Prenaponska zaštita ekrana visokonaponskih podzemnih kabela

master's thesis

• Title (english): Overvoltage protection of screens in high voltage underground cables
• Author: Bruno Benc
• Mentor: Božidar Filipović-Grčić (mentor)
• Committee member: Božidar Filipović-Grčić (predsjednik povjerenstva)
• Committee member: Viktor Milardić (član povjerenstva)
• Committee member: Goran Grdenić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2022-07-13, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

Kabel čini jednu kompleksu cjelinu, a izvedbe i dimenzije su različite i ovise o potrebama naponske razine i području primjene. Kod izrade se zahtijeva visoka preciznost kako bismo mogli svaki put pouzdano baratati podatcima za tip kabela koji odlučujemo položiti za određenu primjenu.
Najjeftinija i najjednostavnija opcija je direktno uzemljenje na oba kraja, ali stvara nam jako velike gubitke. Dobra je strana što su ekrani kabela na krajevima na potencijalu zemlje, no nemamo kontrolu nad iznosom induciranog napona uzduž kabela.
Najskuplja i najefikasnija metoda, ujedno i najkompliciranija za izvesti je potpuni preplet ekrana i faznih vodiča. U teoriji se postiže potpuno poništenje cirkulacijskih struja, no u praksi zbog nesavršenosti izrade samog kabela i eventualne nemogućnosti izvedbe prepleta u jednakim intervalima ipak teku male struje. Osim što smo gubitke uslijed cirkulacijskih struja gotovo potpuno reducirali, zbog ugradnje odvodnika prenapona na mjestima gdje se obavlja preplet, imamo kontrolu nad iznosom induciranog napona uzduž kabela. Važno je motriti iznose prenapona, pogotovo kod kvarova i atmosferskih pražnjenja kada postoji opasnost od proboja ukoliko ne kontroliramo iznose induciranih napona.
EMTP pruža mogućnost preciznog modeliranja i promatranja induciranih napona u ekranima kabela u raznim pogonskim stanjima mreže. Podjelom trase na više dijelova jednostavno je modelirati razne konfiguracije uzemljenja kabelskih ekrana i motriti inducirane napone uzduž trase kabela.

Abstract (english)

A cable is a complex unit. There are numerous types and dimensions which depend on requirements of voltage level and area of use. High manufacturing precision is necessary for insurance of reliable data usage for particular cables.
The method with the lowest cost and the simplest installation for earthing cable screens is direct earthing on both cable ends, but it implies high losses. The advantage of this method is having screen potential equal to zero on both cable ends, but there is no control over sheath voltage along the cable route.
The method with the highest cost and the most complicated to perform is full cross bonding of cable sheaths and conductors. In theory, complete annulment of circulation currents is achieved, but in practice, due to the imperfection of the cable itself and the imposibility of cable route division into three equally long parts, relatively low circulation currents are flowing. Except for reducing losses, which are a consequence of circulation currents, because of installing sheath voltage limiters in locations where cross bonding is done, we have control over sheath induced volatges along the cable route. It is important to have control over those voltages, especially in the case of faults and atmospheric discharges when the danger of outer insulation breakdown occurs.
EMTP provides the possibility of precise cable modeling and observation of cable sheath induced voltages in specific network operation conditions. By sectioning the cable route, it is simple to implement different schemes of cable sheath earthing and observe sheath induced voltages alongside the cable route.

• Keywords: visokonaponski kabel; metalni ekran kabela; prenaponi na ekranu kabela; odvodnik prenapona za ekran kabela; EMTP simulacija; metode uzemljenja kabelskih ekrana
• Keywords (english): HV cable; cable screen; cable screen overvoltage; cable screen voltage limiter (SVL); EMTP simulation; cable screen earthing schemes
• Language: croatian
• URN:NBN: urn:nbn:hr:168:024367
• Study programme: Title: Electrical Engineering and Information Technology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije (magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2023-01-14 08:27:30