Buka i vibracije namota energetskog transformatora

master's thesis

• Title (english): Noise and vibrations of power transformer windings
• Author: Dominik Brezetić
• Mentor: Marko Jokić (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2019-01-21, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Tema ovog diplomskog rada je predviđanje buke u energetskim transformatorima koja se razvija uslijed radijalnih vibracija namota. Na samom početku dane su teoretske osnove energetskih transformatora te područja vibracija i akustike. Vibroakustička analiza provedena je pomoću metode konačnih elemenata za konkretan, već instaliran transformator tvrtke Končar Energetski Transformatori, stoga su u narednom poglavlju dani opći podaci o transformatoru te podaci potrebni za postavljanje i provođenje analize. Realna konstrukcija namota koja se sastoji od transformatorskog ulja, vodiča, papirnih izolacija i umetaka koji osiguravaju hlađenje i pozicioniranje vodiča, zamijenjena je pojednostavljenim modelom koji podrazumijeva tri homogena šuplja cilindra uronjena u transformatorsko ulje. Kako masa i krutost tih cilindara nisu niti približno jednake onima stvarnog namota, njihova gustoća i modul elastičnosti određeni su pomoću detaljnog modela namota koji uzima u obzir razmake i umetke između vodiča namota. Poznavajući materijalna svojstva pojednostavljenog modela, provedena je modalna analiza kojom su dobivene vlastite frekvencije sustava ulje-namoti i njegove forme vibriranja. Nakon toga je analiziran odziv sustava na harmonijsko opterećenje silama na namote koje se javljaju uslijed elektromagnetskog polja. Odziv je prikazan u obliku radijalnih pomaka namota, ekvivalentnog naprezanja u namotima te zvučnog tlaka (Pa) odnosno jakosti zvuka (dB(A)). Dobivena prosječna jakost zvuka u transformatorskom ulju iznosi cca. 85 dB(A). Obzirom da izmjerena jakost zvuka u okolini kućišta transformatora iznosi 57 dB(A), može se zaključiti da je model, obzirom na to koliko je konstrukcijskih detalja uzeto u obzir, dobra aproksimacija stvarnog ponašanja transformatora. Naposljetku je dan komentar rješenja i uvedenih pojednostavljenja te njihov utjecaj na rješenje.

Abstract (english)

Subject of this Master's thesis is prediction of noise which is a consequence of radial vibrations of power transformers' windings. At the very beginning of the thesis basic concepts of power transformers, vibrations and acoustics are given. Vibroacoustic analysis is conducted by means of the finite element method (FEM). Since a particular, already installed power transformer produced by Končar Energetski Transformatori is analysed, in subsequent chapter general data on this transformer are given. These data are used for setting up a numerical analysis. Actual design of the windings, which consists of transformer oil, conductors, paper insulations and spacers which ensure cooling and positioning of conductors, is simplified and modeled as three hollow cylinders immersed in transformer oil. For mass and stiffness of these cylinders are far greater than those of actual windings, their density and modulus of elasticity are determined by means of a detailed model of the windings which accounts spacers between the conductors. With material properties of the simplified model of windings being determined, a modal analysis is carried out and eigenfrequencies along with eigenmodes of the oil-windings system are obtained. Hereafter harmonic response of the system is observed with electromagnetic forces acting upon the windings included. Results are given as radial displacements of the windings, equivalent stress of the windings and acoustic pressure (Pa) i.e. A-weighted sound pressure level (dB(A)) in the acoustic medium (transformer oil). Averaged obtained value of A-weighted sound pressure level, in transformer oil, is approx. 85 dB(A). Since measured sound pressure level in the vicinity of the transformer's housing amounts 57 dB(A), it can be concluded that, this model is, considering level of details included in it, a good approximation of actual transformer's response. In the conclusion of the thesis a comment on results is given and influence of the introduced simplifications on the results is discussed.

• Keywords: energetski transformator; vibroakustika; analiza; predviđanje buke; metoda konačnih elemenata (MKE)
• Keywords (english): power transformer; vibroacoustics; analysis; noise prediction; finite element method (FEM)
• Language: croatian
• URN:NBN: urn:nbn:hr:235:746063
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2024-01-15
• Created on: 2019-05-22 23:39:59