EQUIPMENT CONDITION AND PERFORMANCE MONITORING USING COMPREHENSIVE PROCESS MODEL BASED UPON MASS AND ENERGY CONSERVATION

• US 20120095574A1
• Filed: 10/13/2010
• Published: 04/19/2012
• Est. Priority Date: 11/30/2001
• Status: Active Grant

• Current Assignee: Schneider Electric Systems USA, Inc. (Schneider Electric SE)
• Original Assignee: Invensys Systems Incorporated (Invensys PLC)
• Inventors: Greenlee, Terrill L.
• Granted Patent: US 8,781,635 B2
• Time in Patent Office: Days
• US Class Current: 700/30
• CPC Class Codes: G05B 2219/31357 Observer based fault detection, use model
• CPC Class Codes: G05B 23/0245 based on a qualitative model, e.g. rule based; if-then decisions
• CPC Class Codes: G05B 23/0283 Predictive maintenance, e.g. involving the monitoring of a system and, based on the monitoring results, taking decisions on the maintenance schedule of the monitored system; Estimating remaining useful life [RUL] preventive maintenance, i.e. planning maintenance according to the available resources without monitoring the system G06Q10/06
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A method and apparatus capable of monitoring performance of a process and of the condition of equipment units effecting such process is disclosed. A process model predicated upon mass and energy balancing is developed on the basis of a plurality of generally nonlinear models of the equipment units. At least one or more of such equipment models are characterized by one or more adjustable maintenance parameters. Data relating to mass and energy transfer within the process is collected and is reconciled with the mass and energy characteristics of the process predicted by the model. The condition of the equipment units and process performance may then be inferred by monitoring the values of the maintenance parameters over successive data reconciliation operations.

Claims

1. A method of processing signals representative of a process effected by one or more units of equipment in operative communication through one or more resource flows therebetween, said method comprising:

measuring flow rates of at least first and second of said resource flows in order to generate respective first and second measured resource flow signals;

formulating a model of said process based upon conservation of a process parameter characterizing said first and second resource flows, said model including at least a first maintenance parameter; and

adjusting a first value of said first measured resource flow signal, a second value of said second measured resource flow signal, and said first maintenance parameter such that said process parameter is conserved consistent with said model.

2. The method of claim 1 wherein said model is further based upon a second maintenance parameter, said adjusting including modifying a value of said second maintenance parameter.

3. The method of claim 1 wherein said adjusting includes minimizing a sum of squared difference values representative of error differentials in said first and second measured resource flow signals.

4. The method of claim 3 wherein a weighting factor is assigned to each of said squared difference values based upon accuracy of a corresponding sensor disposed to measure one of said flow rates.

5. The method of claim 1 wherein said adjusting includes modifying said first value so as to be outside of a predetermined range and associating an error condition with a first sensor disposed to generate said first measured resource flow signal.

6. The method of claim 1 wherein said adjusting includes adjusting said first value by a first offset, adjusting said second value by a second offset, and providing a user indication of said first offset and said second offset.

7. A computer-based system for processing signals representative of a process effected by one or more units of equipment in operative communication through one or more resource flows therebetween, said system comprising:

a first sensor for measuring a flow rate of a first of said resource flows in order to generate a first measured resource flow signal;

a second sensor for measuring a flow rate of a second of said resource flows in order to generate a second measured resource flow signal;

a model generation module operative to formulate a model of said process based upon conservation of a process parameter characterizing said first and second resource flows, said model including at least a first maintenance parameter; and

a reconciliation module operative to adjust a first value of said first measured resource flow signal, a second value of said second measured resource flow signal, and said first maintenance parameter such that said process parameter is conserved consistent with said model.

8. The system of claim 7 wherein said model is further based upon a second maintenance parameter, said reconciliation module modifying a value of said second maintenance parameter.

9. The system of claim 7 further including a third sensor for measuring an energy of said first of said resource flows in order to generate a first measured energy signal and a fourth sensor for measuring an energy of said second of said resource flows in order to generate a second measured energy signal, said reconciliation module adjusting a first value of said first measured energy signal and a second value of said second measured energy signal so as to conserve energy consistent with said model.

