Smanjenje pogrešnih prorada relejne zaštite u uzemljenim mrežama srednjeg napona

scientific master's theses

• Title (english): Reduction of wrongly triggered relay protection in earthed middle-voltage power networks
• Author: Silvano Drandić
• Mentor: Ante Marušić (mentor)
• Committee member: Slavko Krajcar (član povjerenstva)
• Committee member: Ante Marušić (član povjerenstva)
• Committee member: Juraj Šimunić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Energy and Power Systems); Zagreb
• Defense date and country: 2001-09-25, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Power Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

U ovom radu analizirana je mogućnost smanjenja pogrešnih prorada relejne zaštite u uzemljenim mrežama srednjeg napona. U radu su razmatrane srednjenaponske elektroenergetske mreže uzemljene posredstvom zajedničkog maloomskog otpora. Uključenjem transformatora u paralelni rad dolazi do prijelazne pojave na vezi između neutralnih točaka transformatora koja zbog dugog trajanja može uzrokovati nepotrebnu proradu zaštite otpornika za uzemljenje. Spomenuti problem detaljno je razrađen u prvom poglavlju. U sljedećem poglavlju je obrađeno rješenje uzemljenja posredstvom maloomskog otpora uz primjenu tipskog rješenja sheme uzemljenja i zaštite otpornika. U trećem poglavlju teorijski je obrađena problematika struje uključenja transformatora. Slijedećim poglavljima prikazani su rezultati izvršenih istraživanja vrijednosti struja na vezama između neutralnih točaka transformatora za slučajeve uključenja transformatora, kratkotrajnog nestanka primarnog napona i kvarova prema zemlji. Izvedena je analiza djelovanja relejne zaštite. U posljednjem, devetom poglavlju, obrađena je mogućnost zaštite otpornika korištenjem odgovarajućih inverznih I-t karakteristika. Predložena je zaštita otpornika upotrebom digitalnih releja koji objedinjuju više zaštitnih funkcija čime se postiže potpuna zaštita otpornika u skladu s njegovom termičkom karakteristikom. Korištenjem digitalnih releja uz pravilno konfiguriranje i parametriranje postiže se bitno smanjenje pogrešnih prorada u krugu zaštite otpornika.

Abstract (english)

The possibility of reduction of wrongly triggered relay protection in earthed middlevoltage power networks is analized. In addition, middle-voltage power networks earthed by means of common lowresistence resistor are treated. By switching the transformer in parallel operation transition takes place in the connection between the neutral points of transformers which causes unnecessary operation of the earthing resistor relay protection. An detailed analization of mentioned problem is given in chapter one. The solution of earthing via a lowresistence resistor by using common scheme of earthing and protection of the resistor is treated in the next chapter. Theoretical grounds of the switching current of the transformer is given in the third section. In the next chapter are shown the results of the research of the current values on the connections between the neutral points of the transformers for cases of switching on the transformer, short-term lack of primary voltage and earth faults. The action of the relay protection is analized. The possibility of resistor protection by using the appropriate inverse I-t characteristics is analized in the last ninth section. It's been proposed protection of the resistor by using digital relays which involve more protectional functions by which is brought the complete resistor protection considering its thermical characteristics. By using digital relays with correct configuration and parameters is achieved a minimum of wrongly triggered relay protection in the circuit of resistor protection is achieved.

• Keywords: Otpornik za uzemljenje; inverzna I-t karakteristika; digitalni releji; relejna zaštita; uzemljenje zvjezdišta transformatora; paralelni rad transformatora; prijelazne pojave
• Keywords (english): Earthing resistor; inverse I-t characteristics; digital relays; relay protection; neutral earthing; transformer in parallel operation; transients
• Language: croatian
• URN:NBN: urn:nbn:hr:168:615993
• 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: 2019-04-19 09:04:28