In electrical engineering, the designer is often presented with the problem of synthesizing a circuit for which the mathematical specifications are unsuitable for physical realization. Hence, the engineer must approximate as well as possible the prescribed network function by another function which is realizable. This paper describes a new approximation method for solving the problem of realizing passive network transfer functions, where the realization is carried out through the use of passive, reciprocal,lumped, linear, and time-invariant elements.

Στην παρούσα διπλωματική εργασία μελετήθηκαν οι αιτίες, οι επιπτώσεις και η αντιμετώπιση σε προβλήματα που αφορούν διείσδυση ανώτερων αρμονικών σε δίκτυο μέσης τάσης. Μοντελοποιήθηκε και εισήχθη ένα κομμάτι πραγματικού δικτύου μέσης τάσης στο υπολογιστικό πακέτο MATLAB. Ο εξαχθείσες προσομοιώσεις τόσο της εμπέδησης-συχνότητας όσο και της τάσης παρουσία αρμονικών, έδωσαν συμπεράσματα για τη συμπεριφορά του δικτύου. Τέλος εξετάστηκε η συμπεριφορά του παρουσία παθητικών φίλτρων. / In the present "Diploma Thesis" the causes,the effects and the treatment of high harmonics penetration in middle voltage electric distribution systems were studied.A real middle voltage electric distribution system was modeled with the use of Matlab.The simulations (impedance vs. frequency and voltage with presence of high harmonics) resulted conclusions over the behavior of such system.At last,the behavior of the electric distribution system in presence of passive filters was studied.

Submitted by JUAN JOSE PEREZ ALVAREZ null (yuanjpa@gmail.com) on 2016-09-09T18:04:31Z No. of bitstreams: 1 Final.pdf: 4688581 bytes, checksum: ffc24669bda0a26530c5591cfd508d95 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-09-13T13:20:34Z (GMT) No. of bitstreams: 1 alvarez_jjp_me_ilha.pdf: 4688581 bytes, checksum: ffc24669bda0a26530c5591cfd508d95 (MD5) / Made available in DSpace on 2016-09-13T13:20:34Z (GMT). No. of bitstreams: 1 alvarez_jjp_me_ilha.pdf: 4688581 bytes, checksum: ffc24669bda0a26530c5591cfd508d95 (MD5) Previous issue date: 2016-09-01 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Neste trabalho apresenta-se um algoritmo para o dimensionamento de um sistema híbrido de filtragem passivo que considera os filtros ressonantes e os dispositivos eletromagnéticos para mitigação de correntes harmônicas de sequência zero. O objetivo do algoritmo proposto é acrescentar o estudo dos filtros passivos mediante a utilização de métodos de otimização nos modelos matemáticos dos filtros ressonantes e do filtro eletromagnético considerando a interação destes dispositivos com o sistema de distribuição de energia elétrica (SDEE). Os estudos realizados visam aplicar o algoritmo na avaliação de três casos de estudo com diferentes características com o objetivo de verificar: a efetividade dos modelos propostos no cálculo dos parâmetros construtivos das topologias consideradas; o impacto do desequilíbrio das fases no ponto de acoplamento comum (PAC) no dimensionamento e na operação dos filtros passivos estudados; e, por meio da operação conjunta, a eficiência dos filtros medida individualmente, bem como do sistema híbrido de filtragem passivo resultante. Um critério de dimensionamento para o bloqueador eletromagnético usado no algoritmo proposto é também discutido. / This work presents an algorithm for designing a passive filtering hybrid system considering resonant and zero-sequence electromagnetic filters. The proposed algorithm objective is to enrich the study of passive filters by applying optimization methods to the resonant and zerosequence electromagnetic filter models considering their interaction with the distribution energy system (DER). The obtained results, applying the algorithm on three diverse study cases, indicate: the effectiveness of the proposed models in calculating the parameters of the passive filters studied, the negative impact of phase unbalance in the point of common coupling (PCC) over the designing and operation of the passive filters studied and, through a combined operation, a filter efficiency improvement seen individually and by evaluating the passive filtering hybrid system. A criterion for the zero-sequence electromagnetic blocker used by the proposed algorithm is also discussed. / CNPq: 163977/2014-3

