The first annual maintenance of the Jinshang-Hubei ±800 kV UHV DC transmission project concluded successfully

China News Service, Chengdu, September 29 (Reporter Liu Zhongjun) On September 28, with the successful bipolar unlocking of the Kamai and Bangguo converter stations, the first annual maintenance of the Jinshang-Hubei ±800 kV UHV DC transmission project (hereinafter referred to as the "Jinshang-Hubei Project") was successfully completed.

Workers are inspecting the insulator string of Tower 762 of the Jinshang-Hubei ±800 kV UHV DC transmission project. Photo by Cao Qi

It is understood that as the first UHV DC transmission project in China that goes deep into the hinterland of the Sichuan-Tibet Plateau, the Jinshang-Hubei project will be completed and put into operation at the end of 2025. The project starts from the upper reaches of the Jinsha River, and the line crosses Tibet, Sichuan, Chongqing, and Hubei. The two converter stations are built in Qamdo, Tibet and Bangguo, respectively. In Sichuan alone, the line mileage exceeds 860 kilometers, running through the Garze Plateau, the Hengduan Mountains of Ya'an and the hills of northeastern Sichuan. Large span, many points, and short effective window period are unavoidable difficulties in maintenance operations.

The annual maintenance lasted for 15 days. The two converter stations and transmission lines were simultaneously inspected for the first time. More than 1,600 workers stayed on the front line. State Grid Sichuan Electric Power Company took the lead in coordinating the work, and multiple participating inspection units worked together. Preparatory work such as on-site survey, plan preparation, and plan deduction were implemented in advance, laying a solid foundation for the safe and orderly advancement of maintenance.

The two converter stations, Kamai and Bangguo, adopt the world's first "location cascade" construction and coordinated operation model, which is highly innovative in technology and has high operation and maintenance standards. The maintenance of the converter station adopts the model of "two stations in one, main station coordination, and cross-station linkage". The operators have to withstand the test of extreme weather such as plateau hypoxia, strong winds and rainfall, and strong ultraviolet rays. The team refined the tasks at each stage before, during, and after the inspection into more than 400 items, and a total of more than 300 defects of various types were eliminated. The equipment operates stably and performs well.

Workers at the ±800 kV Bangguo converter station are inspecting the converter valve tower. Photo by An Wei

During line maintenance, drones came in handy. It is equipped with X-ray inspection equipment to conduct non-destructive inspection of key hardware such as tension clamps and connecting pipes, and can accurately detect internal crimping defects. Compared with traditional manual tower climbing inspection, this method not only improves efficiency, but also effectively reduces the risk of high-altitude operations.

The Jinshang-Hubei project is the core channel for green and clean energy export in Sichuan and Tibet. This annual maintenance has further improved the operational stability and power supply reliability of the UHV transmission channel, adding a guarantee for the continued and stable delivery of clean energy such as hydropower in the upper reaches of the Jinsha River and the regional power supply in autumn and winter. (over)