Patent ID: 7657399

Claim:
A method for facilitating detection of abnormal operation of a process in a process plant, comprising: receiving process variable data associated with the process plant; generating predicted process variable data using a model; generating a difference signal based on the received process variable data and the predicted process variable data; detecting whether the difference signal is increasingly deviating from zero over a plurality of values of the difference signal using a processor hardware device; and generating an indicator of significant deviation based on whether the difference signal is increasingly deviating from zero using the processor hardware device; wherein detecting whether the difference signal is increasingly deviating from zero comprises at least one of: determining whether Z k1 >Z k2 > . . . >Z kB >X, wherein Z k1 , Z k2 , . . . , Z kB are at least a subset of B values within a set of A consecutive values of the difference signal at time indexes k1, k2, . . . kB, wherein A is a positive integer greater than 2, B is a positive integer less than or equal to A and greater than 2, wherein X is a first threshold, and wherein k1>k2 . . . >kB; and determining whether Z k1 <Z k2 < . . . <Z kB <Y, wherein Y is a second threshold.