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Using power system temperature sensors for moreuses than originally intended: Exemplified by investigating dynamic rating possibilities
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. (RCAM)ORCID iD: 0000-0001-6882-3642
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. (RCAM)ORCID iD: 0000-0002-2462-8340
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. (RCAM)ORCID iD: 0000-0002-2964-7233
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 [en]
Better utilization, Correlations, Dynamic rating, Power components, Power transmission, Transfer limitation, Weather sensors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-151015OAI: oai:DiVA.org:kth-151015DiVA: diva2:746295
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
In thesis
1. Condition measuring and lifetime modelling of electrical power transmission equipment
Open this publication in new window or tab >>Condition measuring and lifetime modelling of electrical power transmission equipment
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
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:nbn:se:kth:diva-167136 (URN)978-91-7595-611-4 (ISBN)
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

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