Method for controlling impulse rotation of intermediate pressure cylinder of steam turbine in FCB process of thermal power generating unit

The invention discloses a method for controlling impulse rotation of an intermediate pressure cylinder of a steam turbine in the FCB process of a thermal power generating unit. The method comprises the following control steps that S1, when the FCB function of a generator unit is triggered, steam turbine DEH load pre-judgment logic enables a protection system OPC to act, a high pressure cylinder main valve and control valve of a steam turbine are forcibly closed, and an intermediate pressure cylinder control valve is rapidly closed. By adopting the scheme of transferring the plant power load of the generator set from a high pressure cylinder to the intermediate pressure cylinder of the steam turbine for operation and utilizing the control strategy of impulse rotation of the intermediate pressure cylinder of the steam turbine, the plant power load after the FCB action of the thermal power generating unit is transferred from the high pressure cylinder to the intermediate pressure cylinder so as to solve the problem that after the FCB function of the generator set is triggered, the exhaust steam temperature of the high pressure cylinder abnormally rises is solved, safe and stable operation of the steam turbine is ensured, the FCB function of the generator set is achieved, and therefore the problems that if heat of the high pressure cylinder cannot be taken away in time after a high-exhaust ventilation valve is opened, the high-exhaust temperature can rapidly rise and accumulate to a certain degree, and the cylinders are prone to deformation, cracking and other accidents are solved.