World's first UHV flexible DC single-station test begins in Zhejiang

On Oct 27, the Yuezhou Converter Station of the Gansu-Zhejiang ±800 kV ultra-high-voltage direct current (UHVDC) transmission project began a single-station system and power self-circulation test.

The test marks a major step toward bringing the station into operation and is the first of its kind at a dual-terminal ±800 kV flexible DC converter station worldwide. Its results could help guide the use of the technology in future projects.

The test allows the converter station to circulate power internally without relying on the station at the other end of the transmission line. Engineers can use it to assess equipment performance, power transmission and the flow of active and reactive power between converter valve groups.

It also tests the reliability and stability of auxiliary systems, control and protection systems, and networking logic.

Before a station is ready for operation, engineers must test its converter valves, converter transformers, and control and protection systems to ensure everything is functioning correctly.

The self-circulation approach allows Yuezhou Station to complete its first energization and comprehensive DC system testing independently, laying a foundation for later dual-terminal joint debugging and full-capacity commissioning.

Core equipment at Yuezhou Station, including converter transformers and valves, has been installed, and the project will now carry out a series of commissioning activities.

It is expected to begin operating in April 2027, when it will transmit more than 36 billion kWh of clean electricity to East China each year, supporting energy mix optimization and the dual-carbon goals.