Patent Document ID: 4755925
Application ID: 06910687
Patent Flag: 1

Claim One:
1. A plant diagnosis system comprising: a plant diagnostic model for representing a plant system to be diagnosed by a mathematical model; first means for determining a time constant at which a change of one plant value has the greatest influence on the plant value or other plant values by using a coefficient matrix of an auto-regressive model; second means for calculating a time series of residual difference from an estimated value calculated by using said plant diagnostic model and an actual plant value obtained from said plant system so as to obtain the time series of residual differences; third means for qualifying whiteness of the time series of residual difference from said second means and the time constant from said first means so as to produce an index; fourth means for determining an abnormality from the index produced by said third means; fifth means for determining a failure source from the index and the result; and sixth means for outputting the abnormality and the failure source according to the results obtained by said fourth means and said fifth means.