Reliability & Availability of Wind Turbine Electrical & Electronic Components Electrical & Electronic Components Peter Tavner, Professor of New & Renewable Energy Energy Group Energy Group Head of School of Engineering, Durham University “One has to consider causes rather than symptoms of undesirable events and One has to consider causes rather than symptoms of undesirable events and avoid uncritical attitudes.” Prof Dr Alessandro Birolini 1 of 23
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Peter Tavner, Professor of New & Renewable EnergyEnergy GroupEnergy GroupHead of School of Engineering, Durham University
“One has to consider causes rather than symptoms of undesirable events andOne has to consider causes rather than symptoms of undesirable events and avoid uncritical attitudes.” Prof Dr Alessandro Birolini
Availability & Reliability•• Mean Time To Failure, Mean Time To Failure, MTTFMTTF•• Mean Time to Repair, or downtime Mean Time to Repair, or downtime MTTRMTTR•• Mean Time Between Failures, Mean Time Between Failures,
•• Operator’s or Technical Availability, Operator’s or Technical Availability, A=MTTF/MTBF < 1A=MTTF/MTBF < 1−−(λ/μ)(λ/μ)
•• Typical UK valuesTypical UK values–– Operators Availability Operators Availability 97%, 97%, –– Manufacturers Availability Manufacturers Availability 98%98%
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Capacity FactorCapacity Factor•• Energy generated in a year= C x Turbine rating xEnergy generated in a year= C x Turbine rating x•• Energy generated in a year= C x Turbine rating x Energy generated in a year= C x Turbine rating x
87608760C i FC i F CC•• Capacity Factor, Capacity Factor, CC
•• 8760 number of hours in a year8760 number of hours in a year•• Therefore:Therefore:•• C=Energy generated in a year/ Turbine rating xC=Energy generated in a year/ Turbine rating xC Energy generated in a year/ Turbine rating x C Energy generated in a year/ Turbine rating x
87608760•• CC incorporates the Availabilityincorporates the Availability AA and thereforeand therefore•• C C incorporates the Availability, incorporates the Availability, A, A, and therefore and therefore
the MTBF, the MTBF, 1/1/λλ
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Cost of Energy, COE•• COE, £/kWh= COE, £/kWh=
O&M+ {[(ICC*FCR) + LRC]/O&M+ {[(ICC*FCR) + LRC]/AEPnetAEPnet} } { ( ){ ( ) }}–– O&M=O&M=Cost of Operations & Maintenance, £Cost of Operations & Maintenance, £–– ICC=ICC=Initial Capital Cost, £Initial Capital Cost, £–– FCRFCR=Fixed Charge Rate, interest, %=Fixed Charge Rate, interest, %–– LCRLCR==LevelisedLevelised Cost of Replacement, replacing unavailable Cost of Replacement, replacing unavailable
ti £ti £generation, £generation, £–– AEPAEP=Annualised Energy Production, kWh=Annualised Energy Production, kWh
total test time [turbines * year] Figure 4.4: Variation between the failure rates of generator subassemblies, in the LWK
population of German WTs, using the PLP model. The upper two are low speed direct drive generators while the lower two are high speed
i di t d i t
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indirect drive generators.
Reliability & Time, LWKG bGearboxes
1.0
LWK, TW600, gearbox
r] yea
rs 1.0
LWK, V39/500, gearbox
r] year
s
0.4
0.6
0.8
tens
ity [
failu
res
/ yea
r
actu
al e
laps
ed ti
me:
12
0.4
0.6
0.8
tens
ity [
failu
res
/ yea
r
actu
al e
laps
ed ti
me:
11
0 100 200 300
0.0
0.2
total test time [turbines * year]
failu
re in
t
industrial value
0 100 200 300 400 500
0.0
0.2
total test time [turbines * year]
failu
re in
t
industrial value
0.8
1.0
LWK, N52/N54, gearbox
s / y
ear]
d tim
e: 7
yea
rs
0.8
1.0
LWK, Micon M530, gearbox
s / y
ear]
time:
12
yea
rs
0.2
0.4
0.6
ailu
re in
tens
ity [
failu
res
actu
al e
laps
ed
industrial value
0.2
0.4
0.6
ailu
re in
tens
ity [
failu
res
actu
al e
laps
ed
industrial value
0 20 40 60 80 100
0.0
total test time [turbines * year]
fa industrial value
0 50 100 150 200 250
0.0
total test time [turbines * year]
fa industrial value
Figure 4.5: Variation between the failure rates of gearbox subassemblies, using the
PLP model in the LWK population of German WTs
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PLP model, in the LWK population of German WTs.
Reliability & Time, LWK El t iElectronics
81.
0
LWK, E40, electronics
year
]
: 11
yea
rs
81.
