The paper describes some jamming phenomena at intermediate pressure main stop valve on a 600MW steam turbine,reasons are analyzed and some effective methods are carried out.

In the light of frequent jamming at intermediate pressure main stop valve of homemade 300MW turboset,disassembly analysis of the faulty main stop valve was carried out and appropriate modification was made.

IMC-PI cascade control for main steam pressure system of power plant;

Using this model,the quantify influence of the disturbance of main steam temperature,main steam pressure,vacuum,reheat steam temperature,superheater spray quantity and reheater spray quantity on the unit efficiency and the standard coal consumption was ob.

During the accident, the main steam pressure drops rapidly, the current and outlet temperature of pulverizer become abnormal.

During the study of dynamic characteristics of primary frequency modulation it is usually supposed that the boiler in a power plant has sufficient large heat-storage capacity to keep main steam pressure constant and its flow rate in direct proportion to the valve opening degree.

Because boiler burning behaviour varies greatly and the model of main steam pressure is of highly uncertainty,conventional control method can not obtain the expected control effect.

By studying the strategy of setting turbine inlet main steam pressure,the paper proposed the requirements in the pressure setting to ensure unit safety and efficiency.