http://hdl.handle.net/2117/3808 2013-05-22T05:07:01Z 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/2117/18257 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/2117/17783 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/2117/17618 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/2117/17568 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/2117/17112 Title: Hysteresis current control technique of VSI for compensation of grid-connected unbalanced loads Authors: Pouresmaeil, Edris; Akorede, Mudathir Funsho; Montesinos Miracle, Daniel; Gomis Bellmunt, Oriol; Trujillo Caballero, Juan Carlos Abstract: The global trends nowadays in the power generation industry are to supplement the electricity production using distributed generation (DG) technologies based on renewable energy resources such as photovoltaic, wind power, etc. However, failure to properly control the operation of distributed energy resources as they connect to the exiting power grid could provoke many power quality problems on the grid side. For this reason, due considerations must be given to power generation and safe running before DG units is actually integrated into the power grid. The main aim of this paper is to address the grid interconnection issues that usually arise as DG units connect to the electric grid. The proposed strategy, implemented in Matlab/Simulink environment in different operating scenarios, provides compensation for active, reactive, unbalanced, and harmonic current components of grid-connected nonlinear unbalanced loads. The simulation results obtained in this study demonstrate the level of accuracy of the proposed technique, which ensure a balance in the overall grid phase currents, injection of maximum available power from DG resources to the grid, improvement of the utility grid power factor, and a reduction in the total harmonic distortion of grid currents. 2012-12-12T10:28:07Z http://hdl.handle.net/2117/16210 Title: Autonomous cascaded PV system Authors: Hafez, Ahmed A. A.; Montesinos Miracle, Daniel; Sudrià Andreu, Antoni Abstract: This paper proposes multi-level PV system; three PV generators each coupled to a buck cell. Each PV-generator-buckconverter channel is controlled such that maximum power is captured independently under different irradiation and temperature levels. The system operation under normal/abnormal conditions is investigated by thoroughly mathematical and simulation work. 2012-07-09T14:44:53Z http://hdl.handle.net/2117/16066 Title: Control scheme of three level NPC inverter for integration of renewable energy resources into AC grid Authors: Pouresmaeil, Edris; Montesinos Miracle, Daniel; Gomis Bellmunt, Oriol Abstract: This paper presents a multiobjective control scheme based on the dynamic model of three-level, neutral-point-clamped voltage source inverter for integration of distributed generation (DG) resources based on renewable energy resources to the distribution grid. The proposed model has been derived from the abc/αβ and αβ/dq transformation of the AC system variables. The proposed control technique generates the compensation current references and by setting appropriate references of DG control loop, the DG link not only provides active and reactive currents in fundamental frequency, but also it can supply nonlinear load harmonic currents with a fast dynamic response. Simulation results and mathematical analysis have achieved a reduced total harmonic distortion, increased power factor, inject maximum power of renewable energy resources via a multilevel converter as an interface to the AC grid. It also compensated the active and reactive powers of linear and nonlinear loads. The analyses and simulation results show the high performance of proposed control scheme in the integration of renewable energy resources to the AC grid. 2012-06-16T10:41:48Z http://hdl.handle.net/2117/15898 Title: Probabilistic method to assess the impact of charging of electric vehicles on distribution grids Authors: Valsera Naranjo, Eduardo; Sumper, Andreas; Villafafila Robles, Roberto; Martínez Vicente, David Abstract: This paper describes a grid impact analysis of charging electric vehicles (EV) using charging curves with detailed battery modelling. A probabilistic method using Monte Carlo was applied to a typical Spanish distribution grid, also using mobility patterns of Barcelona. To carry out this analysis, firstly, an IEEE test system was adapted to a typical distribution grid configuration; secondly, the EV and its battery types were modeled taking into account the current vehicle market and the battery characteristics; and, finally, the recharge control strategies were taken into account. Once these main features were established, a statistical probabilistic model for the household electrical demand and for the EV charging parameters was determined. Finally, with these probabilistic models, the Monte Carlo analysis was performed within the established scenario in order to study the lines’ and the transformers’ loading levels. The results show that an accurate model for the battery gives a more precise estimation about the impact on the grid. Additionally, mobility patterns have been proved to be some of the most important key aspects for these type of studies. 2012-05-21T09:10:54Z http://hdl.handle.net/2117/14441 Title: Optimization techniques to improve energy efficiency in power systems Authors: Pezzini, Paola; Gomis Bellmunt, Oriol; Sudrià Andreu, Antoni 2012-01-10T10:02:04Z http://hdl.handle.net/2117/13382 Title: Reactive power dispatch in wind farms using particle swarm optimization technique and feasible solutions search Authors: Martinez Rojas, Marcela; Sumper, Andreas; Gomis Bellmunt, Oriol; Sudrià Andreu, Antoni Abstract: In this paper, an optimization method for the reactive power dispatch in wind farms (WF) is presented. Particle swarm optimization (PSO), combined with a feasible solution search (FSSPSO) is applied in order to optimize the reactive power dispatch, taking into consideration the reactive power requirement at point of common coupling (PCC), while active power losses are minimized in a WF. The reactive power requirement at PCC is included as a restriction problem and is dealt with feasible solution search. Finally an individual set point, particular for each wind turbine (WT), is found. The algorithm is tested in a WF with 12 WTs, taking into consideration different control options and different active power output levels. 