Automated system to prioritize repair of plant equipment

• US 5,132,920 A
• Filed: 02/16/1988
• Issued: 07/21/1992
• Est. Priority Date: 02/16/1988
• Status: Expired due to Term

• Current Assignee: Siemens Power Generation, Inc.
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Gonzalez, Avelino J., Kemper, Christian T., Bellows, James C., Osborne, Robert L.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): TRANS, VINCENT N
• Application Number:
  US07/156,064
• Time in Patent Office: 1,617 Days
• Field of Search: 364/200, 364/424.03, 364/506, 364/580, 364/551.01, 364/138, 364/492, 364/513, 364/900, 364/550, 235/151.3, 371/18, 371/28, 371/29
• US Class Current: 702/184
• 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: G06Q 10/06 Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling

Abstract

The system of the present invention uses the importance of a piece of malfunctioning equipment, the severity and the confidence level in a diagnosis to determine repair priority of the equipment by obtaining the product (46) of the confidence level (CF), importance (IMP) and severity (SEV). The these variables are determined by expert system rules. The severity is the reciprocal (88) of the time to failure. The importance (44) is the cost to repair the maximum damage when the malfunction continues. A malfunction can affect several pieces of equipment in combination, the severity and importance associated with each piece is combined (70) with the confidence and used to determine the repair priority. When the diagnosis of a malfunction is by malfunctioning sensors, the expected equipment life (40) and the availability (86) of sensors that provide a partial backup are considered in prioritizing sensor as well as equipment repair. When a primary piece of equipment is backed up (100), the effect of both pieces of equipment failing (106) is considered in prioritizing the repair. The system ranks the repair of all possible malfunctions on a common scale. The system gives a complete repair priority picture and allows the cost effectiveness to be maximized.

Claims

1. A method of determining the priority of repair of malfunctioning equipment components in a system, comprising the steps of:

(a) sensing a state of the equipment components using sensing mans and a computer;

(b) diagnosing, using the computer, malfunctions of the equipment components from the state and determining a confidence level in each diagnosis; and

(c) determining a severity of the malfunctions and an importance of the equipment components and ranking, using the computer, the malfunctions in the priority of repair in accordance with the severity of the malfunction, the importance of the equipment components and the confidence level.

2. A method as recited in claim 1, wherein step (c) includes the steps of:

(c1) determining a priority of each malfunction as a product of the confidence level, the severity and the importance; and

(c2) sorting the malfunctions based on priority.

3. A method as recited in claim 1, wherein step (c) includes the steps of:

(c1) determining the severity of each component of equipment affected by the malfunction;

(c2) determining the importance of each component of equipment affected by the malfunction;

(c3) obtaining respective products of the severity and importance of the equipment components;

(c4) summing the products to produce a sum;

(c5) obtaining a priority of each malfunction as the product of the confidence level and the sum; and

(c6) sorting the malfunctions based on priority.

4. A method as recited in claim 1, wherein the importance is the cost of repairing the component and the severity is reciprocal of the time until the component fails.

5. A method as recited in claim 1, wherein said system is monitored by sensors and one of the sensors is malfunctioning and step (c) comprises the steps of:

(c1) determining a loss in confidence level caused by the malfunctioning sensor and converting the loss into malfunction severity when the component malfunction can be diagnosed by an alternate diagnostic path;

(c2) determining the severity when the alternate diagnostic path does not exist;

(c3) determining sensor importance as a function of minimum system damage and component malfunction importance;

(c4) determining a priority as a product of the confidence level, severity and importance; and

(c5) sorting the malfunctions based on priority.

6. A method as recited in claim 5, wherein step (c2) comprises the steps of:

(i) determining whether other sensors are indicating changes;

(ii) setting the severity as an inverse of expected component life when the other sensors do not indicate changes; and

(iii) setting the severity as an inverse of the estimated time to failure of the component with the malfunction being diagnosed continuing.

7. A method as recited in claim 1, wherein the component has a backup and step (c) comprises the steps of:

(c1) determining the importance of a combined failure of the component and the backup;

(c2) determining the severity as a reciprocal of an expected life of the backup when the backup is not monitored;

(c3) determining the severity as the reciprocal of the estimated time to failure of the backup when the backup is monitored;

(c4) determining a priority as a product of the confidence level, severity and importance; and

(c5) sorting the malfunctions based on priority.