Orientador: Júlio Borges Souza / Resumo: Neste trabalho apresenta-se um algoritmo para o dimensionamento de um sistema híbrido de filtragem passivo que considera os filtros ressonantes e os dispositivos eletromagnéticos para mitigação de correntes harmônicas de sequência zero. O objetivo do algoritmo proposto é acrescentar o estudo dos filtros passivos mediante a utilização de métodos de otimização nos modelos matemáticos dos filtros ressonantes e do filtro eletromagnético considerando a interação destes dispositivos com o sistema de distribuição de energia elétrica (SDEE). Os estudos realizados visam aplicar o algoritmo na avaliação de três casos de estudo com diferentes características com o objetivo de verificar: a efetividade dos modelos propostos no cálculo dos parâmetros construtivos das topologias consideradas; o impacto do desequilíbrio das fases no ponto de acoplamento comum (PAC) no dimensionamento e na operação dos filtros passivos estudados; e, por meio da operação conjunta, a eficiência dos filtros medida individualmente, bem como do sistema híbrido de filtragem passivo resultante. Um critério de dimensionamento para o bloqueador eletromagnético usado no algoritmo proposto é também discutido. / Abstract: This work presents an algorithm for designing a passive filtering hybrid system considering resonant and zero-sequence electromagnetic filters. The proposed algorithm objective is to enrich the study of passive filters by applying optimization methods to the resonant and zerosequence electromagnetic filter models considering their interaction with the distribution energy system (DER). The obtained results, applying the algorithm on three diverse study cases, indicate: the effectiveness of the proposed models in calculating the parameters of the passive filters studied, the negative impact of phase unbalance in the point of common coupling (PCC) over the designing and operation of the passive filters studied and, through a combined operation, a filter efficiency improvement seen individually and by evaluating the passive filtering hybrid system. A criterion for the zero-sequence electromagnetic blocker used by the proposed algorithm is also discussed. / Mestre

This dissertation covers several issues related to the ac-dc bus-interface bi-directional converters in renewable energy systems. The dissertation explores a dc-electronic distribution system for residential and commercial applications with a focus on the design of an ac-dc bi-directional converter for such application. This converter is named as the "Energy Control Center" due to its unique role in the system. First, the impact of the unbalanced power from the ac grid, especially the single-phase grid, on the dc system operation is analyzed. Then, a simple ac-dc two-stage topology and an advanced digital control system is proposed with a detailed design procedure. The proposed converter system significantly reduces the dc-link capacitor volume and achieves a dynamics-decoupling operation between the interfaced systems. The total volume of the two-stage topology can be reduced by upto three times compared with the typical design of a full-bridge converter. In addition, film capacitors can be used instead of electrolytic capacitors in the system, and thus the whole system reliability is improved. A set of ac passive plus active filter solutions is proposed for the ac-dc bus-interface converter which significantly reduces the total power filter volume but still eliminate the total leakage current and the common-mode conducted EMI noises by more than 90%. The dc-side low-frequency CM voltage ripple generated by the unbalanced ac voltages can be eliminated as well. The proposed solution features a high reliability and fits three types of the prevalent low-voltage ac distribution systems. Grid synchronization, a critical interface control in ac-dc bus-interface converters, is discussed in detail. First, a novel single-phase grid synchronization solution is proposed to achieve the rejection of multiple noises as well as the capability to track the ac voltage amplitude. Then, a comprehensive modeling methodology of the grid synchronization for three-phase system is proposed to explain the output frequency behaviors of grid-interface power converters at the weak grid, at the islanded condition, and at the multi-converter condition. The proposed models provide a strong tool to predict the grid synchronization instabilities raised from industries under many operating