umu.sePublications
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
Användande av lokala nollpunktsreaktorer: Hantering av kapacitiva jordfelsströmmar i kabelnät
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
2017 (Swedish)Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesisAlternative title
Using local neutral point reactors : Dealing with capacitive earth fault currents in cable grids (English)
Abstract [en]

The rural power grid has traditionally mostly consisted of overhead power lines. In recent years the trend has been to replace the overhead lines with cables instead. The reason is that overhead lines are relatively vulnerable, strong winds and storms can cause trees and branches to fall over the power lines and cause a phase to ground fault. This will then trip the ground fault relays and disconnect the faulty power line. A cable grid is not vulnerable in the same way, and could be considered a solution to make the power grid more reliable. A cable grid does come whit other types of problems instead. It generates about 50 times more phase to ground capacitance compared with the same length of overhead lines. When a phase to ground fault occurs the capacitance in the healthy phases will generate a current to ground and then through the fault. On average a cable grid generates about 2 A per kilometer. Large cable grids can therefore cause very large capacitive currents to flow through the fault.  To counter this, a reactor is placed between the neutral point of the transformer and ground. When a phase to ground fault occurs, the reactor will generate an inductive current which is in the opposite phase compared to the capacitive current. This current will flow through the faulty line and cancel out the capacitive current. In a perfectly tuned power grid the only component left in the fault is a smaller resistive current. Large cable grids will require a large reactor to generate the large inductive current, which might need to flow over a great distance in the grid to reach the fault location. To reduce the inductive current from the central reactor, it is possible to install smaller local reactors in the grid. These will then in the event of a phase to ground fault generate a part of the inductive current, which will reduce the currents from the central reactor. This report will look at the factors related to grounding systems and how these factors affect the ground fault currents. The purpose of the report is to give recommendations to Umeå Energi on where in their grid they should install additional local reactors and also which factors they should consider when doing future expansions and rebuilds of their power grid.  

Place, publisher, year, edition, pages
2017. , 38 p.
Series
EL, 1703
Keyword [sv]
Nollpunktsreaktor, p-spole, petersen-spole, släckspole, kapacitiva strömmar, kabelnät, systemjordning, jordfelsskydd, högspänningskablar
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:umu:diva-136842OAI: oai:DiVA.org:umu-136842DiVA: diva2:1114192
External cooperation
Umeå Energi
Subject / course
Elektronik
Educational program
Högskoleingenjörsprogrammet i Elkraftteknik - nätbaserat
Presentation
2017-06-01, Mithuset, Umeå Universitet 901 87, Umeå, 15:06 (Swedish)
Supervisors
Examiners
Available from: 2017-06-22 Created: 2017-06-22 Last updated: 2017-06-22Bibliographically approved

Open Access in DiVA

Användande av lokala nollpunktsreaktorer(1981 kB)10 downloads
File information
File name FULLTEXT01.pdfFile size 1981 kBChecksum SHA-512
51f7ccfda7f32aa127589d67a30f5dd48453b819c604f41a9a7cd3cd3f4566b320a50d7ea06fc903e7d6bf87fb1097fa16f499c34bbbc1538baa478ac5c2215a
Type fulltextMimetype application/pdf

By organisation
Department of Applied Physics and Electronics
Other Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 10 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

Total: 71 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