Orientadores: Luiz Antonio Barrera San Martin, Paulo Regis Caron Ruffino / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-04T03:20:41Z (GMT). No. of bitstreams: 1 Lopez_JorgeNicolas_D.pdf: 956037 bytes, checksum: ce1c7712a7ab2ad21d0e46479e50f04a (MD5) Previous issue date: 2005 / Doutorado / Matematica / Doutor em Matemática

Harmonics in systems are conventionally suppressed using passive tuned filters, which have practical limitations in terms of the overall cost, size and performance, and these are particularly unsatisfactory when large number of harmonics are involved Active power filtering is an alternative approach in which the filter injects suitable compensation currents to cancel the harmonic currents, usually through the use of power electronic converters. This type of filter does not exhibit the drawbacks normally associated with its passive counterpart, and a large number of harmonics can be compensated by a single unit without incurring additional cost or performance degradation. This thesis investigates an active power filter configuration incorporating instantaneous reactive power theory to calculate the compensation currents. Since the original equations for determining the reference compensation currents are defined in two imaginary phases, considerable computation time is necessary to transform them from the real three-phase values. The novel approach described in the thesis minimises the required computation time by calculating the equations directly in terms of the phase values i. e. three-phase currents and voltages. Furthermore, by utilising a sufficiently fast digital signal processor ( DSP ) to perform the calculation, real-time compensation can be achieved with greater accuracy. The results obtained show that the proposed approach leads to further harmonic suppression in both the current and voltage waveforms compared to the original approach, due to considerable reduction in the computation time of the reference compensation currents.

M.Ing. / Line commutated thyristor converters are proven to be natural line harmonic currentgenerating sources regardless of their operating modes. The quality of harmonic current components induced back to the lines is commonly described to be similar under both states of operation. This however does not seem to be quite obvious as far as the aggregate harmonic current contribution to the phase inputs per operating region of thyristor converters. It becomes thus important to examine the degree of association between thyristor converter operating states and the magnitude of current harmonic pollution induced back to the input lines to subsequently establish the most current harmonic polluting region of operation. For the purpose of this study, the Nyquist-Shannon theorem, best known as the sampling theorem, whereby the converter output signal or waveform is sampled by the switching function to reconstruct the input waveform, is numerically applied in conjunction with the MatLab/Simulink 7.0 which enables the simulation of the two-quadrant operation of direct current variable speed drive (DC VSD) and that of high voltage direct current link (HVDC) converter station operation, as well as physical measurements on the twoquadrant operation of the DC VSD (Saftronics DC2L) with the aid of the digital scope meter (DSO)1200 series. However, numerical analysis based on the sampling theorem, practical measurements obtained and the MatLab/Simulink simulations indicate that the converter operating states cause a randomly distributed harmonic current generation trend in the input lines as the firing angle is increased and the most harmonic current contribution cannot be attributed to a specific region of the controlled converter firing angle.

