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This article presents a new modulation technique called three-dimensional sigma–delta (3D-S¿ ) modulation for high-frequency three-leg four-wire voltage source converters (VSCs) that use wide-bandgap (WBG) semiconductors. These WBG devices allow for the use of high switching frequencies with a greater efficiency than silicon devices. The proposed 3D-S¿ technique enables operation at a variable switching frequency, resulting in a significant reduction in switching losses compared to classical pulse-width modulation (PWM) techniques. Moreover, the 3D-S¿ technique uses a fast-processing 3D quantiser that simplifies implementation and considerably reduces computational costs. The behaviour of the 3D-S¿ modulation is analysed using MATLAB/Simulink and PLECS. The experimental results performed on an active power filter that uses silicon carbide (SiC) MOSFETs demonstrate an improvement in converter efficiency compared to the conventional SPWM technique. Additionally, the experimental results show how 3D-S¿ allows for the compensation of harmonics and homopolar currents, thereby balancing the electrical grid currents. The experiments also show that the proposed 3D-S¿ modulation outperforms an SPWM technique in terms of power quality, since the former achieves a larger reduction in the harmonic content of the power grid. In conclusion, the proposed modulation technique is an attractive option for improving the performance of four-wire converters in active power filter applications., This work was supported by the Industrial Doctorates Plan of the Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya, and the Ministerio de Ciencia e Innovación of Spain within the projects PID2019-111420RB-I00 and PID2022-138827OB-I00, Peer Reviewed, Postprint (published version)

We consider a Thévenin equivalent circuit capturing the dynamics of a power grid as seen from the point of common coupling with a power electronic converter and propose a solution to the problem of online identification of the corresponding circuit parameters. For this purpose, we first derive a linear regression model in the conventional abc coordinates that, unfortunately, suffers from severe lack of identifiability properties. In spite of this fact, we design a bounded observer-based composite identifier that, requiring only local measurements and knowledge of the grid frequency, ensures global boundedness of the parameters estimation error and convergence to a practically small residual set. An extension that guarantees exponential convergence of these errors to zero, in the case that the grid is dominantly inductive, is further provided. The performance of the proposed identifier, which subsumes a conventional gradient descent algorithm, is illustrated via detailed computer simulations., The work of Oriol Gomis-Bellmunt was supported by the Institució Catalana de Recerca i Estudis Avançats (ICREA), Spain Academia Program. Ministerio de Ciencia e Innovación (Proyecto Equired) (PID2021-124292OB-I00)., Postprint (published version)

This paper discusses that the existing grid codes on the fault ride-through (FRT) opera-tion have certain complications to be implemented in the grid-forming (GFM) converters.In particular, they do not provide a clear guidelines on the suitable prioritization of thepositive- and negative-sequence currents needed for a desired voltage profile during FRToperation. To address this challenge, two FRT controls which are based on (i) voltagebalancing priority, and (ii) voltage magnitude priority are investigated for GFM convert-ers. The former gives priority to the elimination of negative-sequence voltage, while theremaining converter’s capacity is used to increase the positive-sequence voltage. On thecontrary, the latter prioritizes the increase of positive-sequence voltage, while it tries toreduce negative-sequence voltage by using the remaining converter’s capacity. The dynamicperformances of these two FRT controls are thoroughly discussed, and the simulationresults show that depending on the desired voltage profile during fault, one of them canbe implemented., Peer Reviewed, Postprint (published version)