8. A method of determining the priority of repair of malfunctioning equipment components in a system, comprising the steps of:

(a) sensing a state of the equipment components using sensing means and a computer;

(b) diagnosing, using a computer, malfunctions of the equipment components from the state and determining a confidence level in each diagnosis; and

(c) determining a severity of the malfunctions and ranking, using the computer, the malfunctions in the priority of repair in accordance with severity of the malfunction and each confidence level.

9. A method of determining the priority of repair of malfunctioning equipment components in a system, comprising the steps of:

(a) sensing a state of the equipment components using sensing means and a computer;

(b) diagnosing, using a computer, malfunctions of the equipment components from the state and determining a confidence level in each diagnosis; and

(c) determining an importance of the equipment components and ranking, using the computer, the malfunctions in the priority of repair in accordance with the importance of the equipment components and the confidence level.

10. A system for determining the priority of repair of malfunctioning equipment components in a system, comprising:

sensors for determining a state of the equipment components; and

a computer connected to said sensors and comprising;

diagnosis means for diagnosing malfunctions of the equipment components in dependence on the state and determining a confidence level in each diagnosis;

severity means for determining a severity of the malfunctions;

importance means for determining an importance of the equipment components; and

prioritizing means for ranking the malfunctions in the priority of repair in accordance with the severity of the malfunctions, the importance of the equipment components and the confidence level.

11. A system for determining the priority of repair of malfunctioning equipment components in a system, comprising:

sensors for determining a state of the equipment components; and

a computer connected to said sensors and comprising;

diagnosis means for diagnosing malfunctions of the equipment components in dependence on the state and determining a confidence level in each diagnosis;

severity means for determining a severity of the malfunctions; and

prioritizing means for ranking the malfunctions in the priority of repair in accordance with the severity of the malfunction and the confidence level.

12. A system for determining the priority of repair of malfunctioning equipment components in a system, comprising:

sensors for determining a state of the equipment components; and

a computer connected to said sensors and comprising;

diagnosis means for diagnosing malfunctions of the equipment components in dependence on the state and determining a confidence level in each diagnosis;

importance means for determining an importance of the equipment components; and

prioritizing means for ranking the malfunctions in the priority of repair in accordance with the importance of the equipment components and the confidence level.

13. A method of determining the priority of repair of malfunctioning equipment components in a power plant, comprising the steps of:

(a) sensing a state of the components using sensing means and a computer;

(b) diagnosing malfunctions of the components from the state and determining a confidence level in each diagnosis using a computer; and

(c) determining severity of the malfunction and importance of the component and ranking, using the computer, the malfunctions in accordance with the severity of the malfunction, the importance of the component and the confidence level, wherein;

step (c), when a single component is malfunctioning, no sensors are malfunctioning and no backup component exists, includes the steps of;

(1) determining a priority of each malfunction as a product of the confidence level, the severity and the importance; and

(2) sorting the malfunctions based on priority;

step (c), when several components are affected by a malfunction, includes the steps of;

(3) determining the severity of each component of equipment affected by the malfunction;

(4) determining the importance of each component of equipment affected by the malfunction;

(5) obtaining respective products of the severity and importance of the components of equipment;

(6) summing the products to produce a sm;

(7) obtaining the priority of each malfunction as a product of the confidence level and the sum; and

(8) sorting the malfunctions based on priority;

step (c), when said system is monitored by sensors and one of the sensors is malfunctioning comprises the steps of;

(9) determining a loss in confidence level caused by the malfunctioning sensor and converting the loss into malfunction severity when the component malfunction can be diagnosed by an alternate diagnostic path;

(10) determining the severity when the alternate diagnostic path does not exist;

(11) determining sensor importance as a function of the minimum system damage and the component malfunction importance;

(12) determining the priority as a product of the confidence level, severity and importance; and

(13) sorting the malfunctions based on priority; and

step (c), when the component as a backup, comprises the steps of;

(14) determining the importance of the combined failure of the component and the backup

(15) determining the severity as a reciprocal of an expected life of the backup when the backup is not monitored;

(16) determining the severity as the reciprocal of the estimated time to failure of the backup when the backup is monitored;

(17) determining the priority as a product of the confidence level, severity and importance; and

(18) sorting the malfunctions based on priority.