Matematički model cijevnoga hidroagregata za utvrđivanje uzroka njihanja snage

doctoral thesis

• Title (english): Mathematical model of bulb hydropower unit for determining the cause of power oscillations
• Author: Miljenko Brezovec
• Mentor: Igor Kuzle (mentor)
• Committee member: Igor Kuzle (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Energy and Power Systems); Zagreb
• Defense date and country: 2018, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Power Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

Njihanje snage u hidroelektranama i općenito pojave povezane s oscilacijama i vibracijama, su česti pogonski problemi u radu pojedinih agregata. Primjeri istraživanja takvih pojava na cijevnim hidroagregatima s horizontalnim Kaplan turbinama su rijetki. Takvi agregati zbog svoje složene konstrukcije mogu imati različite probleme s oscilacijama i vibracijama, a zbog malog momenta tromosti imaju loša svojstva s aspekta stabilnosti. Pojave njihanja snage na HE Dubrava prisutne su na oba agregata od početka rada elektrane. U slučaju pojave većeg poremećaja kod većih snaga, njihanje snage postaje problematično za rad agregata. Provedena su brojna istraživanja no tumačenja ove pojave se razlikuju. Jedan pristup polazi od poremećaja mehaničkog momenta kao uzroka njihanje snage, dok je prema drugom njihanje snage uzrokovano elektromehaničkom rezonancijom. Analizom velikom broja slučajeva identificirane su pojave njihanja snage, a usporedbom mjerenih i simuliranih rezultata pokazano je da se njihanje snage može interpretirati simulacijama na matematičkom modelu agregata. Može se zaključiti da povremeno njihanje snage nastaje uslijed poremećaja mehaničkog momenta koje uzrokuju hidrauličke pojave u protočnom traktu. Dodatno su istraženi efekti djelovanja dodatnih regulacijskih signala sustava uzbude, no tu su mogućnosti ograničene. S obzirom da se mogućnost pojave njihanja ne može isključiti, definiran je algoritam odlučivanja o potrebnom djelovanju u slučaju intenzivnog njihanja snage ovisno o parametrima poremećaja.

Abstract (english)

Power swings in hydroelectric power plants as well as oscillations and vibrations, are common problems in operation of some power units. Researches of such phenomena on bulb type units with horizontal Kaplan turbines are rare. Because of their complex design, such units can have a variety of problems with oscillations and vibrations, and due to small moment of inertia have poor stability characteristics. Power oscillations have been present on the HPP Dubrava since the operation beginning. In the case of large disturbances appearance, power oscillations become problematic for unit operation. Numerous researches were carried out, but explanations of the phenomenon are different. One approach starts from mechanical torque disturbance, and second from electromechanical resonance as the cause of power oscillations. Analyzing a large number of cases, power oscillations phenomena are identified, and comparison of measured and simulated results have shown that power oscillations could be interpreted by simulation on mathematical model. It may be concluded that occasional power oscillations appear due to mechanical torque disturbances caused by hydraulic phenomena in water conduit system. Furthermore, effects of additional control signal in excitation system are analyzed, but with presence of forced oscillations possibilities of power system stabilizer action are limited. Considering that the possibility of oscillations appearance can’t be eliminated, decision algorithm for treatment of large power oscillations based on disturbance parameters is defined.

• Keywords: hidroagregat; dvostruko regulirana cijevna turbina; elektromehaničke oscilacije; vlastita frekvencija; dinamika rotora; njihanje snage; kavitacija; stablo odlučivanja
• Keywords (english): hydroelectric unit; double regulated bulb turbine; electromechanical oscillations; natural frequency; rotordynamics; power oscillations; cavitation; decision tree
• Language: croatian
• URN:NBN: urn:nbn:hr:168:234663
• Study programme: Title: Electrical Engineering and Computing; Study programme type: university; Study level: postgraduate; Academic / professional title: Doktor znanosti elektrotehnike i računarstva (Doktor znanosti elektrotehnike i računarstva)
• Type of resource: Text
• Extent: 145 str. ; 30 cm.
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2019-04-02 13:28:41