Power system harmonics are always an important issue in power networks as they can cause many negative impacts, such as equipment thermal stress, on installations within power networks. Recently, with the increasing connections of power electronic devices based Renewable Energy Source (RES) and High Voltage Direct Current (HVDC) transmission applications, harmonics in power networks, especially high frequency harmonics (>50th order or 2.5 kHz) are on the rise. Currently, the majority of conventional VTs, such as Wound-type Voltage Transformers (WVT) and Capacitor Voltage Transformers (CVT), are widely installed and used in High Voltage (HV) and Extra High Voltage (EHV) power networks for voltage measurement. Since most of them were mainly designed to measure voltage with the required accuracy at the fundamental frequency (i.e. 50Hz in the UK), they are limited to measuring high frequency harmonics due to the coupling of their internal inductive and capacitive elements. To achieve high frequency harmonic measurements, voltage measurement devices with wide frequency bandwidths are required. Recently, non-conventional VTs, such as optical voltage transducers, are commercially available, which could provide accurate voltage measurements over a wide range of frequency. However, before they can be considered by any power utilities, their frequency response performances must be tested at a rated fundamental voltage with required minimum harmonic injections from 100Hz to 5 kHz. This must require a test system which should be capable of providing a rated fundamental voltage up to 400kV with controllable harmonic injections at required levels from 100Hz to 5 kHz. Therefore, the objective of this project is to design and implement such a test system in the National Grid (NG) HV laboratory at the University of Manchester. However, the design and the implementation of such a test system bring many challenges; for instance, a lack of adequate equipment and considerable power to provide the required harmonic injections above 0.5% to the test object.In this thesis, an Instrument Voltage Transformer Frequency Response (VTFR) test system with three different voltage power source designs is presented; The voltage power source designs are: (i) Design 1 is based on a single power source inductive coupling method to provide both a rated fundamental voltage and controllable harmonics; (ii) Design 2 is based on two separate voltage power sources inductive coupling method to provide both a rated fundamental voltage and controllable harmonics; and (iii) Design 3 is based on two separate voltage power sources capacitive coupling method to provide both the rated fundamental voltage and controllable harmonics. A hybrid approach, which combines the VTFR test system with both the voltage power sources Design 2 and 3, is proposed for testing the frequency response of any type of VTs at their rated fundamental voltages with 1% harmonic injections from 100Hz to 5 kHz. The proposed VTFR test system with voltage power source designs were firstly validated at a relatively low voltage of 33kV in the HV laboratory. Then three different VTFR test systems were constructed based on available equipment for testing VTs from 11kV to 400kV. An 11kV, a 33kV WVT and a 400kV WVT and a 275kV CVT were tested. The test results were analyzed, compared and discussed. The models of the test systems were also established and simulated. Simulation results were analysed, compared and discussed.

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Neste trabalho estudaremos subconjuntos especiais da esfera unitária Sm-1 de Rm, m 2, comumente chamados na literatura de designs esféricos. Os objetivos principais são analisar várias equivalências para o conceito, suas conexões com ambos, rotações sobre Sm?1 e mergulhos em esferas de dimensão superior, e resultados sobre a cardinalidade dos designs esféricos / In this work we will study specials subsets of the unitary sphere Sm-1 of Rm, m 2, usually called in literature spherical designs. The main objectives are to analyze many equivalences for the concept, its connections with both, rotations on Sm?1 and embedded in spheres of higher dimension, and results on the cardinality of spherical designs

In this thesis we explore the geometric representation theory of shifted quantum affine algebras 𝒜^𝜇, using the critical K-theory of certain moduli spaces of infinite flags of quiver representations resembling the moduli of quasimaps to Nakajima quiver varieties. These critical K-theories become 𝒜^𝜇-modules via the so-called critical R-matrix 𝑅, which generalizes the geometric R-matrix of Maulik, Okounkov, and Smirnov. In the asymptotic limit corresponding to taking infinite instead of finite flags, singularities appear in 𝑅 and are responsible for the shift in 𝒜^𝜇. The result is a geometric construction of interesting infinite-dimensional modules in the category 𝒪 of 𝒜^𝜇, including e.g. the pre-fundamental modules previously introduced and studied algebraically by Hernandez and Jimbo. Following Nekrasov, we provide a very natural geometric definition of qq-characters for our asymptotic modules compatible with the pre-existing definition of q-characters. When 𝒜^𝜇 is the shifted quantum toroidal gl₁ algebra, we construct asymptotic modules DT_𝜇 and PT_𝜇 whose combinatorics match those of (1-legged) vertices in Donaldson--Thomas and Pandharipande--Thomas theories. Such vertices control enumerative invariants of curves in toric 3-folds, and finding relations between (equivariant, K-theoretic) DT and PT vertices with descendent insertions is a typical example of a wall-crossing problem. We prove a certain duality between our DT_𝜇 and PT_𝜇 modules which, upon taking q-/qq-characters, provides one such wall-crossing relation.

