Izolacijski sustav kombiniranih mjernih transformatora

doctoral thesis

• Title (english): Insulation System of Combined Instrument Transformers
• Author: Miroslav Poljak
• Mentor: Željko Štih (mentor)
• Committee member: Zlatko Maljković (član povjerenstva)
• Committee member: Željko Štih (član povjerenstva)
• Committee member: Zvonimir Valković (član povjerenstva)
• Committee member: Ivo Uglešić (član povjerenstva)
• Committee member: Mladen Boršić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Electrical Engineering Fundamentals and Measurements); Zagreb
• Defense date and country: 2006-07-13, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Electromechanical Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

U radu su razmotrene osnovne znaajke kombiniranih transformatora i izdvojene njihove tehnike i ekonomske prednosti. Posebno su istaknute prednosti vlastite koncepcije kombiniranih transformatora s jedinstvenim izolacijskim sustavom. Metodologija prorauna izolacijskog sustava kombiniranih transformatora ukljuivala je istraživanje parcijalnih izbijanja na modelima papirno uljne izolacije s ciljem da se procijeni starenje izolacije, a rezultati istraživanja statistiki su obraeni pomou Weibullove distribucije. Definiran je matematiki model aktivnog dijela kombiniranog transformatora za proraun naponskih naprezanja u niskofrekventnom i visokofrekventnom podruju. Valorizirano je nekoliko naina odreivanja nadomjesnih ulaznih parametara modela. Za to su korištene mjerne metode, metode izrauna na temelju analitikih izraza i konano numeriki 2D i 3D prorauni metodom konanih elemenata. Za usvojeni model opisani su prorauni raspodjele izmjeninog napona industrijske frekvencije, te atmosferskog i sklopnog udarnog napona uzduž visokonaponskog namota kombiniranog transformatora. Na primjeru kombiniranog transformatora za najviši napon opreme 420 kV, detaljno je opisan postupak iznalaženja zadovoljavajueg projektnog rješenja pri emu su proraunski rezultati usporeeni s rezultatima mjerenjima. Pokazano je da se ti rezultati izuzetno dobro meusobno slažu. Prototip transformatora, izraen na temelju istraživanja opisanih u disertaciji, zadovoljio je propisana tipska i komadna ispitivanja. U nastavku je dan prijedlog projektnog rješenja kombiniranog transformatora za najviši napon opreme 550 kV.

Abstract (english)

The main features of combined transformers are considered, and their technical and economical advantages singled out. It is pointed in particular to the advantages of Konar’s own concept of combined transformers with a integral insulation system. The methodology of calculation of combined transformer insulation system includes an investigation of partial discharges on models of oil-paper insulation with a view to assessing insulation ageing, and its results have been statistically processed applying Weibull distribution. A mathematical model of the active part of combined transformers has been defined for calculation of voltage stress in both low-frequency and high frequency ranges. Several modes of determination of equivalent input parameters of the model have been evaluated. For that purpose measurement methods, calculation methods based on analytical expressions, and finally numerical 2D and 3D computations based on finite elements method were used. For the adopted model, computations of the distribution of power-frequency voltage, and of lightning and switching impulse voltages along the highvoltage winding of the combined transformer are described. On the example of a combined transformer for the highest voltage for equipment of 420 kV, the procedure for finding a satisfactory design solution is described in detail, comparing computation and measurement results. It is shown that these results are in exceptionally good agreement. A prototype of the transformer made on the basis of investigations described in this thesis has passed the prescribed routine and type tests. A design solution for a combined transformer for the highest voltage for equipment of 550 kV is given as well.

• Keywords: mjerni transformator; kombinirani transformator; napon nastanka parcijalnih izbijanja; Weibullova distribucija; raspodjela napona; izolacijski sustav; namot transformatora; napon industrijske frekvencije; udarni napon; numerički proračun
• Keywords (english): instrument transformer; combined transformer; PD inception voltage; Weibull distribution; voltage distribution; insulation system; transformer winding; power-frequency voltage; impulse voltage; numerical calculation
• Language: croatian
• URN:NBN: urn:nbn:hr:168:395149
• Study programme: Title: Doctoral study programme "Electrical Engineering and Computing"; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, po-dručje tehničkih znanosti (doktor/doktorica znanosti, po-dručje tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2019-06-28 08:10:23