conditions, which is critical in future more-distributed-generation power systems. Islanding detection issues in ac-dc bus-interface converters are discussed in detail. More than five frequency-based islanding detection algorithms are proposed. These solutions achieve different performances and are suitable for different applications, which are advantageous over existing solutions. More importantly, the detailed modeling, trade-off analysis, and design procedures are given to help completely understand the principles. In the end, the effectiveness of the proposed solutions in a multiple-converter system are analyzed. The results drawn from the discussion can help engineers to evaluate other existing solutions as well. / Ph. D.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Pectin obtained from cocoa husks has recently been investigated because of its gelling and stabilizing properties that have great potential for the food, cosmetic and pharmaceutical industries. However, its production at the industrial level has not been studied or developed in Peru. A fundamental part of the extraction process is the stage of hydrolysis and filtering of the cocoa shell. Because of this, an automated system for acid-thermal hydrolysis and shell filtration is proposed. The control of both processes is of great importance because the quality and efficiency of the extracted pectin will depend on it. The tests will be carried out in a cylindrical taper with a 100 L capacity which is adapted to contain a 20 L cylindrical filter, both made of AISI 304 stainless steel. The filter has a motor to homogenize the temperature and pH of the mix. The pH of the process is 2 and the temperature is 90 ± 2 °C, since in these ranges the pectin is released more easily from the cocoa shell. The method consists of the structural design of the tank and the filter, and in the design of the pH regulator and the heating system. The yield of the extraction process was achieved by 10%. / Revisión por pares

Firstly, this thesis investigates the electrical power harmonics in an attempt to utilize harmonic current and its distortion power in a novel idea to reconvert the distortion power into useful power. This is done, in order to feed different DC or AC loads in single and three-phase power system by using passive or active filters and accordingly, develop a new topology of hybrid active power filter (HAPF). In addition, this circuit can be considered as a power factor corrector (PFC) because it reduces the total harmonic distortion (THD) and improves the power factor (PF). Secondly, this thesis works on a new design of active power factor correction (APFC) circuit presenting two circuits with the same design principle: the first design consists of two active switches without an external complex control circuit, while the second design contains a single active switch with an additional control circuit. The main contribution of this circuit is 98% reduction of the inductor's value used in the newly proposed PFC circuit in comparison with the conventional boost converter which may lead to a huge reduction in size, weight and the cost of the new PFC circuit. Also, the active switches depend on a carefully designed switching pattern that results in an elimination of the third order harmonic from the input source current which decreases the value of total current harmonic distortion (THDI) to (14%) and improves the input PF to (0.99). Consequently, the simplicity of the design without requiring a complex control circuit and without a snubber circuit plus the minimum size of inductor, gives the newly proposed circuit the superiority on other PFC circuits. Thirdly, this research aims to describe the distortion power through submitting two novel power terms called effective active power (Pef ) & reactive power (Qef ) terms with a new power diagram called Right-Angled Power Triangle (RAPT) Diagram. In addition, a novel de nition of total apparent power (St) has been submitted in order to illustrate the physical meaning of (St) in non-sinusoidal systems. The new RAPT Diagram is based on the orthogonality law and depends on geometrical summation to describe the relationship between different aspects (apparent-active-reactive) of power, and different components (total-fundamental distortion), drawing a bridge to connect the time domain with the frequency domain in a two-dimensional diagram.

