Showing papers by "V. Fernao Pires published in 2012"
TL;DR: A fast and robust control strategy for a multilevel inverter in grid-connected photovoltaic system is presented and several test results are presented in order to verify the effectiveness of the proposed system controller.
68 citations
24 Dec 2012
TL;DR: The application of PCA and average value computation to detect and identify faulty power switches in voltage source inverters and results in a fast and reliable fault detection methodology.
Abstract: One of the most used power converters is the three-phase voltage source power inverter. This is one of the reasons why it is so important to assure a continuous and safety operation of this power converter. This paper considers the application of PCA and average value computation to detect and identify faulty power switches in voltage source inverters. The PCA is applied to the inverter output currents in order to get a specific pattern that allows the identification of the fault. This results in a fast and reliable fault detection methodology. The applicability of the proposed technique is confirmed through simulation and experimental results.
16 citations
01 Nov 2012
TL;DR: In this article, a photovoltaic electric vehicle charger that also supports reactive power compensation is presented, in order to keep the system as cheap as possible the apparent power of the system is not increased.
Abstract: As the penetration of electric vehicles increases the number of chargers for these vehicles are also increasing and therefore, will increase the electric energy grid consumption. To integrate these needs with the green energy, the use of electric chargers with a solar photovoltaic installation makes perfect sense. However, these charges can also be used for the support of the reactive power compensation. In this way, a photovoltaic electric vehicle charger that also supports reactive power compensation is presented. In order to keep the system as cheap as possible the apparent power of the system is not increased. If the photovoltaic panel is supplying energy to the electric vehicle or the vehicle is not charging at full power then the power converter connected to the power grid will compensate the reactive power. Furthermore, the batteries on board of the electric vehicle can be seen as part of the photovoltaic system, running not only as traction batteries but also as backup energy storage.
15 citations
19 Mar 2012
TL;DR: A new hybrid multilevel inverter using a single DC source for open-end winding induction motor is proposed, which uses one three phase bridge inverter and three single-phase inverters, while using only one DC source.
Abstract: A new hybrid multilevel inverter using a single DC source for open-end winding induction motor is proposed. This power converter uses one three phase bridge inverter and three single-phase inverters, while using only one DC source. Due to the topology and voltage values, this power converter works as three single-phase multilevel inverters. In order to maximize the inverter output voltage levels there is an asymmetry between the amplitude of the three phase bridge inverter DC source and the single-phase inverter capacitor voltages. To control the three-phase inverter a SPWM modulator is used. Since the three single-phase inverters do not have DC sources an algorithm is required to maintain the capacitor voltage balanced. In this work a sliding mode control based approach is used to control the capacitor voltage of the single-phase inverters. In order to verify the proposed topology and proposed system converter several simulation results are presented.
13 citations
TL;DR: This paper presents an experimental system that can be used with a standard industrial electrical induction machine, based on only one healthy induction machine that is operated under faulty operating modes, and allows testing the behavior of the electrical machine for different load types.
Abstract: The study of fault detection and diagnosis of electrical machines, in particular induction motors, as well as the teaching of their behavior requires practical experience in this field. To provide this experience to the students this paper presents an experimental system that can be used with a standard industrial electrical induction machine. This system is based on only one healthy induction machine that is operated under faulty operating modes. Several fault types such as stator winding faults, bearing faults, or broken bars can be tested. The developed system also allows testing the behavior of the electrical machine for different load types. Several typical loads in which the torque depends of time or speed were implemented. The system is based on computer equipment with a DSPIC, a testing system and an induction machine. © 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 611–618, 2012
13 citations
TL;DR: In this paper, a new IPFC steady-state model is presented, which provides automatic IPFC parameter adjustment and accounts for IPFC operating limits, and a case-study is presented with the aim of showing the performance of the proposed IPFC model.
9 citations
19 Mar 2012
TL;DR: In this paper, the authors used the inverter output currents to obtain a typical pattern in a 3D referential, which is used to detect and identify the faulty power switch.
Abstract: This paper investigates the use of the current trajectory mass center in a three dimensional referential. The proposed approach uses the inverter output currents. These currents are used to obtain a typical pattern in a three dimensional referential. According the fault type different patterns is obtained. In this way, with the proposed approach it is possible to detect and identify the faulty power switch In order to automatically identify the different patterns, it is used an algorithm to obtain a mass center of the 3D current trajectory. This results in a fast and reliable fault detection method. The applicability of the proposed technique, are confirmed through several simulation and experimental results.
