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  • Evaluating the new control structure for the promotion of grid connected photovoltaic systems in Spain: Performance analysis of the period 2008¿2010

     de la Hoz Casas, Jordi; Martin Cañadas, Maria Elena; Ballart Prunell, Jordi; Corcoles Lopez, Felipe; Graells Sobre, Moises
    Renewable and sustainable energy reviews
    Date of publication: 2013-03-01
    Journal article

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  • Saturation Effects on Torque- and Current-Slip Curves of Squirrel-Cage Induction Motors

     Monjo Mur, Lluis; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    IEEE transactions on energy conversion
    Date of publication: 2013-03
    Journal article

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    This paper measures and analyzes the saturation effects on torque-and current-slip curves of three squirrel-cage induction motors. Motor saturation is illustrated by three sets of measurements: I) torque and current for each slip measured at three voltage levels; II) short-circuit impedance measured at different current levels; and III) no-load impedance measured at different voltage levels. In test I, torque and current measured at reduced voltage are prorated to full voltage for comparison purposes. A double-cage model is used to model the motors, and the nonlinearity of their reactances is examined. In order to evaluate the individual weight of every nonlinear reactance on the observed saturated behavior, we try to fit the measurements considering that only one reactance of the double-cage model is nonlinear. Good agreement is obtained only when the stator leakage reactance is considered nonlinear. On the contrary, when magnetizing or remaining leakage reactances are considered nonlinear, they predict machine behaviors inconsistent with measurements. In other words, the saturation of the stator leakage reactance is the main contributor to torque and current behavior, while the saturation of the remaining reactances has a negligible influence. Consequently, when all voltage levels are considered, the squirrel-cage induction motors can be accurately modeled (with reasonable accuracy) with a double-cage model where only the stator leakage reactance is considered nonlinear. When only a constant voltage level is considered, the paper also proves that a linear double-cage model (all reactances are linear) accurately predicts machine behavior at such voltage level.

  • Aportacions a la modelització de la màquina d'inducció de gàbia d'esquirol  Open access

     Monjo Mur, Lluis
    Defense's date: 2013-07-25
    Universitat Politècnica de Catalunya
    Theses

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    En aquesta tesi es tracten en profunditat diversos aspectes sobre la modelització de la màquina d’inducció de gàbia d’esquirol. En el primer capítol, a partir dels paràmetres i de les característiques elèctriques i mecàniques pels fabricants d’aerogeneradors de velocitat fixa, s’analitza la bondat dels models lineals clàssics de la literatura: el model de simple gàbia i el model de doble gàbia. Els resultats de l’estudi permeten concloure que, el model de doble gàbia és més flexible i permet ajustar completament tots els requeriments. Aquests resultats teòrics, són validats en diferents motors de baixa potència. En el segon capítol s’analitza el comportament no lineal de la màquina degut a l’efecte de la saturació magnètica. L’assaig de diferents motors amb diferents nivells de saturació, mostra experimentalment que les corbes de parelllliscament i corrent-lliscament es veuen afectades pel grau de saturació de la màquina. Per modelitzar analíticament la saturació es proposa una funció que ajusta les mesures experimentals. Com a solució òptima es proposa la utilització del model de doble gàbia en el què la reactància de dispersió de l’estator és no lineal. En el tercer capítol, s’analitza el comportament de la màquina en la zona de fre i es presenten mesures experimentals que mostren que es deformen el alguns motors les corbes de parell-lliscament en aquesta zona de treball. Aquest efecte pot ser explicat per la presència d’harmònics de camp, motiu pel que els models lineals no són capaços de reproduir-lo. En aquest capítol s’analitza la presència d’aquests harmònics de camp i s’utilitza un esquema equivalent que ajusta de manera satisfactòria els resultats obtinguts al laboratori. Finalment en el quart capítol, s’analitzen els efectes dels sots de tensió en els aerogeneradors de velocitat fixa. S’estudia l’efecte del model de la màquina i de la debilitat o no de la xarxa a la què roman connectada la màquina quan aquesta es veu sotmesa a un sot de tensió. Es proposa alguns indicadors per avaluar l’estabilitat de la màquina en aquestes condicions.

