Monjo Mur, Lluis
Total activity: 15
Doctoral courses
Enginyeria Industrial
Research group
QSE - Power Quality
Department
Department of Electrical Engineering
School
Barcelona School of Industrial Engineering (ETSEIB)
E-mail
lluis.monjoupc.edu
Contact details
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Orcid
0000-0001-6106-097X Open in new window

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Scientific and technological production
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1 to 15 of 15 results
  • Parameter estimation of wound-rotor induction motors from transient measurements

     Kojooyan, Hengameh; Monjo Mur, Lluis; Corcoles Lopez, Felipe; Pedra Duran, Joaquin
    IEEE transactions on energy conversion
    Vol. 29, num. 2, p. 300-308
    DOI: 10.1109/TEC.2014.2300236
    Date of publication: 2014-06
    Journal article

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    A new method for determination of the steady-state equivalent circuit parameters of wound-rotor induction motors using experimental data from starting transient measurements is presented. The algorithm data are the stator currents and voltages andmechanical speed. The algorithm uses the least-square method and motor dynamic equations in the synchronous reference frame. Moreover, an approximation of the rotor flux that improves the accuracy of the estimation method, as well as a detailed study of errors, is included. The estimation method is applied to starting transient measurement data of a 2 kW wound rotor induction motor, and the accuracy of the obtained parameters is verified by comparing steady-state torque- and current-slip curves calculated with the estimated parameters and those measured in the laboratory

    A new method for determination of the steady-state equivalent circuit parameters of wound-rotor induction motors using experimental data from starting transient measurements is presented. The algorithm data are the stator currents and voltages andmechanical speed. The algorithm uses the least-square method and motor dynamic equations in the synchronous reference frame. Moreover, an approximation of the rotor flux that improves the accuracy of the estimation method, as well as a detailed study of errors, is included. The estimation method is applied to starting transient measurement data of a 2 kW wound rotor induction motor, and the accuracy of the obtained parameters is verified by comparing steady-state torque- and current-slip curves calculated with the estimated parameters and those measured in the laboratory

  • Evaluating the approach to reduce the overrun cost of grid connected PV systems for the Spanish electricity sector: Performance analysis of the period 2010¿2012

     de la Hoz Casas, Jordi; Martin Cañadas, Maria Elena; Ballart Prunell, Jordi; Monjo Mur, Lluis
    Applied energy
    Vol. 121, p. 159-173
    DOI: 10.1016/j.apenergy.2014.01.083
    Date of publication: 2014-05-15
    Journal article

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  • Aplicaciones de la corriente continua de media tensión en sistemas eléctricos

     Pedra Duran, Joaquin; Cunill Sola, Jordi; Mesas García, Juan José; Monjo Mur, Lluis; Sainz Sapera, Luis
    Competitive project

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  • Statistical study of resonance in AC traction systems equipped with Steinmetz circuit

     Monjo Mur, Lluis; Sainz Sapera, Luis; Rull Duran, Joan
    Electric power systems research
    Vol. 103, p. 223-232
    Date of publication: 2013-10
    Journal article

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    tAC traction systems can be 25 kV/50 Hz single-phase, non-linear, time-varying loads of random naturecausing unbalance and distortion of the supply voltages. To reduce voltage unbalance, thyristor controlledreactances are usually delta-connected with traction systems. This setup, called Steinmetz circuit, canadapt reactance values to traction load fluctuations in order to balance consumed currents. To avoidvoltage distortion problems due to harmonic currents injected by traction loads, resonances betweenthe Steinmetz and supply system reactances ¿observed¿ from the traction system must be analyzed. Thispaper characterizes stochastic behavior of these resonances, which is caused by random variations intraction power consumption. The study used simulations of an AC traction system with intercity servicesand measurements of a French railway traction substation.

    AC traction systems can be 25 kV/50 Hz single-phase, non-linear, time-varying loads of random naturecausing unbalance and distortion of the supply voltages. To reduce voltage unbalance, thyristor controlledreactances are usually delta-connected with traction systems. This setup, called Steinmetz circuit, canadapt reactance values to traction load fluctuations in order to balance consumed currents. To avoidvoltage distortion problems due to harmonic currents injected by traction loads, resonances betweenthe Steinmetz and supply system reactances “observed” from the traction system must be analyzed. Thispaper characterizes stochastic behavior of these resonances, which is caused by random variations intraction power consumption. The study used simulations of an AC traction system with intercity servicesand measurements of a French railway traction substation.

  • Model of discharge lamps with saturated magnetic ballast and non-square arc voltage

     Molina, Julio; Sainz Sapera, Luis; Monjo Mur, Lluis
    Electric power systems research
    Vol. 104, p. 42-51
    Date of publication: 2013-11-01
    Journal article

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    Harmonic modeling of high intensity discharge lamps with magnetic ballast has been extensively studied because they are energy-efficient lighting devices commonly used in industrial and public installations, and can be an important source of harmonics. This kind of modeling usually considers the linear saturation curve of the magnetic ballast and represents the arc voltage by a square waveform. However, both assumptions can be far from describing actual lamp behavior, affecting the accuracy of the model. This paper proposes a novel characterization of high intensity discharge lamps considering both the nonlinear behavior of the magnetic ballast and the non-square waveform of the arc voltage. The accuracy of the new model is validated with experimental measurements and compared to that of the traditional models.

