Perfil del técnico de fútbol en escuelas de clubes de primera división en la Comunitat Valenciana

Actualmente son pocos los estudios que se han preocupado de caracterizar el perfil de los técnicos deportivos de fútbol base. Por este motivo desarrollamos un estudio de corte descriptivo e inferencial. Elaboramos un cuestionario administrado a un grupo de 20 técnicos deportivos de fútbol que desarrollaban su labor en la etapa de iniciación deportiva en escuelas de clubes que militaban en la primera división. El objetivo fundamental era analizar si el nivel de formación de los entrenadores influía en la forma de desempeñar su labor profesional. Los resultados nos muestran que los técnicos deportivos con formación universitaria le dan más importancia a la finalidad educativa del proceso de enseñanza-entrenamiento, incluyen más contenidos relacionados con la Educación Física y dan más protagonismo a metodologías inclusivas que aquellos técnicos que solo han cursado enseñanzas deportivas. En conclusión, para conseguir desarrollar un correcto proceso de formación del deportista en la etapa de iniciación, es necesario aumentar la presencia de titulados universitarios en el ámbito de la actividad física y del deporte que trabajen como técnicos deportivos de fútbol. Pues han recibido una formación mucho más extensiva en aspectos relacionados con la Pedagogía, de forma que desarrollan un proceso de enseñanza-aprendizaje de la modalidad deportiva mucho más adecuado a la etapa de iniciación deportiva.Actualmente son pocos los estudios que se han preocupado de caracterizar el perfil de los técnicos deportivos de fútbol base. Por este motivo desarrollamos un estudio de corte descriptivo e inferencial. Elaboramos un cuestionario administrado a un grupo de 20 técnicos deportivos de fútbol que desarrollaban su labor en la etapa de iniciación deportiva en escuelas de clubes que militaban en la primera división. El objetivo fundamental era analizar si el nivel de formación de los entrenadores influía en la forma de desempeñar su labor profesional. Los resultados nos muestran que los técnicos deportivos con formación universitaria le dan más importancia a la finalidad educativa del proceso de enseñanza-entrenamiento, incluyen más contenidos relacionados con la Educación Física y dan más protagonismo a metodologías inclusivas que aquellos técnicos que solo han cursado enseñanzas deportivas. En conclusión, para conseguir desarrollar un correcto proceso de formación del deportista en la etapa de iniciación, es necesario aumentar la presencia de titulados universitarios en el ámbito de la actividad física y del deporte que trabajen como técnicos deportivos de fútbol. Pues han recibido una formación mucho más extensiva en aspectos relacionados con la Pedagogía, de forma que desarrollan un proceso de enseñanza-aprendizaje de la modalidad deportiva mucho más adecuado a la etapa de iniciación deportiva

Perfil del tècnic de futbol en escoles de clubs de primera divisió en la Comunitat Valenciana

Actualment són pocs els estudis que s’han preocupat de caracteritzar el perfil dels tècnics esportius de futbol base. Per aquest motiu fem un estudi d’estil descriptiu i inferencial. Elaborem un qüestionari administrat a un grup de 20 tècnics esportius de futbol que desenvolupaven la seva feina en l’etapa d’iniciació esportiva en escoles de clubs que militaven en la primera divisió. L’objectiu fonamental era analitzar si el nivell de formació dels entrenadors influïa en la manera d’exercir la seva feina professional. Els resultats ens mostren que els tècnics esportius amb formació universitària donen més importància a la finalitat educativa del procés d’ensenyament-entrenament, inclouen més continguts relacionats amb l’educació física i donen més protagonisme a metodologies inclusives que aquells tècnics que només han cursat ensenyaments esportius. En conclusió, per aconseguir desenvolupar un correcte procés de formació de l’esportista en l’etapa d’iniciació, és necessari augmentar la presència de titulats universitaris en l’àmbit de l’activitat física i de l’esport que treballin com a tècnics esportius de futbol. Perquè han rebut una formació molt més extensiva en aspectes relacionats amb la pedagogia, de manera que desenvolupen un procés d’ensenyament-aprenentatge de la modalitat esportiva molt més adequat a l’etapa d’iniciació esportiva