    This Thesis analyzes some aspects of the modelisation of the squirrel-cage induction machine. The first step analyzed is, from parameters and conditions given from a manufacturer of fixed-speed induction generators, the Thesis studies the classic linear models in the literature: the single- and double-cage induction machine models. The study results confirm that the double-cage model is able to fit all the requirements. Results of the theoretical study are also validated with experimental measurements obtained from several test in different motors. Secondly, the non-linear behavior of the induction machine due to the magnetic saturation has been treated. From experimental measurements, it could be demonstrated that the torque- and current-slip curves are affected by the saturation. In order to model this phenomenon, a magnetic saturation function is presented and its goodness is validated with the experimental data. To fit the torque- and current-slip curves, a steady-state equivalent circuit with a non-linear leakage stator reactance is presented as the best solution. The following step is to analyze the behavior of the induction machine in the braking regime. Measurements in these conditions are made, and they show how torque-slip curves are deformed with and high increase of the torque. This behavior cannot be reproduced by the single- and the double-cage model. One explanation of this phenomenon is the presence of space harmonics. In this chapter, space harmonics are presented and a justification of the equivalent chain single-cage circuit is made. With this steady-state equivalent circuit it is possible to estimate parameters that can fit the measurements made in laboratory. Finally, the Thesis analyzes the effects of the voltage sags in fixed-speed wind turbines which are based in squirrelcage induction machines. For this task, the effects of the modelisation of the induction machine and the weakness of the grid are studied. In this point, some indicators are presented to evaluate the stability of the machine in these conditions.

  • Electrotecnia. Problemas de examen resueltos

     Pedra Duran, Joaquin; Corcoles Lopez, Felipe; Sainz Sapera, Luis
    Date of publication: 2013-09
    Book

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  • On fixed-speed WT generator modeling for rotor speed stability studies

     Pedra Duran, Joaquin; Corcoles Lopez, Felipe; Monjo Mur, Lluis; Bogarra Rodriguez, Santiago; Rolan Blanco, Alejandro
    IEEE transactions on power systems
    Date of publication: 2012-01-20
    Journal article

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    This paper analyzes fixed-speed induction generator modeling oriented to rotor speed stability studies. The single- and double-cage models are compared. The effects of symmetrical voltage sags on generator behavior are studied in detail. The rotor speed stability of the turbine is also examined and rotor speed recovery time is proposed as an indicator of system stability. Significant differences in the results obtained for both models were found, e.g., the double-cage model shows better speed and voltage stability. For some generator designs, the single-cage model can lead to erroneous stability predictions because manufacturer data of such designs can only be fulfilled with a double-cage model. The use of the latter to simulate fixed-speed wind turbines with this type of designs is therefore strongly recommended. The simulations were carried out using PSpice and PSCAD/EMTDC.

  • Behaviour of the doubly fed induction generator exposed to unsymmetrical voltage sags

     Rolan Blanco, Alejandro; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    IET electric power applications
    Date of publication: 2012-09
    Journal article

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  • Saturation effects on torque- and current¿slip curves of squirrel-cage induction motors

     Monjo Mur, Lluis; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    IEEE transactions on energy conversion
    Date of publication: 2012-12-24
    Journal article

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    This paper measures and analyzes the saturation effects on torque- and current–slip curves of three squirrel-cage induction motors.Motor saturation is illustrated by three sets of measurements: I) torque and current for each slip measured at three voltage levels; II) short-circuit impedance measured at different current levels; and III) no-load impedance measured at different voltage levels. In test I, torque and current measured at reduced voltage are prorated to full voltage for comparison purposes. A double-cage model is used to model the motors, and the nonlinearity of their reactances is examined. In order to evaluate the individual weight of every nonlinear reactance on the observed saturated behavior, we try to fit the measurements considering that only one reactance of the double-cage model is nonlinear. Good agreement is obtained only when the stator leakage reactance is considered nonlinear. On the contrary, when magnetizing or remaining leakage reactances are considered nonlinear, they predict machine behaviors inconsistent with measurements. In otherwords, the saturation of the stator leakage reactance is the main contributor to torque and current behavior, while the saturation of the remaining reactances has a negligible influence. Consequently, when all voltage levels are considered, the squirrel-cage induction motors can be accurately modeled (with reasonable accuracy) with a double-cage modelwhere only the stator leakage reactance is considered nonlinear. When only a constant voltage level is considered, the paper also proves that a linear double-cage model (all reactances are linear) accurately predicts machine behavior at such voltage level.

