wind turbine induction generator bearing fault detection using stator current analysis
DESCRIPTION
Wind turbine induction generator bearing fault detection using stator current analysis. By. D.S. Vilchis-Rodriguez, S. Djurovic, A.C. Smith. School of Electrical and Electronic Engineering The University of Manchester. Content. Wind generator failure figures Ball bearing frequencies - PowerPoint PPT PresentationTRANSCRIPT
Wind turbine induction generator bearing fault detection using
stator current analysis
By
School of Electrical and Electronic Engineering The University of Manchester
D.S. Vilchis-Rodriguez, S. Djurovic, A.C. Smith
Content
1. Wind generator failure figures
2. Ball bearing frequencies
3. Mathematical model
4. Simulation results
5. Experimental results
6. Fault detection improvement
7. Conclusions
Wind turbine reliability
Feng Y. and Tavner P., “Introduction to Wind Turbines and their Reliability & Availability”, Warsaw, EWEC 2010, 2010.
Wind generator failure occurrence
1-2 MW >2 MW
Alewine K. and Chen W., “Wind Turbine Generator Failure Modes Analysis and Occurrence”, Windpower 2010, Dallas, Texas, May 24-26, 2010.
Rolling bearing race frequencies
1 cos2b b
o rc
N Df f
D
Outer race Inner race
1 cos2b b
i rc
N Df f
D
Bearing fault mechanical effects
Shaft displacement Rolling element drop
Air-gap modulation
Air-gap variations Periodic eccentricity
IG modelling for condition monitoring purposes
• Based on coupled-circuit approach
• Localized bearing faults are modelled as temporary eccentricity variations
• Axial asymmetry is taken into account in the model by averaging both machine ends eccentricity
• This approach makes it possible to analyze with detail incipient bearing faults
Bearing fault simulation results
0 50 100 150 200 250 300 350 400 450 500
10-6
10-4
10-2
100
stator current frequency spectrum
I s [n
orm
alize
d]
Frequency [Hz]
healthy1 mm2 mm3 mm4 mm5 mm6 mm7 mm
fo- f
s
fundamental
fs+ f
o
2fo- f
s 3fo - f
s
fs + 2fo
slot harmonicslot harmonic
fs + 3f
o
4fo - f
s5f
o - f
s
fs + 4f
o
6fo - f
s
fs + 5f
o
127 128 129 130 131 132 133 134 135 136 137
10-5
stator current frequency spectrum
I s [no
rm
alized
]
Frequency [Hz]
healthy1 mm2 mm3 mm4 mm5 mm6 mm7 mm
fs+f
o
Stator current frequency spectrum
Principal bearing fault frequency
detail
f s of f kf
1,2,3...k
Test rig layout
Laboratory test bed(viewed from above)
Load side bearing
Test rig description
Artificial bearing fault Test rig bearing data
Drive-end Non-drive-end
SKF 6313 SKF 6214
Nb = 8 Nb = 10
fo=3.07fr fo=4.11fr
fi=4.93fr fi=5.89fr
Bearing faultMeasured Frequency spectrum
Vibration spectrumStator line current spectrum
110 115 120 125 130 1350
0.5
1
1.5
2
2.5x 10-3 Stator current frequency spectrum, 1600 rpm
Frequency [Hz]
I s [n
orm
aliz
ed
]
healthyfaulthy
2fo-f
sfo+f
s
80 90 100 110 120 130 140 150 160 170
10-4
10-3
10-2
10-1
100
Frequency [Hz]
Acc
ele
ratio
n [
m/s
2]
Vibration frequency spectrum 1600 rpm
healthyfaulthy
2fo
fo
Instantaneous complex current signal
0 0.02 0.04 0.06 0.08 0.1-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
Time [s]
Ma
gn
itud
e [
no
rma
lize
d]
Intantaneous complex signal
is(t)
is(t-t)
magnitude (envelope)
Stator current and current envelope frequency spectrums
127 128 129 130 131 132 133 134 135 1360
0.5
1
1.5
2x 10
-3 Is normalized frequency spectrum
Frequency [Hz]
I s [nor
mal
ized
]
77 78 79 80 81 82 83 84 85 860
0.005
0.01
0.015
0.02
0.025Complex envelope spectrum
Frequency [Hz]
mag
nitu
de [n
orm
aliz
ed]
faulthyhealthy
faulthyhealthy
fo
fs+f
oStator current
spectrum
Complex signalmagnitudespectrum
Complex signal magnitude frequency spectrumper phase
Stator currentsComplex signal magnitude spectrum
81 82 83 84 85 860
2
4
6
8
10
12
14
16
x 10-3 Complex envelope frequency spectrum, 1630 rpm
Frequency [Hz]
ma
gn
itud
e [
no
rma
lize
d]
Ias
Ibs
Ics
fo
Instantaneous negative sequence magnitude
Instantaneous symmetrical components
02
2
1 1 111
31
a
b
c
I t i t
I t a a i t
I t a a i t
02
2
1 1 111
31
a a
b b
c c
I t i t ji t t
I t a a i t ji t t
I t a a i t ji t t
Real valued instantaneous symmetrical components
Complex valued instantaneous symmetrical components
2
3j
a e
Complex signals frequency spectrum
0
0.02
0.04
0.06
mag
nitu
de
Frequency spectrum, 1630 rpm
0
1
2
3
4x 10
-3
mag
nitu
de
79 80 81 82 83 84 85 86 87 880
0.005
0.010
0
0.005
Frequency [Hz]
mag
nitu
de
fo
fo
fo
a) Current envelope spectrum average
b) Complex valued Instantaneous
negative sequence spectrum
c) Real valued Instantaneous
negative sequence spectrum
Fault severity analysis
Artificial bearing fault Fault frequency amplitude variation
0 1 2 3 4 5 6 71
1.5
2
2.5
3
3.5
4
4.5
5x 10-3
Defect width [mm]
f o a
mp
litu
de
[n
orm
aliz
ed
]
Fault frequency amplitude versus fault severity
Conclusions
• An IG analytical model was developed and a commercial machine test rig was used to verify the findings
• Research shows that there are frequency components in IG steady state stator current that are directly related to existence of bearing fault.
• Simulation and experimental data indicate that conventional CSA is not well suited for bearing fault detection.
• The use of complex signals is shown to considerably improve the fault detection using stator current analysis.
Thank You