Edited by WANG Xiaoxia

After 15 long years of effort, toiling high above the shimmering heat of the Taklamakan Desert, tens of thousands of powerline workers have finally completed the 4,197-km-long 750 kV power transmission loop, a major infrastructure milestone along the edge of the Tarim Basin, the country's largest inland basin.

The loop is the driving force for the development of southern Xinjiang Uygur autonomous region, while also being a confidence booster for the many ethnic groups in southern Xinjiang seeking an improved lifestyle.

Overcoming challenges

Most of the construction of the loop project was carried out along the Taklamakan Desert, the world's second-largest drifting desert, lying within the Tarim Basin, where relentless sandstorms brought a raft of challenges.

As there was no road in the desert, large construction vehicles could not operate, and faced a risk of falling into sand pits, so workers had to build roads along the entire line to transport materials, said Li Jun, a manager at State Grid Xinjiang Electric Power Co., Ltd., contractor of the project. To prevent material to build the steel power line towers from being lost or buried by the sand dunes, tall layers of color-marked sandbags were used as identifying markers.

During the construction process, which the State Grid Xinjiang Electric Power Co., Ltd., said included nine substations and nearly 10,000 steel towers, the engineering team applied new technologies and processes according to local conditions.

For the first time in Xinjiang, the spiral anchor technique was used in the foundation construction of an extra-high voltage project. With a high degree of mechanization, few processes and high efficiency, each tower foundation was completed in three days.

The engineering team adopted new technology to install lines, which integrates an UAV and intelligent control system. The UAVs replace the manual work to erect the primary guide lines, with a remote centralized control console set up in the tension field and traction field, and monitoring device installed in the tower, to ensure control of equipment and monitoring of risks.　　

To minimize the project's environmental impact, particularly on native desert plants such as populus euphratica, engineers adjusted tower heights, made minor route modifications, and laid more than 480,000 square meters of straw checkerboard, a widely used method in China to stabilize sand, Li explained.

Meet urgent demand

"The 220 kV power supply in Qiemu County cannot run high-voltage equipment, and many development projects in the county can only stay on the blueprint," said Dilshat, an official from Qiemo county, located in the heart of the desert. "The construction of the 750 kV power grid is an urgent project," he added.

Before the construction of the extra-high voltage power transmission loop, the power supply of the Tarim Basin mainly relied on a 220 kV power grid, which satisfies urban power supply and regional power distribution. Dubbed the "power expressway loop," the new 750 kV transmission project can send power to a distance of more than 600 kilometers with a capacity of 3 million kilowatts, which can realize large-scale power transmission across regions, provinces and even countries.

The project, expected to become fully operational by November 2025 according to the contractor, will change the southern Xinjiang power grid and its long-chain power supply pattern. It is estimated that local maximum power supply capacity will increase by 800,000 kilowatts to 1 million kilowatts, and the new energy acceptance capacity will be increased by 8 million kilowatts, greatly improving the collection and transmission of new energy such as photovoltaics, and effectively alleviating the grid connection bottleneck of large-scale wind power and photovoltaic power bases in southern Xinjiang.

In addition, the five prefectures in southern Xinjiang are rich in minerals, oil, natural gas, solar and thermal resources, and sufficient power supply is needed to achieve large-scale development and utilization and attract related industrial chains.

Green development

In southern Xinjiang, clean energy such as wind, solar and water accounts for more than 66 percent of the total installed capacity, and the construction of new power systems has achieved remarkable results. Ten-million-kW new energy bases have been built in Bayingoleng Mongolian Autonomous Prefecture and Kashgar.

Apart from meeting local electricity consumption, Xinjiang serves as a key hub in China's west-to-east power transmission program. The 750 kV transmission loop builds an efficient channel for the eastward delivery and local consumption of clean energy.

Xinjiang Guosheng Qicheng New Energy Co., Ltd. mainly produces photovoltaic panels, and it selected Ruoqiang as a base because the starting point of the fourth DC channel of Xinjiang electricity eastward transmission is here, said Song Xiaojun, equipment director of the company.

In recent years, the development of new energy projects in southern Xinjiang has been accelerated, including the 2.05 million kW photovoltaic and sand control project in Qiemu County, the 1 million kW wind power project of PetroChina, and the 250,000 kW independent energy storage project of Rongyu Energy Storage.

It is estimated that after the 750 kV transmission project is put into operation, it will drive the development of 50 million kW of new energy in southern Xinjiang, with an industrial investment of more than 28.3 billion RMB and more than 8,000 jobs.