Στην παρούσα διατριβή αναπτύσσονται κατάλληλα μοντέλα για τις επιμέρους μονάδες φωτοβολταϊκού (ΦΒ) συστήματος συνδεδεμένου στο δίκτυο. Στόχος είναι να αντιμετωπιστούν ταυτόχρονα και αποτελεσματικά οι ιδιαιτερότητές του, που οφείλονται στη συμπεριφορά των διακοπτικών στοιχείων και στα μη γραμμικά χαρακτηριστικά της ΦΒ γεννήτριας και του μετασχηματιστή απομόνωσης. Αναπτύσσονται μέθοδοι που αυξάνουν την ταχύτητα εξομοίωσης. Αυτό επιτυγχάνεται με χρήση αυξητικών μοντέλων για τα μη γραμμικά στοιχεία και αποτελεσματικών αλγορίθμων για την αντιμετώπιση της μεταβλητής τοπολογίας. Τα μοντέλα που παρουσιάζονται μπορούν να χρησιμοποιηθούν για συνδεδεμένα στο δίκτυο ΦΒ συστήματα οποιασδήποτε διάταξης. Μέσω εξομοιώσεων της λειτουργίας ενός οικιακού ΦΒ συστήματος συνδεδεμένου στο δίκτυο διερευνάται η ευαισθησία της αρμονικής παραμόρφωσης τάσεων και ρευμάτων σε μεταβολές παραμέτρων του συστήματος. Στη συνέχεια παρουσιάζεται ένα νέο μοντέλο για τη ροή ενέργειας σε κυκλώματα με μη ημιτονοειδείς κυματομορφές. Το μοντέλο παρέχει μαθηματική περιγραφή μέσω του πολυδιανύσματος της ισχύος, το οποίο γεφυρώνει το χάσμα μεταξύ στιγμιαίας και φαινομένης ισχύος, όπως η μιγαδική ισχύς υπό ημιτονοειδείς συνθήκες. Το πολυδιάνυσμα της ισχύος επιτρέπει συστηματική και ενιαία αντιμετώπιση όλων των περιπτώσεων. Το μοντέλο ροής ενέργειας που παρουσιάζεται περιγράφει τις συνιστώσες ισχύος όχι μόνο ποσοτικά, αλλά και ποιοτικά. Από φυσικής πλευράς βασίζεται στη γενίκευση της έννοιας της αμοιβαίας σύζευξης. Η προσέγγιση που ακολουθείται επιτρέπει την φυσική ερμηνεία όλων των συνιστωσών της ισχύος, οι οποίες συνδέονται με μια αναπαράσταση μέσω ισοδυνάμου κυκλώματος. Οι προϋπάρχουσες μέθοδοι μπορούν να προκύψουν ως ειδικές περιπτώσεις του μοντέλου. Η βαθύτερη κατανόηση των φαινομένων ισχύος που παρέχει θέτει το θεωρητικό υπόβαθρο για την επίλυση πρακτικών προβλημάτων, όπως η αντιστάθμιση. Ακολούθως εξετάζεται η επιλογή του βέλτιστου μεγέθους παθητικών φίλτρων με παράλληλους συντονιζόμενους κλάδους. Η διερεύνηση λαμβάνει υπόψη όχι μόνο πηγές αρμονικών ρευμάτων λόγω μη γραμμικών φορτίων αλλά και την παρουσία προϋπάρχουσας αρμονικής παραμόρφωσης της τάσης. Μέσω αναλυτικής μεθόδου προκύπτουν εκφράσεις κλειστής μορφής για απλοποιημένες περιπτώσεις. Αυτές μπορούν να βοηθήσουν στην κατανόηση της επίδρασης διαφόρων παραμέτρων. Επίσης διαμορφώνεται η γενικότερη περίπτωση του προβλήματος και αντιμετωπίζεται με Γενετικούς Αλγόριθμους. Μέσα από εκτεταμένες εξομοιώσεις για διάφορα επίπεδα αρμονικών τάσης και ρεύματος, διερευνώνται διεξοδικά οι δυνατότητες των παθητικών φίλτρων. Τα πρακτικά συμπεράσματα που προκύπτουν μπορούν να βοηθήσουν στη λήψη αποφάσεων για τον έλεγχο των αρμονικών σε διάφορες εφαρμογές. / In this thesis, appropriate models for the individual components of a grid-connected photovoltaic (PV) system are developed. The aim is to simultaneously and efficiently handle its peculiarities, which are due to the switching action of the switching devices and the nonlinear characteristics of the PV generator and the isolation transformer. Methods that increase simulation speed are developed. This is accomplished by using incremental models for the nonlinear components and efficient algorithms to handle the variable topology. The presented models can be used for grid-connected PV systems of any configuration. Through simulations of the performance of a residential grid-connected PV system the sensitivity of the harmonic distortion of voltages and currents to variations in system parameters is investigated. Next, a novel model for the energy flow in circuits with nonsinusoidal waveforms is presented. This model provides a mathematical description through the power multivector, which bridges the gap between the instantaneous and apparent power, like the complex power does under sinusoidal conditions. The power multivector permits a systematic and uniform treatment of all cases. The presented energy flow model describes power components not only quantitatively but also qualitatively. From a physical perspective it is based on the generalization of the concept of mutual coupling. The approach that is followed permits the physical interpretation of all power components, which are associated with an equivalent circuit representation. Pre-existing methods can be derived as special cases of the model. The deeper understanding of power phenomena it provides sets the theoretical foundation for the solution of practical problems, such as compensation. Next, the optimal sizing of shunt, passive, single-tuned filters is examined. The investigation takes into account not only harmonic current sources due to nonlinear loads but also the presence of background voltage harmonic distortion. Through an analytical approach closed-form expressions are derived for simplified cases. These can help in the comprehension of the influence of various parameters. Moreover, the general case of this problem is formulated and solved using Genetic Algorithms. Through extensive simulations for various current and voltage harmonic levels, the potentialities of these filters are thoroughly investigated. The practical conclusions that are drawn can facilitate decisions regarding harmonic control in various applications.

