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SEMINAR PRESENTATION ON
DETECTION OF WINDING
DEFORMATION IN POWERTRANSFORMER
PISE SUMIT GOVIND
P13PS012
M.Tech POWER SYSTEMS
Dr. H. G. Patel
(Supervisor)
SARDAR VALLABHBHAI NATIONAL INSTITUTE OF TECHNOLOGY
SURAT-395007, GUJARAT, INDIA
DEPARTMENT OF ELECTRICAL ENGINEERING
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Outline
Introduction
Modelling a transformer winding
Frequency response analysis method
Deformation coefficient method
Conclusion
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Introduction
Overview
Detection winding deformation
Reactance comparison method
Frequency response analysis(FRA)
Using deformation coefficient
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Modelling a transformer winding
L11 L22 Lnn
L1n
L2n
Cg/2 Cg Cg Cg Cg/2
Cs Cs Cs
1 2 n
1
1'
2
2'
Fig. 1: Lumped parameter model
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Number of sections = 8
Number of turns in each section = 2018 SWG (Standard Wire Gauge)
Mean diameter of winding = 185 mm
Height of winding = 225 mm
Sectional series capacitance Cs= 2.2 nF
Sectional ground capacitance Cg = 1.0 nF
Inductance values (H)
L M1 M2 M3 M4 M5 M6 M7
117 58.1 31.4 19.14 12.55 8.6 5.95 4.45
(The measured self and mutual inductances are given in the table. Here, L
is the self-inductance of the sections, and M1, M2, etc., are the mutual
inductances between the sections. The suffix indicates sectional separation.
For example, mutual inductance between sections 1-4 or 2-5 or 3-6 or 4-7
is M3and that between sections 1-8 is M7.)
Parameters of the winding
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Frequency Response
AnalysisMethod Principle
Fault Diagnosis using FRA
Analysis with known reference recordings
Analysis without reference recordings
using different phases of the same transformer.
using a twin transformer.
Simulation Results
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0 1 2 3 4 5 6 7 8 9 10
x 104
100
1010
Impedance
Impeda
nce(ohms)
Frequency (Hz)
0 1 2 3 4 5 6 7 8 9 10
x 104
-100
-50
0
50
100
Phase
Phase(deg)
Frequency (Hz)
Fig. 2 Driving point impedance characteristic of a winding with terminals
22' shorted
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0 1 2 3 4 5 6 7 8 9 10
x 104
100
1010
Impedance
Impedance
(ohms)
Frequency (Hz)
0 1 2 3 4 5 6 7 8 9 10
x 104
-100
-50
0
50
100Phase
Phase(deg)
Frequency (Hz)
Fig. 3 Driving point impedance characteristic of a winding with terminals
22' open circuited
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0 1 2 3 4 5 6 7 8 9 10x 10
4
100
Impedance
Impedance(ohm
s)
Frequency (Hz)
0 1 2 3 4 5 6 7 8 9 10
x 104
-100
-50
0
50
100Phase
Phase
(deg)
Frequency (Hz)
No deformation
Section 4 radially deformed by 5%
Section 6 radially deformed by 15%
Section 8 radially deformed by 30%
Fig. 4 Driving point characteristic (open circuited farther end 22')
Comparison of FRA signatures for radially deformed section
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Comparative study of shift in natural frequencies due to radial deformation at different sections
Section Pole Zero
Frequency
kHz
Log(Z) Frequency
kHz
Log(Z)
Pole/zero number 1 1
No deformation
Section 4 by 5%
Section 6 by 15%
Section 8 by 30%
96.75
96.8
97.55
103
4.66
4.663
4.6548
4.685
41.1
41.2
42.2
44
0.34
0.34
0.335
0.325
Pole/zero number 2 2
No deformation
Section 4 by 5%
Section 6 by 15%
Section 8 by 30%
186
186.6
186.8
193
4.55
4.545
4.563
4.545
138
138.2
138.7
146
0.63
0.632
0.625
0.635
Pole/zero number 3 3