Peak current mode control of three-phase boost rectifiers in discontinuous conduction mode for small wind power generators

[EN] This paper presents a peak current mode control scheme of a boost rectifier with low distortion of the input current for wind power systems based on permanent magnet synchronous generators with variable speed operation. The three-phase boost rectifier is operated in discontinuous conduction mode (DCM), and power factor correction techniques are applied. It is shown that the DCM operation significantly reduces the total harmonic distortion of the currents in the permanent magnet synchronous generator, increasing the power factor of the system, so that the vibrations and mechanical stress of the generator are minimized. The characteristics of the DCM boost rectifier are studied considering: (1) the series resistance of the inductors; (2) the modeling and adjustment of peak current mode control yielding a stable loop; (3) the design of an input filter that reduces the switching noise in the currents of the generator.This work was supported by the Spanish Ministry of Science and Innovation under Grants ENE2006- 15521-C03-02 and ENE2009- 13998-C02-02. The first author thanks the support of the Instituto Politecnico Nacional (IPN) and of the Comision de Operacion y Fomento de Actividades Academicas (COFAA) to finance his stay at the Universidad Politecnica de Valencia (UPV).Carranza, O.; Garcerá, G.; Figueres Amorós, E.; González, L. (2010). Peak current mode control of three-phase boost rectifiers in discontinuous conduction mode for small wind power generators. Applied Energy. 87(8):2728-2736. https://doi.org/10.1016/j.apenergy.2010.02.010S2728273687

Maximum-power-point tracking with reduced mechanical stress applied to wind-energy-conversion-systems

[EN] This paper presents an improved maximum-power-point tracking algorithm for wind-energy-conversion-systems. The proposed method significantly reduces the turbine mechanical stress with regard to conventional techniques, so that both the maintenance needs and the medium time between failures are expected to be improved. To achieve these objectives, a sensorless speed control loop receives its reference signal from a modified Perturb&Observe algorithm, in which the typical steps on the reference speed have been substituted by a fixed and well-defined slope ramp signal. As a result, it is achieved a soft dynamic response of both the torque and the speed of the wind turbine, so that the whole system suffers from a lower mechanical stress than with conventional P&O techniques. The proposed method has been applied to a wind turbine based on a permanent magnet synchronous generator operating at variable speed, which is connected to the distribution grid by means of a back to back converter.González, L.; Figueres Amorós, E.; Garcerá, G.; Carranza, O. (2010). Maximum-power-point tracking with reduced mechanical stress applied to wind-energy-conversion-systems. Applied Energy. 87(7):2304-2312. doi:10.1016/j.apenergy.2009.11.030S2304231287

An adaptive synchronous-reference-frame phase-locked loop for power quality improvement in a polluted utility grid

Si el © es de IEEE cuando se deposite una versión de autor hay que poner el siguiente texto en "descripción": “© © 20xx 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 proper operation of grid-connected power electronics converters needs using a synchronization technique to estimate the phase of the grid voltage. The performance of this synchronization technique is related to the quality of the consumed or delivered electric power. The synchronous-reference-frame phase-locked loop (SRF-PLL) has been widely used due to its ease of operation and robust behavior. However, the estimated phase can have a considerable amount of unwanted ripple if the grid voltage disturbances are not properly rejected. The aim of this paper is to propose an adaptive SRF-PLL which strongly rejects these disturbances even if the fundamental frequency of the grid voltage varies. This is accomplished by using several adaptive infinite-impulse-response notch filters, implemented by means of an inherently stable Schur-lattice structure. This structure is perfectly suited to be programmed in fixed-point DSPs (i.e., it has high mapping precision, low roundoff accumulation, and suppression of quantization limit cycle oscillations). The proposed adaptive SRF-PLL has been tested by means of the TI TMS320F2812 DSP. The obtained experimental results show that the proposed synchronization method highly rejects the undesired harmonics even if the fundamental harmonic frequency of a highly polluted grid voltage abruptly varies. © 2011 IEEE.This work was supported by the Spanish Ministry of Science and Innovation under Grants ENE2009-13998-C02-02 and ENE2006-15521-C03-02.González Espín, FJ.; Figueres Amorós, E.; Garcerá Sanfeliú, G. (2012). An adaptive synchronous-reference-frame phase-locked loop for power quality improvement in a polluted utility grid. IEEE Transactions on Industrial Electronics. 59(6):2718-2731. doi:10.1109/TIE.2011.2166236S2718273159

