China - Shen Tou

BRUSH was selected to provide four 500MW turbogenerators for the Shen Tou bituminous coal-fired power station in the Chinese province of Shan-Xi. The first unit entered service in 1992 and the second in 1993. A contract for the supply of two additional units was signed in 1999; these units will be commissioned into service in 2005.

The generators supplied are combined hydrogen & water cooled units of a proven design. To date, a total of 69 combined hydrogen & water cooled generators have entered service, providing a total of over 17GW of installed capacity.

 

Specifications

Output

  • 588MVA

Power factor

  • 0.85

Voltage

  • 20kV

Speed

  • 3000 rev/min

Hydrogen pressure

  • 500kPa absolute

Excitation:

  • AC exciter with static excitation set
  • (AC4A in accordance with IEEE 421.5)
  • Units 1 and 2 have analogue excitation controllers
  • Units 3 and 4 have digital excitation controllers

 

Gas Supply System

The gas supply system incorporates the equipment for scavenging air from the turbogenerator with carbon dioxide and for first fill and subsequent continuous maintenance of the hydrogen coolant, including hydrogen drying on the “freezing out” principle.

 

Oil seal system

Shaft seals are of radial type with two oil flows. The oil seal system is formed by the hydrogen system side seals (the oil is in contact with hydrogen) and the air circuit side seals. The oil on the hydrogen side is vacuum treated to remove absorbed gas. For the air side of the seals, oil is taken from the turbine oil system.

 

Water cooling system for the stator winding

The circulation of chemically pure cooling water in the stator winding circuit is effected by a centrifugal pump with an identical standby pump. The whole circuit is constructed from stainless steel, with the exception of the copper winding itself.

 

Benefits

Wide experience gained from the long established manufacture of this range of turbogenerators has resulted in the following benefits:

  • Higher machine utilisation factor
  • Substantial reduction in stator winding temperature rise
  • Extended insulation life
  • Improved efficiency as a result of significantly reduced ventilation losses