Design and test of a simplified and reliable cryogenic system for high speed superconducting generator applications

► A simplified and reliable cryogenic system was designed and tested for a HTS generator. ► Generator was successfully full-load tested with 1.3 MW output power at 10,500 rpm. ► High reliability of the cryogenic system was verified through long-term run. Under the contract with Air Force Research Lab (AFRL), General Electric has successfully tested a high speed, superconducting generator for a Multimegawatt Electric Power System (MEPS). As the first successful full-power test of a superconducting generator for the Air Force, the demonstration tested the generator’s load up to 1.3 MW and over 10,000 rpm. A key component of the generator system is a closed loop cryo-refrigeration system to cool the field excitation coil at liquid neon temperature. This paper reports the design and tests of the cryogenic system, including the liquid neon dewar, cryogenic cooling loop for the high temperature superconducting (HTS) field coil and the cryostat. Performance data during both short-term load run and long-term non-load run were presented. Also, some key issues to design a reliable cryogenic system for a superconducting generator were discussed.