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Condition measuring and lifetime modelling of electrical power transmission equipment
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. (RCAM)ORCID iD: 0000-0002-2462-8340
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The electric grid is important in modern society, so the outages should be few. The transmission grid should have a real high availability, since it transports electrical energy across the country. Then, it is difficult to plan outages for maintenance and installation. This thesis lists twenty surveys about failures of circuit breakers and disconnectors, with data about the cause and the lifetime. It also contains a survey of about forty condition-measuring methods for circuit breakers and disconnectors, mostly applicable to the electric contacts and the mechanical parts.

As there is no published method to monitor the electric contacts at voltages around 400 kV, a system with IR sensors has been installed at the nine contacts of six disconnectors. The purpose is to avoid outages for maintenance by estimating the condition of the contacts while the disconnectors are still connected to high voltage. The measured temperatures are collected by radio and regressed against the square of the current, since the best exponent for the current was found to be 2.0. The coefficient of determination $R^2$ is high, greater than 0.9. This gives for each contact a regression coefficient, which can serve as an estimate of the condition of the contact. The higher the coefficient is, the more heat is produced at the contact, which can damage the material. This enables a ranking of the different contacts and shows which the worst ones are. This coefficient can also give a dynamic rating of the disconnector.

Abstract [sv]

Elnätet är viktigt i det moderna samhället, så antalet avbrott bör vara lågt. Särskilt stamnätet bör ha en särskilt hög tillgänglighet, då det transporterar elektrisk energi tvärsöver landet. Då blir det svårt att planera avbrott för underhåll och utbyggnad. Denna avhandling tar upp tjugo studier av fel i brytare och frånskiljare med data om felorsak och livslängd. Den har också en översikt av ett fyrtiotal olika metoder för tillståndsmätningar för brytare och frånskiljare, som huvudsakligen rör de elektriska kontakterna och de mekaniska delarna.

Eftersom det inte finns någon beskriven metod för att övervaka elektriska kontakter för spänningar på runt 400 kV, har ett system med IR sensorer installerats på de nio kontakterna på sex frånskiljare. Målet är att minska antalet avbrott för underhåll genom att skatta skicket hos kontakterna, när frånskiljarna fortfarande är kopplade till högspänning. De uppmätta temperaturerna tas emot genom radio och behandlas genom regression mot kvadraten av strömmen, då den bästa exponenten för strömmen visade sig vara 2,0. Förklaringsfaktorn $R^2$ är hög, över 0,9. För varje kontakt ger det en regressionskoefficient, som blir en skattning av kontaktens skick. Ju högre koefficienten är, desto mer värme utvecklas det i kontakten, vilket kan leda till skador på materialet. Kontakternas olika koefficienter ger en rankordning dem och därmed en möjlighet att prioritera vilken frånskiljare som ska underhållas först. Systemet kan också användas för att minska eller öka den tillåtna strömmen baserat på skicket.

Place, publisher, year, edition, pages
Stockhom: KTH Royal Institute of Technology, 2015. , xii, 26 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2015:026
Keyword [en]
disconnectors, circuit breakers, reliability, lifetime, electric contacts, electric power transmission
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-167136ISBN: 978-91-7595-611-4 (print)OAI: oai:DiVA.org:kth-167136DiVA: diva2:813154
Presentation
2015-06-12, Seminarierum H21, Teknikringen 33, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy Storage
Note

QC 20150522

Available from: 2015-05-22 Created: 2015-05-21 Last updated: 2015-05-22Bibliographically approved
List of papers
1. Benefits of Reliability Centred Asset Management
Open this publication in new window or tab >>Benefits of Reliability Centred Asset Management
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2013 (English)In: 22nd International Conference and Exhibition on Electricity Distribution (CIRED 2013), 2013, 0668- p.Conference paper, Published paper (Refereed)
Abstract [en]

This paper provides an overview of risk and reliability assessment techniques, some which are available for distribution system operators, and others that are in the process of development. The main contribution of this paper is showing the possibilities and benefits of detailed risk and reliability analysis. Six samples of findings from research developed over the last decade within the RCAM group (Reliability Centred Asset Management) at the Royal Institute of Technology, Stockholm Sweden, are presented. The research is directly associated with risk and asset management applied to power systems. The first three examples are within developed research, followed by three areas where great potential is seen: 1) The value of accurate thermal models of transformers; 2) The impact of tariff regulation on asset management decisions; 3) Detailed interruption studies; 4) Dynamic rating; 5) Combined risk and reliability analysis of primary equipment and control equipment; 6) Systematic diagnostic measures for asset management.

