Patent ID: 8005645

Claim:
A method for abnormal event detection (AED) absent before specification of the abnormal event for a set of process units of a hydrocracker (HDC) unit of a petroleum refinery comprised of: (a) determining online measurements of an array of sensors corresponding to said process units of said hydrocracker, (b) substituting said online measurements from said array of sensors of said hydrocracker in a set of principal component analysis models wherein said set of principal component analysis models includes at least two principal component analysis models, (c) comparing said set of principal component analysis models to a set of models for normal operation of the corresponding process units, wherein said process units of said hydrocracker are divided into at least two equipment groups with minimal interaction between groups, wherein each principal component analysis model corresponds to an equipment group, wherein the principal components of each principal component analysis model correspond to the sensors in said array of sensors, and wherein said equipment groups are defined by including all major material and energy interactions and quick recycles in the same equipment group and said online measurements are cross-correlated with each other, (d) determining if the current operation differs from expected normal operations so as to indicate the presence of an abnormal condition in a process unit, and (e) determining the underlying cause of an abnormal condition in the HDC process unit.