DGen-W — hydrogen-water-cooled turbogenerator, 400–1390 MVA

Description

DGen-W is a series of powerful two-pole turbogenerators with combined hydrogen-water cooling for large power units: supercritical and ultra-supercritical coal-fired units and high-power multi-shaft combined-cycle plants. In such machines the stator winding is cooled by distilled water flowing directly through hollow conductors, while the rotor and core are cooled by hydrogen. This makes it possible to remove heat from the most heavily loaded parts and to reach a unit power above 1000 MVA with dimensions and mass limited by transport conditions. According to the manufacturer's catalogue, the DGen-W series is produced at 400–1390 MVA for 50 Hz networks (3000 rpm, stator voltage 21–30 kV) and at 450–1240 MVA for 60 Hz networks (3600 rpm, 19–30 kV). By power, the series matches 400–1300 MW power units, for which the manufacturer's DST-S20 and DST-S30 steam turbines are intended (steam parameters up to 300 bar and 630 °C). All of the manufacturer's 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 operation and requires practically 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. The generators are manufactured and tested at the plant in Changwon (Korea). The company supplies turbine islands on a turnkey basis, from the generator to the machine hall, and modernises operating generators to raise their power through new insulation. The DGen-W series corresponds in purpose to the largest hydrogen-water-cooled turbogenerators used at 500–1200 MW units.

Technical specifications