6 citations
TL;DR: A new approach for the practical learning of power system relaying is presented, which consists of a computer‐based testing system of relay‐operating characteristic that is possible to understand the performance and limitations of different protective relay systems and to test a real relay disoperation.
Abstract: Teaching power system relaying is a fundamental issue in a power system high-level course. However, for an effective instruction of this topic an experience with real equipments can be considered as fundamental. To achieve this purpose, in this paper a new approach for the practical learning of power system relaying is presented. This consists of a computer-based testing system of relay-operating characteristic. Different relay types and developed specific software are also an important piece of the laboratory practice. Using this system it is possible to understand the performance and limitations of different protective relay systems and to test a real relay disoperation. The benefit of using this system is not available through traditional lectures and textbooks. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 19–28, 2012
6 citations
TL;DR: A dynamic model of the STATCOM in αβ coordinates is used as a basis for control design, which uses a cascade structure where a fast ac current inner loop and a slow dc current control outer loop is used.
3 citations
13 Jun 2012
TL;DR: A methodology that analysis and classifies the EMG and MMG signals using a linear neural network to control prosthetic members and shows a promising performance in classification of motions based on both MMG and EMG signals.
Abstract: This paper proposes a methodology that analysis and classifies the EMG and MMG signals using a linear neural network to control prosthetic members. Finger motions discrimination is the key problem in this study. Thus the emphasis is put on myoelectric signal processing approaches in this paper. The EMG and MMG signals classification system was established using a linear neural network and it is presented the comparison with the classification based on the LVQ neural network. Experimental results show a promising performance in classification of motions based on both MMG and EMG signals.
3 citations
11 Dec 2012
TL;DR: In this article, a fault detection and diagnosis method for a six-phase voltage source inverter (VSI) is proposed based on an equivalent six dimension of a current trajectory mass center of the VSI output currents.
Abstract: This paper presents a new fault detection and diagnosis method for a six-phase voltage source inverter (VSI). The proposed method is based on an equivalent six dimension of a current trajectory mass center of the VSI output currents. This approach allows detecting and identifying the faulty power switch. The proposed approach results in a fast and reliable fault detection method. The performance of a proposed technique, are confirmed through several simulation and experimental results.
11 Dec 2012
TL;DR: This paper is a case study and it presents a multilevel single-phase induction motor drive with a diametrical inversion (DI) control scheme based on a modulation of the rotating field from two others that rotate in opposing directions.
Abstract: This paper is a case study and it presents a multilevel single-phase induction motor drive with a diametrical inversion (DI) control scheme. This control scheme is based on a modulation of the rotating field from two others that rotate in opposing directions. In this way, the controller changes the stator voltage phasor with jumps of 180 degree. The multilevel inverter uses two DC voltage multilevel power converter switches are generated by a SPWM modulator. However, the DI control system changes by 180 degree the phase of the sinusoidal modulator. Several simulation results are presented in order to verify the good performance of the proposed motor drive.
13 Jun 2012
TL;DR: In this article, a system controller for a power converter connoted to a photovoltaic system and in a smart grid is presented, where a sliding mode approach is used to control this converter.
Abstract: In this paper it is presented a system controller for a power converter connoted to a photovoltaic system and in a smart grid. This system controller has been developed in order to transmit all the produced active power of the photovoltaic system to the grid. However, it was also developed to use the power converter as reactive power compensator. Most of the time the photovoltaic system it is not producing its rated value. In this way, the power converter can also be used as a reactive power compensator in order to exploit the apparent power of the power converter. A single-stage three-phase power converter is used. To control this converter a sliding mode approach is used. This allows obtaining a fast and robust controller. A maximum power point tracking algorithm associated to the sliding mode controller is used. Several numerical simulations are presented in order to confirm the effectiveness of the proposed system.
24 Dec 2012
TL;DR: The S-Transform is applied to the inverter output currents in order to get a specific pattern that allows the identification of the fault, which results in a fast and reliable fault detection methodology.
