DGen-H — hydrogen-cooled turbogenerator, 200–510 MVA

Description

DGen-H is a series of two-pole turbogenerators with hydrogen cooling for medium- and large-power power units. The generators operate in tandem with DST-S steam turbines and class F/H gas turbines at coal-fired, gas-oil-fired and combined-cycle power plants. Hydrogen as a cooling medium, owing to its high thermal conductivity and low density, makes it possible to obtain a higher unit power in the same frame size than with air cooling, and to reduce ventilation losses. According to the manufacturer's catalogue, the series covers the range of 200–500 MVA for 50 Hz networks (3000 rpm, stator voltage 15–19 kV) and 200–510 MVA for 60 Hz networks (3600 rpm, 18–21 kV). Thus the DGen-H fills the gap between air-cooled DGen-A generators (up to 200 MVA) and hydrogen-water-cooled DGen-W generators (from 400 MVA). All turbogenerators share common design solutions. The stator insulation system is designed for both continuous operation and daily starts and stops, and is confirmed by more than twenty years of operating experience. The stator end windings are secured by a system that withstands the forces of normal and emergency conditions and practically requires no maintenance. The bars in the slots are held by top wedges and wave springs, which eliminates bar vibration and extends insulation life. The core is stacked from low-loss electrical steel and mounted on a support system that isolates its vibration from the frame. The rotor retaining rings are made of non-magnetic 18Mn-18Cr steel, resistant to stress corrosion cracking; the field winding has direct cooling and uniform temperature distribution. Excitation is a static digital system, DS-DEX. Manufacturing and testing are carried out at the plant in Changwon (Korea), where the turbine and generator shops are located. The manufacturer supplies generators both separately and as part of turbine sets, machine halls and combined-cycle power blocks, and also offers rewinding of stators and rotors of machines in operation using new insulating materials.

Technical specifications