  • Estudio del efecto de los huecos de tensión en el generador de inducción doblemente alimentado  Open access

     Rolan Blanco, Alejandro
    Defense's date: 2012-02-17
    Department of Electrical Engineering, Universitat Politècnica de Catalunya
    Theses

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    The aim of this doctoral thesis is to analyse the dynamic behaviour of the doubly-fed induction generator exposed to voltage sags. This electrical machine is mainly used in variable-speed wind turbines. Due to the noticeable increase in recent years in grid integration of wind turbine energy systems, the transmission system operators have developed the grid codes, which are the technical specifications that wind turbines have to achieve when a fault occurs. Faults are the most common causes that originate voltage sags. Therefore, the first step to ensure electricity supply continuity as well as to improve power quality when this kind of faults occur is to analyse the dynamic behaviour of the generator exposed to voltage sags. The stator of the doubly-fed induction generator is directly connected to the grid, whereas its rotor is connected by means of a power converter. The converter consists of a rectifier or rotor-side converter and an inverter or grid-side converter, which are linked by a DC bus. It is assumed that the rotor-side converter keeps constant the rotor current in the synchronous reference frame during the entire event. This hypothesis allows the electrical transient to be solved analytically. The voltage limit of the rotor-side converter is also taken into account in order to determine the situations where the rotor current can be controlled. This doctoral thesis is structured as follows. Firstly, the mathematical model of voltage sags is given. Secondly, both dynamic and steady-state models of the doubly-fed induction machine are obtained. Thirdly, the steady-state behaviour of the doubly-fed induction generator is analysed for different generated powers and it is studied, by means of an analytical approach, its electrical transient when exposed to voltage sags. The analytical results are validated by numerical integration of the system of equations with a MATLAB ode solver and by means of the PSpice circuit simulator. It is also carried out an exhaustive study of the effect that voltage sags cause on the doubly-fed induction generator, considering all the typologies (symmetrical and unsymmetrical voltage sags) and varying their parameters (duration and depth). Moreover, the fault-clearing process is taken into account, which has a strong influence on the voltage that the rotor-side converter requires to control the rotor current. The terms abrupt sag and discrete sag stand for voltage sags whose voltage recovery is produced instantaneously or in different steps, respectively. Finally, by means of an analytical study, which is validated by the simulation of different loads exposed to voltage sags, a grouping of voltage sags whose voltage recovery is produced in different steps is proposed. It is observed that from the fourteen discrete voltage sag types in the literature, it is enough to consider only five types. This is a significant advantage, as the number of simulations or laboratory tests carried out on an electrical device exposed to voltage sags is reduced.

    El objetivo principal de la presente tesis doctoral es analizar el comportamiento dinámico del generador de inducción doblemente alimentado sometido a huecos de tensión. La aplicación por excelencia de esta máquina eléctrica se encuentra en los aerogeneradores de velocidad variable. Debido al considerable aumento en los últimos años de la integración a la red eléctrica de los sistemas eólicos de generación de energía eléctrica, los operadores del sistema de distintos países han creado los códigos de red, en los cuales se especifican las características de funcionamiento que deben cumplir los aerogeneradores cuando se produce una falta en la red. Las faltas son las causas más comunes que provocan huecos de tensión. Por tanto, el primer paso para garantizar una continuidad del suministro y unos determinados niveles de calidad de la energía eléctrica cuando se originan este tipo de perturbaciones es analizar el comportamiento dinámico del generador sometido a huecos de tensión. El generador de inducción doblemente alimentado se caracteriza por tener tanto el estator como el rotor conectados a la red eléctrica, el estator directamente y el rotor por medio de un convertidor electrónico. El convertidor está constituido por un rectificador o convertidor del lado de rotor y por un inversor o convertidor del lado de red, unidos mediante un bus de continua. Se considera que el convertidor del lado de rotor permite mantener constante la corriente del rotor en referencia sincronismo durante todo el evento. Esta hipótesis permite resolver analíticamente el transitorio eléctrico de la máquina. También se tiene en consideración el límite de tensión de dicho convertidor con el fin de determinar las situaciones en las que se puede controlar la corriente del rotor. La presente tesis doctoral se estructura de la siguiente manera. En primer lugar, se modelizan los huecos de tensión. En segundo lugar, se obtiene el modelo dinámico y el de régimen permanente de la máquina de inducción doblemente alimentada. En tercer lugar, se analiza el comportamiento de régimen permanente del generador de inducción doblemente alimentado para distintas potencias generadas y se estudia analíticamente el transitorio eléctrico del mismo cuando se somete a los distintos huecos de tensión. Los resultados analíticos se validan por medio de la integración numérica del sistema de ecuaciones mediante MATLAB y también utilizando el programa de simulación de circuitos PSpice. Por último, se realiza un estudio exhaustivo del efecto de los huecos de tensión sobre el generador de inducción doblemente alimentado, considerando todas las tipologías de huecos (simétricos y asimétricos) y la variación de sus parámetros (duración y profundidad). Además, se tiene en cuenta la influencia de la recuperación de la tensión, lo cual repercute notablemente en la tensión requerida por el convertidor para controlar la corriente del rotor. Los términos hueco abrupto y hueco discreto hacen referencia a un hueco de tensión cuya recuperación se produce de forma instantánea o por etapas, respectivamente Finalmente, por medio de un estudio analítico, validado por la simulación de distintas cargas sometidas a huecos de tensión, se propone un agrupamiento de los huecos con recuperación por etapas. Se observa que de las catorce tipologías de huecos discretos de la literatura, tan sólo es necesario estudiar cinco de ellas. Esto supone una notable ventaja, ya que se reduce considerablemente el número de simulaciones o de ensayos de laboratorio de un dispositivo eléctrico sobre el cual se desean estudiar los efectos de los huecos de tensión.

