Some methodologies for facts controllers
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Date
1997
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Publisher
University of Dar es Salaam
Abstract
Flexible AC Transmission Systems (FACTS) have been conceived to increase the transmissibility of electric power without the necessity of building new transmission lines. An important family of controllers proposed for FACTS are based on high power solidstate switches, such as the gate-turn-off thyristor (GTO), which is presently rated at 6kV, 6kA. The FACTS controller operates at the transmission voltage, in the order of SOOkV, and it must be rated at hundreds of MVA. The research of this thesis contributes in developing the methodologies necessary for the integration of the solid-state switches so that the FACTS controllers have the voltage withstand and the current carrying capacity. The methodologies followed in the thesis are based on organizing the solid-state switches firstly in the forms of: (a) 2-level, voltage-source converter modules or (b) multilevel, voltage-source, converter modules. Thereafter, the modules are connected in series and/or in parallel. Switching strategies such as: (i) the phase-shifted triangle carrier technique and (ii) the fundamental frequency switching, are shown to be promising. The thesis addresses the methodologies of uniting the modules: (i) in parallel, (ii) in series and (iii) in parallel groups of series-connected modules. Series connections require magnetic transformers. Transformers also enable 6-phase and 12-phase ac systems to be produced from the standard 3-phase ac utility supply. The thesis has initiated research in incorporating the multi-phase ac systems to the multi-modular, multi-level converters. The thesis has also developed the interface methodology for digital (digital signal processor, DSP) control of the array of modules in real-time. The methodologies of the thesis have been proven in digital simulations and experimentally in laboratory models
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Keywords
Power electronics, Electronic current converters, Electronic controllers
Citation
Mwinyiwiwa, B. M. M. (1997) Some methodologies for facts controllers, Doctoral dissertation, University of Dar es Salaam. Available at (http://41.86.178.3/internetserver3.1.2/detail.aspx)