Patent Document ID: 4630189
Application ID: 06618713
Patent Flag: 1

Claim One:
1. A method for diagnosing a thermal power plant system including a thermal power plant, provided with an automatic power plant control system receiving feedback signals of state variables of the plant and performing PID control, a control model formed of a mathematical model representing the combination of the plant and the automatic power plant control system, and a direct digital control system utilizing the control model and controlling the plant to conduct an optimum control, the automatic power plant control system and the direct digital control system conducting control complementarily, said method comprising the steps of: providing a plant diagnostic model formed of a mathematical model representing the combination of the plant, the automatic power plant control system, the control model and the direct digital control system, determining predicted values of the plant variables, by means of the plant diagnostic model, determining a difference between the predicted value of each of the plant variables and the actual value of the same plant variable, storing the determined difference successively thereby to provide a time series of the differences which have been successively determined, determining whiteness indexes used for testing the whiteness level of the time series of the differences in accordance with the time series of the differences, judging whether or not any of the plant variables is abnormal in accordance with the whiteness indexes, judging whether or not any of the manipulated variables is faulty in accordance with the whiteness indexes and the result of judgement as to abnormality, and outputting an alarm when an abnormality or a fault is detected.