Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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
Anti-Islanding Protection in Distribution Grids
KTH, School of Electrical Engineering and Computer Science (EECS).
2019 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The growing number of distributed generation in the electrical system increasesthe risk of unintentional islanding. Power system islanding is the eventthat a part of the grid is continuously powered by the distributed generation,while it is already electrically separated from the power grid[1]. Several consequencescan be caused by unintentional islanding, such as endangerment ofpersonnel, uncontrolled voltage and frequency operation and equipment damagedue to unsynchronised reclosing. Therefore, it’s important to detect islandingevents quickly and reliably.The main objective of this thesis was to investigate the performance ofthree passive islanding detection methods for Ellevio’s 50kV distribution network.These detection methodswere under/over voltage, under/over frequencyand rate of change of frequency (ROCOF). Aiming at the objective, a dynamicmodel was built in MATLAB/Simulink for Ellevio’s distribution network,where the three methods were implemented and applied to the DGs.Moreover, the performance of the methods was evaluated by the non detectionzone (NDZ) and detection time, and it was studied under several simulations.Firstly, a NDZ of each method was found for a Single Machine Infinite Bus(SMIB) system and compared with the results obtained in Ellevio’s network.Besides, the detection time was measured under various islanding conditionsto evaluate the response speed of the detection methods. Apart from the sensitivityand response speed, the reliability of the detection methods was alsoinvestigated because the detection methods should not mistakenly operate inthe case of non-islanding events. Thus, the load switchings and short-circuitfaults were simulated as the disturbance events to test the reliability of detectionmethods. In the end, all three methods were compared, and their advantagesand disadvantages were summarized.

Abstract [sv]

Det växande antalet av distribuerad generering i elsystemet ökar risken föroavsiktlig ö-drift. Ö-drift innebär att en del av elnätet kontinuerligt drivs avden distribuerade genereringen, medan den redan är elektriskt separerad frånelnätet [1]. Flera konsekvenser kan orsakas av oavsiktlig ö-drift, till exempelutsätta personal för fara, okontrollerad spänning och frekvens och skador påutrustning på grund av osynkroniserad återinkoppling. Därför är det viktigt attupptäcka ö-drift snabbt och tillförlitligt.Huvudsyftet med denna avhandling var att undersöka prestanda av tre passivametoder för att upptäcka ö-drift för Ellevios 50kV distributionsnät. Dessadetektionsmetoder var under-/överspänning, under-/överfrekvens och frekvensförändring(ROCOF). I syfte att uppnå målet byggdes en dynamisk modelli MATLAB / Simulink för Ellevios distributionsnät, där de tre metodernaimplementerades och tillämpades på den distribuerade genereringen. Dessutomutvärderades metodens prestanda av icke-detekteringszonen (NDZ) ochdetekteringstiden, och det studerades under flera simuleringar.För det första hittades en NDZ av varje metod för ett SMIB-system ochde jämfördes med de funna NDZ i Ellevios nätverk. Vidare uppmättes detekteringstidenunder olika ö-driftsförhållanden för att utvärdera svarshastighetenhos detekteringsmetoderna. Bortsett från känslighets- och svarshastighetenundersöktes också detekteringsmetodernas tillförlitlighet, eftersom detekteringsmetodernainte skulle fungera felaktigt då ö-drift inte sker. Sålunda simuleradesbelastningsomkopplingarna och kortslutningsfel som störningshändelserför att testa pålitligheten för detekteringsmetoderna. I slutet jämfördesalla tre metoderna, och deras fördelar och nackdelar sammanfattades.

Place, publisher, year, edition, pages
2019. , p. 44
Series
TRITA-EECS-EX ; 2019:298
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-254420OAI: oai:DiVA.org:kth-254420DiVA, id: diva2:1332058
External cooperation
Ellevio
Educational program
Master of Science - Electric Power Engineering
Examiners
Available from: 2019-06-27 Created: 2019-06-27 Last updated: 2019-06-27Bibliographically approved

Open Access in DiVA

fulltext(1629 kB)45 downloads
File information
File name FULLTEXT01.pdfFile size 1629 kBChecksum SHA-512
0bd540db49369fc2b802226290a45b428b3ea24202b153e36d727e975f0e3ee97235cbbcfbe7b65783dacc5b86190672361c7c790bafbeaf5945b617e32b7209
Type fulltextMimetype application/pdf

By organisation
School of Electrical Engineering and Computer Science (EECS)
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 45 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

urn-nbn

Altmetric score

urn-nbn
Total: 106 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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