© 2023 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0, Interfacial engineering of two-dimensional (2D) monometallic phosphides enables remarkable structural and electrochemical properties in energy storage devices. Herein, 2D nanosheets (NSs) of FeP2/Co2P were grown on Ni-foam (FCP) using a solution-based and phosphorization approach to be used as freestanding for high-performance energy storage devices. An effective phosphorization strategy is successfully developed to improve the overall crystalline phase, tailor the morphology, and boost the electrochemical performances of electrodes. The FCP NSs electrode exhibits a battery-type redox behavior with a maximum high areal capacity of 1.96 C cm–2 at 4 mA cm–2 in 6 M KOH aqueous electrolyte compared to the other counterparts. The superior electrochemical performance was achieved by increasing the electroactive sites and high conductivity via surface tailoring and fast redox reactions. Moreover, a supercapattery was assembled utilizing FCP and activated carbon (AC) electrodes and it revealed maximum specific energy (Es) and specific power (Ps) of 41.2 Wh kg–1 and 7578 W kg–1 with good cycling stability of 91% after 10,000 cycles at 5 A g–1. Eventually, the supercapattery has been explored in practical applications by lighting up light-emitting diodes (LEDs), representing the real-time performance of superior energy storage devices., Peer Reviewed, Postprint (author's final draft)

L'objectiu del present Treball Final de Grau és examinar diferents metodologies que permeten el càlcul del valor mitjà de la tensió de sortida en enllaç DC de rectificadors en pont no controlats multifàsics quan aquests rectificadors treballen sota determinades condicions de tensió d'alimentació equilibrada i desequilibrada. Es consideren diverses tècniques de càlcul, tant numèriques com analítiques, les quals seran avaluades no sols en termes de precisió del resultat proporcionada, sinó també en termes de l'esforç matemàtic requerit per a la seva elaboració o de l'esforç computacional requerit per a la seva aplicació. Així mateix, es presentarà un nou mètode innovador denominat “Mètode de l'envolupant convexa fasorial” que es basa en la fórmula de Cauchy. A més, es realitzaran uns programes a l'entorn de MATLAB per a realitzar el càlcul del valor mitjà de la tensió de sortida en enllaç DC, programes en els quals s'implementaran les tècniques contemplades., El objetivo del presente Trabajo Final de Grado es examinar diferentes metodologías que permiten el cálculo del valor medio de la tensión de salida en enlace DC de rectificadores en puente no controlados multifásicos cuando dichos rectificadores trabajan bajo determinadas condiciones de tensión de alimentación equilibrada y desequilibrada. Se consideran diversas técnicas de cálculo, tanto numéricas como analíticas, las cuales serán evaluadas no sólo en términos de precisión del resultado proporcionada, sino también en términos del esfuerzo matemático requerido para su elaboración o del esfuerzo computacional requerido para su aplicación. Así mismo, se presentará un nuevo método innovador denominado “Método de la envolvente convexa fasorial” que se basa en la fórmula de Cauchy. Además, se realizarán unos programas en el entorno de MATLAB para realizar el cálculo del valor medio de la tensión de salida en enlace DC, programas en los que se implementarán las técnicas contempladas., The objective of this Final Degree Project is to examine different methodologies that allow the calculation of the average value of the DC-link output voltage of multi-phase uncontrolled bridge rectifiers when such rectifiers operate under certain conditions of balanced and unbalanced supply voltage. Various calculation techniques, both numerical and analytical, are considered, which will be evaluated not only in terms of the accuracy of the result provided, but also in terms of the mathematical effort required for its elaboration or the computational effort required for its application. Likewise, a new innovative method called “Phasorial convex hull method” will be presented which is based on the Cauchy formula. In addition, some programs will be made in the MATLAB environment to calculate the average value of the DC-link output voltage, programs in which the techniques contemplated will be implemented.

