General Design of a 300-Kvar HTS Synchronous Condenser Prototype

China Southern Power Grid Corporation has started a project to study the feasibility of large-scale high-temperature superconducting (HTS) dynamic synchronous condensers (DSC) in Ultra High Voltage Direct Current (UHVDC) transmission grid. To investigate some key technologies, a small-scale prototype of HTS DSC of 300 kvar/2 poles/3000 RPM is under development. The electromagnetic design, especially the critical current of REBCO rotor coils was discussed. Besides, the configuration and properties of the air-core stator, the damper and the rotor were also described. Water-cooled windings in the air-core stator have a rated current density of 9.55 A/mm². Helium cooling pipes were embedded within REBCO rotor coils, and HTS windings will be cooled down to <; 30 K (<; 25 K for better) through conduction cooling. Two REBCO coil assemblies were manufactured and successfully tested in liquid nitrogen for several thermal cycles, which validated the manufacture techniques.