Measurement and analysis of 70 MW superconducting generator constants

The constants of a superconducting synchronous generator (SC-generator) were measured to prove its design method and electromagnetic analysis. This paper describes the test results related to the measurements of synchronous machine constants, and the comparison between the test results and the values which are calculated by a 3 dimensional finite element method (3D-FEM) for the electromagnetic analysis of SC-generator. The test items compared with the analysis are no load saturation curve of armature voltage at rated speed, armature current of steady state short circuit, air gap magnetic flux to add the armature current and synchronous reactance (Xd). The constants for the transient state of SC-generator were measured by three-phase sudden short circuit current. The effect to improve the electric power system stability is analyzed by decreasing Xd of SC-generator and by comparing the stability of a conventional generator for the same power system disturbances.