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    Effect of shape factor on structural reliability analysis of a surface cracked pipeline-parametric study
    (2019) Guillal, Abdelkader; Abdelbaki, Noureddine; Bensghier, Mohamed El Amine; Betayeb, Mourad; Kopei, Bogdan
    The variation of crack shape factor (a/c) during propagation has an important role on calculation of the stress intensity factor (SIF), where imprecise estimation of this latter can lead us to an inaccurate prediction of failure probabilities. For the case of external cracked surface pipeline carried oil and gas products, such estimation can results undesired fault decisions like excessive repairs action or inspection planning. In this paper, the structural integrity analysis of pipeline with semi elliptical crack on the external surface is evaluated. Reliability calculations expressed in term of reliability index β are carried out based on Monte Carlo simulation and First Order reliability Method (FORM). The crack shape factors are varied to cover a variety of geometries from shallow to deep cracks while fatigue crack growth is assumed in depth direction. For SIF estimation, surface and deep point are considered. Results of the analysis indicate that for a constant crack depth a/t, the reliability index is strongly affected by a/c ratio and the trend is not similar in deep and surface point for different crack shapes.
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    Impact of integrating DERs and ESS on Smart-Grid supply continuity : a review
    (IEEE, 2022) Kaddour, Djillali; Belaidi, Hadjira
    Smart-grid power distribution system's ideal objective is to provide a continuous power supply. The voltage waveform, Frequency also amplitude must meet their expected values in all respects, defining the power supply's quality. Electric distribution system continuity is essential for utilities as well as consumers. Progress in the economy, public health, and general well-being are all affected by the continuity and reliability of the power-grid distribution system. When the power supply goes down, The term "interruption of supply" or simply "interruption" is used to describe this. From the client's point of view, less frequent and briefer interruptions improve supply quality and continuity. By integrating distributed energy resources (DERs) and energy storage systems (ESS) into the power grid, reliability and continuity of power supply in the Smart-grid distribution system will increase. It is necessary to use continuity indicators, also known as "continuity indices" or "reliability indices", to quantify the continuity of the power supply. The main indices used in most countries are the SAIDI, SAIFI, and CAIDI. These indices are specified in IEEE Std. 1366. In this work, various studies are discussed and some researches on supply continuity in smart grids and the effects of integrating DERs and ESS on the reliability and continuity of power supply based on continuity indicators (SAIFI, SAIDI and CAIDI) are reviewed. Case studies on African countries is also included to demonstrate the usefulness and significance of continuity indicators to evaluate the grid distribution system's continuity
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    Guest editorial : reliability and quality : analysis and applications
    (Emerald Group Holdings, 2022) Bhargava, Cherry; Sharma, Pardeep Kumar; Patil, Rajkumar Bhimgonda; Mellal, Mohamed Arezki
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    Reliability, availability, maintainability, and dependability analysis of Tube-wells Integrated with Underground Pipelines in agricultural fields for irrigation
    (2022) Kumar, Ashish; Saini, Monika; Rajkumar Bhimgonda, Patil; Sameer, Al-Dahidi; Mellal, Mohamed Arezki
    Reliability, Availability, Maintainability, and Dependability (RAMD) study of Tube-wells Integrated with Underground Pipelines (TIUP) is crucial as they are the backbone of the irrigation system. This study is carried out with an objective to perform RAMD analysis, and Failure Modes and Effects Analysis (FMEA) unified with the development of a novel stochastic model using Markovian approach to estimate the Steady-State Availability (SSA) of the TIUP. A real case study of a conventional TIUP system has been performed to validate theoretical and practical results of the proposed model. The failure and repair rates of all subsystems followed exponential distribution, and their impact on system/subsystem’s availability and other reliability measures has been investigated. All the repairs are perfect and random variables associated with failure and repair rates are statistically independent. The centrifugal pump and power supply units are the most critical components as far as reliability and maintainability aspects. The labor also plays a critical role in the operation of the TIUP system
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    Modeling the Effect of PV Module Orientation on the Encapsulant Browning Degradation Rate in Algeria Region
    (IEEE, 2022) Bouguerra, Sara; Agroui, Kamel; Kaaya, Ismail; Bouraiou, Ahmed; Yaiche, Mohamed Rédha; Mansour, Djamel Eddine
    The encapsulant browning degradation mode of photovoltaic (PV) modules is affected by ultraviolet irradiance, ambient temperature, and humidity of the installation site. In this article, the degradation rate for encapsulant browning, measured by short-circuit current degradation, is estimated for different PV module tilt and orientation angles in the Algiers region, characterized by a temperate climate. The activation energy for encapsulant browning is calculated using the acceleration factor modeling of the field-to-field degradation and physical models, in conjunction with the meteorological data of two locations in Algeria, where the same module type is fielded for 9–10 years. The tradeoff between the PV energy production and the PV module lifetime is carried out for different PV module positioning, assuming that encapsulant browning is the main failure mechanism experienced in the field. The results reveal that the orientation angle affects the PV module lifetime, where orienting the PV module from east to west increases the lifetime up to 30%, and the lifetime energy production up to 6%, due to reduced degradation. It is also presumed that although the Saharan region of Adrar receives more UV light and ambient temperatures throughout the year in Algeria, the PV modules fielded in the Mediterranean region of Algiers suffer higher degradation, which is explained by the high humidity experienced in Algiers that accelerates the encapsulant browning failure mechanism.
