sandstorms, building an integrated management system combining smart maintenance with on-site precision inspections. The station uses 17 digital subsystems to support an intelligent operations platform, alongside manual inspections, to achieve full-time equipment monitoring and control.