Abstract: One of the most used power converters is the three-phase voltage source power inverter. This is one of the reasons why it is so important to assure a continuous and safety operation of this power converter. This paper considers the application of the S-Transform to detect and identify faulty power switches in voltage source inverters. The S-Transform is applied to the inverter output currents in order to get a specific pattern that allows the identification of the fault. This results in a fast and reliable fault detection methodology. The applicability of the proposed technique is confirmed through simulation and experimental results.
19 Mar 2012
TL;DR: In this article, the S-Transform is applied to the stator currents in order to get a specific pattern that allows the identification of the rotor fault, which is used for diagnosing the occurrence of rotor electrical fault.
Abstract: This paper proposes the use of the S-Transform applied to the stator currents as a method for diagnosing the occurrence of rotor electrical fault (broken bars or faulty rotor windings) in induction motor. Induction motor stator currents are first measured and recorded. Then, the S-Transform is applied to the obtained currents in order to get a specific pattern that allows the identification of the rotor fault. Simulation and experimental results, for both a healthy motor and a motor with a rotor electrical fault, are presented in order to show the effectiveness of the proposed method.
Journal Article•
TL;DR: In this article, the authors proposed a three-phase multilevel power conversion structure using a three single-phase voltage source inverters and a Scott transformer, which can derive two-phase waveforms and connect to the Scott transformer.
Abstract: In this paper it is proposed a new three-phase multilevel power conversion structure. This structure uses a three single-phase voltage source inverters and Scott transformer. The structure composed by the three single-phase voltage source inverters has two single-phase outputs. These outputs will connect to the Scott transformer. This transformer allows deriving two-phase voltage to a three-phase source. The proposed multilevel power conversion structure allows obtaining a five-level three-phase inverter. To control the proposed power converter it is used a sliding mode controller with a vectorial modulator. Several test results of the proposed converter structure with their control system are presented. From the obtained results it is possible to confirm the voltage multilevel waveforms and the effectiveness of the proposed control system technique. Streszczenie. W artykule zaproponowano nową strukture wielopoziomowego przeksztalcania energii elektrycznej. W strukturze tej uzyto trzy jednofazowe falowniki napiecia oraz transformator Scotta. Struktura ta posiada dwa jednofazowe wyjścia. Wyjścia te są polączone z transformatorem Scotta. Transformator ten umozliwia zamiane napiec dwufazowych na napiecia trojfazowe. Proponowana struktura multipoziomowego przeksztalcania energii elektrycznej umozliwia otrzymanie trojfazowego, pieciopoziomowego falownika napiecia. W ukladzie sterowania wykorzystano sterowanie ślizgowe (sliding mode) z modulatorem wektorowym. Zaprezentowano kilka wynikow badan proponowanej struktury z uzyciem tego typu ukladu sterowania. Z otrzymanych wynikow mozliwe jest potwierdzenie uzyskania napiec wielopoziomowych oraz efektywności proponowanego ukladu sterowania. (Przeksztaltnik wielopoziomowy bazujący na trzech jednofazowych falownikach napiecia).
01 Jan 2012
TL;DR: This paper presents a new approach to a numerical current differential protection for the transmission lines using a pattern recognition method and the obtained results allow verifying the effectiveness of the proposed approach.
Abstract: This paper presents a new approach to a numerical current differential protection for the transmission lines. The current differential algorithm uses a pattern recognition method. First the acquired current signals are transformed into “dqo” components by applying the Park transformation. The transformed currents will originate typical patterns according the fault type. Using a pattern recognition algorithm the different faulty conditions are identified. Several tests under different fault conditions were performed. The obtained results allow verifying the effectiveness of the proposed approach.
11 Dec 2012
TL;DR: In this paper, a new structure for a photovoltaic system is introduced, which is based on a string architecture with four power electronic conditioning units, and the inverters are connected to the utility grid through a special transformer.
Abstract: This paper introduces a new structure for a photovoltaic system. This system is based on a string architecture with four power electronic conditioning units. In order to keep it as simple as possible, it uses four single-phase voltage source inverters. The inverters are connected to the utility grid through a special transformer. This transformer is based on a Scott transformer and allows connecting the four inverters to a three-phase system. Several simulation results are presented in order to evaluate the feasibility of the proposed photovoltaic system.