Wind Gearbox Workscope Optimization - PHM Society...Wind Gearbox Workscope Optimization PHM Society...

Wind Gearbox Workscope Optimization

PHM Society 2013 Wind Energy Workshop

October 16th, 2013

StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com October 16th, 2013

Introduction Today’s presentation is based on the following proposition: •  The most sophisticated sensors & predictive / diagnostic

software in the world won’t help equipment stay in service and control Life Cycle Costs if asset owners / maintainers don’t make smart decisions during maintenance events

A Prime Example: •  Wind industry doesn’t agree on optimum strategy for bearing

replacement during heavy maintenance events, opting to: -  Only replace damaged bearings (to keep shop visit $ low), or -  Replace all bearings regardless of their condition or time in service

to avoid unplanned events •  Neither approach is optimal

-  The “Best” option is somewhere in-between


Introduction (con’t) StandardAero has developed new reliability-based methods & tools to enable smarter maintenance decision-making •  Goal: Work with asset owners to improve revenue generating

capability and minimize long term costs due to off-tower maintenance

•  Created several workscoping and fleet modeling tools for multiple customers / applications

•  Jet Engines: 10-20% improvement in Cost / Reliability Undertook engineering study to investigate wind gearbox workscope question (as it applies to bearings)


The Maintainer’s Dilemma Workscoping question is common to many industries •  Often referred to as the “Maintainer’s Dilemma”

How can you optimize maintenance to maximize revenue & minimize life-cycle costs? •  Plot amortized cost per operating hour (shop visit cost / life expectancy) vs. life

expectancy for each possible workscope to identify the best choice

Too Little Maintenance

Poor Availability

Too Much Maintenance

High Cost

Cost

High

Low

Maintenance WorkscopeLight Heavy


Availability

Life

Cyc

le C

ost




Availability

Life

Cyc

le C

ost




Availability

Life

Cyc

le C

ost




Availability

Life

Cyc

le C

ost



Optimum

Repair only what is broken (OCM strategy) & potentially live w/shorter time in service or unexpected times to next failure

Perform extensive overhaul / replacement at this event & potentially incur costs without extending time in service


Creating the Reliability Tools

Failure Analyses Data Collection/Mining Data Analysis & Management

Quality Issue

Random

Normal Wear

High Time Wear Out

Reliability Models

Practical Cost Based Models & Tools Reliability Analyses


Study Methodology Built reliability/cost models for generic gearbox •  Min (L10) lives AGMA spec. 6006-A03

Three (3) workscope approaches analyzed •  OCM (replace only failed bearings) •  Replace 100% (replace all bearings) •  Dynamic Strategy: Bearings replaced based on

individual ages (& time remaining until unit is retired) to optimize LCC @ Shop Visit

Calculate MTBF & cost of each workscope •  MTBF based on the combination of items / ages •  Cost: Unit repair cost + next event cost

-  Crane, lost revenue, shipping, labor RR Gbx

Determined $/Hr of each possible workscope

HSS ISS LSS PLC & PG

Cont

rol D

ata

Control Data

Characteristic Life

Bearing Position:

L10 Life

Data Date: 19-Apr-11

SN-00003 55,000

Bearing Failed? TSO WorkscopePLC-A 15,000PLC-B 15,000

PL-G1-A 15,000PL-G1-B 15,000PL-G2-A 15,000PL-G2-B 15,000PL-G3-A 15,000PL-G3-B 15,000LSS-A 15,000LSS-B 15,000ISS-A 15,000ISS-B 15,000HSS-A 15,000HSS-B 15,000

Cost CPH$0 $0.00

Reliability Reliability Final Incr Counter Accuracy1 0.499831684 0 10,000

23,756

Wind Gearbox Bearing WCO (Rev 2.1)

MTTF

ReplaceReplaceReplaceReplace

Data Date: 19-Apr-11

SN-00003 55,000

Bearing Failed? TSO WorkscopePLC-A 15,000PLC-B 15,000

PL-G1-A 15,000PL-G1-B 15,000PL-G2-A 15,000PL-G2-B 15,000PL-G3-A 15,000PL-G3-B 15,000LSS-A 15,000LSS-B 15,000ISS-A 15,000ISS-B 15,000HSS-A 15,000HSS-B 15,000

Cost CPH$0 $0.00

Reliability Reliability Final Incr Counter Accuracy1 0.499831684 0 10,000

23,756

Wind Gearbox Bearing WCO (Rev 2.1)

MTTF

ReplaceReplaceReplaceReplace

Cos

t Per

Hou

r

Time on Wing

Optimum Work Scope

Mean Time to Next Failure

AGMA Specification


Results: OCM vs Replace 100% Reliability Impact: •  OCM:

-  MTBF after repair continually decreases as unit ages

•  Replace 100%: -  Buys reliability that can’t be used

Cost / Hr Impact: •  OCM:

-  Typically more expensive -  Trends upward until MTBF

exceeds planned life •  Replace 100%:

-  Generally better than OCM -  Buys reliability that can’t be used

Avg Total O-M Costs: $10/MWH (Wind Energy Update)

