Analysis and synthesis of a 2 MVA series-stacked power-quality conditioner

Mouton, Hendrik (Du Toit) (1999-12)

Dissertation (Ph.D.) -- University of Stellenbosch, 1999.

Thesis

ENGLISH SUMMARY: This thesis describes the development of a power electronic converter for a 2 MVA series-injection power-quality device. The converter is designed to interface directly with superconducting magnetic energy storage devices and operates at a nominal DC-bus voltage of 2.4 kV. In the first part of the thesis the viability of soft-switching for application to the 2 MVA converter is investigated. A new resonant turn-off snubber topology is introduced and a detailed theoretical study of the converter and snubber switching losses is carried out. An optimal snubber design procedure is derived. This is followed by a theoretical investigation of the effects of the different parasitic components on the snubber operation. In the final part of the investigation, a turn-on snubber is added to the turn-off snubber topology. An experimental evaluation of both the turn-off and combined turn-on and turn-off snubbers is carried out. In order to obtain a DC-bus voltage of 2.4 kV, a series-stacked converter topology, for use in the 2 MVA series-injection device, is investigated. A detailed theoretical analysis of the DC-bus balancing mechanisms is conducted. This theoretical analysis makes use of fundamental results from the theory of systems of linear differential equations; in particular of Floquet theory. In the final part of the thesis an experimental 700 kVA series-stacked phase-arm, operating at a 2.4 kV DC-bus voltage, is constructed. The operation of this converter is verified through a range of experiments and the measured results are compared with the theoretical predictions.

AFRIKAANSE OPSOMMING: Hierdie proefskrif bespreek die ontwikkeling van 'n drywingselektroniese omsetter vir 'n 2 MVA serie-injeksie toevoerkwaliteittoestel. Die omsetter is ontwerp om direk aan 'n supergeleidende magnetiese energiestoor te koppel en werk by 'n nominale GS-busspanning van 2.4 kV. In die eerste deel van die proefskrif word die moontlike toepassing van 'sagte skakeling' by hoe drywingsvlakke ondersoek. 'n Nuwe afskakelgapser word ondersoek en 'n deeglike teoretiese studie van die verliese in die gapser en omsetter word uitgevoer. Hierdie ondersoek gee aanleiding tot 'n optimale ontwerpprosedure. 'n Teoretiese analise van die effek van die verskillende parasitere komponente op die werking van die gapser word gedoen. Laastens word getoon hoe 'n aanskakelgapser met die afskakelgapser gelntegnier kan word. Die werking van beide gapserbane word eksperimenteel bevestig. Aangesien die serie-injeksie omsetter by 'n GS-busspanning van 2.4 kV moet werk, word 'n seriegeskakelde omsettertopologie ondersoek. 'n Breedvoerige teorie, wat die balansering van die GS-busspannings beskryf, word ontwikkel. Die teorie maak van basiese stellings uit die teorie van stelsels van linieere differensiaalvergelykings gebruik; in die besonder van Floquet-teorie. In die laaste deel van die proefskrif word die ontwerp van 'n eksperimentele 700 k VA seriegeskakelde fase-arm wat by 'n GS-busspanning van 2.4 kV werk, bespreek. Die werking van die omsetter word eksperimenteel geevalueer en die gemete resultate word met die teorie vergelyk.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/51114
This item appears in the following collections: