DGen-N — four-pole turbogenerator for nuclear power plants, 650–1700 MVA

Description

DGen-N is a series of four-pole (low-speed) turbogenerators for nuclear power plants. At NPPs with water-cooled reactors the steam turbines work on saturated steam of large volumetric flow, and for large units they are built at half the rotational speed: 1500 rpm in 50 Hz networks and 1800 rpm in 60 Hz networks. The DGen-N generator is designed for direct coupling with such turbines (the DST-N series) and is the largest generator by power in the manufacturer's range. According to the manufacturer's catalogue, DGen-N generators are produced at 650–1700 MVA with a stator voltage of 18–27 kV for 50 Hz, and at 770–1700 MVA with 22–24 kV for 60 Hz. The catalogue does not state the cooling method separately for this series; at such powers, schemes with water cooling of the stator winding and hydrogen cooling of the rotor are used, similar to the DGen-W series (to be clarified in the project). The manufacturer's overall generator range covers powers up to 1500 MW. 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 company is one of the world's largest suppliers of main nuclear power plant equipment: it holds ASME certificates (N, NA, NPT, NS) and KEPIC and has supplied equipment for 25 nuclear power units in the Republic of Korea, as well as for AP1000 projects in the USA and China. Generators for NPPs are manufactured at the plant in Changwon, which also produces reactor vessels and steam generators. The DGen-N series is a functional analogue of low-speed turbogenerators of 1000 MW and above for NPPs.

Technical specifications