In this special edition the results of a national project on the development of superconducting generators (SCGs) are reported. Before these reports, the history of developing conventional generators, (that is, a larger generator needs higher technology for cooling) motivation for developing SCGs (which is on way of better cooling technologies for larger generator), key technologies of SCGs except superconducting technology, features of SCGs, (that is, larger capacity, small size, high efficiency, good characteristics for power system operation and so on, ) present situation of the development and some comments of real application are described.
A 70MW class model superconducting generator was designed, manufactured, and tested from 1988 to 1999 as phase I. This was a national project on applications of superconductive technology to electric power apparatuses that was commissioned by NEDO as part of the New Sunshine Program of AIST, MITI. And phase II is now being carried out in the same formation as phase I. A 70MW class model superconducting generator had been developed to establish technologies for the 200MW class pilot generator in phase I. The world's highest output (79MW), the world's longest continuous operation (1, 500 hours), and other excellent characteristics have been achieved on a 70MW class model superconducting generator, and the key technologies of design and manufacture required for the 200MW class pilot generator were established. This project contributed to the progress of R & D of power apparatuses. Super-GM has started the following project (phase II), which develops the key technologies for the larger-capacity and more-compact machine, and is scheduled from 2000 to 2003. Phase II will be the first step for the commercialization of superconducting generators.
Since 1988, the development of a practical superconducting generator has been carried out in Japan. The authors have developed a rotor with a highly stabilized superconducting field winding and a stator with an air gap winding composed of double transposed copper coils. A series of tests were completed at the end of 1997. The output of 78.8MW was recorded, which was the highest value obtained worldwide. The development of the generator and the test results are described.