Profile of the Football Coach in First Division Club Academies in the Region of Valencia.

Actualmente son pocos los estudios que se han preocupado de caracterizar el perfil de los técnicos deportivos de fútbol base. Por este motivo desarrollamos un estudio de corte descriptivo e inferencial. Elaboramos un cuestionario administrado a un grupo de 20 técnicos deportivos de fútbol que desarrollaban su labor en la etapa de iniciación deportiva en escuelas de clubes que militaban en la primera división. El objetivo fundamental era analizar si el nivel de formación de los entrenadores influía en la forma de desempeñar su labor profesional. Los resultados nos muestran que los técnicos deportivos con formación universitaria le dan más importancia a la finalidad educativa del proceso de enseñanza-entrenamiento, incluyen más contenidos relacionados con la Educación Física y dan más protagonismo a metodologías inclusivas que aquellos técnicos que solo han cursado enseñanzas deportivas. En conclusión, para conseguir desarrollar un correcto proceso de formación del deportista en la etapa de iniciación, es necesario aumentar la presencia de titulados universitarios en el ámbito de la actividad física y del deporte que trabajen como técnicos deportivos de fútbol. Pues han recibido una formación mucho más extensiva en aspectos relacionados con la Pedagogía, de forma que desarrollan un proceso de enseñanza-aprendizaje de la modalidad deportiva mucho más adecuado a la etapa de iniciación deportiva.Currently there is little research that examines the profile of youth football sports coaches and for this reason we have conducted a descriptive and inferential study. We drew up a questionnaire which was given to a group of 20 football sports coaches working at the introduction to sports stage in the academies of First Division clubs. The main objective was to analyse whether the level of training of the coaches influenced the way they performed their work. The findings show that universitytrained sports coaches attach more importance to the educational purpose of the education and training, include more content related to Physical Education and give more prominence to inclusive methodologies than those coaches who have only studied sports education. In conclusion, the presence of graduates in the field of physical activity and sport who work as football sports coaches needs to be increased in order to implement proper training for young athletes at the introduction to sports stage. This is because they have received much more extensive training in aspects of teaching and hence are able to implement a teaching and learning process for the sport that is much more suited to the introduction to sports stage.Ciencias de la Actividad Física y del Deport

Grid-tie inverter topology with maximum power extraction from two photovoltaic arrays

