http://hdl.handle.net/2117/4008 2013-05-22T11:32:56Z http://hdl.handle.net/2117/19111 Title: Electric drives for light e-scooters Authors: Andrada Gascón, Pedro; Blanqué Molina, Balduino; Martínez Piera, Eusebio; Torrent Burgués, Marcel; Perat Benavides, Josep Ignasi; Sánchez López, José Antonio Abstract: In the next years is expected an important rise in sales of electrical scooters in the entire world but especially in China. In order to address this challenge the electric scooter industry has to be more competitive in the transportation market and therefore important improvements, in terms of energy density and costs, have to be done in the electric storage system and in the electric propulsion system. In this paper, an analytical and experimental comparison of two different drives for electric scooters is carried out. Both are permanent magnet synchronous outer rotor motor drives but one placed inside the rear wheel and the other connected to the wheel trough a mechanical transmission. 2013-05-06T17:52:03Z http://hdl.handle.net/2117/18731 Title: Autonomous photovoltaic lighting system Authors: Hafez, Ahmed A. A.; Montesinos Miracle, Daniel; Sudrià Andreu, Antoni Abstract: This paper introduces a comparison between the conventional and Photovoltaic (PV) lighting systems. A simple sizing procedure for a PV stand-alone system was advised. The paper also proposes a novel PV lighting system. The proposed system is simple, compact and reliable. The system operation was investigated by thoroughly mathematical and simulation work. 2013-04-09T11:31:27Z http://hdl.handle.net/2117/18267 Title: Lightning initiation from a tall structure in the Basque Country Authors: López, Javier; Montañá Puig, Juan; Maruri, M.; De la Vega, D.; Aranda, J.A.; Gaztelumendi, S. Abstract: Lightning detection in the Spanish Basque Country is performed using the LF TOA, VHF interferometer and the VLF lightning detection technologies in which two independent networks are based, providing a better detection quality due to the combination of these different techniques. Total lightning activity related to the tall structure of the weather radar operated by the Basque Meteorology Agency (Euskalmet) is presented. The tall structure is a 50 m tower located on the top of Kapildui Mountain (at about 1169.48 m ASL). Remarkable electrical activity associated to this place has been witnessed in the last two years. Two particular flashes during November 30th 2009 caused damage to the weather radar. Two different lightning detection networks detected five and six cloud-to-ground strokes, respectively. Only nine VHF sources were detected in the first flash without any VLF detection classified as intracloud. But for the second flash non VHF source was detected and two detections were reported by the VLF system. In both cases some intracloud detections were reported before cloud-to-ground strokes and some others during the flash. This paper presents the study of a winter episode with a special impact in the tower, the research carried out for characterizing the lightning events and the measures taken in order to achieve a better protection mechanism for the radar site 2013-03-13T15:22:51Z http://hdl.handle.net/2117/18262 Title: High-speed video of lightning and x-ray pulses during the 2009–2010 observation campaigns in northeastern Spain Authors: Montañá Puig, Juan; Van der Velde, Oscar Arnoud; March Nomen, Víctor; Romero Durán, David; Solà de Las Fuentes, Gloria; Pineda Ruegg, Nicolau Abstract: This paper summarizes results obtained by the 2009–2010 field campaigns conducted in northeastern Spain using a high speed camera, VHF interferometer, VLF lightning location system and scintillation detectors for energetic radiation. The main purpose was to obtain new insight into the lightning processes which emit x/γ radiation. For just one (very close) lightning strike, 99 x-ray pulses were emittedwithin 0.86 ms and had an energy higher that 10 keV. This burst was associated with the final stages of a downward negative leader. The high-speed camera data also allowed to identify various previously unreported features in different types of cloud-to-ground lightning flashes. At video frame rates of 10,000 fps, some branches of negative leaders of cloud-to-ground flashes were illuminated for the duration of only one frame. During positive cloud-to-ground flashes, the high speed videos showed an intense activity of recoil leaders. In the case of intra-cloud lightning, the VHF interferometer network did not present a clear relation between detections and visible leader. Instead, bursts of VHF detections corresponded visually to a long-lasting bright channel under the cloud base 2013-03-13T14:47:48Z http://hdl.handle.net/2117/18257 Title: Pareto optimal reconfiguration of power distribution systems using a genetic algorithm based on NSGA-II Authors: Tomoiaga, Bogdan; Chindris, Mircea; Sumper, Andreas; Sudrià Andreu, Antoni; Villafafila Robles, Roberto Abstract: Reconfiguration, by exchanging the functional links between the elements of the system, represents one of the most important measures which can improve the operational performance of a distribution system. The authors propose an original method, aiming at achieving such optimization through the reconfiguration of distribution systems taking into account various criteria in a flexible and robust approach. The novelty of the method consists in: the criteria for optimization are evaluated on active power distribution systems (containing distributed generators connected directly to the main distribution system and microgrids operated in grid-connected mode); the original formulation (Pareto optimality) of the optimization problem and an original genetic algorithm (based on NSGA-II) to solve the problem in a non-prohibitive execution time. The comparative tests performed on test systems have demonstrated the accuracy and promptness of the proposed algorithm. 