Recently, Dongfang Electric successfully completed the runaway speed test for the 1:1 rotor of the 300MW-class variable-speed pumped storage unit generator-motor, a key technological equipment project by the National Energy Administration in the energy sector. The rotor's dynamic stability and reliability were fully verified, marking a significant breakthrough in China's independent development of variable-speed pumped storage units.

The 1:1 rotor of the 300MW-class variable-speed pumped storage unit generator-motor

The rotor adopts an innovative integrated end-ring fixing structure and employs a new wiring method for the rotor windings. It also features the development of an ultra-large diameter non-magnetic metal end ring. These innovations have overcome challenges in the design, manufacturing process, and assembly of large-size wound rotors operating at high speeds, ensuring the stability and reliability of the entire rotor system. This lays a solid foundation for the development and application of variable-speed pumped storage units in China.

The 1:1 rotor of the 300MW-class variable-speed pumped storage unit generator-motor

In recent years, China's rapid development in the new energy industry has raised higher demands for flexibility and stability in the power system. With its advantages in flexible, stable, and fast response operations, the variable-speed pumped storage unit has become a focal point in the industry. In 2021, the National Energy Administration included the "300MW-class Variable-Speed Pumped Storage Unit Equipment" in the list of key technological equipment projects in the energy sector. In 2022, the China Association for Science and Technology identified "how to develop large-scale variable-speed pumped storage units" as one of the "Top Ten Industrial Technology Issues."

Since 2013, Dongfang Electric has focused on overcoming the most challenging "hard nut" in the development of variable-speed pumped storage units—the critical issue of rotor dynamic stability. The company has pursued two technical routes: the non-magnetic integrated end ring and the distributed bolt fixing method for the rotor's end structure. Extensive research, testing, and optimization have been carried out, involving the application of new materials, new structures, innovative designs of tools and fixtures, as well as the adoption of new manufacturing and assembly processes. Following the overall strategy of "verifying technical routes" and "developing a 1:1 rotor for engineering product verification," the testing was successfully completed, ensuring that the rotor's performance fully meets engineering application requirements.

In the future, these technologies will be applied to the first-of-its-kind "300MW-class Variable-Speed Pumped Storage Unit Equipment" project by the National Energy Administration, which will be implemented at the Phase II of the Shandong Taian Pumped Storage Power Station and the Guangdong Zhaoqing Langjiang Pumped Storage Power Station. (By Fan Yiling and Yang Wenhan)