0
LWK, E66, electronics
ear]
7 y
ears
0.2
0.4
0.6
0.
ure
inte
nsity
[fa
ilure
s / y
actu
al e
laps
ed ti
me:
20.
40.
60.
8
re in
tens
ity [
failu
res
/ ye
actu
al e
laps
ed ti
me:
0 100 200 300 400 500
0.0
0
total test time [turbines * year]
failu
industrial range
0 20 40 60 80
0.0
0.
total test time [turbines * year]
failu
r
industrial range
LWK TW 1 5s electronics
0.6
0.8
1.0
LWK, TW 1.5s, electronics
y [f
ailu
res
/ yea
r]
tual
ela
psed
tim
e: 5
yea
rs
0 10 20 30 40 50
0.0
0.2
0.4
failu
re in
tens
ity act
industrial range
total test time [turbines * year] Figure 4.6: Variation between the failure rates of electronics subassemblies, or converter,
using the PLP model, in the LWK population of German WTs. The upper two are low speed direct drive generators with fully rated converters while the lower
two are high speed indirect drive generators with partially rated converters.
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g p g p y
Reliability of Electronicsy
Failure root cause distribution for power electronicsFailure root cause distribution for power electronicsfrom E Wolfgang, 2007
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Variable Load of Wind PowerLi Sid I tLine Side Inverter
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Variable Load of Wind PowerG t Sid I tGenerator Side Inverter
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ConclusionsConclusions•• Definitions of Availability are open to interpretationDefinitions of Availability are open to interpretation•• Unreliability > 1 failure/turbine/year is commonUnreliability > 1 failure/turbine/year is common•• Unreliability increases with turbine sizeUnreliability increases with turbine size•• Unreliability increases with turbine sizeUnreliability increases with turbine size•• Such unreliability will be unacceptable offshoreSuch unreliability will be unacceptable offshore•• Offshore we need unreliability < 0.5 failure/turbine/yearOffshore we need unreliability < 0.5 failure/turbine/year•• Unreliability concentrated mainly in the Drive Train including electricsUnreliability concentrated mainly in the Drive Train including electrics•• Unreliability concentrated mainly in the Drive Train including electricsUnreliability concentrated mainly in the Drive Train including electrics•• Some unreliable subassemblies are surprising:Some unreliable subassemblies are surprising:
–– For example gearboxes are not unreliableFor example gearboxes are not unreliable–– But gearbox failures cause large downtime and costsBut gearbox failures cause large downtime and costsBut gearbox failures cause large downtime and costsBut gearbox failures cause large downtime and costs–– But electrical parts are unreliableBut electrical parts are unreliable–– Cause less downtime but significant costs, their downtime will increase Cause less downtime but significant costs, their downtime will increase
offshoreoffshore•• For electrical parts the root causes from these surveys are not clear:For electrical parts the root causes from these surveys are not clear:
•• But the highly variable loading from the turbine is clearly a factorBut the highly variable loading from the turbine is clearly a factor•• PrePre--testing is essential to eliminate early life failurestesting is essential to eliminate early life failures
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Thank you• P. J. Tavner, C. Edwards, A. Brinkman, and F. Spinato. Inuence of wind
d i d t bi li bilit Wi d E i i 30(1) 2006speed on wind turbine reliability. Wind Engineering, 30(1), 2006.• P. J. Tavner, J. P.Xiang, and F. Spinato. Reliability analysis for wind
turbines. Wind Energy, 10(1), 2007.• F. Spinato, P. J. Tavner, and G.J.W van Bussel. Reliability-growth
l i f i d t bi f fi ld d t P di f AR2TSanalysis of wind turbines from field data. Proceedings of AR2TS conference, Loughborough, 2007.
• Tavner, P J, van Bussel, G J W, Spinato, F, Machine and converter reliabilities in WTs. Proceedings of IEE PEMD Conference, Dublin, April 2006April 2006.
• Hansen, A D., Hansen, L H. ,Wind turbine concept market penetration over 10 years (1995–2004), Wind Energy, 2007; 10:81–97
• Ribrant J., Bertling L.M.: Survey of failures in wind power systems with f S di h i d l t d i 1997 2005 IEEE Tfocus on Swedish wind power plants during 1997–2005, IEEE Trans. Energy Conversion, 2007, EC22 (1), pp. 167–173
• Wolfgang, E. Examples for failures in power electronics systems, in EPE Tutorial ‘Reliability of Power Electronic Systems’, April 2007.B k d hl P Skii I lli b P M d l f i d bi• Beckendahl, P, Skiip, an Intelligenb Power Module for wind turbine inverters, EPE Wind Chapter Mtg, Stockholm, May 2009
25of 64RELIAWIND Training Course, 1st June 2009, Helsinki