Numerički proračun zagrijavanja trofazno oklopljenog generatorskog voda

scientific master's theses

• Title (english): Numerical Calculation of Temperature Rise in 3-phase Metal-Enclosed Busbars
• Author: Dalibor Gorenc
• Mentor: Zijad Haznadar (mentor)
• Committee member: Željko Štih (član povjerenstva)
• Committee member: Zijad Haznadar (član povjerenstva)
• Committee member: Stjepan Car (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Electrical Engineering Fundamentals and Measurements); Zagreb
• Defense date and country: 2007-03-07, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

U radu su prikazane teoretske osnove za proračun elektromagnetskog polja, gubitaka i prijenosa topline u trofazno oklopljenim vodovima kod nazivne struje. Na primjeru fazno pregrađenog generatorskog voda, metodom konačnih elemenata, izvršen je proračun raspodjele elektromagnetskog polja i gubitaka, na 2D modelu. Gubici u vodiču i plaštu izračunati na ovaj način, osnova su za analitički i numerički proračun zagrijanja. Metodom toplinske mreže, analitički su izračunate nadtemperature vodiča, plašta i zraka unutar plašta u stacionarnom stanju. Proračun raspodjele temperatura proveden je zatim metodom konačnih elemenata, na 2D modelu, uzimajući u obzir sva tri načina prijenosa topline: vođenje, konvekciju i zračenje. Pritom je pretpostavljeno da su gubici jednoliko raspodijeljeni po presjeku vodiča odnosno plašta. Kako bi se obuhvatio prijenos topline konvekcijom, u zraku unutar plašta, rješavane su simultano s jednadžbom za provođenje topline i jednadžbe za dinamiku fluida. Prijenos topline konvekcijom na vanjskoj površini plašta obuhvaćen je empirijskim formulama. Rezultati analitičkog i numeričkog proračuna uspoređeni su s rezultatima mjerenja na ispitnom modelu. Zbog velikog broja pojednostavljenja, rezultati analitičkog proračuna slabo se podudaraju s rezultatima mjerenja. S druge strane, rezultati numeričkog proračuna vrlo dobro se podudaraju s rezultatima mjerenja. Stoga je zaključeno da se prikazani numerički pristup može primjenjivati u postupku dimenzioniranja trofazno oklopljenih vodova.

Abstract (english)

The thesis presents theoretical background for calculation of the electromagnetic field, losses and heat transfer in 3-phase metal-enclosed busbars at rated current. On the example of a segregated generator phase bus, the distribution of electromagnetic field and losses was computed on a 2D model using the finite element method. The losses in conductors and enclosure calculated in this way were the basis for analytical and numerical calculations of temperature rise. Thermal network method was used for analytical calculation of steady-state temperature rises in conductors, the enclosure and the air in the enclosure. Temperature distribution on a 2D model was computed using the finite element method, taking into account all the three modes of heat transfer: heat conduction, convective and radiative heat transfer. In these computations it was assumed that the losses had uniform distribution along the cross sections of conductors and the enclosure. To take into account the convective heat transfer in air in the enclosure, the heat equation and the fluid dynamics equations were coupled and solved simultaneously. Convective heat transfer from outer surface of the enclosure was described using empirical relations. The results of analytical and numerical calculations are compared with measurement results obtained on a test model. Due to large number of simplifications, the results of analytical calculation are in poor agreement with measurement results. On the other hand, the results of numerical calculation are in very good agreement with measurement results. It is concluded that the presented numerical procedure can be applied to the design of 3-phase metal enclosed busbars.

• Keywords: trofazno oklopljeni vod; fazni vodič; oklop (plašt); nadtemperatura (zagrijanje); vođenje topline; prijenos topline konvekcijom; prijenos topline zračenjem; dinamika fluida; metoda toplinske mreže; metoda konačnih elemenata
• Keywords (english): 3-phase metal-enclosed bus; phase conductor; enclosure; temperature-rise; heat conduction; convective heat transfer; radiative heat transfer; fluid dynamics; thermal network method; finite element method
• Language: croatian
• URN:NBN: urn:nbn:hr:168:781304
• 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: 2020-01-17 11:30:08