Browsing by Author "Tumbo, Siza Donald"

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    Effects of excitation parameters on the performance of computer controlled variable: speed dual-excited synchronous generator.
    (University of Dar es Salaam, 1996) Tumbo, Siza Donald
    It is known that excitation systems of synchronous machines in a power system can affect the performance of such machines. In this dissertation, an analytical study of a computer-controlled variable-speed constant-frequency (VSCF) generating system which incorporates a variable-speed synchronous generator (DESG) with respect to its excitation parameters is presented. The computer-controlled DESG has a voltage regulation (VR) scheme which is a feedback system. This VR scheme may experience oscillations even becoming unstable due to inappropriate tuning of the excitation parameters and variable-speed operation of the DESG. The described investigation includes the determination of stability limits of the VR scheme and the study of the effects of variable speed operation of the DESG and tuning of the excitation parameters on the performance of the VR scheme. It is shown that, under variable speed operation, the generator has a varying gain which strongly affects the selection of excitation system parameters. With the limits of stability known in terms of excitation parameters and the varying gain, results show that it is possible to select values of the parameters which will optimize the performance of the VSCF generating system for a specified operating speed range.