  • Mejora del comportamiento ante huecos de tensión de los convertidores industriales para accionamientos a velocidad variable y de los

     Bogarra Rodriguez, Santiago; de la Hoz Casas, Jordi; Monjo Mur, Lluis; Rolan Blanco, Alejandro; Suelves Joanxich, Francisco Jose; Corcoles Lopez, Felipe
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    Control proposals for the operation of power converters in wind power systems  Open access

     Luna Alloza, Alvaro; Aguilar, Daniel; Muñoz Aguilar, Raul Santiago; Corcoles Lopez, Felipe; Rodriguez Cortes, Pedro
    International Conference on Power Engineering, Energy and Electrical Drives
    Presentation's date: 2011-05-11
    Presentation of work at congresses

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    The wind turbines based on Doubly Fed Induction Generators (DFIG) represent almost the 60% of the installed windpower worldwide. Nowadays most of the existing algorithms, used for regulating the production of active and reactive power in such systems, are based on control techniques that use rotational reference frames theories, where the dq0 is maybe the most popular. Despite of its good operation under balanced conditions its behaviour depends on a good phase synchronization, otherwise the different transformations cannot be performed with enough guarantees. Of course this kind of response is becomming insuficient, as far as the windpower penetration is increasing. This paper will present a new control topology for DFIG, that are connected using back to back inverters, that is able to behave better in case of faulty grids. Besides some proposals for improving the operation of the DFIG will be presented as well. The aim of that part is to extend the possibilities that the back to back inverters are able to offer to the generator system by means of including new functionalities, as the active filtering capability or the reduction of the flicker emission that will be later discussed.

  • Control of power converters in distributed generation applications under grid fault conditions

     Rodriguez Cortes, Pedro; Luna Alloza, Alvaro; Muñoz Aguilar, Raul Santiago; Corcoles Lopez, Felipe; Teodorescu, Remus; Blaabjerg, Frede
    IEEE Energy Conversion Congress and Exposition
    Presentation's date: 2011-09-17
    Presentation of work at congresses

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    The operation of distributed power generation systems under grid fault conditions is a key issue for the massive integration of renewable energy systems. Several studies have been conducted to improve the response of such distributed generation systems under voltage dips. In spite of being less severe, unbalanced fault cause a great number of disconnections, as it may produce the injection of unbalanced currents that can easily conduct to the tripping of the converter. In this paper a current control strategy for power converters able to deal with these grid conditions, without exceeding the current ratings of the converter is introduced. Moreover, a novel flexible algorithm has been proposed in order to regulate easily the injection of positive and negative currents for general purpose applications.

  • Voltage feed-forward performance in stationary reference frame controllers for wind power applications

     Ma, Lin; Luna Alloza, Alvaro; Rocabert Delgado, Joan; Muñoz Aguilar, Raul Santiago; Corcoles Lopez, Felipe; Rodriguez Cortes, Pedro
    International Conference on Power Engineering, Energy and Electrical Drives
    Presentation's date: 2011-05-11
    Presentation of work at congresses

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  • Doubly fed induction generator subject to symmetrical voltage sags

     Rolan Blanco, Alejandro; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    IEEE transactions on energy conversion
    Date of publication: 2011-12
    Journal article

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  • Discrete fault-clearing instant influence on the simulation of voltage-source-inverter-fed adjustable-speed drives subjected to voltage sags

     Corcoles Lopez, Felipe; Bogarra Rodriguez, Santiago; Pedra Duran, Joaquin; Luna Alloza, Alvaro
    IET electric power applications
    Date of publication: 2011-05
    Journal article