    Harmonic modeling of high intensity discharge lamps with magnetic ballast has been extensively studied because they are energy-efficient lighting devices commonly used in industrial and public installations, and can be an important source of harmonics. This kind of modeling usually considers the linear saturation curve of the magnetic ballast and represents the arc voltage by a square waveform. However, both assumptions can be far from describing actual lamp behavior, affecting the accuracy of the model. This paper proposes a novel characterization of high intensity discharge lamps considering both the nonlinear behavior of the magnetic ballast and the non-square waveform of the arc voltage. The accuracy of the new model is validated with experimental measurements and compared to that of the traditional models.

  • Theoretical study of the steinmetz circuit design

     Monjo Mur, Lluis; Sainz Sapera, Luis; Riera Galceran, Sara; Bergas Jane, Joan Gabriel
    Electric power components and systems
    Vol. 41, num. 3, p. 304-323
    DOI: 10.1080/15325008.2012.742944
    Date of publication: 2013-01-11
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  • Aportacions a la modelització de la màquina d'inducció de gàbia d'esquirol  Open access

     Monjo Mur, Lluis
    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 gàbiad¿esquirol.En el primer capítol, a partir dels paràmetres i de les característiques elèctriques i mecàniques pels fabricantsd¿aerogeneradors de velocitat fixa, s¿analitza la bondat dels models lineals clàssics de la literatura: el model desimple gàbia i el model de doble gàbia. Els resultats de l¿estudi permeten concloure que, el model de doble gàbia ésmés flexible i permet ajustar completament tots els requeriments. Aquests resultats teòrics, són validats en diferentsmotors 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 parelllliscamenti corrent-lliscament es veuen afectades pel grau de saturació de la màquina. Per modelitzar analíticamentla saturació es proposa una funció que ajusta les mesures experimentals. Com a solució òptima es proposa lautilització 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 experimentalsque mostren que es deformen el alguns motors les corbes de parell-lliscament en aquesta zona de treball. Aquestefecte pot ser explicat per la presència d¿harmònics de camp, motiu pel que els models lineals no són capaços dereproduir-lo. En aquest capítol s¿analitza la presència d¿aquests harmònics de camp i s¿utilitza un esquemaequivalent 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 màquinaquan aquesta es veu sotmesa a un sot de tensió. Es proposa alguns indicadors per avaluar l¿estabilitat de la màquinaen aquestes condicions.

    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.

  • 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
    Vol. 27, num. 1, p. 397-406
    DOI: 10.1109/TPWRS.2011.2161779
    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.

  • Study of the Steinmetz circuit influence on AC traction system resonance

     Sainz Sapera, Luis; Monjo Mur, Lluis; Riera, Sara; Pedra Duran, Joaquin
    IEEE transactions on power delivery
    Vol. 27, num. 4, p. 2295-2303
    DOI: 10.1109/TPWRD.2012.2211084
    Date of publication: 2012-10-01
    Journal article

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    Traction systems are single-phase, nonlinear loads, which can unbalance and pollute supply voltages. To reduce voltage unbalance, reactances are usually connected in delta configuration with traction systems. This setup is called the Steinmetz circuit. Parallel and series resonances can occur between the Steinmetz capacitor and system inductors, increasing voltage distortion. Thus, it is important to analyze the parallel resonance “observed” from the traction system to avoid harmonic problems due to its injected harmonic currents. This paper studies this resonance analytically and presents simple expressions to locate it. Experimental measurements are also provided to validate the obtained analytical results. These expressions are also used to analyze resonance in several power systems in the literature.

  • 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
    Vol. 28, num. 1, p. 243-254
    DOI: 10.1109/TEC.2012.2232672
    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.

  • 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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  • Study of reduced-order models of squirrel-cage induction motors

     Martin Cañadas, Maria Elena; de la Hoz Casas, Jordi; Monjo Mur, Lluis; Pedra Duran, Joaquin
    Electric power components and systems
    Vol. 39, num. 14, p. 1542-1562
    DOI: 10.1080/15325008.2011.596504
    Date of publication: 2011-10-07
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  • ESTUDIO DEL IMPACTO DE LOS HUECOS DE TENSIÓN EN LA ESTABILIDAD DE LOS GENERADORES EÓLICOS

     Monjo Mur, Lluis; Martin Cañadas, Maria Elena; Bogarra Rodriguez, Santiago; Suelves Joanxich, Francisco Jose; Bargalló Perpiñà, Ramon; Reus Pinilla, Jordi; Pedra Duran, Joaquin
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  • Electric liberalization: a questionable process

     Palacin Farre, Pedro; de la Hoz Casas, Jordi; Martins Rodriguez, Blanca Maria; Monjo Mur, Lluis; Martínez Sánchez, Joan
    International Journal of Integrated Energy Systems
    Vol. 1, num. 1, p. 17-27
    Date of publication: 2009-06-01
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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
    Competitive project

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