Transient modelling of induction motors in a petrochemical plant using Matlab

Claassens, Andries Johannes (2008-03)

Thesis (MScIng)--University of Stellenbosch, 2008.

Thesis

ENGLISH ABSTRACT: The behaviour of induction motors at a petrochemical plant under transient conditions was investigated with the view to improve plant immunity to voltage fluctuations. The benefits of using a phase-variable induction motor model rather than the simpler d-q models usually employed are investigated. A simplified model of the plant electrical distribution system was derived. Phase variable and d-q induction motor models were implemented as well as a synchronous generator model. Practical considerations precluded the use of commercial software for the simulation of transient conditions and a basic simulation program was developed using Matlab to evaluate the behaviour of the dynamic machine models and distribution system. It was established that the configuration of the installed re-acceleration system can be optimised to reduce the possibility of plant outages as a result of voltage fluctuations. It was found that the use of more detailed induction machine models provide valuable insight into system behaviour and is justified if accurate motor parameters are available or can be estimated. The simplified plant model yielded useful results and enabled the identification of incorrect system data. The investigation showed that Matlab is suitable for the rapid development of a basic transient simulation program that can be used to study the behaviour of different interconnected dynamic machine models.

AFRIKAANSE OPSOMMING: Die gedrag van induksiemotors in 'n petrochemiese aanleg onder oorgangstoestande is ondersoek ten einde die immuniteit van die aanleg vir spanningsfluktuasies te verbeter. Die voordele van die gebruik van 'n fase-veranderlike induksiemotor model eerder as die eenvoudiger d-q modelle wat normaalweg gebruik word is ondersoek. 'n Vereenvoudigde model van die aanleg se elektriese distribusiestelsel is afgelei. Faseveranderlike en d-q induksiemotor modelle is geimplementeer sowel as 'n sinkroongenerator model. Praktiese oorwegings het die gebruik van kommersiële programmatuur vir die simulasie van oorgangstoestande verhoed en 'n basiese program is in Matlab ontwikkel om die gedrag dinamiese masjienmodelle en die distribusiestelsel te evalueer. Daar is vasgestel dat die konfigurasie van die geinstalleerde herversnellerstelsel geoptimeer kan word om die moontlikheid van aanleg onderbrekings as gevolg van spanningsfluktuasies te verminder. Daar is gevind dat die gebruik van meer gedetaileerde induksiemasjien modelle waardevolle insig in die gedrag van die stelsel lewer en geregverdig is indien akkurate motorparameters beskikbaar is of afgeskat kan word. Die vereenvoudigde model van die aanleg het bruikbare resultate gelewer en die het die identifikasie van foutiewe stelseldata moontlik gemaak. Die ondersoek het getoon dat Matlab geskik is vir die snelle ontwikkeling van 'n basiese oorgangsimulasie program wat gebruik kan word om die gedrag van verskillende gekoppelde dinamiese masjienemodelle te bestudeer.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/20432
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