Verification test results of 70 MW class of slow-response type B superconducting generator

Super-GM has been vigorously promoting R&D of three types of 70 MW class superconducting model generators to establish technologies required for the design and manufacture of a practical 200 MW class superconducting pilot generator. In 1998 the verification test on the second model generator with slow-response-excitation-type rotor (slow-response-type B machine) has been conducted since March, and completed successfully by September. This paper describes the major test results which verify the excellent characteristics and reliability of the superconducting generators. The motor-generator testing method (pumping-back method) was adopted to perform the actual load tests and severe test (such as sudden-short-circuit test). Typical results are shown. (i) The world´s highest output of 79.7 MW as a superconducting generator was achieved. (ii) The world´s longest continuous operation of 1500 hr was demonstrated successfully. Temperatures of the rotor and stator, vibration and helium evaporation of the rotor were stable. (iii) DSS (daily start and stop) operation test was conducted 44 times in 4 weeks. It verified the good operational reliability. (iv) The measured Xd (synchronous reactance) 0.42 pu is 1/5-1/4 that of conventional generators, which leads to enhancement of the power system stability and transmission capacity. Also, the measured value is in good agreement with the analyzed value by three-dimensional FEM code