Recent Trends in the Condition Monitoring of Transformers: Theory, Implementation and Analysis

289 Pages·2013·6.785 MB·English

by  Sivaji Chakravorti, Debangshu Dey, Biswendu Chatterjee (auth.)

Power Systems
Sivaji Chakravorti
Debangshu Dey
Biswendu Chatterjee
Recent Trends
in the Condition
Monitoring of
Transformers
Theory, Implementation and Analysis
Power Systems
For furthervolumes:
http://www.springer.com/series/4622
Sivaji Chakravorti Debangshu Dey
•
Biswendu Chatterjee
Recent Trends in the
Condition Monitoring
of Transformers
Theory, Implementation and Analysis
123
SivajiChakravorti
DebangshuDey
BiswenduChatterjee
Electrical EngineeringDepartment
JadavpurUniversity
Kolkata
India
ISSN 1612-1287 ISSN 1860-4676 (electronic)
ISBN 978-1-4471-5549-2 ISBN 978-1-4471-5550-8 (eBook)
DOI 10.1007/978-1-4471-5550-8
SpringerLondonHeidelbergNewYorkDordrecht
LibraryofCongressControlNumber:2013949664
(cid:2)Springer-VerlagLondon2013
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Dedicated to
our parents
and also to
Mrs. Manidipa Chakravorti
Ms. Tatiana Chakravorti
Ms. Titir Chakravorti
and
Mrs. Tanaya Dey
who are the strength, support and inspiration
behind each word…
Foreword
Transformers are a major component of electric power systems and are well
studied by electric power engineers. The key components of most power trans-
formers are the three phases of electrical copper/aluminum wire windings wound
aroundhighmagneticpermeabilitycoressurroundedbyinsulatingtransformeroil
andpaper/pressboardinsulation.TheintroductioninChap.1discussestransformer
failures and statistics, aging of transformers, diagnosis methods, transformer oil
and paper insulation, and remaining life analysis. Chapter 2 analyzes impulse
faults in transformers using modern circuit analysis including time-frequency
domain methods, wavelet transforms, and fractals. Chapter 3 treats partial
discharge measurement and analysis, detection methods, and signal analysis.
Chapter 4 treats conventional diagnostic techniques of chemistry, dissolved gas
analysis, degree of polymerization measurements, furan in oil analysis, insulation
resistancemeasurements,anddielectricloss-factormeasurements.Chapter5treats
time domain dielectric response measurements, time domain response of trans-
former insulation, effect of noise on dielectric response measurements in field
conditions,modelingofdielectricresponse,andinterpretationoftimedomaindata
using a dielectric response model. Chapter 6 on frequency domain spectroscopy
treats the basic theory of frequency domain measurements, modeling dielectric
response in the frequency domain, and advises on the advantages and disadvan-
tages of dielectric response measurements in time and frequency domains.
Chapter 7 on methods offrequency response analysis treats basic measurements,
basic features of swept frequency response analysis and measurement connection
methods, transfer function features including isolated two-winding transfer func-
tions,layer-typehelicalwinding,continuousdiskwinding,shieldeddiskwinding,
interleaved disk winding, windings placed on outer and middle limbs, and high
voltage high power autotransformers. Chapter 7 also treats an assessment of
mechanical integrity of a transformer winding, key factors and comparisons of
frequency response measurements, and online frequency response analysis.
Chapter8concludesthebookonthetopicofremaininglifeanalysesincludinglife
estimation based on thermal modeling, cellulose degradation kinetics, and prob-
abilistic approaches. This is a ‘‘must have’’ reference book for anyone working
with modern power transformers.
The first author of the book, Prof. S. Chakravorti, was Chairman of the IEEE
KolkataSectioninIndia,andiswellexperiencedtowritesuchacompletebookon
vii
viii Foreword
the important topic ofmodern power transformers. He is a Professor of Electrical
Engineering at Jadavpur University, Kolkata, India, and has been elected to the
Fellowship of the National Academy of Sciences India and the Indian National
AcademyofEngineering.HereceivedhisPh.D.in1993fromJadavpurUniversity
andbecameaLecturerin1985workinghiswaytoProfessorin2002.Hisresearch
group,includingtwoco-authors,worksonnumericalfieldcomputation,condition
monitoring of transformers, partial discharge analysis, data acquisition and signal
conditioning in high voltage systems, computer aided design and optimization of
insulation systems, application of artificial intelligence to high voltage systems,
andlifelonglearningtechniques.From1992to2013hepublishedabout49papers
in refereed international journals and about 26 papers in refereed Indian journals.
He has completed 11 sponsored projects and has 2 ongoing projects and has
published one book on ‘‘Electrical Machines’’ in 1993. The three authors of this
book have one US Patent entitled ‘‘Remote Monitoring System’’ issued on
December 25, 2012. From 2005 to 2012 Prof. Chakravorti has given 14 IEEE
Power Engineering Society Distinguished Lectures; 15 invited lectures outside
India and 11 special invited lectures in India, and 95 other invited lectures within
India.Thisbookisavaluablecontributiontotheteachingandlearningofmodern
power transformers and their applications to modern electric power networks
around the world.
July 2013 Prof. Markus Zahn
Department of Electrical Engineering
and Computer Science
Massachusetts Institute of Technology,
Cambridge, MA, USA
Preface
Impulse testing of transformers is being carried out in the High Tension Labora-
toryofJadavpurUniversityinKolkata,India,formorethanfourdecades.Thefirst
authorofthisbookisafacultymemberassociatedwiththislaboratoryforthelast
28 years and is the In-Charge of this laboratory for the last decade. The insight
gained through such testing and also the specific queries of the designers of
transformers, which are being tested, gave the impetus to carry out detailed
researchonimpulsefaultanalysisoftransformers.Theauthorswouldliketothank
thebrilliantresearchscholars,whohadtakenpartinthisresearchprogramfunded
by national funding agencies. This research led to the development of accurate
tools for impulse fault diagnosis in transformers. However, impulse tests are
design acceptance tests that are performed on transformers before they are put in
service. In the early parts of the last decade, the first author was having regular
