By analyzing the coupling problems in coal mill control system

optimization on control system of the original coal mill was conducted.Decoupling link was added in the control system

and the speed instruction of coal feeder was set as the feedforward signal of control system for inlet primary air flow and outlet temperature of the coal mill.The optimized coal mill control system can make the outlet temperature deviation be within ±1 ℃

and the inlet primary air flow(which varied with the coal feed) deviation be within ±2 t/h

under steady unit load and coal feed condition.When the unit load increased from 200 MW to 230 MW

the inlet primary air flow varied with the coal feed

its dynamic deviation can be controlled within ±3 t/h

and the outlet temperature deviation can be kept within ±1.5 ℃.