JPS56153405A - Control system for thermal power plant - Google Patents

Abstract

PURPOSE:To improve controllability and facilitate backup by providing a predictive controller which predicts the dead time of the response of control target values of the PID controllers which control a once-through type thermal power plant, and correcting the target values. CONSTITUTION:The target values r1-r5 of the generation quantity, main steam output, main steam temp., desuperheater temp. difference and reheat steam temperatures x1-x5 outputted from a plant 140 are inputted to a predictive controller 100. This controller 100 compares the target values with the approximate prediction values of the dead time of the response and outputs target value correction quantities DELTAr1-DELTAr5. These correction quantities DELTAr1-DELTAr5 are added 111-115 to the target values r1-r5 via switches 151-155, and are inputted to the comparators 121-125 on the input side of PID controllers 131-135. For example, when the reheat steam temp. target value r5 changes, the lambda5 time is predicted by the controller 100 and with r5+DELTAr5 as a new target value, the movement is made faster like manipulated variable y5', whereby controlling is accomplished with less overshoot.