Modelling corona noise on high voltage transmission lines

Urban, R. G. (2001)

Thesis (MScEng.) -- Stellenbosch University, 2001.

Some digitised pages may appear illegible due to the condition of the original hard copy.

Thesis

ENGLISH ABSTRACT: The corona performance of a compact transmission line design must be accurately determined. In particular, the conducted radio interference (RI) noise level will significantly affect the power line carrier communication used for teleprotection on the line. This conducted RI noise can be calculated with a numerical transmission line code. This thesis investigates the extraction of corona and RI noise elements for inclusion into such a code. The required RI noise measurements are made in a small laboratory corona cage in the bandwidth 5 kHz to 1 GHz. The measurement system is modelled for frequencies below 30 MHz and corona and RI noise elements are extracted in this low-frequency regime. RI noise measurements are made with a time domain oscilloscope and with a frequency domain EMI receiver and spectrum analyser. A strong correlation is observed between the narrowband peak EMI receiver measurements and the swept narrowband spectrum analyser measurements. Accurate quasi-peak measurements cannot be made in the small corona cage due to a low number of RI sources on the short corona cage centre conductor. The work presented in this thesis will be used in future research to develop a smallscale corona cage, a generation transform for small corona cages and a conversion between peak and quasi-peak or RMS measurements made in the small corona cage.

AFRIKAANSE OPSOMMING: Die korona-werkverrigting van ‘n kompakte transmissielyn ontwerp moet akkuraat bepaal word. Die vlak van radio interferensie (RI) ruis het ‘n groot invloed op die kraglyn-dragolf kommunikasie wat tele-beveiliging aan die lyn verskaf. ‘n Numeriese transmissielyn programkode kan gebruik word vir die bepaling van hierdie Rl-vlak. Hierdie tesis ondersoek die onttrekking van korona en Rl-ruis elemente vir insluiting in so ‘n programkode. Die Rl-ruis word in ‘n klein korona-kou gemeet in die frekwensiegebied vanaf 5 kHz tot 1 GHz. Die meetstelsel is gemodelleer vir frekwensies laer as 30 MHz. Die korona en Rl-ruis elemente is vir hierdie frekwensiegebied onttrek. Die metings is met ‘n tydgebied-ossilloskoop asook ‘n frekwensiegebied EMI-ontvanger en spektrumanaliseerder gemaak. ‘n Sterk korrellasie is tussen die nouband EMI-ontvanger metings en die geveegde nouband spektrumanaliseerder metings gevind. Die klein korona-kou kan nie gebruik word om akkurate kwasi-piek metings te neem nie. Dit is waarskynlik omdat daar te min Rl-bronne bestaan op die kort middelste geleier van die klein korona-kou. Die werk in hierdie tesis gaan gebruik word in toekomstige navorsing om ‘n korona-kou op kleinskaal te ontwikkel asook vir omskakelings tussen piek en kwasi-piek of WGK metings, gemeet in ‘n klein korona-kou.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/52342
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