Yasuomi Yagi

Development of superconductors for a 70 MW class superconducting generator

Since 1988 a project has been underway in Japan in which superconducting generators for utility applications are being developed. The aim of the project is the development of a 200-MW-class superconducting pilot generator. During development work, of 70-MW-class superconducting, model generators are being run in order to clarify the problems in manufacturing and operating the pilot generator. The design of the model generator and the development of the components, especially the superconductors for the generator are discussed. Details of the development of the superconductor installed in the rotor are described.

Analysis of turbine generator steady-state reactances for load conditions

This paper describes variations of turbine generator steady-state reactances for load conditions. When the turbine generator is of small size, magnetic saturation of the stator and rotor core is a problem. Therefore, it is important to understand the variations of the reactances for load conditions. The reactances of a 592-MVA turbine generator are calculated with d- and q-axis equations considering magnetic saturation and two-dimensional numerical magnetic field analysis. The results are as follows. (1) The equivalent synchronous reactances considering cross-magnetizing are smaller than the original synchronous reactances for load conditions. (2) Numerical values of the d- and q-axis mutual reactance and the field and q-axis mutual reactance are at their maximum when the d-axis linkage flux is nearly equal to the q-axis linkage flux under constant voltage. (3) The d-axis synchronous reactance drops with increasing reactive power under constant voltage and active power, but the q-axis synchronous reactance increases. (4) The variation of the equivalent d-axis synchronous reactance with increasing reactive power is similar to that of the d-axis synchronous reactance, but the variation of the equivalent q-axis synchronous reactance is different from that of the q-axis synchronous reactance.