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Improved transmission line protection performance concerning high resistance faults.

dc.contributor.advisorZivanovic, Rastko.
dc.contributor.advisorIjumba, Nelson Mutatina.
dc.contributor.authorMatshidza, Rhulani Daphney.
dc.date.accessioned2011-01-20T05:49:34Z
dc.date.available2011-01-20T05:49:34Z
dc.date.created2006
dc.date.issued2006
dc.descriptionThesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2006.en_US
dc.description.abstractESKOM has relied primarily on impedance-based measurement protection relays for the protection of transmission lines. One of the main disadvantages of distance relays is the limited fault resistance measurement capability. High-resistance faults are characterised by low fault currents, therefore the impedance calculated would be much bigger and so the fault will appear to be beyond the protected line. The main aim of the study is to gain clear understanding of the capability of the existing relays used in Eskom Transmission network, to be able to give recommendations on the refinements to the transmission line protection philosophy required to improve future protection performance. Omicron relay tests, showed that the dynamic characteristics of the three selected relays which were tested covers more fault resistance than that of the normal static impedance and also that the effect of DC offset is negligible with regards to fault resistance measurement capability. Normally the relays have built in algorithms which are able to filter nuisance signals. Theoretical case study that compared the most used relays in Eskom Transmission was done and the results are documented. Settings recommendations to improve fault resistance coverage were deduced from the above study. Fault investigation by using digital simulations (Matlab simulations) has proven the lack of capability to operate for some impedance relays in some fault conditions, as the fault resistance sometimes moves fault impedance beyond relay characteristic even when actual . polarization of the relay is considered. Analysis of the protection performance in transmission proved that high resistance faults accounts for at least half of protection equipment performance index (PEPI) incidents. Finally the author made recommendations to improve the protection performance concerning high resistance faults.en_US
dc.identifier.urihttp://hdl.handle.net/10413/2211
dc.language.isoenen_US
dc.subjectElectric lines.en_US
dc.subjectElectric power distribution.en_US
dc.subjectTheses--Electrical engineering.en_US
dc.titleImproved transmission line protection performance concerning high resistance faults.en_US
dc.typeThesisen_US

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