This study presents a transformerless topology for a grid-tied single-phase inverter capable of performing the simultaneous maximum power point tracking of two independent and series connected photovoltaic sources. This topology is derived from the neutral point clamped multilevel inverter in half-bridge configuration. The use of a half-bridge topology reduces the leakage current to very low values, whereas the multilevel topology presents an output voltage quality similar to that of a full-bridge inverter. To simultaneously track the maximum power of both photovoltaic sources, a generation control circuit is used. With this topology, it is possible to improve the performance of the converter under partial shadowing conditions, very common in photovoltaic facilities operating in residential areas. A 5 kW prototype of this topology has been implemented and tested in the laboratory.This work is supported by the Spanish Ministry of Science and Innovation under grants ENE2009-13998-C02-02 and ENE2012-37667-C02-01.Patrao Herrero, I.; Gabriel Garcerá; Figueres Amorós, E.; González Medina, R. (2014). Grid-tie inverter topology with maximum power extraction from two photovoltaic arrays. Renewable Power Generation, IET. 8(6):638-648. doi:10.1049/iet-rpg.2013.0143S63864886Bevrani, H., Ghosh, A., & Ledwich, G. (2010). Renewable energy sources and frequency regulation: survey and new perspectives. IET Renewable Power Generation, 4(5), 438. doi:10.1049/iet-rpg.2009.0049Zhu, J., Bründlinger, R., Mühlberger, T., Betts, T. R., & Gottschalg, R. (2011). Optimised inverter sizing for photovoltaic systems in high-latitude maritime climates. IET Renewable Power Generation, 5(1), 58. doi:10.1049/iet-rpg.2009.0162Amoiralis, E. I., Tsili, M. A., & Kladas, A. G. (2012). Power Transformer Economic Evaluation in Decentralized Electricity Markets. IEEE Transactions on Industrial Electronics, 59(5), 2329-2341. doi:10.1109/tie.2011.2157291Bowtell, L., & Ahfock, A. (2010). Direct current offset controller for transformerless single-phase photovoltaic grid-connected inverters. IET Renewable Power Generation, 4(5), 428. doi:10.1049/iet-rpg.2009.0043Patrao, I., Figueres, E., González-Espín, F., & Garcerá, G. (2011). Transformerless topologies for grid-connected single-phase photovoltaic inverters. Renewable and Sustainable Energy Reviews, 15(7), 3423-3431. doi:10.1016/j.rser.2011.03.034Kjaer, S. B., Pedersen, J. K., & Blaabjerg, F. (2005). A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules. IEEE Transactions on Industry Applications, 41(5), 1292-1306. doi:10.1109/tia.2005.853371Puttgen, H. B., MacGregor, P. R., & Lambert, F. C. (2003). Distributed generation: Semantic hype or the dawn of a new era? IEEE Power and Energy Magazine, 1(1), 22-29. doi:10.1109/mpae.2003.1180357Nian, H., & Zeng, R. (2011). Improved control strategy for stand-alone distributed generation system under unbalanced and non-linear loads. IET Renewable Power Generation, 5(5), 323. doi:10.1049/iet-rpg.2010.0216Thomson, M., & Infield, D. G. (2007). Impact of widespread photovoltaics generation on distribution systems. IET Renewable Power Generation, 1(1), 33. doi:10.1049/iet-rpg:20060009Karatepe, E., Syafaruddin, & Hiyama, T. (2010). Simple and high-efficiency photovoltaic system under non-uniform operating conditions. IET Renewable Power Generation, 4(4), 354. doi:10.1049/iet-rpg.2009.0150Wang, Y.-J., & Hsu, P.-C. (2010). Analytical modelling of partial shading and different orientation of photovoltaic modules. IET Renewable Power Generation, 4(3), 272. doi:10.1049/iet-rpg.2009.0157López, Ó., Freijedo, F. D., Yepes, A. G., Fernández-Comesaña, P., Malvar, J., Teodorescu, R., & Doval-Gandoy, J. (2010). Eliminating Ground Current in a Transformerless Photovoltaic Application. IEEE Transactions on Energy Conversion, 25(1), 140-147. doi:10.1109/tec.2009.2037810Cavalcanti, M. C., Farias, A. M., Oliveira, K. C., Neves, F. A. S., & Afonso, J. L. (2012). Eliminating Leakage Currents in Neutral Point Clamped Inverters for Photovoltaic Systems. IEEE Transactions on Industrial Electronics, 59(1), 435-443. doi:10.1109/tie.2011.2138671Wu, T.-F., Chang, C.-H., Lin, L.-C., & Kuo, C.-L. (2011). Power Loss Comparison of Single- and Two-Stage Grid-Connected Photovoltaic Systems. IEEE Transactions on Energy Conversion, 26(2), 707-715. doi:10.1109/tec.2011.2123897Shimizu, T., Hirakata, M., Kamezawa, T., & Watanabe, H. (2001). Generation control circuit for photovoltaic modules. IEEE Transactions on Power Electronics, 16(3), 293-300. doi:10.1109/63.923760Gonzalez-Espin, F., Figueres, E., & Garcera, G. (2012). An Adaptive Synchronous-Reference-Frame Phase-Locked Loop for Power Quality Improvement in a Polluted Utility Grid. IEEE Transactions on Industrial Electronics, 59(6), 2718-2731. doi:10.1109/tie.2011.2166236Mastromauro, R. A., Liserre, M., & Dell’Aquila, A. (2012). Control Issues in Single-Stage Photovoltaic Systems: MPPT, Current and Voltage Control. IEEE Transactions on Industrial Informatics, 8(2), 241-254. doi:10.1109/tii.2012.2186973Delfino, F., Denegri, G. B., Procopio, R., & Invernizzi, M. (2012). Feedback linearisation oriented approach to Q–V control of grid connected photovoltaic units. IET Renewable Power Generation, 6(5), 324-339. doi:10.1049/iet-rpg.2011.0075Ishaque, K., & Salam, Z. (2013). A review of maximum power point tracking techniques of PV system for uniform insolation and partial shading condition. Renewable and Sustainable Energy Reviews, 19, 475-488. doi:10.1016/j.rser.2012.11.03

