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Power line corona noise prediction from small cage measurement

Thesis (PhD) -- Stellenbosch University, 2004. / Some digitised pages may appear illegible due to the condition of the original hard copy. / ENGLISH ABSTRACT: The radio noise (RN) performance of an AC high voltage transmission line is a determining
factor when accessing the reliability of the design. The conducted RN level across the terminals
of a PLC receiver, used in the teleprotection system of the line, is of particular concern. In this
dissertation, existing empirical and semi-analytical RN prediction methods are evaluated by
comparing the conducted RN levels of four South African lines to the predicted levels.
Existing RN measurement protocols are consolidated and a new RN measurement protocol is
proposed for the comparison. A prediction methodology, based on the EdF, EPRI and IREQ
semi-analytical methods, is formulated. The semi-analytical methods are not able to accurately
predict the variation of the conducted RN with frequency in the PLC band, nor are they able to
predict the RN performance of short lines. A wideband excitation function, which considers the
statistical characteristics of the measured RN pulse train, is therefore proposed in this
dissertation. Having investigated the extraction of this excitation function from ESKOM’s
Megawatt Park corona cage, it is concluded that a small corona cage is required. The design of
a small cage is presented and the extraction of the excitation function is described. Attention is
given to assessing the effect of changes in space charge distributions. The effect of space charge
collision with an insulated cage on the extracted pulse parameters is linear, provided space charge
diffusion is negligible. The onset streamer, positive streamer and negative streamer corona modes
were identified as the only modes with measurable RN in the frequency regime 150 kHz to 30
MHz. Formulas are derived for the prediction of the inception gradients for these modes. The RN
performance of an ACSR Hare conductor is extracted from the small cage. The RN performance
of the Acacia-Koeberg line is also approximated in the PLC band.
The dissertation concludes that the proposed wideband excitation function method is capable of
accurately predicting the variation of RN levels with frequency. It can also be used to predict the
RN performance of short line sections, as well as the relationship between RMS, QP and average
RN levels from a transmission line. / AFRIKAANSE OPSOMMING: Die korona-werkverrigting van ‘n WS hoogspanningstransmissielyn het belangrike gevolge vir
die betroubaarheid van die ontwerp van die lyn. Die geleide radioruis (RR) vlak op die kraglyndragolf
kommunikasie sisteem, wat vir tele-beveiliging gebruik word, is veral van belang. In
hierdie werkstuk word bestaande metodes gebruik om die korona-werkverrigting te bepaal en
dan met gemete waardes van vier Suid Afrikaanse lyne te vergelyk.
Bestaande RR meetmetodes word saamgevat en ‘n nuwe metingsprotokol word voorgestel om
resultate te vergelyk. Na aanleiding van hierdie vergelykings word ‘n tegniek ontwikkel om die
RR van ‘n lyn te voorspel. Hierdie tegniek gebruik die EdF, EPRI en IREQ metodes. Die
voorgestelde tegniek kan nie die verandering van die RR met frekwensie bepaal nie. Dit kan ook
nie die RR van kort lyne bepaal nie. ‘n Wyeband RR bron word dus voorgestel. Nadat ESKOM
se Megawatt Park korona-kou ondersoek is, is die gevolgtrekking gemaak dat ‘n klein koronakou
die nodige wyeband RR bron sal voorsien. Ruimtelading bots met die klein korona-kou. Die
effek van hierdie botsings op die pulsparameters is lineer indien ladingsdiffusie nie plaasvind nie.
Die aanvangs, positiewe en negatiewe kanaalontladings (“streamers”) is identifiseer as die
enigste koronamodusse wat RR veroorsaak tussen 150 kHz en 30 MHz. Die spanning waarby
hierdie modusse voorkom, is bepaal. Die korona-werkverrigting van ‘n “ACSR Hare” geleier is
bepaal. Die korona-werkverrigting van die Acacia-Koeberg transmissie lyn is ook gekwantifiseer
by die kraglyn-dragolf kommunikasie frekwensies.
Die wyebandbron metode kan die verandering in RR met frekwensie goed voorspel. Die nuwe
metode kan ook gebruik word om die RR van kort lyne te bepaal, asook die verband tussen RMS,
QP en gemiddelde RR vlakke.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/50063
Date12 1900
CreatorsUrban, Rodney Gordon
ContributorsReader, H. C., Holtzhausen, J. P., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
PublisherStellenbosch : Stellenbosch University
Source SetsSouth African National ETD Portal
Languageen_ZA
Detected LanguageEnglish
TypeThesis
Format190 . : ill.
RightsStellenbosch University

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