2013-03-13T12:54:14Z http://hdl.handle.net/2117/18053 Title: Dielectric, mechanical, and thermal characterization of high-density polyethylene composites with ground tire rubber Authors: Mujal Rosas, Ramón María; Marín Genescá, Marcos; Orrit Prat, Jordi; Rahhali, Ahmed; Colom Fajula, Xavier Abstract: The mass manufacture of tires and the difficulty in storing or disposing them constitute a serious environmental problem. At present, various recycling methods for tires are used, such as grinding, which separates the steel and fibers from the vulcanized rubber, then using the rubber in numerous industrial applications such as pavements, insulators, footwear, etc. The aim of this article focuses on finding a new application for the ground tire rubber (GTR). This would allow including GTR in industrial applications of recycled high-density polythene (HDPE). Tire dust and HDPE thermoplastic have been mixed, and the maximum accepted values of GTR concentration that can be admitted while keeping dielectric, mechanical, and thermal properties within acceptable values, as well as initial polymer microstructure, have been checked. In addition, the suitability of the compounds for antistatic applications is studied. The recycled tire dust which results from the industrial milling processes has been divided by sieve in three different categories according to the size of the particles (<200, 200–500, and >500 mm). This has then been mixed with HDPE in different GTR concentrations (0%, 5%, 10%, 20%, 40%, 50%, and 70%) in order to establish its conduct through electrical, mechanical, thermal, and microstructure tests, which will be held in a temperature range 30–120_C, and with a frequency range 1 _ 10_2 and 3 _ 106 Hz. The thermal tests determined the enthalpies and fusion temperatures which allow for the observation of changes in crystalline and microstructure of the matrix, and finally, the fracture surfaces of the compound samples have been evaluated using scanning electron microscopy 2013-03-05T10:41:14Z http://hdl.handle.net/2117/17783 Title: Model of discharge lamps with magnetic ballast Authors: Molina, Julio; Sainz Sapera, Luis; Mesas García, Juan José; Bergas Jané, Joan Gabriel Abstract: Magnetic ballast discharge lamp modeling has been extensively studied because these lamps can be an important source of harmonics. Discharge lamp models usually represent the arc voltage by a square waveform. However, this waveform can be far from actual arc voltages, which affects the accuracy of the lamp models. This paper investigates the actual arc voltage behavior of discharge lamps from laboratory measurements and proposes a novel characterization of these voltages to reformulate the conventional models. The accuracy of the new model is validated with experimental measurements. 2013-02-15T10:49:21Z http://hdl.handle.net/2117/17751 Title: Saturation effects on torque- and current–slip curves of squirrel-cage induction motors Authors: Monjo Mur, Lluís; Córcoles López, Felipe; Pedra Durán, Joaquim Abstract: 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. 2013-02-14T10:08:24Z http://hdl.handle.net/2117/17636 Title: Study on dielectric, mechanical and thermal properties of polypropylene (PP) composites with ground tyre rubber (GTR) Authors: Mujal Rosas, Ramón María; Orrit Prat, Jordi; Ramis Juan, Xavier; Marín Genescá, Marcos; Rahhali, Ahmed 2013-02-11T14:57:40Z http://hdl.handle.net/2117/17618 Title: Design and control of a modular multilevel DC/DC converter for regenerative applications Authors: Montesinos Miracle, Daniel; Massot Campos, Miquel; Bergas Jané, Joan Gabriel; Galcerán Arellano, Samuel; Rufer, Alfred Abstract: This paper compares different cascaded and multilevel topologies to interface supercapacitors to a dc bus in regenerative braking applications. It is shown that the modular multilevel dc/dc converter (MMC) can benefit from both reduced voltage and increased frequency across the inductor to reduce its weight and volume when using phase shifting modulation. The proposed controlmethod is able to balance supercapacitor voltage while providing precise output current control. The converter topology and control method are validated with simulations and experimental results. 