URUMQI, March 7 (Xinhua) -- Construction work began Tuesday on a high-cost 750-kilovolt ultra-high voltage power transmission and electrical substation project in northwest China's Xinjiang Uygur Autonomous Region, the regional power supplier has announced.

The project has a total investment of 4.62 billion yuan (about 667 million U.S. dollars), which is the largest single investment of any power grid project in the region.

It will be built in Bayingolin Mongolian Autonomous Prefecture, and will go into operation in 2025, according to State Grid's Xinjiang branch.

The project is expected to promote the interconnection of power grids in Xinjiang and its neighboring province Qinghai, supply power for a railroad connecting the two provincial-level regions and boost energy storage.

During the 14th Five-Year Plan period (2021-2025), over 110 billion yuan will be invested in Xinjiang's power grid, up 55 percent from the 13th Five-Year Plan period (2016-2020).