Modelling and Control of Parallel-Connected Transformerless Inverters for Large Photovoltaic Farms

[EN] This paper presents a control structure for transformerless photovoltaic inverters connected in parallel to manage photovoltaic fields in the MW range. Large photovoltaic farms are usually divided into several photovoltaic fields, each one of them managed by a centralized high power inverter. The current tendency to build up centralized inverters in the MW range is the use of several transformerless inverters connected in parallel, a topology that provokes the appearance of significant zero-sequence circulating currents among inverters. To eliminate this inconvenience, this paper proposes a control structure that avoids the appearance of circulating currents by controlling the zero-sequence component of the inverters. A second contribution of the paper is the development of a model of n parallel-connected inverters. To validate the concept, the proposed control structure has been applied to a photovoltaic field of 2 MW managed by four 500 kW photovoltaic inverters connected in parallel.This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO), the European Regional Development Fund (ERDF) under Grant ENE2015-64087-C2-2-R and the Spanish Ministry of Education (FPU15/01274).Liberos-Mascarell, MA.; González-Medina, R.; Garcerá, G.; Figueres Amorós, E. (2017). Modelling and Control of Parallel-Connected Transformerless Inverters for Large Photovoltaic Farms. Energies. 10(8):1-25. https://doi.org/10.3390/en10081242S125108Pazheri, F. R., Othman, M. F., & Malik, N. H. (2014). A review on global renewable electricity scenario. Renewable and Sustainable Energy Reviews, 31, 835-845. doi:10.1016/j.rser.2013.12.020Subudhi, B., & Pradhan, R. (2013). A Comparative Study on Maximum Power Point Tracking Techniques for Photovoltaic Power Systems. IEEE Transactions on Sustainable Energy, 4(1), 89-98. doi:10.1109/tste.2012.2202294Borrega, M., Marroyo, L., Gonzalez, R., Balda, J., & Agorreta, J. L. (2013). Modeling and Control of a Master–Slave PV Inverter With N-Paralleled Inverters and Three-Phase Three-Limb Inductors. IEEE Transactions on Power Electronics, 28(6), 2842-2855. doi:10.1109/tpel.2012.2220859Araujo, S. V., Zacharias, P., & Mallwitz, R. (2010). Highly Efficient Single-Phase Transformerless Inverters for Grid-Connected Photovoltaic Systems. IEEE Transactions on Industrial Electronics, 57(9), 3118-3128. doi:10.1109/tie.2009.2037654PowerGate Plus 500 kWhttp://www.satcon.comAgorreta, J. L., Borrega, M., López, J., & Marroyo, L. (2011). Modeling and Control of $N$ -Paralleled Grid-Connected Inverters With LCL Filter Coupled Due to Grid Impedance in PV Plants. IEEE Transactions on Power Electronics, 26(3), 770-785. doi:10.1109/tpel.2010.2095429Power Electronicshttp://www.power-electronics.comPVS980—1818 to 2091 kVAhttp://new.abb.comInfineon, Central Inverter Solutionshttps://www.infineon.com/cms/en/applications/solar-energy-systems/central-inverter-solutions/Xiao, H., Xie, S., Chen, Y., & Huang, R. (2011). An Optimized Transformerless Photovoltaic Grid-Connected Inverter. IEEE Transactions