Publications Scientifiques

Permanent URI for this communityhttps://dspace.univ-boumerdes.dz/handle/123456789/10

Browse

Author: search.filters.author.Chafai, M.

Search Results

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    A new PMU based power swing detector to prevent mal-operation of distance relay
    (Russian electrical engineering, 2016) Ouadi, A.; Bentarzi, Hamid; Chafai, M.
    In conventional transmission line protection, a distance relay is used to provide the primary as well as remote 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. To mitigate these effects and hence improve the relay reliability, this work proposes a new real-time power swing detector using phasor measurement units for blinding the distance relay only during this transient disturbance. However, this developed detector will not block relay when the power swing accompanied with faults. To validate the present work, the performance of developed enhanced distance relay is tested by signals generated by Simulink/MATLAB simulator under different conditions. The test results show that this proposed scheme provides good discrimination between the transient currents and the fault current which in turn it may contribute in enhancing the reliability of Distance relay
  • No Thumbnail Available
    Item
    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
  • No Thumbnail Available
    Item
    Reliability assessment and improvement of large power transformer protection system using predictive analysis
    (2012) Chafai, M.; Bentarzi, Hamid
    A Failure of large power transformer protection not only reduces the reliability of power system but also has significant effects on power quality since one of the important components of any system quality is the reliability of that system. This paper presents a reliability assessment of a typical protection system of large power transformer. In conjunction with published field failure data of transformer, this assessment is based on an integrated predictive analysis using three methods: (1) a Fault Tree Analysis (FTA) that allows to identify and then quantify the initiating failure cause 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 to set the stage for developing a preventive maintenance plan. The latter is vigorous to keep up the transformer protection system reliability at the required level with special attention given to aggressive environmental factors