LHASA, Nov. 16 (Xinhua) -- Southwest China's Tibet Autonomous Region completed the trial of a 220-kilovolt power substation at an altitude of 4,688 meters on Monday.

The station, located in Saga County, Xigaze, was constructed following a challenging high-altitude power transmission and transformation project across Tibet's Ngari Prefecture and the middle part of the region, the world's highest power structure of its kind.

The project, with a total investment of 7.4 billion yuan (about 1.12 billion U.S. dollars), plans to build six substations, all above 4,000 meters above sea level. The total length of the transmission lines will reach 1,689 kilometers across ten counties and two prefecture-level cities.

Three of the substations have been completed since the construction began in September 2019, and the project will start operation in 2021, enabling safe and stable electricity use for nearly 380,000 residents along the lines.

After completion, the project will facilitate the main electric grid in Tibet to cover 74 counties, and 97 percent of the regional population will benefit by then, said Losang Dawa, deputy commander of the project.