Development and Testing of a 300-kvar HTS Synchronous Condenser Prototype

China Southern Power Grid Corporation started a project to develop a 10-Mvar high-temperature superconducting (HTS) dynamic synchronous condenser (DSC). As the first stage of the project, a 300-kvar HTS DSC prototype was developed to verify some key technologies, such as HTS rotor magnets, helium gas circulating cooling and rotating signal acquisition. In this prototype, conduction-cooled REBCO coils were installed in the rotor and air-core copper windings were used in the stator. Cold helium gas at around 20 K was used as the coolant circulating between the rotor and the external cryogenic unit through a cryogenic rotary coupling. The REBCO coils were conduction cooled by distributed helium-gas tubes embedded in the cover plates of the coils. The rotor magnet was successfully charged up to 200 A under both static and rotating conditions. For the requirement of an HTS DSC, rapid excitation tests from 170 A to 200 A were carried out at both 500 rpm and 1500 rpm.