The integration of Distributed Generators (DGs) into distribution systems (DSs) leads to more reliable and efficient power delivery for customers. However, the possibility of bi-directional power flow creates new technical problems for protection schemes. This poses a threat to conventional strategies because the relay settings have to be adjusted depending on the network topology and operational mode. As a solution, it is important to develop novel fault protection techniques to ensure reliable protection and avoid unnecessary tripping. In this regard, Total Harmonic Distortion (THD) can be used as a key parameter for evaluating the grid’s waveform quality during fault events. This paper presents a comparison between two DS protection strategies that employ THD levels, estimated amplitude voltages, and zero-sequence components as instantaneous indicators during the faults that function as a kind of fault sensor to detect, identify, and isolate faults. The first method uses a Multiple Second Order Generalized Integrator (MSOGI) to obtain the estimated variables, whereas the second method uses a single SOGI for the same purpose (SOGI-THD). Both methods rely on communication lines between protective devices (PDs) to facilitate coordinated protection. The effectiveness of these methods is assessed by using simulations in MATLAB/Simulink considering various factors such as different types of faults and DG penetrations, different fault resistances and fault locations in the proposed network. Moreover, the performance of these methods is compared with conventional overcurrent and differential protections. The results show that the SOGI-THD method is highly effective in detecting and isolating faults with a time interval of 6–8.5 ms using only three SOGIs while requiring only 447 processor cycles for execution. In comparison to other protection methods, the SOGI-THD method exhibits a faster response time and a lower computational burden. Furthermore, the SOGI-THD method is, Peer Reviewed, Postprint (published version)

The dominance of power electronics in modern power systems makes it difficult to study stability with sufficient accuracy given the available information, so it is necessary to enhance current frequency-based stability methods. The positive-mode damping (PMD) criterion is a recently powerful proposed frequency domain method to study the stability of multi-infeed VSCs grid-connected networks in the nodal admittance matrix form. The integration of black-box models and the introduction of participation factors have been identified as key lines of this work for stability studies completeness. For this purpose, a case study is built in Matlab/Simulink to address the oscillatory phenomena of modern power systems modelled in the nodal admittance matrix form with the integration of black-box models. Furthermore, this study successfully tests the performance of the participation factors applied to the PMD, which have proven to be as useful as the ones of the state-space representation in a 7-bus network example., This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 765585. This document reflects only the author’s views; the European Commission is not responsible for any use that may be made of the information it contains.This work has also been partially funded by the National Priorities Research Programn under Grant 11S-1125-170027 from the Qatar National Research Fund (a member of Qatar Foundation); FEDER/Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación, SpainProject RTI2018-095429-B-I00; and by the ICREA Academia program ., Peer Reviewed, Postprint (published version)

The aim of this research is to manage the voltage of an active distribution grid with a low X/R ratio and multiple Photovoltaic Distributed Generators (PVDGs) operating under varying conditions. This is achieved by providing a methodology for coordinating three voltage-based controllers implementing an Adaptive Neuro-Fuzzy Inference System (ANFIS). The first controller is for the On-Line Tap Changer (OLTC), which computes its adequate voltage reference. Whereas the second determines the required Active Power Curtailment (APC) setpoint for PVDG units with the aim of regulating the voltage magnitude and preventing continuous tap operation (the hunting problem) of OLTC. Finally, the last component is an auxiliary controller designed for reactive power adjustment. Its function is to manage voltage at the Common Coupling Point (CCP) within the network. This regulation not only aids in preventing undue stress on the OLTC but also contributes to a modest reduction in active power generated by PVDGs. The algorithm coordinating between these three controllers is simulated in MATLAB/SIMULINK and tested on a modified IEEE 33-bus power distribution grid (PDG). The results revealed the efficacy of the adopted algorithm in regulating voltage magnitudes in all buses compared to the traditional control method., Peer Reviewed, Postprint (published version)

In this Master thesis, the reader will find the development of a project consisting on the design and implementation of a functional test instrumentation setup that evaluates and validates the charging system of batteries. In this development, different hardware, software and mechanical techniques and skills will be applied in order to reach the aim of the project: automatizing the test plan process that takes many days to complete, and that right now is a problem due to the commitment of the operator responsible for the test., En este trabajo de fin de máster, el lector encontrará el desarrollo de un proyecto consistente en el diseño e implementación de instrumentación que evalúe y valide el sistema de carga de baterías. En este desarrollo se aplicarán diferentes técnicas de hardware, software y mecánica para alcanzar el objetivo del proyecto: automatizar el proceso del ensayo que lleva muchos días completar y que ahora mismo es un problema debido al compromiso que debe tener el operador responsable de la prueba., En aquest treball de fi de màster, el lector trobarà el desenvolupament d'un projecte consistent en el disseny i la implementació d'instrumentació que avaluï i validi el sistema de càrrega de bateries. En aquest desenvolupament s'aplicaran diferents tècniques de hardware, software i mecànica per assolir l'objectiu del projecte: automatitzar el procés de l'assaig que porta molts dies completar i que ara mateix és un problema a causa del compromís que ha de tenir l'operador responsable de la prova.