No deformation
Section 4 by 5%Section 6 by 15%
Section 8 by 30%
257.5
257.7259.3
261.5
4.325
4.3294.32
4.305
228
228230
234
1.015
1.0161.01
1.04
Pole/zero number 4 4
No deformation
Section 4 by 5%
Section 6 by 15%
Section 8 by 30%
322
322.5
323
324.6
4.035
4.03
4.03
4.025
303
304
304.5
306.25
1.3
1.3
1.31
1.31
Pole/zero number 5 5
No deformation
Section 4 by 5%
Section 6 by 15%Section 8 by 30%
380
380.5
381383
3.68
3.68
3.673.67
369
369.5
370.5372
1.595
1.595
1.5951.6
Pole/zero number 6 6
No deformation
Section 4 by 5%
Section 6 by 15%
Section 8 by 30%
432
432.5
433
434.2
3.32
3.325
3.32
3.305
425
425.5
426.2
427.9
1.86
1.86
1.865
1.87
Pole/zero number 7 7
No deformation
Section 4 by 5%
Section 6 by 15%
Section 8 by 30%
472
472
473.5
473.5
2.92
2.91
2.92
2.905
468
468.2
469.6
469.9
2.2
2.21
2.21
2.21
Frequency and amplitude of natural frequencies
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Deformation Coefficient Method
Principle
Procedural steps After isolating the transformer and removing electrical connections of the
winding under test with other windings and connecting all terminals of otherwindings to ground, the following four capacitance measurements need to bedone:
The capacitance (C1H) between winding terminals 1 and 1 at selected highfrequency (FH): The high frequency needs to be selected only once initially, andis such that the impedance offered by the winding remains capacitive beyond thatfrequency. This can be easily ensured by observing the phase of the impedance.
The capacitance (C2H) across winding terminals 2 and 2 at the same highfrequency.
The capacitance (C12H) across winding terminals 1 and 2 at the same high
frequency. The capacitance (CL) between winding terminals 1 and 1 or terminals 2 and 2 at
FL(a low frequency, say about 50 to 100 Hz): The low frequency is selected suchthat the measured impedance value is predominantly decided by the parallelcombination of sectional ground capacitances.
Only these four measured capacitances and two selected frequencies need tobe preserved as the fingerprint or reference values for the winding under test (for the
purpose of future diagnostics).
'
1 110 '
2 2
log H HH H
C CDC C C
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Uniqueness of Deformation Coefficient
For the eight sections winding model considered in this
work the expressions for DC as a function of p. u. changein sectional ground capacitance are given below.
For sections at the extreme ends,
Whereas, for the rest of the sections
The DC as a function of p.u. change in sectional series
capacitance is
Similarly, the expression for C12His of the form
2
10log
g
x a x bx cDC s k
x d x e
2
10 2log
g
x a x bx cDC s k
x d x ex f
10log sy g
DC s k y h
12H
yC k
y i
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Coefficient Sec-1 Sec-2 Sec-3 Sec-4 Sec-5 Sec-6 Sec-7 Sec-8
s
kg
a
b
c
d
e
f
ks
g
h
k
i
+
-1337.1
10.8
13.931
26.77
8.985
8.53
-----
74083
1.1830
1.9386
-196.1
1.4734
+
954.4
10.798
15.747
42.302
9.898
19.32
72.745
1146.1
1.3805
1.5703
-55.0
1.4734
+
56.0
10.794
16.545
49.947
10.502
17.529
57.402
59.08
1.445
1.4945
-17.6
1.4734
+
3.8
10.777
16.977
52.702
10.755
17.15
54.164
3.8387
1.4644
1.4743
-8.3
1.4734
-
3.8
10.777
16.977
52.702
10.755
17.15
54.164
3.8387
1.4644
1.4743
-8.3
1.4734
-
56.0
10.794
16.545
49.947
10.502
17.529
57.402
59.08
1.445
1.4945
-17.6
1.4734
-
954.4
10.798
15.747
42.302
9.898
19.32
72.745
1146.1
1.3805
1.5703
-55.0
1.4734
-
-1337.1
10.8
13.931
26.77
8.985
8.53
-----
74083
1.1830
1.9386
-196.1
1.4734
