Izbor parametara transformatora za uzemljenje

scientific master's theses

• Author: Martina Čorak
• Mentor: Zijad Haznadar (mentor)
• Committee member: Željko Štih (predsjednik povjerenstva)
• Committee member: Zijad Haznadar (član povjerenstva)
• Committee member: Zvonimir Valković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2002-10-25, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Electromechanical Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

U srednjenaponskoj mreži Hrvatske postoji nekoliko naponskih nivoa (10 kV, 20 kV, 30 kV i 35 kV). To otežava nabavku, poskupljuje izradu i zahtjeva veći broj transformatora koje treba držati u pričuvi. Hrvatska elektroprivreda priprema uvođenje jedinstvenog distribucijskog napona 20 kV koji bi zamijenio ostale. Novi su mrežni transformatori zbog toga na srednjenaponskoj strani prespojivi s 10 na 20 kV. Međutim, da bi se iskoristili postojeći transformatori 110/36.75/10.5 kV u spoju YNyn0d5 najekonomičnije rješenje je prespajanje na srednjenaponskoj strani tako da se u spoju YNd5d5 dobije omjer transformacije 110/21.22/10.5 kV. Da bi se 20 kV mreža takvih transformatora mogla uzemljiti potreban je transformator za uzemljenje, kojeg bi bilo dobro standardizirati. U okviru magistarskog rada definiran je transformator za uzemljenje, opisana su njegova svojstva i namjene te je dan pregled izvedbi takvog transformatora ovisno o zahtjevima koji se mogu postaviti. Izveden je analitički proračun rasipne i nulte reaktancije transformatora prilagođen izvedbama transformatora za uzemljenje. Za izoliranu 20 kV mrežu Hrvatske dan je prijedlog parametara transformatora za uzemljenje koji bi bio prikladan za uzemljenje takve mreže te tehnički podaci tog transformatora dobiveni izradom projekta.

Abstract (english)

In the Croatian medium-voltage network there are several voltage levels (10 kV, 20 kV, 30 kV and 35 kV), what makes purchases rather difficult, production costs higher and requires a number of stand-by transformers. Hrvatska Elektroprivreda d.d. (HEP) is making preparations for introduction of a single 20 kV distribution voltage, which will replace the above-mentioned voltages. Therefore the new network transformers are reconnectable from 10 kV to 20 kV. For the existing 110/36.75/10.5 kV transformers in the connection YNyn0d5, the most efficient solution is reconnection on their mediumvoltage side, so that in the connection YNd5d5 the transformation ratio is 110/21.22/10.5 kV. To be able to earth 20 kV network of such transformers it is necessary to have an earthing transformer, and it would be well to standardize it.
In this master’s thesis, such an earthing transformer is defined, its characteristics and applications described, and a survey is given of its possible designs in dependence on various requirements. An analytical computation is made of stray and zero reactances adjusted to various designs of the earthing transformer. Parameters of an earthing transformer that would be suitable for the insulated 20 kV network in Croatia are proposed, and technical data obtained during its design process are presented.

• Keywords: Transformator za uzemljenje; spoj cik-cak; izolirana 20kV mreža; zemni spoj
• Keywords (english): Earthing transformer; zigzag connection; insulated 20 kV network; earth fault
• Language: croatian
• URN:NBN: urn:nbn:hr:168:613760
• Study programme: Title: Postgraduate master programme in electrical engineering; Study programme type: university; Study level: postgraduate; Academic / professional title: Magistar znanosti elektrotehnike (Magistar znanosti elektrotehnike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2019-04-30 06:47:48