In this article we are interested in the problem of adaptive synchronization of a voltage source converter with a possibly weak grid with unknown angle and frequency, but knowledge of its parameters. To guarantee a suitable synchronization with the angle of the three-phase grid voltage we design an adaptive observer for such a signal requiring measurements only at the point of common coupling. Then we propose two alternative certainty-equivalent, adaptive phase-locked loops that ensure the angle estimation error goes to zero for almost all initial conditions. Although well-known, for the sake of completeness, we also present a PI controller with feedforward action that ensures the converter currents converge to an arbitrary desired value. Relevance of the theoretical results and their robustness to variation of the grid parameters are thoroughly discussed and validated in the challenging scenario of a converter connected to a grid with low short-circuit-ratio., Postprint (published version)

[ES] El campo de la electrónica de potencia se ha ido entretejiendo progresivamente en el tejido de nuestra vida cotidiana, abarcando un vasto espectro que va desde las placas solares hasta los vehículos eléctricos. Esta tesis de máster introduce un innovador concepto de conversión de energía mediante una novedosa topología de convertidor DC-DC. A la luz de la profunda transformación que está sufriendo la industria del transporte, numerosos fabricantes de equipos originales han apostado recientemente por los vehículos eléctricos para sobrevivir. Es un hecho ampliamente reconocido que el proceso de conversión DC/DC se cuenta entre los procedimientos de diseño más intrincados dentro del campo de la electrónica de potencia. Una de las principales complejidades surge del ambicioso objetivo de la industria de alcanzar un amplio espectro de tensiones de salida y, al mismo tiempo, suministrar el mismo nivel de potencia en todo el rango manteniendo una eficiencia aceptable. El objetivo de esta tesis es permitir el suministro de energía de alta potencia a una amplia gama de dispositivos electrónicos a partir de una fuente de energía universalmente estandarizada unificando diferentes tipologías de convertidores. Varias simulaciones y cálculos esbozados en esta tesis validan la solidez de este concepto, demostrando un rango de voltaje de salida de 100VDC a 1000VDC, entregando 11kW a través de casi todo el rango de voltaje de salida. Es importante señalar que esta tesis de máster sigue siendo puramente conceptual, y como tal, no hay planes para construir un prototipo para el concepto propuesto., [EN] The domain of power electronics has progressively woven itself into the fabric of our everyday lives, spanning a vast spectrum ranging from solar cells to electric vehicles. This master’s the sis introduces an innovative energy conversion concept via a novel DC-DC converter topology. In light of the profound transformation sweeping the transportation industry, numerous OEMs have recently placed their bets on electric vehicles for survival. It’s widely acknowledged that the process of DC/DC conversion ranks among the most intricate design procedures within the field of power electronics. A primary complexity arises from the industry’s ambitious goal of attaining a broad spectrum of output voltages while consistently delivering the same level of power across the entire range by maintaining an acceptable efficiency. The goal of this thesis is to enable the provision of high-powered energy to a wide array of electronic devices from a universally standardized energy source by unifying different converter typologies. Various sim ulations and calculations outlined in this thesis validate the soundness of this concept, demon strating an output voltage span from 100VDC to 1000VDC, delivering 11kW across nearly the entirety output voltage range. It is important to note that this Master’s thesis remains purely conceptual, and as such, there are no plans to construct a prototype for the proposed concept.

© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works, The Thévenin equivalent is considered as the standard grid equivalent for power system analysis. The integration on power electronics components in the power systems introduces non-linear operation characteristics that cannot be captured by Thévenin equivalent. Therefore, an alternative grid equivalent representation is required. This paper presents a steady-state equivalent representation of power systems with penetration of power electronics, which is suitable for both normal operation studies and short-circuit calculations. This equivalent grid representation is developed based on the voltage-current (U-I) characteristic of a power system to map the relationship between voltages and currents of a specific network node. Such grid equivalent representation has been presented for single-phase, balanced and unbalanced three-phase power systems in this paper. A methodology is presented to identify operation points when the equivalent system under study is connected to any external system. The proposed equivalent grid representation and the methodology for operation points identification have been tested on the Voltage Source Converter (VSC) based test system and are validated through dynamic simulations., This work was supported by FEDER / Ministerio de Ciencia e Innovación - Agencia Estatal de Investigación, Spain, through projects PID2021- 124292OB-I00 and PID2019-103849GB-I00 as well as Generalitat de Catalunya through project 2021-SGR-00603. Marc Cheah-Mane is also a Serra Húnter Lecturer. Eduardo Prieto-Araujo is also a Serra Húnter Associate Professor. Oriol Gomis-Bellmunt is also an ICREA Academia researcher., Postprint (author's final draft)

This short-communication presents a steady-state analysis of a grid-forming Modular Multilevel Converter (MMC) providing optimal voltage support to the AC network under normal and constrained conditions. The analysis is performed based on a multi-objective function (OF) optimization problem which prioritizes to maximize the positive-sequence and to minimize the negative- and zero-sequence voltage components at the point of common coupling (PCC) while it also considers the minimization of the arm impedance losses, respectively. If the voltage condition at the PCC is satisfied, the optimization attempts to reduce the arm impedance losses; otherwise, the algorithm prioritizes the PCC’s voltage components in order to minimize the error. Different network voltage and internal fault scenarios are evaluated, where it is shown that the suggested problem formulation can be used to obtain the optimal MMC’s quantities, providing voltage support during the faults., This work was supported by the Ministerio de Ciencia e Innovación (Proyecto Equired) under Grant PID2021-124292OB-I00. This work was also supported by the Agencia Estatal De Investigación, Spain under Grant PID2021-127788OA-I00. Eduardo Prieto-Araujo is an associate professor of the Serra Húnter programme. The work of Oriol Gomis-Bellmunt was also supported by the Institució Catalana de Recerca i Estudis Avançats (ICREA), Spain Academia Program., Peer Reviewed, Postprint (published version)

En el presente estudio se simula y analiza el comportamiento y desempeño de un convertidor DAB resonante para diversas topologías de tanques resonantes considerando modulaciones de frecuencia fija del tipo phase-shift. Además, se estudia el transformador presente en el tanque resonante que lo provee de aislamiento galvánica; sus propiedades, se simula mediante el método elementos finitos y se implementa. Respecto a las topologías resonantes se ha estudiado cómo se comportan las corrientes y tensiones en el tanque resonante, qué diferencia tiene este comportamiento con el de un DAB convencional y se obtiene la eficiencia considerando dos tipos de modulación phase-shift. El convertidor DAB resonante simulado consta de dos puentes completos con transistores de Nitruro de Galio (GaN). Para las simulaciones se han considerado dos fuentes de tensión en la entrada y la salida del convertidor. Para la realización del presente estudio se ha utilizado Matlab-Simulink-PLECS. Mediante este programa se ha podido obtener además de las simulaciones y el comportamiento del circuito, el cálculo directo de las pérdidas de conducción, conmutación y resistivas. Esto último ha permitido realizar un estudio en detalle de cómo se comporta la eficiencia para distintas modulaciones y topologías, así como ver cómo varía el aporte que realiza cada una a la disminución en el desempeño del convertidor. Para el caso del transformador se ha obtenido una aproximación para las pérdidas magnéticas a partir de simulaciones de elementos finitos y las curvas provistas por el fabricante, para luego proceder a su implementación real y la obtención experimental de los valores de sus parámetros

