Technologies for high efficiency large capacity turbine generator

For large capacity turbine generators of thermal power plants, water-cooling system has widely been applied to stator windings. TOSHIBA has developed generators using hydrogen indirectly cooled windings, which are more suitable for high efficiency and easy to maintain, with capacity of 670 MVA and efficiency of 99.1%. As the bars of stator windings are cooled with hydrogen gas through the insulation surrounding the bars, it is important to suppress the temperature rise. In this paper, some technologies to realize high efficiency turbine generators, such as multiple parallel circuit winding to reduce current per single bar and ventilation system optimization are described.