discussions with academics as well as engineers from power utilities not only in
India but also in Europe, USA, and Australia, wherein the main focus of the
discussions mainly veered on development of accurate methodologies for esti-
matingtheconditionoftransformersinservice.Thisisofgreatimportanceinview
of the large number of transformers that have been installed over the globe in the
1960sand1970sandarestillinservice.Fromthemaintenancepointofview,these
transformersposeathreattocontinuityofservice,butfromtheeconomicpointof
view these units cannot be replaced overnight. Hence, condition-based mainte-
nance and estimation of remaining life are of paramount importance to power
utilities in this deregulated era.
At this juncture, the first author thought of initiating a research program on
conditionmonitoringtechniquesoftransformers.Needlesstosay,theconventional
techniques of transformer condition monitoring have been in place for several
decades. But during the last two decades, major works are being carried out at
different laboratories around the world for development of reliable and accurate
conditionmonitoringtechniques,whicharenoninvasiveinnature.Inthiscontext,
promising electrical methods were being proposed. So the research at the High
TensionLaboratoryofJadavpurUniversitywasalsofocussedinthisdirection.The
greatest difficulty that was faced in this context was the inhibiting cost of diag-
nostic equipments that were available in the market. The first author did nothave
enough funds to procure such equipments to carry out the intended research. So
thereweretwoalternatives:eithertodeveloptheequipmentsstartingfromscratch
ix
x Preface
or to abandon the research. At this hour of despair came two outstanding
researchers, who not only developed required equipments but also developed
accurateanalysistoolsusingstate-of-the-artdataacquisitionandsignalprocessing
tools. The efforts of these three have resulted in filing several patents in India as
wellasintheUS,outofwhichonehasalreadybeengranted.Thenewsaboutthe
workcarriedoutbythisresearchgroupspreadwidelywithinIndiaandquiteafew
leading power utilities came for cooperative work. One such work has led to
successful implementation of the techniques developed by this research group in
one of the largest power companies in India. After the completion of the doctoral
work of these two bright researchers and successful practical implementation of
their techniques in real life, the first author requested them to write this book,
wherein they can share their expertise and insight gained through research works
over several years.
The authors feel that during the course of these research works and in the
preparation of this manuscript they have successfully transcended from acade-
miciansinvolvedinlaboratoryresearchtooneswhoknowhowtoimplementtheir
researchworksinreallifetakingintoaccountallthenuancesofpracticality.These
experiences have enriched their vision of engineering research enormously.
Asubstantialproportionofthematerialisoriginal,andhasbeentheoutcomeof
theresearchescarriedoutbytheauthors.However,helphasalsobeentakenfrom
thepublishedliterature.Inwritingthisbook,theauthorshaveassumedthatreaders
arewellacquaintedwiththeverybasicconceptsoftransformerdesign,operation,
and testing. The main characteristics of this book are:
(i) it assumes that the reader’s goal is to understand the critical balance of cost
and quality along with the pros and cons of different condition monitoring
techniques;
(ii) itpresentsaselectionoftechniqueswithappropriatetechnicalbackgroundto
understand their domain of applicability and to consider variations to suit
technical and organizational constraints;
(iii) it intends to extend the vision of condition monitoring testing and analysis
which is integral to modern maintenance practice; and
(iv) ittreatsconditionmonitoringtestingandanalysistoolstogetherinacoherent
framework, as complementary approaches so that adequate quality is
achieved at acceptable cost.
By going through this book, students and researchers will gain a proper
understandingoftheprinciplesandissuesinconditionmonitoringoftransformers.
Practicing engineers,including quality assurance professionals, will find a variety
of techniques with enough discussion on technical issues to support adaptation to
the specific requirements of their organization and application domain. Technical
managers will find a coherent approach to weaving condition monitoring tech-
niques into the overall maintenance strategy.
The authors would like to express their thanks to many colleagues and pro-
fessionals who gave constructive criticism and useful suggestions, all of whom
could not be mentioned by name here. However, the authors wish to express
Preface xi
sincere thanks to the following colleagues, former scholars and professionals,
without whom this book would not have materialized: Prof. Sugata Munshi, Dr.
Prithwiraj Purkait, Dr. Chiranjib Koley, Mr. P. Rajamani, Mr. Sovan Dalai, Mr.
Arijit Baral, and Mr. Monotosh Bhuti. This list of people is necessarily very
incomplete. The authors also wish to acknowledge the help and support extended
bytheMaster’sstudentswhohadatonepointoftimeorothertakenpartinthese
research works. This book could not have been completed without the help and
support of the families of the three authors. Hence, the authors sincerely thank
their families for having the patience and for selflessly cooperating with the
authors in taking the challenge, which decreased the amount of time the authors
could spend with their families during the course of this book writing.
TheauthorsareindebtedtoProf.MarkusZahnforhisgenerositytofindtimein
his demanding schedule to write the foreword to this book. The contribution of
Prof. Zahn in this context is gracefully acknowledged by the authors from the
bottom of their hearts.
In addition, the authors would like to acknowledge Jadavpur University and
DepartmentofScienceandTechnology,GovtofIndia,forprovidingthefinancial
and infrastructural support necessary for these research and development works.
Finally,theresponsibilitiesforanymistakesandfortheideasexpressedinthis
book are those of the authors’ only.
Kolkata, India, July 2013 Sivaji Chakravorti
Debangshu Dey
Biswendu Chatterjee