China marked a major milestone in its energy infrastructure on Friday as the rotor of the country's largest-capacity pumped storage unit was successfully installed at the Tiantai Pumped Storage Power Station in Tiantai County, east China's Zhejiang Province.
The rotor of Unit 1 at the Tiantai Pumped Storage Power Station, a key project under China's 14th Five-Year Plan (2021-2025), was successfully hoisted into place, signaling the start of full assembly for the country's most powerful pumped storage unit.
Often referred to as the "power bank" of the electric grid, pumped storage power stations are crucial for regulating energy supply and storing power on a large scale. The Tiantai station consists of upper and lower reservoirs, a water conveyance system, and an underground powerhouse. It will house four pump-turbine generator units, each with a capacity of 425 megawatts -- the largest of their kind in the country.
The rotor installed on Friday, a core component of the unit, weighs an impressive 481 tons and measures around five meters in diameter. It is also the heaviest part of the entire installation process. The lift took over an hour, during which the massive rotor was moved horizontally more than 120 meters by two bridge cranes before being precisely placed.
"During the hoisting process, we had to control the rotor's center deviation within 0.1 millimeters and horizontal deviation within just 0.02 millimeters, about one-third the diameter of a human hair. We used 3D laser positioning to ensure the rotor was placed accurately in one go," said Mao Langfei, section chief of the hydropower installation team from Sinohydro Bureau No. 14 Co., Ltd.
The station's massive tunnels, which connect the twin reservoirs, are built to withstand significant hydraulic impacts. To ensure their strength, engineers used 26,000 tons of high-strength steel -- equivalent to the weight of 17,000 cars.
"For the first time, we developed and applied 1,000-megapascal high-strength hydropower steel on a large scale, along with domestically produced welding materials. This steel is more than twice as strong as conventional steel, reducing overall material usage while greatly improving welding efficiency. The technology is now world-leading," said Qiang Linlin, deputy director of engineering management for the project.
The 425-megawatt pump-turbine units installed at the station are not only the largest in China, but also boast cutting-edge features, including a newly designed disk-type runner, 3D-printed cast components, precision CNC machining, and advanced welded assembly, marking a major step forward in the country's push to upgrade its pumped storage technology to a more advanced level.
"To ensure the first unit is generating power by the end of this year, more than 2,200 workers are continuing construction through the May Day holiday. We've now completed roughly 70 percent of the overall construction," said Jing Maogui, project manager at the station.
With a total installed capacity of 1,700 megawatts, the Tiantai pumped storage station will primarily serve the Zhejiang power grid and help balance electricity supply across east China. Upon completion, it is expected to generate 1.7 billion kilowatt-hours of clean electricity annually, enough to meet the yearly electricity needs of 1.6 million people.
China installs nation’s largest pumped storage rotor