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    This study analyses the influence of modelling sags with discrete fault-clearing instants on the behaviour of adjustablespeed drives (ASDs) subjected to sags caused by faults. The effects are compared with those of sags modelled with simultaneous fault clearance in all faulted phases (i.e. abrupt fault clearance; the most common approach to voltage sag modelling). In many cases, abrupt fault clearance is far more severe than discrete fault clearance. Thus, if an ASD rides through a more severe case of an abrupt fault clearance test, it will likely ride through a discrete fault clearance sag. As current protocols for testing the immunity of ASDs to voltage sags only consider abrupt fault clearance, it is not necessary to consider the more complicated discrete fault clearance in equipment sag-testing methodology if more severe abrupt clearance sags are properly chosen and tested.

  • Grid synchronization for advanced power processing and FACTS in wind power systems

     Luna Alloza, Alvaro; Rocabert Delgado, Joan; Vazquez, Gerardo; Rodriguez Cortes, Pedro; Teodorescu, Remus; Corcoles Lopez, Felipe
    IEEE International Symposium on Industrial Electronics
    Presentation's date: 2010-07-04
    Presentation of work at congresses

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    Simulation of wound rotor synchronous machine under voltage sags  Open access

     Aguilar Galván, Daniel; Vázquez Guzmán, Gerardo; Rolan Blanco, Alejandro; Rocabert Delgado, Joan; Corcoles Lopez, Felipe; Rodriguez Cortes, Pedro
    IEEE International Symposium on Industrial Electronics
    Presentation's date: 2010-07-06
    Presentation of work at congresses

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    This paper presents a study of the Wound Rotor Synchronous Machine (SM) stability under voltage sags (dips). Machine behavior has been analyzed by considering different magnitudes (or depths) and duration of the sag. Voltage sags cause speed variations on SM (with possible lost of synchronism), current and torque peaks and hence may cause tripping and equipment damage, which leads to financial losses. Three machines of different nominal power have been modeled and simulated with MATLAB in order to study its behavior under voltage sags. These SM’s have been analyzed operating as generator, as motor, and in both cases, working under-excited and overexcited.

  • Estudio y caracterización de cargas no lineales  Open access  awarded activity

     Mesas García, Juan José
    Defense's date: 2010-01-27
    Department of Electrical Engineering, Universitat Politècnica de Catalunya
    Theses

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    As a continuation of the work done by the QSE (Electrical Supply Quality) research group at the UPC (Polytechnic University of Catalonia) on non-linear load modelling to determine harmonic distortion in electrical power systems, this thesis consists of the carrying out of a series of studies of the most usual non-linear loads in the said systems (single-phase and three-phase rectifiers with capacitive filter, three-phase 6-pulse rectifiers and discharge lamps), basically aiming to characterize their behaviour and assess their influence on electrical power systems. The thesis was prepared in cooperation with the GNOM (Group of Numerical Optimization and Modelling) research group at the UPC in order to be able to analyse the numerical problem raised by the system of non-linear equations which characterizes each of the non-linear loads, as well as being able to approach optimization issues with some certainty of success. In summary, the aims of this thesis are as follows: -To analyse modelling of the most usual four non-linear loads in electrical power systems in order to incorporate the invariant concept in a justified way and establish ranges of values for the said invariants depending on their usual operating conditions. -To exploit the possibilities offered by invariants and, on the basis of the ranges of values obtained for each of them, to proceed to characterize the deterministic behaviour of the non-linear loads which are the object of the study and also to analyse the phenomena of harmonic cancellation and interaction. -To describe and study experimentally, also on the basis of invariants, the fundamental and harmonic currents (magnitude and angle) consumed by the non-linear loads considered in this thesis, whether by obtaining experimental models (databases) validated both experimentally and numerically, by validating the studied analytical models experimentally or by fitting the parameters of any of the previous models (parameter estimation) on the basis of experimental acquisitions. -To study the neutral conductor current in three-phase systems to which single-phase non-linear loads are connected (in particular, single-phase rectifiers with capacitive filter), by using invariants and validating the results of this experimentally.