HVDC technologies are very effective on long distance power transmission but generally raise large interrogations as how to determine an effective configuration. This thesis propose part of an optimization process in order to determine an optimal configuration for an HVDC installation, emphasizing in this report the impact of the conductor selection and of the filter design.  The conductor selection, including varying voltages raises concern about the knowledge of the energy cost evolution in order to determine its optimum and a sensitivity analysis is proposed to evaluate the impact of this factor on the final design. The conductor selection approach made it possible to determine the key parameters in choosing a conductor which are the radius and number of conductors. Different types of conductors and configurations were compared with different scenari for energy cost in order to determine the most economical conductor.  Filter design is a matter that concerns both the internal components and the AC components of the HVDC station but can also be considered as an optimization process, considering the total losses of the filters and the total harmonic distortion and using a minimax approach.  The optimization approach, based on a Newton-Raphson algorithm, made it possible to determine an optimal combination of filters in order to account for all the power range in the HVDC link. It was observed that even though the actual choice for the design was close to the final design selected, it was not optimal for low power harmonics. / HVDC är en mycket effektiv teknik för kraftöverföring av elektrisk energi på långa avstånd, men ställer generellt stora krav på hur man genomför en effektiv konfiguration. Denna avhandling föreslår en del av en optimeringsprocess för att bestämma en optimal konfiguration för en HVDC-anläggning. Det som betonas i denna rapport är effekterna av val av ledare och design av filter. Ledarvalet, inklusive val av spänning, kräver en prognostisering av energikostnadernasutvecklingen för att optimera designen och göra en känslighetsanalys för att utvärdera effekterna av dessa faktorer på den slutliga utformningen. Tillvägagångssättet för ledarval gjorde det möjligt att fastställa de viktigaste parametrarna att välja en ledare som är radien och antal delledare. Olika typer av ledare och konfigurationer jämfördes med olika scenario för energikostnaden för att bestämma denmest ekonomiska ledaren. Filterdesignen är en fråga som berör både de inre komponenterna och AC komponenter i HVDC-stationen, men kan också betraktas som en optimeringsprocess, med avseende på de totala förlusterna av filtren och total harmonisk distorsion och med hjälp av en minimax tillvägagångssätt. Optimeringsstrategin som bygger på en Newton-Raphsons algoritm, gjorde det möjligt att fastställa en optimal kombination av filter för att ta hänsyn till alla effektområden i HVDC-förbindelsen. Det observerades att även om det faktiska valet för konstruktionen var nära den slutliga utformning som valdes, så var den inte optimala för låga  övertoner.

