Stability Criteria for Superconducting Generators-Electrical System and Cryostability Consideration

Superconducting generators, which are rapidly approaching the electric power system application stage, exhibit improved stability during steady-state and transient operating conditions, but also respond to system disturbances somewhat differently than conventional machines. Studies of the 300 MVA EPRI/Westinghouse demonstration unit have elucidated the connection between power system transients and the transients produced by them in the field winding's cryogenic cooling system. Measures required to ensure continuity of field winding superconductivity and excitation through severe power system transients dominate the rotor design and result in a relatively complex and costly rotor construction. In performance specifications of future units, these costs should be weighed against alternate means of addressing the issue of system security and integrity.