Costs Per Hour of Use vs Work Scope StrategyOCM, 100% Replacement, Replace ISS / HSS Brgs

75,000 hr Planned Life

$-

$5.00

$10.00

$15.00

$20.00

$25.00

$30.00

$35.00

$40.00

$45.00

$50.00

5,000 15,000 25,000 35,000 45,000 55,000 65,000 75,000

Total Age At Work Scope (Hrs )

Cos

ts P

er H

our o

f Use

(C

ost o

f Rem

oval

+Shi

ppin

g+R

epai

r)

/MT

TFOCM

Repaplace 100%

Mean Time To Next Failure After a Repair Dynamic vs Static Approach


05

10152025303540

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Thou

sand

s

Total Age At Work Scope (Hrs)

MTT

F (H

ours

)

OCM

Replace 100%Un-useable Reliabilty


Results: OCM vs Replace 100%




05

10152025303540

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Thou

sand

s


MTT

F (H

ours

)

OCM

Replace 100%Un-useable Reliabilty


Results: OCM vs Replace 100%


Costs Per Hour of Use vs Work Scope StrategyOCM, 100% Replacement, Replace ISS / HSS Brgs


$-

$5.00

$10.00

$15.00

$20.00

$25.00

$30.00

$35.00

$40.00

$45.00

$50.00

5,000 15,000 25,000 35,000 45,000 55,000 65,000 75,000


Cos

ts P

er H

our o

f Use

(C

ost o

f Rem

oval

+Shi

ppin

g+R

epai

r)

/MT

TF

OCM

Repaplace 100%


Results: Dynamic vs Static Strategy Reliability Impact: •  Dynamic strategy is less than

100% replacement, but more than OCM

•  Much less unused reliability Cost / Hr Impact: •  Dynamic always Lowest •  Equivalent to “OCM” very

young and very old lives

Avg Total O-M Costs: $.01/MWH (Wind Energy Update)

Costs Per Hour of Use vs Work Scope StrategyOCM, 100% Replacement, Minimum


$-

$5.00

$10.00

$15.00

$20.00

$25.00

$30.00

5,000 15,000 25,000 35,000 45,000 55,000 65,000 75,000


Cos

ts P

er H

our o

f Use

(C

ost o

f Rem

oval

+Shi

ppin

g+R

epai

r) /M

TTF OCM

Repaplce 100%

Dynamic Strategy



05

10152025303540

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Thou

sand

s


MTT

F (H

ours

)

OCM

Replace 100%Un-useable ReliabiltyOptimized

Workscope Occures Between Avg Cost

Delta ($/Hr) $/KWH21-30,000 Hours 2.22$ 0.0015$ 30-45,000 Hours 5.19$ 0.0035$ 45-63,000 Hours 11.24$ 0.0075$ 63-72,000 Hours 14.41$ 0.0097$ 72-75,000 Hours 36.67$ 0.0246$


Results: Dynamic vs Static Strategy




05

10152025303540

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Thou

sand

s


MTT

F (H

ours

)

OCM

Replace 100%Un-useable ReliabiltyOptimized


Results: Dynamic vs Static Strategy


Costs Per Hour of Use vs Work Scope StrategyOCM, 100% Replacement, Minimum


$-

$5.00

$10.00

$15.00

$20.00

$25.00

$30.00

5,000 15,000 25,000 35,000 45,000 55,000 65,000 75,000


Cos

ts P

er H

our o

f Use

(C

ost o

f Rem

oval

+Shi

ppin

g+R

epai

r) /M

TTF OCM

Repaplce 100%

Dynamic Strategy


Conclusions The main points to take away from this study: •  MTBF of OCM workscopes degrade significantly w/age •  MTBFs for different workscopes are dictated by which components

are replaced or not, their ages, & inherent reliability of components •  Optimum workscope is affected by several factors including:

-  Age of other bearings, and planned retirement age of the unit •  “Static” workscope strategy tends to result in highest LCC

-  Doing the same thing for the entire service life of the unit •  A “Dynamic” strategy is best

-  Determining an “Optimum” build at each point in the unit’s life •  Cost impacts from “Worst” to “Best” workscopes vary widely

-  $2.00/Hr ($.00149/kWH) early in unit’s life -  Over $14.00/Hr ($.0096/kWH) late in unit’s life

•  Wind turbine asset owners need a repair source that can: -  Quantify reliability & costs of different workscopes (thru gbx life) -  AND can act on the data such that it minimizes Life Cycle Costs


For More Information: Alan L. Lesmerises, MS, CRE Reliability & Life Cycle Management Engineer StandardAero Engineering Services 3523 General Hudnell Dr. San Antonio, TX, 78226 United States of America Office: (210) 334-6187 Fax: (210) 334-6181 [email protected]

Wind Gearbox Workscope Optimization - PHM Society...Wind Gearbox Workscope Optimization PHM Society...

Documents

Transcript of Wind Gearbox Workscope Optimization - PHM Society...Wind Gearbox Workscope Optimization PHM Society...