[ES] El creciente número de dispositivos intercambiando datos ha empujado a las empresas del sector espacial a utilizar bandas de frecuencia cada vez más altas, como Ku, K y Ka, ya que permiten emplear canales de frecuencia más anchos. A medida que disminuye la longitud de onda, el tamaño de los filtros se reduce y, por tanto, son más sensibles a las desviaciones de fabricación. Para compensar estos errores, es necesario emplear elementos de sintonía en la etapa de diseño. En este contexto presentamos una estrategia de diseño que permite incluir todos los factores no ideales, como elementos de sintonía o esquinas redondeadas, en las simulaciones finales de filtros y multiplexores. Una vez se han fabricado los filtros es necesario ajustar manualmente los elementos de sintonía hasta recuperar la respuesta objetivo. Sin embargo, para realizar esta tarea con éxito es necesario tener mucha experiencia previa y, aún así, conlleva un tiempo considerable. Por tanto, también proponemos un procedimiento de sintonización eficiente y sistemático que permite a cualquier persona, independientemente de su experiencia previa en sintonización, realizar esta tarea con éxito. Además del aumento de las tasas de transmisión, otros desafíos del sector espacial son reducir el tamaño y peso de sus componentes, así como dotarlos de capacidad dereconfiguración. Emplear dispositivos multifunción como filtros multibanda o dispositivos reconfigurables es una posible solución. En este contexto, proponemos una nueva familia de filtros multibanda en guía de ondas que puede adaptarse a las futuras necesidades del sector espacial. Con el mismo objetivo, también proponemos una familia de dispositivos reconfigurables de varios estados discretos que pueden modificar su comportamiento de forma remota. / [CA] El creixent nombre de dispositius intercanviant dades ha empés a les empreses del sector espacial a utilitzar bandes de freqüència cada vegada més altes, com Ku, K i Ka, ja que permeten fer servir canals de freqüència més amples. A mesura que la longitud d'ona disminueix, la mida dels filtres es redueix i, per tant, són més sensibles a les desviacions de fabricació. Per compensar aquests errors, és necessari fer servir elements de sintonia en l'etapa de disseny. En aquest context presentem una estratègia de disseny que permet incloure tots els factors no ideals, com a elements de sintonia o cantonades arrodonides, en les simulacions finals de filtres i multiplexors. Una vegada s'han fabricat els filtres és necessari ajustar manualment els elements de sintonia fins a recuperar la resposta objectiu. Però, per realitzar aquesta tasca amb èxit és necessari tenir molta experiència prèvia i, així i tot, comporta un temps considerable. Per tant, també proposem un procediment de sintonització eficient i sistemàtic que permet a qualsevol persona, independentment de la seua experiència prèvia en sintonització, realitzar aquesta tasca amb èxit. A més de l'augment de les taxes de transmissió, altres desafiaments de el sector espacial són reduir la mida i pes dels seus components, així com dotar-los de capacitat de reconfiguració. Emprar dispositius multifunció com filtres multibanda o dispositius reconfigurables és una possible solució. En aquest context, proposem una nova família de filtres multibanda en guia d'ones que pot adaptar-se a les futures necessitats del sector espacial. Amb el mateix objectiu, també proposem una família de dispositius reconfigurables de diversos estats discrets que poden modificar el seu comportament de forma remota. / [EN] The need for ever increasing data rate of modern communication systems has motivated companies in the space sector to exploit higher frequency bands, such as Ku, K and Ka, in order to offer wider bandwidths to their customers. However, as the frequency increases, the wavelength decreases, and all waveguide hardware becomes smaller and more sensitive to deviations from the ideal dimensions that normally occur when manufacturing the devices. In order to compensate for these deviations (or errors), tuning elements must then be added to the hardware and included in the design process. In this context, therefore, we focus on the investigation of novel design strategies for filters and multiplexers with the objective of including all necessary non-ideal factors in the design process. It is important to note in this context that, once the filters are manufactured, the tuning elements are usually adjusted manually until the desired target performance has been achieved. However, successfully performing this task requires a considerable amount of time and very significant previous experience in tuning microwave filters. Consequently, an additional goal of our research work is to propose efficient and systematic tuning procedures so that anyone, regardless of their previous tuning experience, can successfully perform this difficult task. In addition to the increasing data rates, another current challenge of advanced communication systems is the ability to be reconfigured remotely to adjust to changes in costumer demands. The use of multi-function or reconfigurable devices is then an attractive possible solution. In this context, therefore, we also investigate new families of multi-band waveguide filters that can be used to accommodate several pass bands in the same filtering device. Furthermore, we also propose a new family of reconfigurable devices with several discrete states that can be easily controlled remotely. / Melgarejo Lermas, JC. (2021). Advanced Techniques for the Design and Optimization of Multi-Band and Reconfigurable Microwave Waveguide Filters [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172728