    Como continuación de los trabajos realizados por el grupo de investigación QSE (Calidad del Suministro Eléctrico) de la UPC (Universidad Politécnica de Cataluña) sobre modelización de cargas no lineales para la determinación de la distorsión armónica en los sistemas eléctricos de potencia, se ha realizado como tesis una serie de estudios sobre las cargas no lineales más habituales en dichos sistemas (rectificadores monofásicos y trifásicos con filtro capacitivo, rectificadores trifásicos de 6 pulsos y lámparas de descarga) encaminados básicamente a la caracterización de su comportamiento y al análisis de su influencia en los sistemas eléctricos de potencia. La tesis se ha desarrollado en colaboración con el grupo de investigación GNOM (Grupo de Optimización Numérica y Modelización) de la UPC para poder analizar el problema numérico planteado por el sistema de ecuaciones no lineales que caracteriza cada una de las cargas no lineales, así como poder abordar con garantías problemas de optimización. Resumidamente, los objetivos de esta tesis son: -Analizar la modelización de las cuatro cargas no lineales más habituales en los sistemas eléctricos de potencia con el objetivo de introducir de forma justificada el concepto de invariante y establecer rangos de valores para dichos invariantes de acuerdo a sus condiciones habituales de funcionamiento. -Aprovechar las posibilidades que ofrecen los invariantes y, a partir de los rangos de valores obtenidos para cada uno de ellos, proceder a caracterizar el comportamiento determinístico de las cargas no lineales objeto de estudio y también a analizar los fenómenos de la cancelación y la interacción armónica. -Caracterizar y estudiar experimentalmente, también a partir de los invariantes, las intensidades fundamental y armónicas (módulo y ángulo) que consumen las cargas no lineales consideradas en esta tesis, ya sea mediante la obtención de modelos experimentales (bases de datos) validados tanto experimental como numéricamente, la validación experimental de los modelos analíticos estudiados o bien el ajuste de los parámetros de cualquiera de los anteriores modelos (estimación de parámetros) a partir de adquisiciones experimentales. -Estudiar la intensidad del neutro en sistemas trifásicos en los que hay conectadas cargas no lineales monofásicas (en particular, rectificadores monofásicos con filtro capacitivo), utilizando los invariantes y validando experimentalmente los resultados que se obtengan.

  • Estudio del circuito simetrizador Steinmetz en sistemas con polución armónica  Open access

     Caro Huertas, Manuel
    Defense's date: 2010-01-27
    Department of Electrical Engineering, Universitat Politècnica de Catalunya
    Theses

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    The main bulk of electric power systems use a three¿phase configuration with an alternating current flow. Pursuing the optimal performance of these networks and avoiding possible technical problems, it is preferred balanced operating conditions, i.e., the currents of all phases have the same magnitude and form a direct sequence with a phase of 120º. However, if several single¿phase loads (such as high speed traction systems) are present in these systems, the operating condition turns unbalanced, provoking an asymmetric voltage supply. This undesirable working condition can be avoided by the use of two reactances connected with the single-phase load using a triangle configuration, in such a way that the total current consumption turns out to be balanced. This approach is commonly known as Steinmetz circuit or symmetrizing circuit. Due to the reactances of the symmetrizing circuit, the connection of the circuit in an electric network changes the system frequency response, appearing new resonances of several types and presenting impedance values too small or too large. Moreover, the quantity of nonlinear loads (i.e., loads with consume nonsinusoidal currents, such as arc furnaces, power electronics devices like high-speed rail systems...) is increasing nowadays. The harmonic current injection by these charges may interact with the resonances caused by the Steinmetz circuit, resulting in a large harmonic distortion in voltage. The aim of this doctoral thesis is to analyze the presence of several types of resonances in order to avoid this problem. It is used a simplified scheme of a network in which the single¿phase load and the symmetrized circuit are connected. This system also encloses nonlinear loads that generate harmonic currents. This set is analyzed from the viewpoint of nonlinear loads and of the network for parallel and series resonance frequencies location, respectively. By obtaining these resonant frequencies and knowing the harmonic injection of nonlinear loads, the trouble of voltage supply distortion can be anticipated and avoided.

  • Aportaciones al filtrado híbrido paralelo en redes trifásicas de cutaro hilos

     Candela Garcia, Jose Ignacio
    Defense's date: 2009-09-08
    Department of Electrical Engineering, Universitat Politècnica de Catalunya
    Theses

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    Control of DFIG-WT under unbalanced grid voltage conditions  Open access

     Luna Alloza, Alvaro; Rodriguez Cortes, Pedro; Lima, Kleber; Corcoles Lopez, Felipe; Watanabe, Edson H.; Teodorescu, Remus
    IEEE Energy Conversion Congress and Exposition
    Presentation's date: 2009-09-22
    Presentation of work at congresses

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    The voltage oriented control in the synchronous reference frame (VOC-SRF) have been extensively used for controlling wind turbines based on doubly fed induction generators (DFIG-WTs) through the rotor side converter of a back to back power processor. Although its performance is fast and accurate under balanced conditions its behaviour is not good enough when the voltage of the mains is unbalanced, unless an independent control for the positive and the negative sequence is implemented. This paper proposes a new control system able to control the DFIG-WT under unbalanced conditions using a simple algorithm, which does not need to be implemented for both symmetrical components but on the static αβ reference frame. The reliability of the presented system will be tested by means of PSCAD simulations under balanced and unbalanced grid conditions.

