The shortcomings of coal quality correction method used in control system of power plants were analyzed and pointed out.A new control scheme based on coal quality correction using air to coal ratio was designed.In this scheme

the variations of coal quality can be real-time distinguished

and the calculated coal-quality correction coefficient can be applied in the combustion automatic control.Moreover

taking the tangential-fired boiler as the example

the feedforward parameters of the auxiliary air control valve for the secondary air were designed for combustion automatic control.Thus

when the coal quality changes

the combustion condition can be regulated through automatic adjustment on the auxiliary air control valve for the secondary air.