Superconducting Generator Transisent Interaction Analysis Using Three-Dimensional Models

A model to study the transient interactions between a superconducting generator and the power system is presented. A large set of equivalent circuits is used to represent the eddy currents on the finite length cylindrical shields which surround the superconducting field winding. The armature and field windings are represented by coupled circuits as in conventional generator models. The rotor-turbine shaft dynamics are introduced in the model by a set of lumped masses representing the various stages of the turbine and rotor connected by springs representing the shafts. A two-mass model is used to represent the rotor of the generator. Conventional d-q axis representation of the machine is used; however, the d-q axis model is expanded to simulate unbalanced faults of the power system. A frequency domain analysis of generator behavior is also performed to derive closed form expressions for the eddy currents in the shields, the field shielding, and the transient reactances at different frequencies.