Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"zero-sequence"”.
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Harmonic control of multiple-stator induction machines for voltage regulation
… to a three-phase rectifier in which a path for zero-sequence current is provided from the winding circuits to the rectifier. The last set of stator winding circuits is connected to another three-phase rectifier, however, the stator circuit star point is floating, not providing a zero-sequence …
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Zero-sum problems in finite cyclic groups
… of combinatorial number theory referred to as zero-sum theory. A zero-sequence in a finite cyclic group G is said to have the basic property if it is equivalent under group automorphism to one which has sum precisely IGI when this sum is viewed as an integer. This thesis investigates two major …
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Modeling and Control of Parallel Three-Phase PWM Converters
… of the parallel three-phase converters is a zero-sequence circulating current. This work proposes a novel zero-sequence control concept that uses variable zero-vectors in the space-vector modulation (SVM) of the converters. The control can be implemented within an individual converter and is …
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Next-generation, phasor-based distance relay with fault-path resistance immunity
… distribution factor phase angle, parallel line zero-sequence current, and parallel line zero-sequence impedance are not required, in the event that they are available, the relay can provide even more refined, accurate results. The advanced distance relay prototype was written in the "C" …
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Fault Location in Series Compensated Transmission Lines
… of the existing fault location algorithms on zero-sequence parameters of the series capacitor compensated transmission line which cannot be estimated accurately. In this thesis, the task of fault location in series capacitor compensated transmission lines has been explored in detail covering …
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Correcting Current Imbalances in Three-Phase Four-Wire Distribution Systems
… Through this redistribution, negative- and zero-sequence currents are eliminated and a balanced system is seen upstream from the point of installation.</p> <p>The UCSC consists of three separate single-phase H-bridge inverters that all share the same dc-link capacitor. Each of these …
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Machine Learning-Based Parameter Validation
… classifiers built using positive, negative, and zero sequence measurements were compared. The negative sequence measurements have consistently produced the best classifiers, with majority of the parameter classes attaining F-measure accuracies greater than 90%. A multiple-parameter error …
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Control Strategies for High Power Four-Leg Voltage Source Inverters
… phase currents, and consequently negative sequence and zero sequence (in four-wire systems) distortion. A proposed control strategy based on synchronous and stationary frame controllers is shown to reduce the phase voltage unbalance from 4.2% to 0.23% for a 100%-100%-85% load imbalance over …
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Novel Control Algorithms for Power Quality Improvement Using Four-Leg Converter
… such circumstances, substantial negative and zero sequence currents are drawn from the utility grid resulting in disrupting the sensitive devices, overheating the neutral conductors, and damaging the power generating sources. Such problems further aggravate by degrading the active power flow …
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Modeling, Analysis, and Design of Distributed Power Electronics System Based on Building Block Concept
… are evaluated for PEBB applications. The Zero-Current-Transition (ZCT) is proved better because the parasitics in the power current flow path are absorbed into the resonant soft-switching operation. This makes the PEBBs insensitive to system integration. Based on the building block …
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Synchronous generator and excitation system response to GIC
… harmonics do not follow the conventional phase sequence. This means that multiples of the third harmonic no longer have a zero sequence. Such harmonics may affect the generator despite delta winding connections of generator step-up transformers (GSUs). The increased var demand due to saturating …
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Generalized theory of static power frequency changers
… changers operated from ac Sources having zero internal impedance. The second part, comprising two chapters, considers sources with finite internal impedances . Chapter 1 introduces the basic concepts of static frequency conversion, outlines the basic mathematical models representing static …
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Implementation of wide area protection system (WAPS) for electrical power system smart transmission grids
… used for faulted zone detection: (A) Positive sequence voltage magnitude (PSVM), (B) Gain in momentum (GIM) and (C) Sum of positive and zero sequence currents (SPZSC). The dissertation investigated their performances in terms of accuracy in detecting the faulted zones and the faulted lines, and …
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Control and operation of HVDC connected offshore windfarm with particular emphasis on faults and black start
… voltage recovery. Therefore, based on a detailed sequence network analysis, an enhanced control strategy is proposed during offshore asymmetrical faults to exploit the induced negative sequence and zero sequence voltages to facilitate controlled injection of negative sequence current while …
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Multiple Three-Phase Induction Generators for Wind Energy Conversion Systems
… into orthogonal two-dimensional subspaces and zero sequence components while making sure that all odd-order harmonics are uniquely mapped. Harmonic mapping analysis is offered as well. Next, relationship between MS and VSD variables has been developed by mapping MS variables into VSD subspaces. …
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Control, Analysis, and Design of SiC-Based High-Frequency Soft-Switching Three-Phase Inverter/Rectifier
… unwanted circulating current formed by shared zero-sequence voltage in the paralleled structure, only two phases in the second channel working in high frequency are shed. The proposed phase shedding control achieves a 0.5 to 3.9 % efficiency improvement with light loads. Third, due to the usage …