Machine implemented system for determining compliance of a complex process plant with technical specifications

Claim 2

A machine implemented method of determining and controlling compliance of operating limitations for a complex process plant having a plurality of interrelated components and systems, wherein the complex process has a plurality of predefined operating limitations identified by respective events in the process, the method comprising the steps of: generating operability trees having cutsets representing various combinations of events associated with the state of operability of said components and systems and the status of said operating limitations, which cutsets taken separately and in sequence with other cutsets, result in an indication of non-compliance with said operating limitations characterized by the method steps of: generating a data base in a digital computer, said data base including a cutset table which includes an event-attribute for identifying each event associated with a cutset and a top level event attribute identifying a higher level event activated by the cutset; selecting a given event; and operating said digital computer to: a) search the event attributes of said cutset table for the selected event to identify as activated all cutsets for which the selected event activates a top event as indicated by the top event attribute; b) as to each such activated cutset, repeat step a) using the associated activated top event attribute as the selected event; c) repeating step b) until the top level event activated by a cutset does not appear as an event attribute in the cutset table and identifying such top event as an ultimate activated top event; and d) generating an output identifying each ulti­mate top event activated by said given event.

Claim 3

The method of claim 1 wherein said step of generating cutsets includes generating some multiple member cutsets requiring more than one event to activate the associated top event, wherein said step of generating said data base includes entering in the cutset table a separate entry for each event in each multiple event cutset, provid­ing each entry in the cutset table with a cutset identifier attribute identifying the cutset with which it is associat­ed, with each such entry for a multiple event cutset having a common cutset identifier attribute, and wherein said digital computer is operated to: i) after step a), search the identifier at­tributes in the cutset table for other entries having the same cutset identifier; ii) determine whether the event attribute for any such other entries has been selected; and iii) identify a multiple event cutset as acti­vated only when all of the events for the multiple event cutset have been selected.

Claim 4

The method of claim 1 wherein the step of generating said data base includes entering in the cutset table a state attribute for each event which indicates the status of the event which will activate the associated top event, wherein the step of selecting a given event includes selecting an input status for such event and wherein said step a) of identifying cutsets as activated includes comparing the input status for a selected event with the state attribute and identifying as activated only those cutsets for which the state attribute for the selected event equals the input status.

Claim 5

The method of claim 2 wherein the step of generating said data base includes providing each entry in the cutset table with a cutset type attribute having a first value for multiple event cutsets and a second value for single event cutsets, wherein said step a) of searching the cutset table includes determining the value of the cutset type attribute and wherein steps i to iii are only carried out for entries in the cutset table having a cutset type attribute of the first value.

Claim 6

The method of claim 4 wherein said digital computer is operated to perform step ii by generating and evaluating a cutset evaluation table having an entry for each multiple event cutset including a multiple event identifier attribute identifying the multiple event cutset and a multiple event counter attribute which counts the number of events in said multiple event cutset which have been selected, and wherein said digital computer is operat­ed to perform step iii by identifying a multiple event cutset as activated when said count attribute reaches a value indicating that all of the events associated with a multiple event cutset have been activated.

Claim 7

The method of claim 5 wherein said multiple event counter attribute for each multiple event cutset is initially set to the number of events in the multiple event cutset and is decremented by one each time an event in the cutset is selected as activated, and wherein the multiple event cutset is identified as activated when the associated multiple event counter reaches zero.

Claim 8

The method of claim 6 including the step of removing the identification of an event as selected when it is no longer activated, and for such events having a multiple event cutset type attribute, incrementing the associated multiple event counter attribute by one.

Claim 9

The method of claim 1 including the following steps for generating an indication of the events which resulted in activation of a top event: selecting an activated top event; and operating said digital computer to: 1) search the cutset table to identify each cutset having as the top event attribute the selected activated top event; 2) as to each identified cutset, repeat step 1 using as the selected activated top event the event at­tribute of the identified cutset; 3) repeat step 2 until the top event attribute of an identified cutset does not appear as an event in the cutset table, and identify such an event; and 4) generate an output identifying the identified events.

