Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Electromagnetic Modelling of Power Transformers with DC Magnetization
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

DC currents that flow through the ground can be injected to the star windings of power transformers from their grounded neutral points and close their path with transmission lines. The geomagnetically induced currents (GICs) and AC/DC convertors of high voltage direct current (HVDC) systems are the sources of such DC currents. These currents may cause saturation of the core in power transformers that leads to destruction in the transformer performance. This phenomenon results in unwanted influences on power transformers and the power system. Very asymmetric magnetization current, increasing losses and creation of hot spots in the core, in the windings, and the metallic structural parts are adverse effects that occur in transformers. Also, increasing demand of reactive power and misoperation of protective relays menaces the power network. Damages in large power transformers and blackouts in networks have occurred due to this phenomenon

Hence, studies regarding this subject have taken the attention of researchers during the last decades. However, a gap of a comprehensive analysis still remains. Thus, the main aim of this project is to reach to a deep understanding of the phenomena and to come up with a solution for a decrease of the undesired effects of GIC.

Achieving this goal requires an improvement of the electromagnetic models of transformers which include a hysteresis model, numerical techniques, and transient analysis.

In this project until now, a new algorithm for digital measurement of the core materials is developed and implemented. It enhances the abilities of accurate measurements and an improved hysteresis model has been worked out. Also, a novel differential scalar hysteresis model is suggested that easily can be implemented in numerical methods. Three dimensional finite element models of various core types of power transformers are created to study the effect on them due to DC magnetization. In order to enhance the numerical tools for analysis of low frequency transients related to power transformers and the network, a distributed reluctance network method has been outlined. In this thesis a method for solving such a network problem with coupling to an electrical circuit and taking hysteresis into account is suggested.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , xv, 86 p.
Keyword [en]
Transformer, Hysteresis, DC magnetization, GICs, FEM, reluctance network method
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-105395ISBN: 978-91-7501-537-8 (print)OAI: oai:DiVA.org:kth-105395DiVA: diva2:570755
Presentation
2012-11-29, Sal F3, Lindstedsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20121121

Available from: 2012-11-21 Created: 2012-11-20 Last updated: 2012-11-27Bibliographically approved
List of papers
1. Differential Approach of Scalar Hysteresis Modeling Based on the Preisach Theory
Open this publication in new window or tab >>Differential Approach of Scalar Hysteresis Modeling Based on the Preisach Theory
2011 (English)In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 47, no 10, 3040-3043 p.Article in journal (Refereed) Published
Abstract [en]

This paper introduces a differential approach to model scalar hysteresis based on the Preisach theory. This model can generate hysteresis trajectories for both symmetrical and asymmetrical minor loops and keep the memory of a material in a proper manner. It can easily be inverted, it has a simple algorithm with suitable computational speed, and is not memory consuming. Also, the obtained results of the model are in very good agreement with measurements.

Keyword
Hysteresis, Preisach theory, magnetic materials, transformers
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-51292 (URN)10.1109/TMAG.2011.2144576 (DOI)000296418200184 ()2-s2.0-80053502096 (Scopus ID)
Note
QC 20111212Available from: 2011-12-12 Created: 2011-12-12 Last updated: 2017-12-08Bibliographically approved
2. Investigation of GIC effects on core losses in single phase power transformers
Open this publication in new window or tab >>Investigation of GIC effects on core losses in single phase power transformers
2011 (English)In: Archives of Electrical Engineering, ISSN 0004-0746, Vol. 60, no 1, 35-47 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents a method for estimation of core losses in banks of single phase power transformers that are subjected to an injected DC current such as geomagnetically induced currents (GIC). The main procedure of the core loss calculation is to obtain a magnetic flux density waveform in both time and location by using a novel algorithm based on 3D FEM inside the core and then to calculate the loss distribution based on loss separation theory. Also, a simple and effective method is proposed for estimation of losses of asymmetric minor loops by using combination of symmetric loops. The effect of DC biasing on core losses in single phase power transformers is investigated and the sensitivity of core type and material is evaluated. the results shows that DC current biasing could increase core losses up to 40 percent or even more.

Keyword
GIC, Power Transformers, Core losses
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-71045 (URN)10.2478/v10171-011-0004-9 (DOI)2-s2.0-79957508246 (Scopus ID)
Note
QC 20120206Available from: 2012-01-30 Created: 2012-01-30 Last updated: 2012-11-21Bibliographically approved
3. Implementation of hysteresis model in transient analysis of nonlinear reluctance networks
Open this publication in new window or tab >>Implementation of hysteresis model in transient analysis of nonlinear reluctance networks
2012 (English)In: ICEMS 2012 - Proceedings: 15th International Conference on Electrical Machines and Systems, 2012, 6401749- p.Conference paper, Published paper (Refereed)
Abstract [en]

This paper introduces a method for implementation of hysteresis models in nonlinear reluctance networks for performing transient analyses. The proposed method for solving the nonlinear circuits is based on local linearization and doesn't have the problems of non-convergency and demands to high number of iteration. The ability of coupling between electrical and magnetic circuit make it very suitable for study transient phenomena in a power network related to nonlinearity of magnetic materials such as ferroresonance, inrush current and DC magnetization.

Keyword
Hysteresis, Nonlinear, Reluctance Network, Transient
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-105394 (URN)000332791700051 ()2-s2.0-84873477149 (Scopus ID)978-488686077-4 (ISBN)
Conference
15th International Conference on Electrical Machines and Systems, ICEMS 2012; Sapporo; 21 October 2012 through 24 October 2012
Note

QC 20121120

Available from: 2012-11-20 Created: 2012-11-20 Last updated: 2014-10-14Bibliographically approved
4. Novel Method for Calculation of Losses in Foil Winding Transformers under Linear and non-Linear loads by Using Finite Element Method
Open this publication in new window or tab >>Novel Method for Calculation of Losses in Foil Winding Transformers under Linear and non-Linear loads by Using Finite Element Method
2010 (English)In: Advanced research workshop on transformers, ARWtr 2010, 2010, 326-331 p.Conference paper, Published paper (Other academic)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-71054 (URN)
Conference
Advanced research workshop on transformers, ARWtr 2010. Santiago de Compostela. Spain. 3 - 6 October 2010
Note
QC 20120425Available from: 2012-01-30 Created: 2012-01-30 Last updated: 2012-11-21Bibliographically approved

Open Access in DiVA

fulltext(4814 kB)2367 downloads
File information
File name FULLTEXT01.pdfFile size 4814 kBChecksum SHA-512
b1ba99db9e988b207c848279350969585def7a24da594a61f4c9b2d1ed20200cc69af9454e2aa185bca5e83aea7cc42efeedeb31640c9c9835a0781d2e34666e
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Mousavi, Seyed Ali
By organisation
Electromagnetic Engineering
Other Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 2367 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 530 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf