To maintain the minimum flow of low-pressure cylinder after cutting the cylinder

thermal power units that participate in deep flexibility peak shaving will add a bypass valve on the basis of the original low-pressure cylinder inlet valve. After the transformation of a 350 MW unit's cylinder cutting process in a power plant

using the characteristics of small cylinder bypass valve stroke

rapid adjustment action and high accuracy of small flow control

the relationship between the change in opening of the bypass valve and the change in electrical load was determined through theoretical calculations. The automatic control scheme and control logic of bypass valve auxiliary power plant frequency modulation were designed. Moreover

the simulation was carried out based on MATLAB software

and the corresponding configuration scheme was imported into the decentralized control system of the unit for experimental verification. The results show that

the application of automatic control scheme of auxiliary frequency modulation for cylinder bypass valve improves the load tracking quality of the unit

effectively reduces the action frequency of the high-control valve participating in the load control

and the main steam pressure of the unit is more stable. The automatic control strategy of the bypass valve auxiliary frequency modulation can provide a certain theoretical basis and practical experience for the same type of units to carry out flexibility transformation and improve productivity.