The supercritical circulating fluidized bed(CFB) boilers use the conventional coal-to-water ratio control strategy

which exists large inertia and long lag problem

resulting in large fluctuation in main steam pressure and poor load response performance. Under area control error(ACE) mode

the rapid change of AGC load will increase the fluctuation of fuel quantity and steam pressure

especially for circulating fluidized bed(CFB) units. Against this problem

according to the characteristics of CFB units

a coordinated control strategy of load rapid response is proposed. In this strategy

the feed water control of the whole process is realized by using the main steam flow rate and the intermediate point temperature. Both the load and the main steam pressure deviation act on the rapid response of the main control of the boiler by the combination of feedforward regulation and PID deviation adjustment. The heat storage of the CFB boiler is fully used and the load change is responded through the main control of the steam turbine and the instruction of each regulating valve. Moreover

this control strategy was applied in a supercritical 350 MW CFB unit of Shanxi Hepo Power Plant

and the results show that

the main steam pressure fluctuation was small

the steam temperature was stable

and the value of the load response comprehensive evaluation index Kp in ACE mode reached 4.21

which proves that the control effect of the supercritical CFB unit in varying load operation is good and the ACE index reaches excellent level.