Cette thèse vise à développer des antennes large bande à double polarisation avec un filtre et un dispositif d’adaptation d’impédance et d’alimentation intégrés, que nous avons définies comme antennes versatiles intriquées. La largeur de la bande et la double polarisation permettent d’utiliser l’antenne avec différents standards et donc d’être versatile. D'autre part, le filtre pour rejeter les harmoniques supérieurs et le réseau d'adaptation sont des parties intégrantes de l'élément rayonnant et lui confèrent le caractère intriqué. La première étude porte sur la conception d'une antenne large bande à double polarisation avec un filtre intégré dans le dispositif d’alimentation. Le filtre permet de rejeter les harmoniques indésirables. La structure complète est compacte et de dimensions 0.9 λ0x0.9 λ0, λ0 étant la longueur d’onde en espace libre à la fréquence basse. Afin d’augmenter la compacité, nous présentons ensuite une antenne à suppression des harmoniques (HSA : Harmonic Suppressed Antenna) large bande à simple et à double polarisation. Ce travail explore les différentes techniques utilisées pour concevoir une HSA. Dans cette approche, l'élément rayonnant, le filtre qui permet de rejeter le rayonnement d’harmoniques hors bande et le réseau d'adaptation, qui sont traditionnellement des circuits séparés, sont intégrés dans une seule unité compacte. La taille totale de l'antenne est 0.53 λ0x0.53 λ0. Le dernier chapitre présente une des HSA développées associée à un conducteur magnétique artificiel non-uniforme. Cette structure permet l’obtention d’une antenne large bande de faible épaisseur et directive. / This thesis aims to develop wideband antennas interrelated with a filter, which we have defined as versatile intricate antennas. The antenna is versatile as it provides wide bandwidth (more than one octave) and has the capability to generate two orthogonal polarizations. On the other hand, the filter for harmonic rejection and the matching network are integrated parts of the radiating element and give it the intricate character.The first study is concentrated on designing a dual polarized antenna with a wide stop filter integrated to the feeding network. This filter enables to reject harmonics and unwanted response. The complete structure is compact with a size of 0.9 λ0x0.9 λ0, λ0 being the free space wavelength at the lowest frequency. In order to improve the compactness of the whole system and to cover more standards, we present a single and dual polarized wideband Harmonic Suppressed Antenna (HSA). This work explores the different techniques used to design a HAS. The proposed antenna is simple in structure but versatile in applications. In this approach, radiating element, filter for harmonic rejection and matching network, which are traditionally separated circuits, are incorporated into a single compact unit. The total size of the antenna is 0.53 λ0x0.53λ0. The final chapter aims to study the previous intricate antenna with a new wideband Artificial Magnetic Conductor (AMC) structure as reflector in order to obtain a low profile and directive antenna.

We developed an extreme ultraviolet (EUV) polarimeter, which employs laser-generated high-order harmonics as the light source. This relatively high-flux directional EUV source has available wavelengths between 8 nm and 62 nm and easily rotatable linear polarization. The polarimeter will aid researchers at BYU in characterizing EUV thin films and improving their understanding of materials for use in EUV optics. This first-time workhorse application of laser high harmonics enables polarization-sensitive reflection measurements not previously available in the EUV. We have constructed a versatile positioning system that places harmonics on the microchannel plate detector with an accuracy of 0.3 mm, which allows a spectral resolution of about 180. We have demonstrated that reflectance as low as 0.2% can be measured at EUV wavelengths and that this data is repeatable to within the error of our source stability (~7% fluctuation). We have compared reflectance data with that taken from the same sample at Beamline 6.3.2 at the Advanced Light Source. This data agrees well from 5 degrees to 30 degrees and the angular locations of the interference fringes also agree.

It is the intent of this study to describe the harmonic activity that is present in the tone of the alto saxophone and to compare the spectra of selected tones when the chamber of the mouthpiece is changed in size and shape. It is hoped that the following questions might be answered: 1. What does the harmonic spectrum of the alto saxophone contain in terms of harmonic activity and the relative intensities of these harmonics? 2. What basic changes in chamber shape and size have evolved from early models? 3. Is there an appreciable change in the envelope of harmonic activity when the mouthpiece chamber is altered in size and shape? 4. Is it possible for these changes to be used to explain common terminology of the musician in describing tone qualities?