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Methods and systems for detecting deviation of a process variable from expected values

  • US 7,657,399 B2
  • Filed: 07/25/2006
  • Issued: 02/02/2010
  • Est. Priority Date: 07/25/2006
  • Status: Active Grant
First Claim
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1. 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 Zk1>

    Zk2>

    . . . >

    ZkB>

    X, wherein Zk1, Zk2, . . . , ZkB 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 Zk1<

    Zk2 <

    . . . <

    ZkB<

    Y, wherein Y is a second threshold.

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