Series
IET Conference Publications, Volume 2013, Issue 615
Keyword
Diagnostic measures, Distribution systems, Management decisions, Primary equipments, Reliability assessments, Risk and reliability analysis, Royal Institute of Technology, Tariff regulation
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-123575 (URN)10.1049/cp.2013.0668 (DOI)2-s2.0-84897619482 (Scopus ID)978-184919732-8 (ISBN)
Conference
22nd International Conference and Exhibition on Electricity Distribution, CIRED 2013; Stockholm; Sweden; 10 June 2013 through 13 June 2013
Note

QC 20130718

Available from: 2013-06-12 Created: 2013-06-12 Last updated: 2015-10-02Bibliographically approved
2. A review of methods for condition monitoring, surveys and statistical analyses of disconnectors and circuit breakers
Open this publication in new window or tab >>A review of methods for condition monitoring, surveys and statistical analyses of disconnectors and circuit breakers
2014 (English)In: Probabilistic Methods Applied to Power Systems (PMAPS), 2014 International Conference on / [ed] Chris Dent, IEEE conference proceedings, 2014, 1-6 p.Conference paper, Published paper (Refereed)
Abstract [en]

There is a need for a new survey of condition-monitoring methods for circuit breakers and disconnectors, since during the last two decades less than ten surveys have been carried out. The paper presents several statistical surveys and analyses. The methods of condition monitoring found are reviewed and classified according to the different types of failure identified in the surveys. Some research gaps are identified, such as the prediction of the degradation of the contacts, the signal processing of coil and motor currents and the switching.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2014
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-166108 (URN)10.1109/PMAPS.2014.6960621 (DOI)000358734100044 ()2-s2.0-84916207673 (Scopus ID)9781479935611 (ISBN)
Conference
2014 International Conference on Probabilistic Methods Applied to Power Systems, PMAPS 2014, Durham, United Kingdom, 7-10 July 2014
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy Storage
Note

In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of [university/educational entity's name goes here]'s products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to http://www.ieee.org/publications_standards/publications/rights/rights_link.html to learn how to obtain a License from RightsLink. If applicable, University Microfilms and/or ProQuest Library, or the Archives of Canada may supply single copies of the dissertation.

QC 20150507

Available from: 2015-04-30 Created: 2015-04-30 Last updated: 2017-09-28Bibliographically approved
3. Using power system temperature sensors for moreuses than originally intended: Exemplified by investigating dynamic rating possibilities
Open this publication in new window or tab >>Using power system temperature sensors for moreuses than originally intended: Exemplified by investigating dynamic rating possibilities
2014 (English)In: NORDAC 2014 (Eleventh Nordic Conference on Electricity Distribution System Management and Development, Stockholm, 8 - 9 September 2014), Elforsk , 2014Conference paper, Published paper (Refereed)
Abstract [en]

Power system owners are facing major challenges with changed electricity consumption and production patterns; more distributed generation and increased demand of cost efficiency while maintaining high reliability. Today, the capacity of power components often is set with static limits based on simulations of worst case scenarios. This leads to a discrepancy between the actually-available capacity and the rating itself which unfortunately is left unused. The approach of dynamic rating implies that the capacity of a component is dynamically varying as a function of external parameters such as weather, load history and diagnostic indicators.

 

Svenska kraftnät (Swedish national grid) has installed temperature sensors with the purpose of developing condition monitoring methods in another research project. Within this project, the same infrastructure can perhaps be used to also evaluate dynamic rating algorithms of power lines or to develop new algorithms regarding e.g. disconnectors. Also the thermal modelling in that project can be reused. This paper hence exemplifies the possibility to get more applications without additional costly and complicated investments. The aim of the paper is hence to show on future research possibilities and bring ideas to discussion.

