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February 27, 1997
Hitachi, Ltd. has developed and factory tested a 70-MW-class superconducting generator. The generator was developed as a project managed by the Engineering Research Association for Superconductive Generation Equipment and Materials (Super-GM), and for NEDO, as part of the New Sunshine Program of the Agency of Industrial Science and Technology, MITI. The generator has a capacity of 83 MVA, making it the world's largest superconducting generator.The powerful 4-tesla magnetic field generated by the field winding in the rotor assembly will make it possible to increase power network transmission capacity, reduce voltage fluctuation and improve power efficiency.
Translated into terms of a 200-MW machine, the power efficiency is 99%. An improvement of approximately 0.4% over a conventional thermal power generator (air-cooled) is possible. Compared to a 200-MW machine, the weight can be decreased by some 30%.
The generator uses a multi-cylindrical rotor internally cooled by liquid helium at -269 degrees centigrade, making the coil superconductive. A vacuum is provided between the layers of the multi-cylindrical structure to reduce the internal transmission of outside heat.
In the factory tests, the generator was run under no-load conditions with the rotor cooled down to -269 degrees centigrade. The rotor showed no problems with respect to strength and axial vibration, even when run at speeds up to 4140 rpm, 115% of its rated speed.
The generator is to be installed in the Super-GM Test Center in the Osaka Power Station of the Kansai Electric Power Co., Inc. for the start of a series of test operations in April. This is to be followed by site tests that will last until August, to verify the performance of the generator under load operation.
Specifications
Item Specification Capacity 83MVA Voltage 10kV Frequency 60Hz Rotor speed 3600rpm Superconducting coil NbTi Internal rotor temperature 4K(-269 degrees centigrade) Dimensions (W x H x L) 3.7 x 3.7 x 9.3 (m) Rotor weight 21 ton Stator weight 67 ton
