SEMINAR PowerPoint Presentation.pptx

8/10/2019 SEMINAR PowerPoint Presentation.pptx

1/18

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


2/18

Outline

Introduction

Modelling a transformer winding

Frequency response analysis method

Deformation coefficient method

Conclusion


3/18

Introduction

Overview

Detection winding deformation

Reactance comparison method

Frequency response analysis(FRA)

Using deformation coefficient


4/18

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


5/18

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


6/18

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


7/18

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


9/18

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%



Fig. 4 Driving point characteristic (open circuited farther end 22')

Comparison of FRA signatures for radially deformed section


10/18

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


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


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


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


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


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


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


11/18

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


12/18

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


13/18

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


14/18

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


15/18

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


16/18

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



sectioin 4 or 5 deformed


17/18

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.


18/18

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,

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SEMINAR PowerPoint Presentation.pptx