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
Variable frequency partial discharge analysis of in-service aged machine insulation
KTH, Superseded Departments, Electrical Systems.
KTH, Superseded Departments, Electrical Systems.
2003 (English)In: Proceedings Nordic Insulation Symposium, 2003, 29-35 p.Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
2003. 29-35 p.
Keyword [en]
variable frequency, phase resolved, partial discharge, machine insulation
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-8456OAI: oai:DiVA.org:kth-8456DiVA: diva2:13785
Conference
Nordic Insulation Symposium, Tampere, June 11-13, 2003
Note
QC 20100722Available from: 2008-05-16 Created: 2008-05-16 Last updated: 2010-11-29Bibliographically approved
In thesis
1. Modelling of cavity partial discharges at variable applied frequency
Open this publication in new window or tab >>Modelling of cavity partial discharges at variable applied frequency
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The presence of partial discharges (PD) in high voltage components is generally a sign of defects and degradation in the electrical insulation. To diagnose the condition of high voltage insulation, PD measurements is commonly used. The Variable Frequency Phase Resolved PD Analysis (VF-PRPDA) technique measures PD at variable frequency of the applied voltage. With this technique, the frequency dependence of PD can be utilized to extract more information about the insulation defects than is possible from traditional PD measurements at a single applied frequency.

In this thesis the PD process in a disc-shaped cavity is measured and modelled at variable frequency (0.01 - 100 Hz) of the applied voltage. The aim is to interpret the PD frequency dependence in terms of physical conditions at the cavity. The measurements show that the PD process in the cavity is frequency dependent. The PD phase and magnitude distributions, as well as the number of PDs per voltage cycle, change with the varying frequency. Moreover, the PD frequency dependence changes with the applied voltage amplitude, the size of the cavity and the location of the cavity (insulated or electrode bounded).

A physical model is presented and used to dynamically simulate the sequence of PDs in the cavity at different applied frequencies. The simulations show that essential features in the measured PD patterns can be reproduced. The PD frequency dependence is interpreted as a variation in influence on the PD activity from the statistical time lag of PD and the charge transport in the cavity surface, at different applied frequencies. The simulation results also show that certain cavity parameters, like the cavity surface conductivity and the rate of electron emission from the cavity surface, change with the time between consecutive PDs, and accordingly with the applied frequency. This effect also contributes to the PD frequency dependence.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. viii, 74 p.
Series
Trita-EE, ISSN 1653-5146 ; 2008:018
Keyword
partial discharges, measurements, modelling, variable frequency, cavities, disc-shaped, polycarbonate
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-4756 (URN)978-91-7178-927-3 (ISBN)
Public defence
2008-06-04, F3, Lindstedtsvägen 26, Stockholm, 13:15
Opponent
Supervisors
Note
QC 20100722Available from: 2008-05-16 Created: 2008-05-16 Last updated: 2010-07-22Bibliographically approved
2. Partial discharges in cylindrical cavities at variable frequency of the applied voltage
Open this publication in new window or tab >>Partial discharges in cylindrical cavities at variable frequency of the applied voltage
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Measurements of partial discharges are commonly used to diagnose the insulation system in high voltage components. Traditionally a single xed frequency of the applied voltage is used for such measurements as in the Phase Resolved Partial Discharge Analysis (PRPDA) technique. With the Variable Frequency Phase Resolved Partial Discharge Analysis (VF-PRPDA) technique the frequency of the applied voltage is instead variable. This technique provides more information about the condition of the insulation than the PRPDA technique. To extract the extra information a physical understanding of the frequency dependence of partial discharges is necessary.

In this thesis partial discharges in cylindrical cavities in polycarbonate are measured using the VF-PRPDA technique in the frequency range 10 mHz { 100 Hz. It is studied how the cavity diameter and height inuence the frequency dependence of partial discharges. Insulated cavities are compared with cavities bounded by an electrode. It is shown that from measurements at variable applied frequency it is possible to distinguish between cavities of di erent dimensions and between insulated and metal bounded cavities.

A two-dimensional eld model of partial discharges in a cylindrical cavity is developed. The sequence of discharges in the cavity is simulated by use of the eld computation program FEMLABR. Discharges are modeled with a voltage and current dependent streamer conductivity and are simulated dynamically to obtain charge and current consistency. It is shown that the frequency dependence of partial discharges is signi - cantly inuenced by the statistical time lag and by the two dielectric time constants related to charge movements on the cavity surface and in the bulk insulation. Simulation results are used to interpret the frequency dependent partial discharge activity in a cylindrical cavity.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. viii, 49 p.
Series
Trita-ETS, ISSN 1650-674X ; 2005:13
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-477 (URN)91-7178-169-2 (ISBN)
Presentation
2005-11-11, Sal H1, Teknikringen 33, Stockholm, 13:00
Opponent
Supervisors
Note
QC 20101129Available from: 2005-11-08 Created: 2005-11-08 Last updated: 2010-11-29Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Edin, HansForssén, Cecilia
By organisation
Electrical Systems
Other Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 245 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