Place, publisher, year, edition, pages
Elforsk, 2014
Series
Elforsk rapport, 14:32
Keyword
Better utilization, Correlations, Dynamic rating, Power components, Power transmission, Transfer limitation, Weather sensors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-151015 (URN)
Conference
NORDAC 2014 (Eleventh Nordic Conference on Electricity Distribution System Management and Development, Stockholm, 8 - 9 September 2014)
Note

QC 20140922

Available from: 2014-09-12 Created: 2014-09-12 Last updated: 2015-05-22Bibliographically approved
4. Reliability Data: A Review of Importance, Use, and Availability
Open this publication in new window or tab >>Reliability Data: A Review of Importance, Use, and Availability
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2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

For reliability studies of power distribution systems availability and collection of data on reliability is a key aspect. The acquirement of data can be challenging, because it endures effort and experience to know where to obtain accessible types of data. This paper gives the reader a guide to why input data to reliability analyses and asset management are useful, which data that can be obtained, and how to access the different types of data. Also, how to measure data accurately and the quality needed are discussed in the paper.

After a general discussion on the benefits of data, we discuss the importance of knowing exactly what the data are measurements of. Furthermore, we argue that data from different contexts, even if seemingly similar, should be used with care. We also state and explain that the amount data restrict the type of analysis that can be conducted. The paper continues with a description of some examples of (to different degrees) open accessible data. Nationally collected reliability data from Swedish utilities, reported to authorities and interest organizations, are described and discussed. We discuss how Swedish weather data, which recently have become free and open, enable more studies on the weather related reliability effects, and some existing test systems are mentioned. A section follows that describes how failure and condition data are typically stored and utilized internally in organizations. Finally, we conclude that the paper is a potential guide and inspiration for anyone planning to conduct a reliability study in the future.

Series
Elforsk rapport 14:32
Keyword
Asset management, DARWin, Data management, Input data, Reliability analysis, Weather Data
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-151014 (URN)
Conference
NORDAC 2014 (Eleventh Nordic Conference on Electricity Distribution System Management and Development, Stockholm, 8 - 9 September 2014)
Note

QC 20140922

Available from: 2014-09-12 Created: 2014-09-12 Last updated: 2016-05-26Bibliographically approved
5. Condition monitoring of disconnectors in the electric power transmission grid with temperature sensors
Open this publication in new window or tab >>Condition monitoring of disconnectors in the electric power transmission grid with temperature sensors
2016 (English)In: International Journal of Industrial and Systems Engineering, ISSN 1748-5045, Vol. 23, no 1, 90-110 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents a method that can be used to rank disconnectors in the electric power system, according to the condition of one of the most critical parts, the contacts. The temperature of the contacts can be continuously measured by a new type of infrared sensor. For the case study, 54 sensors were placed on six disconnectors together with reference sensors measuring the ambient temperature. The measured temperature at each contact is then regressed against the ambient temperature and the current through the disconnector. Both a linear and a quadratic dependency of the current are tested and the quadratic one explains the data best. The coefficient of the current serves as a measure of the condition of the contact. Then, it becomes possible to identify in which contacts the resistance has increased the most. As a consequence, it is possible to make better maintenance decisions for the disconnectors.

Place, publisher, year, edition, pages
InderScience Publishers, 2016
Keyword
Electric power transmission, disconnectors, electric contacts, temperature measurement, infrared sensors, reliability, condition monitoring
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
Identifiers
urn:nbn:se:kth:diva-167119 (URN)10.1504/IJISE.2016.075809 (DOI)2-s2.0-84964761421 (Scopus ID)
Funder
SweGRIDS - Swedish Centre for Smart Grids and Energy Storage
Note

QC 20150522

Available from: 2015-05-21 Created: 2015-05-21 Last updated: 2017-09-28Bibliographically approved

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Licentiate Thesis(657 kB)244 downloads
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Westerlund, Per

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CiteExportLink to record
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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
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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