Browsing by Author "Rusek, Jan Adam"

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Access status: Open Access ,
Diagnosis of rotor eccentricity and clutch wobbling of the induction machines, based on inspection of spectrums of the calculated and registered currents
(Data obrony: 2007) Elawgali, Saleh Suliman Hamad
Wydział Elektrotechniki, Automatyki, Informatyki i Elektroniki
In the dissertation a thesis is investigated, that non-stationary lumped-parameter models are effective tool in the analysis of induction motors properties, which allow obtaining calculation results more credible than in the case of constant-parameter models. In subsequent paragraphs and chapters the research field, which the thesis focuses on was defined, moreover pertinent professional literature was briefly discussed. Experimental tests have been performed, necessary for model identification and verification. The influence of heating -up the winding of the motor has been analysed. Circuit as well as field models describing this phenomenon were proposed and described. With their application exhaustive calculations were performed in order to obtain possibly simple and credible method of taking into account thermal phenomena in the model of the analysed motor with variable parameters. Electromagnetic calculations of the motor with the help of FLUX 2D software for filed calculations have been performed. Obtained results were compared to the measurement in order to assess the possibility to use this method to determine the functions of the parameters of a non-stationary model. A formal definition of a dynamic non-stationary model of the motor is given, and its identification with the method of non-linear regression was carried out. A verification of the developed and tested model is performed as a comparison of simulations and measurements in such motor operation states, which have not been taken into account in the identification.
Access status: Open Access ,
Miary wahania napięcia w sieci elektroenergetycznej wyznaczane z zastosowaniem transformacji Hilberta
(Data obrony: 2008) Wetula, Andrzej
Wydział Elektrotechniki, Automatyki, Informatyki i Elektroniki
Low-frequency disturbances are a separate kind of power system voltage disturbances. They should be interpreted as a complex modulation, or simultaneous amplitude and phase modulation. The thesis presents six measures of the low-frequency disturbances. These measures were designed to obtain high sensitivity, allow to build a quantitive scale, and be computationally effective in order to allow realtime measurements. Above requirements were met by most of proposed measures.Presented measures use a complex envelope signal, calculated using the Hilbert transform based algorithm. The algorithm was implemented in a digital signal processor and a PXI system, and tested using real power grid signals. Proposed algorithm was built for a low-frequency disturbances analysis. However, it is also useful in other kinds of analyses. As an example of another use of the algorithm, usage of calculated complex envelopes for an identification of Thevenin model of a power system was presented. Preliminary simulation results show usefulness of the algorithm in such a kind of analysis. Also, use of one of the developed measures for chosing credible identification results was presented.