Claim 10

A) A computer controlled complex process plant having a plurality of interrelated components and systems; wherein the systems and components are intended to function in a predetermined sequence and manner according to known technical specifications, and wherein inoperability and/or maloperation of any components results in known events, B) means for selecting an event representing the inoperability of at least one of said components and systems; C) a digital computer programmed to determine compliance of said complex process plant with said set of technical specifications and operability of certain of said systems and components; characterized by 1) means for storing a data base including a cutset table having an entry for each cutset in each of a plurality of operability trees, each cutset representing a different combination of events associated with the state of operability of said components and systems and the status of the technical specifications, which cutsets when taken separately and in sequence with other cutsets result in an indication of non-compliance with a technical speci­fication or inoperability of a system, each said entry in the cutset table including an event attribute indicating the event which activates the cutset, and a top event attribute indicating the top event activated by that cutset; and 2) processing means responsive to said input means and including means for: a) searching said cutset table to identify all entries in which the event attribute matches the selected event, b) as to each such entry repeating a) using the top event attribute of the identified entry of the cutset table as the selected event, c) repeating b) until the top event of each identified entry is not found in the cutset table; and d) means for displaying indications of such top events as activated top events at the top of an operability tree.

Claim 11

A) A computer controlled complex process plant having a plurality of interrelated components and systems; wherein the systems and components are intended to function in a predetermined sequence and manner according to known technical specifications, and wherein inoperability and/or maloperation of any components results in known events, B) means for selecting an event representing the inoperability of at least one of said components and systems; C) a digital computer programmed to determine compliance of said complex process plant with said set of technical specifications and operability of certain of said systems and components; characterized by 1) means for storing a data base including a cutset table having an entry for each cutset in each of a plurality of operability trees, each cutset representing a different combination of events associated with the state of operability of said components and systems and the status of the technical specifications, which cutsets when taken separately and in sequence with other cutsets result in an indication of non-compliance with a technical speci­fication or inoperability of a system, each said entry in the cutset table including an event attribute indicating the event which activates the cutset, and a top event attribute indicating the top event activated by that cutset; and 2) processing means responsive to said input means and including means for: a) searching said cutset table to identify all entries in which the event attribute matches the selected event, b) as to each such entry repeating a) using the top event attribute of the identified entry of the cutset table as the selected event, c) repeating b) until the top event of each identified entry is not found in the cutset table; and d) means for displaying indications of such top events as activated top events at the top of an operability tree.

Claim 12

The process plant of claim 9 wherein some top events require multiple selected events to be activat­ed, wherein said means in the computer for storing a data base includes in the cutset table a cutset type attribute identifying multiple event cutsets and said data base including a cutset evaluation table containing entries for each of the multiple event cutsets including a count attribute indicating the number of members of the multiple event cutset which have been activated, and wherein said searching means in the processing means includes means for checking the cutset type attribute of each cutset associat­ed with a selected event, and for multiple event cutsets, indexing said count attribute and repeating the search of the cutset table using the top event attribute of the multiple event cutsets as the selected event only when the count attribute has reached a count indicating that all of the events in the multiple event cutset have been selected.

Claim 13

A machine implemented method of determining activation of a top event in a decision tree comprising the steps of generating cutsets representing the various combinations of events in the decision tree, which when taken separately and in sequence with other cutsets, result in activation of the top event; generating in a digital computer a data base including a cutset table which includes an event attribute for identifying each event associated with a cutset and a top level event attribute identifying a higher level event activated by the cutset; selecting a given event; and operating said digital computer to: a) search the event attributes of said cutset table for the selected event to identify as activated all cutsets for which the selected event activates a top event as indicated by the top event attribute; b) as to each such activated cutset, repeat step a) using the associated activated top event attribute as the selected event; c) repeating step b) until the top level event activated by a cutset does not appear as an event attribute in the cutset table and identifying such top event as an ultimate activated top event; and d) generate an output identifying each ultimate top event activated by said given event.

Claim 14

A machine implemented method of determining activation of a top event in a decision tree comprising the steps of generating cutsets representing the various combinations of events in the decision tree, which when taken separately and in sequence with other cutsets, result in activation of the top event; generating in a digital computer a data base including a cutset table which includes an event attribute for identifying each event associated with a cutset and a top level event attribute identifying a higher level event activated by the cutset; selecting a given event; and operating said digital computer to: a) search the event attributes of said cutset table for the selected event to identify as activated all cutsets for which the selected event activates a top event as indicated by the top event attribute; b) as to each such activated cutset, repeat step a) using the associated activated top event attribute as the selected event; c) repeating step b) until the top level event activated by a cutset does not appear as an event attribute in the cutset table and identifying such top event as an ultimate activated top event; and d) generate an output identifying each ultimate top event activated by said given event.