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Yahia K.,University Mohamed Khider of Biskra | Yahia K.,University of Beira Interior | Sahraoui M.,University of Beira Interior | Sahraoui M.,University Mohamed Khider of Biskra | And 3 more authors.
Proceedings - SDEMPED 2015: IEEE 10th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives | Year: 2015

Induction motors airgap-eccentricity fault detection has attracted the interest of many researchers in last decades. The Discrete Fourier Transform (DFT) has been widely used for that purpose. However, DFT can only give meaningful information for stationary signals. In this paper, an efficient time-domain technique based on a modified Prony's method for the airgap-eccentricity fault detection in induction motors is presented in order to overcome the DFT problems. Using this technique, the apparent power, as processed signal, is divided into short overlapped time windows, and each one is analyzed by the Least Squares Prony's method. The proposed technique allows tracking the frequencies and amplitudes of the airgap-eccentricity fault characteristic frequency component fr with a very high accuracy. A fault severity factor (FSF) based on fr amplitudes is defined. Simulation as well as experimental results are provided to illustrate the effectiveness and accuracy of the proposed method. © 2015 IEEE. Source


Gyftakis K.N.,Coventry University | Antonino-Daviu J.A.,Polytechnic University of Valencia | Garcia-Hernandez R.,Polytechnic University of Valencia | McCulloch M.D.,University of Oxford | And 3 more authors.
IEEE Transactions on Industry Applications | Year: 2016

It has been shown in the past that the zero-sequence current spectrum can be reliably used to detect broken bar faults in induction motors. Previous work was carried out with extensive FEM analysis. Although it allows detailed study of spatial and time-dependent electromagnetic characteristics of induction motors, FEM is a heavily time-consuming tool and this limits full study. So, in this work, extensive experimental testing has been performed to validate the zero sequence current spectrum for detecting rotor asymmetries. Three identical induction motors have been used: one healthy, one with a broken rotor bar, and one with two broken rotor bars. The motors were tested under different voltage supply levels and with different mechanical loads. The zero-sequence current spectrum was calculated after measuring the three phase currents. It is for the first time experimentally shown that this approach offers greater diagnostic potential than traditional MCSA. © 2016 IEEE. Source


Ribeiro E.,University of Beira Interior | Marques Cardoso A.J.,University of Beira Interior | Boccaletti C.,University of Rome La Sapienza | Boccaletti C.,Electromechatronic Systems Research Center
2014 IEEE Energy Conversion Congress and Exposition, ECCE 2014 | Year: 2014

Non-isolated DC-DC converters are the most simple and common power converter topologies and their reliability is of primary importance in many safety critical applications. Therefore, a new fault diagnostic method is presented in this paper for unidirectional non-isolated DC-DC converters using only the converters control variables without requiring extrasensors and with only a minimum computational effort. A laboratory setup of a wind-batteries power system has been used to validate the fault diagnostic method. © 2014 IEEE. Source


Oliveira L.M.R.,University of Algarve | Oliveira L.M.R.,Electromechatronic Systems Research Center | Cardoso A.J.M.,Electromechatronic Systems Research Center | Cardoso A.J.M.,University of Beira Interior
Proceedings - SDEMPED 2015: IEEE 10th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives | Year: 2015

This paper presents a comparison of two of the most sensitive methods to detect low-level turn-to-turn faults in the windings of three-phase transformers. The performance of the negative sequence component and of the space vector protection algorithms is tested under several internal and/or external fault conditions. The simulation results indicate that the fault detection sensitivity of both methods is very similar. © 2015 IEEE. Source


Oliveira L.M.R.,University of Algarve | Oliveira L.M.R.,Electromechatronic Systems Research Center | Cardoso A.J.M.,Electromechatronic Systems Research Center | Cardoso A.J.M.,University of Beira Interior
IEEE Transactions on Power Delivery | Year: 2015

This paper presents a general approach to compute the leakage inductances of power transformers with turn-to-turn winding faults. The leakage inductances are obtained by using well-known conventional formulas, adapted to the asymmetrical conditions produced by the interturn fault in the leakage flux distribution. Two methods for calculating the leakage inductances are presented: the first requires detailed information about the geometry of the windings whereas the second uses simplifying assumptions, allowing to express the leakage inductances as a function of the nameplate short-circuit inductance, the number of turns, and core dimensions. A leakage inductance model of the transformer with faulty turns is also proposed, which is based on the three-winding transformer theory. This leakage inductance equivalent circuit can be easily integrated into other electromagnetic transient simulators. The results obtained from the application of the analytical methods and the equivalent circuit are validated using data obtained from finite-element analysis and experimental short-circuit tests. © 1986-2012 IEEE. Source

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