  • Symmetrical and Unsymmetrical Voltage Sag Effects on the Three-phase Synchronous Machine Stability

     Rolan Blanco, Alejandro; Corcoles Lopez, Felipe; Rodriguez Cortes, Pedro
    European Conference on Power Electronics and Applications
    Presentation of work at congresses

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  • Tecnología eléctrica. 2a. edición

     Boix Aragonès, Oriol; Sainz Sapera, Luis; Corcoles Lopez, Felipe; Suelves Joanxich, Francisco Jose
    Date of publication: 2009-09-14
    Book

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  • Control techniques for power quality improvement in grid-connected DFIG-based wind turbines

     Luna Alloza, Alvaro
    Defense's date: 2009-09-08
    Department of Electrical Engineering, Universitat Politècnica de Catalunya
    Theses

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  • MEJORA ESTABILIDAD RED ELÉCTRICA MEDIANTE EL USO DE FACTS BASADOS EN GENERADORES EÓLICOS

     Bargalló Perpiñà, Ramon; Suelves Joanxich, Francisco Jose; de la Hoz Casas, Jordi; Oseira Goas, Rodolfo; Luna Alloza, Alvaro; Aguilar Galván, Daniel; Monjo Mur, Lluis; Corcoles Lopez, Felipe
    Participation in a competitive project

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  • Three-phase transformer modeling for unbalanced conditions-Part II: General formulation

     Corcoles Lopez, Felipe; Sainz Sapera, Luis; Pedra Duran, Joaquin; Sánchez-Navarro, J; Salichs Vivancos, Miguel
    IET electric power applications
    Date of publication: 2009-01
    Journal article

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  • Optimización y monitorización de la estabilidad de la red eléctrica para maximizar la integración de energía eólica (GEOPTIMA)

     Corcoles Lopez, Felipe; Bargalló Perpiñà, Ramon
    Participation in a competitive project

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  • Effects of balanced and unbalanced voltage sags on DC adjustable-speed drives

     Pedra Duran, Joaquin; Sainz Sapera, Luis; Corcoles Lopez, Felipe; Bergas Jane, Joan Gabriel; Blas Del Hoyo, Alfredo de
    Electric power systems research
    Date of publication: 2008-06
    Journal article

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  • Three-phase transformer modelling for unbalanced conditions, Part 1: core modelling and introductory examples

     Corcoles Lopez, Felipe; Sainz Sapera, Luis; Pedra Duran, Joaquin; Sanchez-Navarro, J; Salichs Vivancos, Miguel
    IET electric power applications
    Date of publication: 2008-03
    Journal article

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  • Effects of symmetrical voltage sags on squirrel-cage induction motors

     Pedra Duran, Joaquin; Sainz Sapera, Luis; Corcoles Lopez, Felipe
    Electric power systems research
    Date of publication: 2007-10
    Journal article

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  • Effects of unsymmetrical voltage sags on squirrel-cage induction motors

     Pedra Duran, Joaquin; Corcoles Lopez, Felipe; Sainz Sapera, Luis
    IET generation, transmission and distribution
    Date of publication: 2007-07
    Journal article

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  • Theoretical calculation of inrush currents in three- and five-legged core transformers

     Sainz Sapera, Luis; Corcoles Lopez, Felipe; Pedra Duran, Joaquin; Guasch, L
    IEEE transactions on power delivery
    Date of publication: 2007-04
    Journal article

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  • Efecto de los huecos de tensión en las màquinas de inducción y en los transformadores trifásicos.

