Optimized asset maintenance and replacement schedule

• US 9,959,514 B2
• Filed: 11/24/2014
• Issued: 05/01/2018
• Est. Priority Date: 11/24/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Phan, Dung, Xiong, Jinjun
• Primary Examiner(s): Yi, Roy Y
• Application Number:
  US14/551,522
• Publication Number:
  US 20160148171A1
• Time in Patent Office: 1,254 Days
• CPC Class Codes: G01M 99/008 by doing functionality tests
• CPC Class Codes: G06Q 10/06312 Adjustment or analysis of established resource schedule, e.g. resource or task levelling, or dynamic rescheduling
• CPC Class Codes: G06Q 10/20 Administration of product repair or maintenance
• CPC Class Codes: Y02P 90/80 Management or planning

Abstract

There are provided a system, a method and a computer program product for generating an optimal preventive maintenance/replacement schedule for a set of assets. The method includes receiving data regarding an asset, said data including a failure rate function of said asset, a cost of preventative maintenance (PM) of said asset, a cost of an asset failure, and a cost of replacing an asset. An optimal number K of preventative maintenance time intervals t_k and an indication of a possible replacement is computed and stored for each asset by minimizing a mean cost-rate value function with respect to an electrical age of the asset. A first PM schedule is formed without consideration of labor and budget resource constraints. The method further generates a second maintenance schedule for a system of assets by minimizing a deviation from the optimal PM time intervals subject to the labor and budget resource constraints.

Claims

1. A system for generating an optimal preventive maintenance/replacement schedule for a set of assets comprising:

a memory storage device for storing data;

a programmed processor device coupled to the memory storage device and configured to;

receive data regarding an asset, said data including a failure rate function capturing a condition of said asset up to a point in time, a cost of preventative maintenance (PM) of said asset, a cost of an asset failure, and a cost of replacing an asset;

receive a further input specifying a time horizon;

determine whether there is a need to replace said asset, and when a replacement of said asset is needed;

compute a mean cost-rate optimization problem formulated as an objective function of a total cost of the asset over said specified time horizon, said total cost being a function of a cost of preventative maintenance (PM) of said asset for K−

1 PMs, and an expected cost of repairs for an asset failure computed as a function of said failure rate function, and the cost of replacing an asset;

compute an optimal number of preventative maintenance actions K and time intervals t_k for each asset independently by minimizing said first objective function with respect to an age of the electrical asset y_k, where k represents a k^th PM, wherein said schedule is formed without considering a labor and budget resource constraint;

store data representing said optimal number of preventative maintenance time intervals for each asset in the memory storage device; and

generate a final maintenance schedule of said optimal number of time intervals from said stored data.

2. The system of claim 1, wherein said processor device is further configured to:

determine a final maintenance schedule for the system of assets by minimizing a deviation from the optimal PM time intervals subject to the labor and budget resource constraints.

3. The system of claim 1, wherein said optimal number of preventative maintenance time intervals includes a number K of PM intervals and an indication of a possible replacement;

and a time interval t_k for the k^th PM.

4. The system of claim 3, wherein said processor device is further configured to:

receive an input specifying a time horizon;

determine whether there is a need to replace said asset, and with no replacement needed,

determine the optimal scheduled intervals t_k by minimizing a first mean cost-rate optimization problem formulated as a first objective function of a total cost of the asset over said specified time horizon, said total cost being a function of a cost of preventative maintenance (PM) of said asset for K−

1 PMs, and an expected cost of repairs for an asset failure computed as a function of a failure rate function.

5. The system of claim 4, wherein the first objective function of a total cost of the asset to be minimized is represented as ƒ

₁(y,K) such that;

6. The system of claim 1, wherein the objective function of a total cost of the asset to be minimized is represented as ƒ

₂(y,K) such that;

7. The system of claim 1, wherein to compute a failure rate function h₀(t) of an asset, said processor device is further configured to:

receive parameter values comprising;

Weibull parameter input values α

, β

, a current age t₀ of the asset, a number of simulation intervals N, a time interval Δ

t for simulation, an asset aging factor acc_factor, and a given time t wherein

8. The system of claim 2, wherein to minimize a deviation from the optimal PM time intervals subject to the labor and budget resource constraints, said processor device is further configured to:

solve, using integer linear programming;

9. The system of claim 8, wherein said processor device is further configured to:

compare said impact weight w_n against a threshold; and

if the impact is bigger than said threshold;

fix a maintenance schedule computed for the n-transformer; and

select values for said lower and upper bounds for PM intervals to reduce a size of parallel integer linear programming problem.

10. A computer program product for determining when to carry out a preventive maintenance/replacement for a set of assets, the computer program product comprising a computer readable storage medium readable by a machine and storing instructions run by the machine to perform a method, said method comprising:

receiving data regarding an asset, said data including a failure rate function capturing a condition of said asset up to a point in time, a cost of preventative maintenance (PM) of said asset, a cost of an asset failure, and a cost of replacing an asset;

receiving a further input specifying a time horizon;

determining whether there is a need to replace said asset, and when no replacement of said asset is needed;

computing a mean cost-rate optimization problem formulated as an objective function of a total cost of the asset over said specified time horizon, said total cost being a function of a cost of preventative maintenance (PM) of said asset for K−

1 PMs, and an expected cost of repairs for an asset failure computed as a function of said failure rate function, and the cost of replacing an asset;

computing an optimal number of preventative maintenance time intervals t_k for each asset independently by minimizing said first objective function with respect to an age of the asset y_k where k represents a k^th PM, wherein said schedule is formed without considering a labor and budget resource constraint; and

storing said optimal number of preventative maintenance time intervals for each asset in a memory storage device, the optimal number of preventative maintenance time intervals including a number K of PM intervals and an indication of a possible replacement; and

a time interval t_k for the k^th PM;

and generating a final maintenance schedule of said optimal number of time intervals from said stored data.

11. The computer program product according to claim 10, wherein the method further comprises:

determining a final maintenance schedule for the system of assets by minimizing a deviation from the optimal PM time intervals subject to the labor and budget resource constraints.