Due to the increase of frequency and amplitude of variable load and the frequent start and stop of coal mills

the main steam pressure of thermal power units fluctuates violently. To solve this problem

a coordinated control optimization logic

consisting of predictive boiler master feed forward and three-stage restricted total air flow

is proposed. This logic adopts several strategies such as the pre-addition coal feed forward control logic based on coal mill start-up prediction

the logic optimization of the total air volume setting value

and the logic optimization of the total air volume feed forward under three-level limit

thus to better respond to the load changes and well match the total volume of air with the amount of fuel changing at high frequencies. Moreover

this optimization strategy is applied in a 600 MW unit

and the variation characteristics of the unit main steam pressure under complex conditions are analyzed through on-site variable load disturbance test

the conditions include high frequency and large-amplitude load variation

start and stop coal mills

and fuel quantity fluctuation. The test shows that this optimization method can comprehensively regulate the unit main steam pressure and ensure the stable operation of the unit under economic conditions.