Publications Scientifiques

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Author: search.filters.author.Bentarzi, HamidSubject: search.filters.subject.Reliability

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Now showing 1 - 10 of 11
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    Differential relay reliability enhancement using fourth harmonic for a large power transformer
    (Springer, 2017) Bouderbala, Rachid; Bentarzi, Hamid
    A differential relay that is very sensitive relayoperating even at its limits may be used for protecting apower transformer. However, this characteristic may leadto unnecessary tripping due to transient currents such as aninrush and over excitation current. In order to avoid thismal-operation of the relay, a second and fifth harmonicblocking technique has been used; however this techniqueis not reliable if a second harmonic magnitude is weak. Inthis paper, a new approach is proposed using even har-monics (second and fourth). The test results show that thisproposed approach is a good blocking technique associatedwith the differential relay even for large modern powertransformer which has small second harmonic as well; itprovides a good discrimination between the transient cur-rents and the internal fault currents during internal fault.
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    A New Frame Work for Protective Relay Tester
    (Inderscience, 2014) Chafai, Mahfoud; Bentarzi, Hamid; Ouadi, ABDERRAHMANE; Sahli, Hichem; Rial, Hichem
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    Distance relay reliability enhancement using false trip root cause analysis
    (Springer, 2017) Zitouni, Abdelkader; Ouadi, Abderrahmane; Bentarzi, Hamid; Chafai, Mahfoud
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    PC based testing system for protective relay
    (IEEE, 2013) Chafai, Mahfoud; Bentarzi, Hamid; Ouadi, Abderrahmane; Zitouni, Abdelkader; Recioui, Abdelmadjid
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    A new PMU based power swing detector to enhance reliability of distance relay
    (2014) Bentarzi, Hamid; Ouadi, Abderrahmane; Maun, Jean Claude
    Power grid protection aim is to make the generation, transmission and distribution of electrical energy as safe as possible from the effects of equipment failures. The operational security of the power system depends on the successful operation of the thousands of relays that protect power elements and hence protect the whole system against cascading failures. Thus, the failure of a relay to operate as intended may place at risk the entire power system and its elements. In conventional transmission line protection, a distance relay is used to provide the primary as well as backup protection. The voltage and current phasors measurement needed by the distance relay for determining the impedance may be affected by the power disturbances such as power swing. Consequently, this power swing may cause mal-operation of Zone three distance relays which in turn may affect on the reliability of the whole protective scheme. The mal-operation of this relay is generally due to not only unnecessary tripping during power swing that reduces the security of protection system and hence its reliability but also unnecessary blocking when symmetrical fault occurs accompanying a power swing. This latter action may affect on a dependability of the relay and hence its reliability. Many techniques have been developed to mitigate these effects and hence improve the relay reliability. One of the earliest techniques is the using of a negative sequence current magnitude and a derivative of current angle. This technique is very fast and its test results were promising in blocking false trip signals during power swing but when it is associated only with unsymmetrical faults. A combination of waveform of swing center’s voltage (WSCV) and synthetic negative vector has been also utilized to block the tripping signals during power swing. The technique seems to be rigorous indiscriminating power swing and high fault resistance. However, it requires two computationally heavy steps of derivative operation. There is also a time delay of about 30-40 ms before a power swing blocking scheme can be activated and hence the method is relatively slow. In order to improve the reliability of the relay, this work proposes a new scheme based on power swing detector using Phasor Measurement Units (PMUs). In addition to the local phasors information, the proposed scheme requires remote phasors information from different locations, which can be provided at high speed by PMUs. These measurements are used for calculating the power and the difference in phase voltages angles that may be used for detecting power swing and distinguishing it from the fault. This detector will not block relay when the power swing associated with any fault types. The MHO relay including power swing detector has been implemented using Simulink block set and S-function. To validate the present work, the performance of developed relay has been tested by signals generated by power network Simulink model running under different conditions. The test results show that this relay provides good discrimination between the transient high currents and the fault current
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    Large power transformer reliability modeling
    (Springer, 2016) Chafai, Mahfoud; Refoufi, Larbi; Bentarzi, Hamid
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    Reliability assessment and improvement of digital protective relays
    (Springer, 2016) Abdelmoumene, Abdelkader; Bentarzi, Hamid; Chafai, Mahfoud; Ouadi, Abderrahmane
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    A review on protective relays’ developments and trends
    (2014) Abdelmoumene, Abdelkader; Bentarzi, Hamid
    One of the most complex disciplines in electrical engineering is power system protection which requires not only the proper understanding of the different components of a power system and their behaviours but also a good knowledge and analysis of the abnormal circumstances and failures that can occur in any element of a power system. Moreover, the rapid changing and development in relays principles as well as in their technologies are additional factors that oblige those people working in the field to expand and update continuously their knowledge. In this paper, we shed light in the evolution of protective relays since the onset of electrical energy to currently. We try also to foresee the future prospects and trends in this area.
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    Reliability assessment and improvement of medium power induction motor winding insulation protection system using predictive analysis
    (Springer, 2009) Chafai, M.; Refoufi, L.; Bentarzi, Hamid
    This chapter presents a reliability assessment of a widely used protection system of medium-power squirrel cage induction motors. In conjunction with published field induction motors reliability data, this assessment effort is based on a predictive analysis integrating three predictive techniques: (1) a fault tree analysis (FTA) that allows to identify and then quantify the initiating events weighting factors; (2) an event tree analysis (ETA) that allows to predict the protection system probability outcomes following an external disturbance; and (3) a failure mode effect and criticality analysis (FMECA) that will help set the stage to develop a preventive maintenance program fit to keep up the induction motor protection system reliability at the required level with particular attention given to aggressive environmental factors such as found in cement plants