Development and production of the world's largest capacity 670MVA high efficiency hydrogen-cooled turbine generator

Heat transfer path of stator bar

Fig.1 Heat transfer path of stator bar

Ventilation system of turbine generator and radial flow cooling rotor

Fig.2 Ventilation system of turbine generator and radial flow cooling rotor

670MVA turbine generator

Photo.1 670MVA turbine generator

For the large capacity turbine generators of thermal and nuclear power plant, stator winding directly-cooling system using water and/or hydrogen as cooling medium has been preferred. Comparing with the stator winding direct-cooling system, hydrogen indirect-cooling system has merits of easier operation and maintenance because there is no auxiliary equipment and piping for the stator winding cooling water. Furthermore, the conductor cross-section area of indirectly cooled stator winding becomes larger than directly cooled winding because the indirectly cooled windings are composed of only solid conductors and this leads to the merit of low copper loss, namely high efficiency.

However, because the cooling ability of indirectly cooling is lower than that of directly cooling, maximum capacity of hydrogen cooled generator had been around the range of 500MW.

Then through technical development such as optimization of the design corresponding to the lager coil current, loss reduction measures, enhanced ventilation system, high thermal conductivity stator coil insulation, hydrogen indirectly-cooled generators for 900MW cross compound thermal power planting system were manufactured and commenced operation in August 2010. The primary 670MVA generator has the world largest capacity and both primary and secondary generators achieved generator efficiency of over 99.1% in the shop test, which widely contributes to the environmental load-reducing, natural resource saving and energy conservation.


[1]M.Fujita, M.Kakiuchi, H.Tomiki, T.Ueda, Y.Taniyama, H.Hatano, K.Nagakura and H.Nakamura,“Development and production of the world’s largest capacity 670MVA high efficiency hydrogen-cooled turbine generator”, IEEJ Technical meeting papers, RM-10-143, pp.55-60, 2010
[2]H. Tomiki, M. Yamakawa, M. Kakiuchi, K. Nagakura, Y. Gunji, S. Nakayama,“670MVA indirectly hydrogen-cooled generator for MAIZURU thermal power plant No.2”,The thermal and nuclear power generation convention, 2009
[3]K.Nagakura, T.Otaka, M. Kakiuchi, Y.Gunji, S.Nakayama, D.Murata,Y.Kabata, and H.Hatano,“Development of the world's Largest Hydrogen Indirectly Cooled Turbine Generator”,ICEMS2009, DS1G5-6, 2009

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