2013-02-11T10:25:07Z http://hdl.handle.net/2117/17612 Title: Aplicaciones eléctricas del acrilonitrilo butadieno estireno (ABS) reforzado con neumáticos fuera de uso (GTR) Authors: Mujal Rosas, Ramón María; Orrit Prat, Jordi; Ramis Juan, Xavier; Marín Genescá, Marcos 2013-02-08T13:57:52Z http://hdl.handle.net/2117/17568 Title: Simulation of an induction hardening system during Curie temperature transition considering converter's performance Authors: Martín Segura, Guillermo; Ferrater Simón, María Misericordia; López Mestres, Quim; Montesinos Miracle, Daniel; Bergas Jané, Joan Gabriel Abstract: Purpose – The aim of this paper is to simulate, test and evaluate an induction heating process considering the converter’s performance. Design/methodology/approach – In case of continuous induction hardening processes, the load changes abruptly during the transition to Curie temperature, becoming significant considering the converter’s behavior. In this paper, an induction heating system is simulated combining the numerical analysis of the electromagnetic-thermal and electrical problem, focusing mainly on the converter’s performance. The simulations are realized by using commercial FEM software and the voltage and the frequency are manually varied according to the converter’s control. The system has also been implemented in an experimental setup and the results obtained have been compared with the simulations. Findings – The importance of considering the converter’s dynamics was observed during the simulations. The simulation results showed a correspondence with the experimental results, validating the simulation procedure and demonstrating that the converter’s behavior has to be considered. Originality/value – A power converter for a real industrial induction heating process where there is a sudden change in the load parameters is simulated and experimentally tested. The importance of considering the variation of frequency and voltage during the simulation of induction heating systems is demonstrated. Some considerations for induction heating modeling regarding converter’s performance are given and the importance of converter’s dynamics is introduced. In addition, a simple and flexible method of simulating the converter operation with commercial software is presented 2013-02-04T14:02:45Z http://hdl.handle.net/2117/17281 Title: Enhanced decoupled double synchronous reference frame current controller for unbalanced grid-voltage conditions Authors: Reyes, M.; Rodríguez Cortés, Pedro; Vazquez, S.; Luna Alloza, Álvaro; Teodorescu, Remus; Carrasco, J.M. Abstract: In the last few years, restrictive grid codes have arisen to ensure the performance and stability of electrical networks, which experience amassive integration of renewable energy sources and distributed generation systems that are normally connected to the grid through electronic power converters. In these codes, the injection of positive- and negative-sequence current components becomes necessary for fulfilling, among others, the low-voltage ride-through requirements during balanced and unbalanced grid faults. However, the performance of classical dq current controllers, applied to power converters, under unbalanced grid-voltage conditions is highly deficient, due to the unavoidable appearance of current oscillations. This paper analyzes the performance of the double synchronous reference frame controller and improves its structure by adding a decoupling network for estimating and compensating the undesirable current oscillations. Experimental results will demonstrate the validity of the proposed decoupled DSRF controller 2013-01-11T13:57:37Z http://hdl.handle.net/2117/17231 Title: Evaluation of storage energy requirements for constant production in PV power plants Authors: Beltran, Hector; Bilbao, Endika; Belenguer, Enrique; Etxeberria Otadui, Ion; Rodríguez Cortés, Pedro Abstract: This paper analyzes the minimum energy capacity ratings that an energy-storage (ES) system should accomplish in order to achieve a defined constant power production in a photovoltaic (PV) power plant. ES is a key issue for the further integration of intermittent and stochastic renewable energy sources, which are not currently dispatchable due to their dependence on real-time weather conditions, as is the case of PV technology. This paper proposes and describes an energy management strategy (EMS) for operating PV power plants with ES in the future. The goal of this EMS is to endow these power plants with a constant production that can be controlled and hence traded on electricity markets. This paper presents simulated results on the percentage of time throughout the year during which a large-scale PV+ES plant operates properly with different ES ratings and according to different configurations of this EMS. Finally, a test bench was developed, and experimental results validating this EMS were obtained 2013-01-09T12:11:07Z http://hdl.handle.net/2117/17230 Title: Direct synchronous-asynchronous conversion system for hybrid electrical vehicle applications. An energy-based modeling approach Authors: Muñoz Aguilar, Raúl Santiago; Dòria Cerezo, Arnau; Puleston, Paul Abstract: This paper presents a proposal for a series hybrid electric vehicle propulsion system. This new configuration is based on a wound-rotor synchronous generator (WRSM) and a doubly-fed induction machine (DFIM). The energy-based model of the whole system is obtained taking advantage of the capabilities of the port-based modeling techniques. From the dq port-controlled Hamiltonian description of the WRSM and DFIM, the Hamiltonian model of the proposed Direct Synchronous-Asynchronous Conversion System (DiSAC) is developed. Subsequently, the bond graph models of the DiSAC and associate systems are also provided. Numerical simulations are also presented in order to validate the proposed system 2013-01-09T11:36:16Z