10. A method of processing signals representative of operation of a process involving one or more mass flows between a plurality of units of equipment, said method comprising:

measuring flow rates of at least first and second of said mass flows in order to generate respective first and second measured mass flow signals;

measuring first and second energies associated with said first and second mass flows in order to generate respective first and second measured energy signals;

formulating a model of said process based upon mass and energy balance of said first and second resource flows; and

adjusting values of said first and second measured mass flow signals and said first and second measured energy signals such that said mass and energy balance is conserved consistent with said model.

11. The method of claim 10 wherein said model includes a first maintenance parameter, said method further including modifying said maintenance parameter in conjunction with said adjusting said values of said first and second measured mass flow signals.

12. The method of claim 10 wherein said adjusting includes minimizing a sum of squared difference values representative of errors in said first and second measured mass flow signals.

13. The method of claim 10 wherein a weighting factor is assigned to each of said squared difference values based upon accuracy of a corresponding sensor disposed to measure one of said flow rates.

14. The method of claim 10 wherein said adjusting includes changing said values of said first and second measured mass flow signals by first and second offsets, respectively, and indicating that said first and second of said mass flows should be modified in accordance with said offsets.

15. A method for controlling operation of a plant process effected by one or more units of equipment in fluid communication through one or more mass flows, said method comprising:

creating, using a graphical user interface, a sequence representative of a mathematical model of said plant process based upon conservation of mass and energy, said sequence including a plurality of tasks defining functions to be performed in controlling said plant process;

measuring a flow rate of a first of said mass flows in order to generate a first measured mass flow signal;

measuring a flow rate of a second of said mass flows in order to generate a second measured mass flow signal;

modifying a first value of said first measured mass flow signal by a first offset, a second value of said second measured mass flow signal by a second offset, and a first maintenance parameter of said mathematical model by a third offset; and

adjusting said first of said mass flows in accordance with said first offset.

16. The method of claim 15 wherein said second offset is larger than a predetermined maximum offset, said method further including associating an error condition with a first sensor disposed to generate said second measured mass flow signal.

17. The method of claim 15 wherein said adjusting includes minimizing a sum of squared difference values representative of error differentials in said first and second measured mass flow signals.

18. The method of claim 17 wherein a weighting factor is assigned to each of said squared difference values based upon accuracy of a corresponding sensor disposed to measure one of said flow rates.

19. A method for monitoring condition of equipment used to effect a process, said method comprising:

formulating a model of said process, said model including at least a first maintenance parameter; and

adjusting a value of said first parameter such that a predicted value of a process parameter of said process is reconciled with a measured value of said process parameter derived from measurements of characteristics of said process; and

monitoring changes in said value of said first maintenance parameter over time wherein changes in said value are indicative of changes in said condition of said equipment.

20. The method of claim 19 further including measuring flow rates of at least first and second of said resource flows in order to generate respective first and second measured resource flow signals wherein said model is based upon conservation of said process parameter and said process parameter characterizes said first and second resource flows.

21. The method of claim 20 wherein said model is further based upon a second maintenance parameter, said adjusting including modifying a value of said second maintenance parameter and said monitoring including tracking changes in said value of said second maintenance parameter.

22. A method for monitoring condition of a plurality of units of equipment used to effect a process involving one or more resource flows, said method comprising:

measuring flow rates of at least first and second of said resource flows in order to generate respective first and second measured resource flows;

formulating a model of said process, said model including a plurality of nonlinear equipment models corresponding to said plurality of units of equipment wherein at least a first of said nonlinear equipment models includes a first maintenance parameter;

adjusting a value of at least said first maintenance parameter such that predictions of said flow rates are reconciled with said first and second measured resource flows; and

monitoring changes in said value of said first maintenance parameter over time in order to enable detection of changes in condition of at least one of said plurality of units of equipment.

23. The method of claim 22 wherein at least a second of said nonlinear equipment models includes a second maintenance parameter, said method including adjusting said second maintenance parameter and monitoring changes in said second maintenance parameter over time.