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.