2011-09-28T16:29:22Z http://hdl.handle.net/2117/13306 Title: LED: ¿la nueva generación en fuentes de luz? Authors: Quintero, Jesus M.; Sudrià Andreu, Antoni; Ramírez Pisco, Rodrigo Abstract: Desde la aparición en el mercado de los LED de potencia de luz blanca a comienzos de la década del 2000, esta tecnología ha venido incursionando con gran fuerza en todas las aplicaciones de iluminación de espacios interiores y exteriores. El hecho de ser una tecnología emergente hace que la aparición en el mercado de nuevas versiones mejoradas de estos LED tenga una dinámica muy alta. Ya están haciendo su aparición en la aplicación específica de iluminación pública de exteriores. 2011-09-22T14:07:45Z http://hdl.handle.net/2117/13305 Title: High-accuracy all-digital resolver-to-digital conversion Authors: Bergas Jané, Joan Gabriel; Ferrater Simón, María Misericordia; Gross, Gabriel; Ramírez Pisco, Rodrigo; Galcerán Arellano, Samuel; Rull Duran, Joan Abstract: In this article, a high-accuracy all-digital resolverto- digital converter is presented. The two basic components of a conventional tracking R/D converter, the phase detector and the loop filter, are software implemented by frequency shifting techniques and a decoupled Double Synchronous Rotating reference Frame-based PLL (DSRF-PLL). This PLL allows the simultaneous extraction of the angular position and speed of the rotatory resolver, even in the presence of gain and phase errors in the resolver. In order to increase accuracy and to minimize the time lag of the whole system, oversampling methods and downsampling FIR digital filters are introduced. Finally, DSP implementation issues, like the use of techniques to synchronize the resolver output signals with the excitation one, are discussed. Using these combined techniques and a standard DSP with a 12-bit ADC, resolutions of up to 14 bits can be achieved with a computation cost of about 13% of the total (100 MIPs). The paper presents the main techniques, simulation and experimental results. 2011-09-22T13:56:07Z http://hdl.handle.net/2117/13242 Title: A hybrid algorithm for fast detection and classification of voltage disturbances in electric power systems Authors: Pouresmaeil, Edris; Akorede, Mudathir Funsho; Hojabri, Mojgan Abstract: To minimize the adverse impacts of power quality disturbances on the electric power supply as well as on the customer equipment, there is clearly a need for detection and classification of such problems. In this paper, a fast detection algorithm for power quality disturbances is presented. The proposed method is a hybrid of two algorithms, abc–0dq transformation and 908 phase shift algorithms. The proposed algorithm is fast and reliable in detecting most voltage disturbances in power systems such as voltage sags, voltage swells, interrupts, flicker, harmonics, etc. In the proposed approach, the three-phase utility voltages are sensed separately by each of the algorithms. These algorithms are combined to explore their individual strengths for a better performance. When a disturbance occurs, both algorithms work together to recognize this distortion and send trip signals to static transfer switches. This control method can be used for critical loads protection in case of utility voltage distortion. Simulation and analysis results obtained in this study illustrate high performance of the strategy in different single-phase and three-phase voltage distortions. 2011-09-19T12:00:00Z http://hdl.handle.net/2117/12955 Title: Instantaneous active and reactive current control technique of shunt active power filter based on the three-level NPC inverter Authors: Pouresmaeil, Edris; Montesinos Miracle, Daniel; Gomis Bellmunt, Oriol; Sudrià Andreu, Antoni Abstract: In this paper, the synthesis and performance of a shunt active power filter (SAPF) based on instantaneous active, and reactive current components (i-d i-q) technique is presented. The proposed active filter acts as a current source, which is connected in parallel with a nonlinear load and controlled to generate the required compensation currents. The proposed control technique for SAPF aims to compensate the harmonic current contents of nonlinear loads by connection of distributed generation (DG) resources based on renewable energy sources to distribution network. This modeling is derived from the 123(abc)to αβ and αβ to dq transformation of the ac system variables. The injected currents by the SAPF to polluted grid are controlled in synchronous orthogonal dq reference frame by using of decoupled current control technique. By use of phase locked loop (PLL) in control circuit of proposed technique, the angle of positive sequence has been detected, in order to synchronize the SAPF injected currents to distribution network. The proposed control strategy has this ability to eliminate wide range of harmonic frequency draws from utility grid, and provide the compensation currents by DG resources. By this control method, replacement of distributed power generation systems as an active power filter can be possible. Three-phase three-level neutral-point-clamped (NPC) voltage source inverter (VSI) is proposed for the interfacing between renewable energy resources and polluted distribution network. The simulation results demonstrate high performances of proposed SAPF technique. 2011-07-13T10:13:10Z