Automatic control of steam turbine two-valve mode under low load condition of coal-fired unit

In order to meet the requirements of deep peak regulation and rapid load change, coal-fired power stations are often under low load condition. Under low load conditions, there are serious throttling loss and poor economy of GV(Governor Valve).Here, based on the DEH sequence valve control of steam turbine, we innovatively propose the two valve operation mode and write the two valve mode control logic, which can automatically switch between the sequence valve and the two valve mode according to the valve flow command. On the premise of ensuring the stable operation of the unit, the purpose of reducing the throttle loss of the turbine can be achieved during the low load and peak regulation of the unit, and the fuel cost can be saved about 970,000 yuan per year. The control method is simple, reliable and practical, and can be widely used in thermal power units involved in peak regulation.