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harmonic content in partial discharge current measured with dielectric spectroscopy
KTH, Tidigare Institutioner                               , Elektrotekniska system.
1998 (engelsk)Inngår i: Annual report. 1998, 1998Konferansepaper, Publicerat paper (Annet vitenskapelig)
Abstract [en]

Phase resolved partial discharge analysis and dielectricspcctroscopy measurements have been performed at50Hz and variable voltage on two artificial defects thathave different average charge phase distributions. Influenceof partial discharges on permittivity and loss-factoris dcduced to the phase position of the partial dischargeactivity. Symmetry properties between positive andnegative charge distributions have been related to theharmonic content of the partial discharge current.

sted, utgiver, år, opplag, sider
1998.
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-13113ISBN: 0-7803-5036-7 (tryckt)ISBN: 0-7803-5035-9 (tryckt)ISBN: 0-7803-5037-5 (tryckt)OAI: oai:DiVA.org:kth-13113DiVA, id: diva2:320947
Konferanse
Conference on Electrical Insulation and Dielectric Phenomena
Merknad
QC 20100527Tilgjengelig fra: 2010-05-27 Laget: 2010-05-27 Sist oppdatert: 2010-05-27bibliografisk kontrollert
Inngår i avhandling
1. Partial Discharges Studied with Variable Frequency of the Applied Voltage
Åpne denne publikasjonen i ny fane eller vindu >>Partial Discharges Studied with Variable Frequency of the Applied Voltage
2001 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis concerns partial discharge (PD) diagnostics withvariable frequency of applied voltage in the frequency range 1mHz - 400 Hz. The exploration of a new type of spectroscopythat combines partial discharge analysis and dielectricresponse is demonstrated. A question addressed is if and howthe PD activity varies with the frequency of the appliedvoltage. The nature of an existing frequency dependence couldbe useful in the classification of different defects and tojudge the degree of progressive ageing.

A Variable-Frequency Phase Resolved Partial DischargeAnalysis (VF-PRPDA) technique is developed for the appliedvoltage frequency range 1 mHz - 400 Hz. The VF-PRPDA techniqueis combined with a system for high voltage dielectricspectroscopy that allows simultaneous measurements. TheVF-PRPDA technique is used for studying the frequencydependence of PD. The PD activity is for example measured byintegrated measures like total charge per cycle and totalnumber of discharges per cycle. Statistical measures like mean,standard deviation, skewness, kurtosis etc. are applied tomeasure the frequency dependence of the phasedistributions.

High voltage dielectric spectroscopy is supplemented withharmonic analysis for studying non-linear dielectric responsecurrents.

The VF-PRPDA technique is demonstrated on defined objectslike point-plane gaps and artificial voids, but also on aninsulated stator bar and a paper insulated cable. Surfacedischarges on insulating surfaces are studied in an environmentwith a controlled relative humidity and temperature. Theadsorption of moisture on the insulating surface alters thesurface conductivity of the surface and the frequencydependence of the PD activity.

The influence of temperature upon the PD activity is studiedfor a oil paper insulated cable.

The results of the measurements show that the partialdischarge activity in general is frequency dependent over thefrequency range 1 mHz - 400 Hz. The reasons behind thefrequency dependence are linked to surface- and bulk-conducting mechanisms, frequency dependent field distributionsand statistical effects of the supply of start electrons.

An algorithm is developed that relates the phase resolved PDcurrent measured with the PRPDA technique to the non-linearcurrent measured with dielectric spectroscopy. The algorithm isexperimentally verified by simultaneous measurements of PRPDAand dielectric spectroscopy on defined objects. The resultsexplain the contribution of PD to the apparent capacitance andloss. Moreover, the harmonics of the fundamental currentcomponent yield information about, for example, polaritydependent discharge sources.

Keywords:diagnostic methods, partial discharges, phaseresolved, variable frequency, dielectric spectroscopy,dielectric response, harmonics, insulation

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2001. s. xiv, 163
Serie
Trita-EEA ; 0102
Emneord
diagnostic methods, partial discharges, phase resolved, variable frequency, dielectric spectroscopy, dielectric response, harmonics, insulation
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-3207 (URN)
Disputas
2001-09-14, 00:00 (engelsk)
Merknad
QC 20100527 NR 20140805Tilgjengelig fra: 2001-09-07 Laget: 2001-09-07 Sist oppdatert: 2010-05-27bibliografisk kontrollert

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Totalt: 173 treff
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