الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Power systems have been experiencing oscillation behavior since the very
beginning. All different forms of this behavior jeopardize the secure
operation and the integrity of the system elements. The main aims of this
research work centralize around mitigating the inter-area oscillations, subsynchronous resonance oscillations, and the rotary shaft torsional oscillations accompanied by the failed autoreclosing operations. Numerous calamitous global power outages with the subsequent multi-million-dollar economic casualties were because of unstable inter-area power oscillations. Subsequently, researching and investigating novel countermeasures for interarea oscillations have always been a subject of overpowering interest in the energy sector during the preceding five decades. This study propositioned a fuzzy-based coordinated switching operation of two dynamic resistor brakes to alleviate the developed inter-area oscillations considering Kundur’s four machine benchmark as a test system. A thorough evaluation of the propositioned scheme considering seven case studies including small, mild, severe, and very severe disturbances to manifest the effectivity of the propositioned scheme under a wide operational spectrum. Series capacitance
application in lengthy transmission corridors emerging from fossil-fueled
power-producing facilities has been for quite some time recognized as
representing expected jeopardy to the rotating shafts of steam urbogenerators after the inauspicious Mohave exciter shaft failure incidents back in the beginning of the seventies. Power systems incorporated with series capacitive compensation are easy targets for subsynchronous resonance conditions where the rotating shafts of steam turbogenerators and the series capacitors in the networks reciprocate energy at one of the natural torsional modes of oscillations. Subsynchronous resonance is a torsional instability condition at a frequency lower than the normal grid frequency resulting in intense torsional
torque oscillations distinguished by ever-growing magnitudes. The rotor
system is then unquestionably destined to encounter surface cracks which
have devastating consequents on thermal power plants. Therefore, mitigation of subsynchronous resonance related oscillations has been a subject of relatively rich academic investigations since 1970. Rectifier controlled resistor brake controlled via fuzzy controller of type-2 will be propositioned in this thesis for the alleviation of subsynchronous resonance torque oscillations. Turbogenerators shaft torsional oscillations could be stimulated
on account of several grid disturbances, such as fault, fault clearing, malsynchronization, and autoreclosing practices. Autoreclosing practices are irreplaceable protective and control schemes that were initially engineered for boosting the system stability in case of transient disturbances predominately
in territories characterized by having high isokeraunic levels. Failed
autoreclosing practices could have dire consequences on the neighboring
turbogenerators. They give rise to exacerbated shaft torsional torque
oscillations at the shaft segments and consequentially a significant loss of the fatigue life of the shaft forging is highly expected. The shaft is then definitely destined to experience irrevocable high-cycle fatigue cracks. A fuzzy logicbased battery energy storage system will be propositioned in this dissertation for minimizing the rotary shaft torsional oscillations accompanied by failed
autoreclosing. Coordinated operation of a fuzzy-based resistor brake will be considered for acquiring superior torsional torque profiles. Comparative
simulation studies are conducted on two various test systems via the
MATLAB/Simulink environment for examining the effectivity of the
propositioned scheme.