Stabilization of Fully Superconducting and Damperless Generator by Excitation Control

The development of ultra-fine filaments superconductors for 50/60Hz use opens a door to a fully superconducting generator which has superconducting field windings and armature windings. Omitting dampers and narrowing gaps between the field and the armature windings, the size and the weight of the fully superconducting generator can be drastically decreased. However, the damperless generator can not be stably operated and needs to be stabilized by an appropriate method. We have investigated a method to stabilize the generator by controlling excitation voltage of the field winding using state-value field-back technique. The state values of the system are estimated by a state-value observer and the feed-back constants are determined according to the optimal control theory. It is shown that this method is effective to stabilize the fully superconducting and damperless generator.