الفهرس 
1.1 ResonanceOnly 14 pages are availabe for public view
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Abstract
This thesis focuses on power transformer overvoltages due to internal transformer resonance and ferroresonance due to cable-transformer interaction. Internal transformer resonance overvoltages are evaluated for two different power transformers. The occurrence of resonance cases can be initiated due to single-phase earth fault and due to capacitor energization. These two situations lead to excessive transient overvoltages at the transformer secondary side. The effect of various factors on these transient overvoltages is studied. Fast Fourier transform is used for defining and analysis of resonance frequencies. Furthermore, this thesis investigates the ferroresonance phenomenon due to single-phase switching in the source feeding an unloaded transformer via a power cable. This study is carried out concerning the transformer constructions and earthing concepts. Also, overvoltages due to load rejections are studied for the three-winding autotransformer where this studied results are compared with the ferroresonance overvoltages. The effect of cable length on the ferroresonance behavior is studied and the ferroresonance mode is defined. The simulation is carried out using Alternative Transients Program (ATP). The feature extractions for each phenomenon are exploited to present a novel discrimination technique of each disturbance using FFT, phase-plane diagram and discreet wavelet transform (DWT).