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    Reliability, maintainability, and availability analysis of a computerized numerical control machine tool using Markov chains
    (Budapest Tech Polytechnical Institution, 2021) Patil, Rajkumar Bhimgonda; Mellal, Mohamed Arezki; Bewoor, Anand K.; Al-Dahidi, Sameer
    eliability, maintainability, and availability analysis of Computerized Numerical Control Machine Tools (CNCMT) is vital as they are widely used in manufacturing industries for mass production. This paper proposes a generalized framework for Time- Between-Failure (TBF) and Time-To-Repair (TTR) data analysis, integrated with Markov chains for estimating the system’s Steady State Availability (SSA). A case study of a typical CNCMT illustrates the applicability and the effectiveness of the proposed framework. The effect of variation of sub-systems' failure and repair rates on the availability of the CNCMT is studied. The critical sub-systems from reliability, maintainability, and availability point of view are identified. The analysis reveals that the CNCMT’s failure and repair rates are nearly constant and the CNCMT fails four times per year. The Lubrication Sub-system (LS) is the utmost severe sub-system as far as maintainability aspect is concerned and Turret Sub-system (TS) is the utmost severe sub-system from a reliability perspective
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    Contribution to The Reliability Study of Photovoltaic Systems Using Static and Dynamic Analysis Methods
    (Inderscience, 2019) Mahdi, Ismahan; Nadji, Bouchra; Simeu-Abazi, Zineb
    The study of reliability has not been received great attention from researchers, an estimation of a lifetime and why not improve enhance is still possible. For that, it is necessary to distinguish the different failure modes, their causes and their effects on solar modules, in our case composed by Silicon, the most spread technology and the most used in the production of electricity. In this article, we will present a contribution to the reliability study of photovoltaic systems. First, the study will be focused on the static analysis of our system by using: structured analysis and design technique and function analysis system technique methods, which make it possible to carry out a functional analysis of our system. Next, our study will be based on the dynamic analysis by using: failure mode, effects, and criticality analysis, fault tree analysis and finally stochastic Petri nets methods. These allow making a dysfunctional analysis of the system by introducing the ‘time’ which is a very important factor in our study
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    Lifetime estimation and reliability of PV inverter with Multi-Timescale thermal stress analysis
    (IEEE, 2019) Bouguerra, Sara; Agroui, Kamel; Gassab, Oussama; Sangwongwanich, Ariya; Blaabjerg, Frede
    The reliability of the PV inverter is a critical issue because it is the less reliable component of the PV system. In order to lower the risks of failure and maintenance in PV systems, the factors that influence the PV inverter lifetime should be analyzed. Thermal stress is the main causes of IGBT failure in a PV inverter, which includes the fast cycling stress due to loss variations in an IGBT, and slow cycling due to mission profile fluctuations. In this paper, the design for reliability (DFR) approach based on mission profile analysis is used and demonstrated on a single phase, single stage, grid connected PV inverter installed in Algeria, where the lifetime is estimated by taking the effect of low frequency thermal cycling under long-term operation into consideration, in addition to the line frequency power cycling due to loss variations. The results reveal that low frequency thermal cycling have a significant impact on lifetime degradation and reliability of the PV inverter after many years of operation
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    The Impact of PV Panel Positioning and Degradation on the PV Inverter Lifetime and Reliability
    (IEEE, 2020) Bouguerra, Sara; Yaïche, Redha mohamed; Gassab, Oussama; Sangwongwanich, Ariya
    The PV inverter lifetime is affected by mission profiles, which include the solar irradiance and ambient temperature of the installation site. In previous research, the design for reliability approach has been used to evaluate the reliability of the PV inverter, where the solar irradiances have been measured on a fixed tilt and orientation angle. In most cases, the tilt is chosen to be the latitude angle and the orientation is facing south for maximum energy production throughout the year. However, the impact of the tilt and orientation of the PV array on the inverter lifetime has not been considered so far. The tradeoff between the PV energy yield and the inverter lifetime can be analysed for different PV array positioning. This paper thus evaluates the lifetime of the PV inverter with varying the tilt and orientation angle of PV panels, where the PV panel degradation rate is also taken into account. The evaluation is based on the mission profiles of Algiers, Algeria. The results reveal that orientation has a strong impact on the PV inverter loading and certain orientations result in high PV energy production and long lifetime of the PV inverter. It is also shown that the PV panel aging in Algeria has a significant impact on the lifetime estimation of the PV inverter for different orientations.
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    Power transformer differential relay reliability assessment using false trip root cause analysis
    (IEEE, 2020) Zitouni, Abdelkader
    Power transformer is vital element in power grid. Its failure may affect on the continuity of supply of electrical energy to the consumers. A differential relay, which is generally used for protecting this power transformer, may be affected by the disturbances such as inrush current, current transformer saturation and over-excitation due to external faults. Accordingly, false trips (mal-operation) of protection system may be resulted in. This research work proposes root cause analysis based on fault tree analysis to be used for assessing disturbances that lead to false trips. When the critical root causes are identified, mitigation measures are used. The model of security can help to quantify analytically the reliability of the considered protection system