     GUASCH PESQUER, LUIS
    Defense's date: 2006-04-28
    Department of Electrical Engineering, Universitat Politècnica de Catalunya
    Theses

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  • Harmonic modelling of induction motors

     Pedra Duran, Joaquin; Sainz Sapera, Luis; Corcoles Lopez, Felipe
    Electric power systems research
    Date of publication: 2006-07
    Journal article

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  • Effects of balanced and unbalanced voltage sags on VSI-fed adjustable-speed drives

     Pedra Duran, Joaquin; Corcoles Lopez, Felipe; Suelves Joanxich, Francisco Jose
    IEEE transactions on power delivery
    Date of publication: 2005-01
    Journal article

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  • Symmetrical and unsymmetrical voltaje sag effects on three-phase transformers

     Pedra Duran, Joaquin; Sainz Sapera, Luis; Corcoles Lopez, Felipe; Guasch, L
    IEEE transactions on power delivery
    Date of publication: 2005-04
    Journal article

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  • A unified and simple model for uncontrolled rectifiers

     Herraiz, S; Sainz Sapera, Luis; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    Electric power systems research
    Date of publication: 2005-06
    Journal article

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  • Study of Aggregate Models for Squirrel-Cage Induction Motors

     Pedra Duran, Joaquin; Sainz Sapera, Luis; Corcoles Lopez, Felipe
    IEEE transactions on power systems
    Date of publication: 2005-08
    Journal article

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  • Ejercicios resueltos de tecnología eléctrica

     Boix Aragonès, Oriol; Sainz Sapera, Luis; Corcoles Lopez, Felipe; Suelves Joanxich, Francisco Jose; Mesas García, Juan José
    Date of publication: 2004-06
    Book

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  • Estudio de los efectos de los huecos de tensión simétricos y asimétricos en los componentes eléctricos

     Pedra Duran, Joaquin; Corcoles Lopez, Felipe; Suelves Joanxich, Francisco Jose; Salichs Vivancos, Miguel; Reus Pinilla, Jordi; Bargalló Perpiñà, Ramon; Martin Cañadas, Maria Elena
    Participation in a competitive project

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  • Transformadores

     Corcoles Lopez, Felipe; Pedra Duran, Joaquin; Salichs Vivancos, Miguel
    Date of publication: 2004-09-30
    Book

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  • Study of voltage sag effects on three-phase transformers

     Sainz Sapera, Luis; Corcoles Lopez, Felipe; Pedra Duran, Joaquin; Guasch, L; Herraiz Jaramillo, Sergio
    11th IEEE International Conference on Harmonics and Quality of Power
    Presentation of work at congresses

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  • Pspice computer model of a non-linear three-phase three-legged transformer

     Pedra Duran, Joaquin; Sainz Sapera, Luis; Corcoles Lopez, Felipe; Salichs Vivancos, Miguel
    IEEE transactions on power delivery
    Date of publication: 2004-01
    Journal article

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  • Effects of symmetrical and unsymmetrical voltaje sags on induction machines

     Guasch, L; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    IEEE transactions on power delivery
    Date of publication: 2004-04
    Journal article

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  • Effects of symmetrical voltaje sags on three-phase three-legged transformers

     Guasch, L; Corcoles Lopez, Felipe; Pedra Duran, Joaquin; Sainz Sapera, Luis
    IEEE transactions on power delivery
    Date of publication: 2004-04
    Journal article

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  • Harmonic non-linear transformer modeling

     Pedra Duran, Joaquin; Corcoles Lopez, Felipe; Sainz Sapera, Luis
    IEEE transactions on power delivery
    Date of publication: 2004-04
    Journal article

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  • Estimation of induction motor double-cage model parameters from manufacturer data

     Pedra Duran, Joaquin; Corcoles Lopez, Felipe
    IEEE transactions on energy conversion
    Date of publication: 2004-06
    Journal article

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  • Tecnologías no convencionales para el almacenamiento de energía

     López García, Ricardo; Rasgado, J P; Pedra Duran, Joaquin; Corcoles Lopez, Felipe
    XVI Reunión de Verano de Potencia, Aplicaciones Industriales y Exposición Industrial
    Presentation of work at congresses

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  • A simple model of a three-phase uncontrolled rectifier

     Herraiz Jaramillo, Sergio; Sainz Sapera, Luis; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    Second IASTED International Conference Power and Energy Systems (EuroPES'02)
    Presentation of work at congresses

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  • Virtual instrumentation system applied to transformer characterisation

     Alzórriz, J A García; Pedra Duran, Joaquin; Corcoles Lopez, Felipe; Sainz Sapera, Luis; Chindris, M D
    8th Int. Conf. on Optimization of Electrical and Electronic Equipment
    Presentation of work at congresses

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  • Effects of voltage sags on three-phase three-legged transformers

     Guasch, L; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    10th International Conference on Harmonics and Quality of Power
    Presentation of work at congresses

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