Coefficient of above expression for different sections
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Simulation Results
0.05 0.1 0.15 0.2 0.25 0.30
0.5
1
1.5
2
2.5
3
3.5
4
p. u . deformation
DeformationCoefficient
Sectional ground capacitance change
For first section
For second section
For third section
For fourth section
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0.05 0.1 0.15 0.2 0.25 0.30.5
1
1.5
2
2.5
3
3.5
4
4.5
5
p. u. deformation
Deforma
tioncoefficient
Sectional series capacitance change
For first section
For second section
For third sectionFor fourth section
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0.05 0.1 0.15 0.2 0.25 0.30
10
20
30
40
50
60
p. u. change in sec tional Cs(Base Cs=2.2nF, Cg=1.0nF)
Changein
C12H(inpF)
Change in C12H v/s sectional deformation
section 1 or 8 deformed
section 2 or 7 deformed
section 3 or 6 deformed
sectioin 4 or 5 deformed
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Conclusion
For FRA method, one requires lengthy algorithms,advanced resources and possibly, the analysis by an
expert to deduce the conclusions about the location and
extent of deformation.
Unlike FRA diagnostic studies, the deformationcoefficient (DC) method does not require frequency
sweep to deduce conclusions about winding state. Also,
the need of interpretation by an expert is not essential.
Hence the method of deformation coefficient is the mostsuitable method for detecting transformer winding
deformation.
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References
[1] E. Al-Ammar, G. G. Karady, and O. P. Hevia, "Improved technique for fault detection sensitivity in transformermaintenance test," inPower Engineering Society General Meeting, 2007. IEEE, 2007, pp. 1-8.
[2] P. M. Joshi and S. V. Kulkarni, "A diagnostic method for determining deformations in a transformer or reactor
winding,"Indian Patent Application No, 1893.
[3] P. M. Joshi and S. V. Kulkarni, "Use of Deformation Coefficient for Transformer Winding Diagnostics,"
International Journal of Emerging Electric Power Systems, vol. Vol. 9, p. Art. 7, October 2008.
[4] E. Dick and C. Erven, "Transformer diagnostic testing by frequency response analysis," Power Apparatus and
Systems, IEEE Transactions on,pp. 2144-2153, 1978.
[5] V. Venegas, J. L. Guardado, S. G. Maximov, and E. Melgoza, "A computer model for surge distribution studies in
transformer windings," inEUROCON 2009, EUROCON'09. IEEE, 2009, pp. 451-457.
[6] S. V. Kulkarni and S. Khaparde, "Transformer engineering: design and practice" Power engineering. New York,
NY: Marcel Dekker, Inc, vol. 25, 2004.
[7] K. Ragavan and L. Satish, "Localization of changes in a model winding based on terminal measurements:
Experimental study,"Power Delivery, IEEE Transactions on, vol. 22, pp. 1557-1565, 2007.
[8] M. Wang, A. J. Vandermaar, and K. Srivastava, "Improved detection of power transformer winding movement by
extending the FRA high frequency range,"Power Delivery, IEEE Transactions on, vol. 20, pp. 1930-1938, 2005.
[9] E. Rahimpour, J. Christian, K. Feser, and H. Mohseni, "Transfer function method to diagnose axial displacement
and radial deformation of transformer windings,"Power Delivery, IEEE Transactions on, vol. 18, pp. 493-505, 2003.
[10] P. M. Joshi and S. V. Kulkarni, "Transformer winding diagnostics using deformation coefficient," in Power and
Energy Society General Meeting-Conversion and Delivery of Electrical Energy in the 21st Century, 2008 IEEE, 2008,
pp. 1-4.
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