on Industrial Electronics, 58(5), 1887-1895. doi:10.1109/tie.2010.2054056Mazumder, S. K. (2003). A novel discrete control strategy for independent stabilization of parallel three-phase boost converters by combining space-vector modulation with variable-structure control. IEEE Transactions on Power Electronics, 18(4), 1070-1083. doi:10.1109/tpel.2003.813770Ching-Tsai Pan, & Yi-Hung Liao. (2008). Modeling and Control of Circulating Currents for Parallel Three-Phase Boost Rectifiers With Different Load Sharing. IEEE Transactions on Industrial Electronics, 55(7), 2776-2785. doi:10.1109/tie.2008.925647Ogasawara, S., Takagaki, J., Akagi, H., & Nabae, A. (1992). A novel control scheme of a parallel current-controlled PWM inverter. IEEE Transactions on Industry Applications, 28(5), 1023-1030. doi:10.1109/28.158825Figueres, E., Garcera, G., Sandia, J., Gonzalez-Espin, F., & Rubio, J. C. (2009). Sensitivity Study of the Dynamics of Three-Phase Photovoltaic Inverters With an LCL Grid Filter. IEEE Transactions on Industrial Electronics, 56(3), 706-717. doi:10.1109/tie.2008.2010175Mohd, A., Ortjohann, E., Hamsic, N., Sinsukthavorn, W., Lingemann, M., Schmelter, A., & Morton, D. (2010). Control strategy and space vector modulation for three-leg four-wire voltage source inverters under unbalanced load conditions. IET Power Electronics, 3(3), 323. doi:10.1049/iet-pel.2008.0281Albatran, S., Fu, Y., Albanna, A., Schrader, R., & Mazzola, M. (2013). Hybrid 2D-3D Space Vector Modulation Voltage Control Algorithm for Three Phase Inverters. IEEE Transactions on Sustainable Energy, 4(3), 734-744. doi:10.1109/tste.2013.224568

Effects of the PWM carrier signals synchronization on the DC-link current in back-to-back converters

[EN] This paper presents a study about the synchronization effects of the PWM carrier signals of a back-to-back converter for grid connection of Wind Energy Conversion Systems based on Permanent Magnet Synchronous Generators. It is demonstrated by means of a spectral analysis that, with the proper synchronization of the carrier signals of both the rectifier and inverter stages, the rms value of the current through the DC-link capacitors is greatly reduced. As a result, the number of capacitors needed to build the back-to-back converter decreases, whereas its life cycle is expanded, so that the Wind Energy Conversion System becomes more cost effective. It is shown that the worst case occurs when the phase difference between both carrier signals is ±¿/2, yielding the highest rms value of the DC-link capacitors current. In that case the harmonic with the highest rms value is located at twice the switching frequency. The theoretical analysis is compared with experimental results from a 10 kW back-to-back converter in order to validate the effects of the carrier signals phase shift on the DC-link capacitors current.Luis Gerardo González Morales; Garcerá, G.; Figueres Amorós, E.; González-Medina, R. (2010). Effects of the PWM carrier signals synchronization on the DC-link current in back-to-back converters. Applied Energy. 87(8):2491-2499. doi:10.1016/j.apenergy.2010.02.023S2491249987