En este trabajo se realiza el prediseño de un convertidor DC/DC bidireccional en corriente, después de un estudio teórico de los convertidores de electrónica de potencia dentro de la tipología de los noaislados. Los convertidores bidireccionales en corriente se utilizan habitualmente en aplicaciones relacionadas con el almacenamiento de energía con baterías y supercondensadores. Un ejemplo práctico de estos convertidores es un sistema de alimentación ininterrumpida o un controlador de batería para un vehículo eléctrico. En el presente TFG, después de la verificación de los elementos asociados al convertidor por simulación, se seleccionarán los diferentes componentes para la implementación del convertidor con referencias de material de varios fabricantes. Por último, se expone un estudio económico y ambiental del trabajo., En aquest treball es realitza el predisseny d’un convertidor DC/DC bidireccional en corrent després d’un estudi teòric dels convertidors d’electrònica de potència dins la tipologia dels no-aïllats. Els convertidors bidireccionals s’utilitzen habitualment en aplicacions relacionades amb l’emmagatzematge d’energia amb bateries i supercondensadors. Un exemple pràctic d’aquests convertidors és un sistema d’alimentació ininterrompuda o un controlador de bateria per a un vehicle elèctric. En aquest TFG, després de la verificació dels elements associats al convertidor per simulació, se seleccionaran els diferents components per a la implementació del convertidor amb referencies de material de diversos fabricants. Per últim, s’exposa un estudi econòmic i ambiental de la feina., In this work is carried out a predesign of a current-bidirectional DC/DC converter, after a theoretical study of power electronic converters within the non-isolated typology. Bidirectional converters are commonly used in applications related to energy storage based on batteries and supercapaciors. An uninterruptible power supply or a battery controller for an electric vehicle are two of its many practical examples. In this TFG, after the system elements verification by simulation, different components will be selected for the implementation of the converter with material references from various manufacturers. Finally, an economic and environmental study of the work is exposed., Incoming

La fiabilidad es una de las características más deseables para los sistemas electrónicos de potencia de propulsión embarcados en los vehículos eléctricos o híbridos. En general, la industria utiliza perfiles de derating preestablecidos que limitan la potencia de salida cuando, durante un tiempo determinado, se sobrepasa la potencia nominal del accionamiento eléctrico. Como alternativa a este tipo de soluciones, es posible utilizar algoritmos que determinen la temperatura de unión de los semiconductores en tiempo real y ajusten alguno de los parámetros de control o de consigna para limitarla. Recientemente, en la literatura se han propuesto soluciones que modifican la frecuencia de conmutación en tiempo real. En este contexto, este trabajo analiza y compara dos técnicas pertenecientes a este grupo, una primera basada en un regulador histéretico y una segunda basada en un algoritmo de seguimiento de temperatura (TCT, Temperature Constraint Tracking). Se presentan resultados de simulación y se discuten las ventajas y desventajas de cada una de estas aproximaciones de control.

La fiabilidad es una de las características mas´ deseables para los sistemas electronicos de potencia de propulsi ´ onémbarcados en los vehículos electricos o h ´ íbridos. En general, la industria utiliza perfiles de derating preestablecidos que limitan la potencia de salida cuando, durante un tiempo determinado, se sobrepasa la potencia nominal del accionamiento electrico. Como álternativa a este tipo de soluciones, es posible utilizar algoritmos que determinen la temperatura de union de los semiconductores én tiempo real y ajusten alguno de los parametros de control o de ´ consigna para limitarla. Recientemente, en la literatura se han propuesto soluciones que modifican la frecuencia de conmutacionén tiempo real. En este contexto, este trabajo analiza y compara dos tecnicas pertenecientes a este grupo, una primera basada en ún regulador histeretico y una segunda basada en un algoritmo ´ de seguimiento de temperatura (TCT, Temperature Constraint Tracking). Se presentan resultados de simulacion y se discuten ´ las ventajas y desventajas de cada una de estas aproximaciones de control., Peer Reviewed, Postprint (published version)