A method for extracting heat release signal from heat-absorbing process in the steam-water system has been proposed

and the heat-absorbing behavior of water-wall in ultra-supercritical 1 000 MW units at home being analysed

it is discovered that the relationship between the amount of heat absorption by water-wall and the calorific value of burned coal to be approximate linearity.Thereby

it can be deduced a method for calculating the released heat by using the heat amount absorbed by the water-wall

and to construct a heat release signal.The results of test carried out on a 1 000 MW unit show that the said signal can be more rapidly and more precissely fed back to the system.Meanwhile

emulation shows that the control quality of a coordinated control system can be improved by adopting the said signal

and it is comparatively easy in practical application.