Publications Scientifiques

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Author: search.filters.author.Bouguerra, Sara

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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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    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 array inclination on the PV inverter reliability and lifetime
    (IEEE, 2020) Bouguerra, Sara; Agroui, Kamel; Yaiche, Mohamed Rédha; Sangwongwanich, Ariya; Blaabjerg, Frede
    The PV inverter lifetime is affected by mission profiles, which include the solar irradiance and ambient temperature of the installation site. In many investigations, the design for reliability approach (DFR) is used to evaluate the reliability of the PV inverter, where the solar irradiances are measured on a certain tilt and orientation angle. In most cases, the tilt is chosen to be the latitude angle of the location or slightly less. However, the latitude angle is not always the best choice in terms of energy and inverter degradation. This paper evaluates the lifetime of the PV inverter for different tilt angles of PV panels. The evaluation is based on the mission profiles of Algiers, Algeria, and the impact of tilt angle on the energy production and reliability of the PV inverter is investigated using mission profile based lifetime estimation
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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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    Efficient analytical model for the transfer impedance and admittance of Noncoaxial/Twinax Braided–Shielded cables
    (2020) Gassab, Oussama; Bouguerra, Sara; Zhou, Liang; Yin, Wen-Yan
    An efficient analytical model for the transfer impedance and admittance of a noncoaxial/twinax braided–shielded cable with apertures on its sheath is proposed by generalizing the old Vance's and Kley's formulas, and it is derived using the complex analyses with an appropriate conformal mapping. Therefore, such a noncoaxial cable is converted into a coaxial one which can be studied using the traditional multiconductor transmission line method. It is shown that the aperture inductance is related to the position of the inner conductor and the radial position of each aperture on its sheath. In addition, the modal domain analysis is performed to obtain the common-mode (CM) and differential-mode (DM) transfer impedance/admittance of the twinax braided–shielded cable, with CM and DM currents inside the inner conductors examined. The proposed model is validated by comparing the results with that obtained by the method of moments (MoM)-based commercial software FEKO. It is found that the uniform distribution of the apertures on the sheath reduces the induced DM current significantly
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    Efficient electronic beam steering method in time modulated linear arrays
    (IET, 2020) Gassab, Oussama; Dahimene, Abdelhakim; Bouguerra, Sara
    An efficient electronic beam steering technique in time modulated linear array (TMLA) is proposed, where the first positive and negative sidebands are utilised to implement the electronic steering process. In this technique, new periodic time sequences are used, in which a positive-ON, negative-ON, and OFF durations are utilised to obtain high sufficient steering in TMLA. Furthermore, it is shown that by using these time sequences, the non-steerable array pattern at the fundamental frequency and also the even sidebands can be eliminated and nulled to zero. In addition, the radiation power and the directivity of this proposed steered-TMLA are formulated in their closed form. The genetic algorithm is implemented to optimise the steered-TMLA by suppressing the remaining odd sidebands and increasing the power radiation at the first positive and negative sidebands. © The Institution of Engineering and Technology 2020
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    Reliability Analysis and Energy Yield of String-Inverter Considering Monofacial and Bifacial Photovoltaic Panels
    (IEEE, 2020) Bouguerra, Sara; Yaiche, M.R.; Sangwongwanich, A.; Blaabjerg, F.; Liivik, E.
    Bifacial PV panels are emerging technologies that can increase the energy yield of the footprint in PV systems and thereby potentially reduce the cost of energy compared to the conventional monofacial PV panels. However, the increased energy yield due to the capability of harvesting the solar energy from both front and rare surfaces of the panel can potentially increase the loading of the inverters used in the system for doing grid connection, and as a consequence affect the inverter reliability performance. This paper thus provides a comparison between monofacial and bifacial PV modules in terms of reliability of the PV inverter and energy yield of the overall system. The analysis is carried out with a mission profile from Algiers, Algeria, where different Albedo and PV module installation heights are considered. The results show that both aspects can affect the lifetime of the PV inverter considerably, and they should be taken into consideration during the design of PV inverter.
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    Stochastic Analysis of Multitwisted Cables With Random Parameters Excited by Random Plane-Wave Fields
    (IEEE, 2020) Gassab, Oussama; Bouguerra, Sara; Zhou, Liang; Zhao, Zhen-Guo; Yin, Wen-Yan
    A generalized multiconductor transmission line (MTL) model is integrated with the polynomial chaos stochastic Galerkin method (PC-SGM) in order to predict the stochastic response of a nonuniform multitwisted bundle of twisted-wire pairs (MTB-TWP) with random parameters, which is excited by random plane waves. The twist pitches of such nonuniform MTB-TWP are considered to be spatial stochastic functions, where its parametric equations are derived in their general form. Moreover, by taking the geometry deformation of the MTB-TWP cable into account, some of its parameters are represented by random variables, and the incident plane-wave fields can also be changed in some ran- dom ways. After that, the PC-SGM is applied to the stochastic telegrapher’s equations in order to obtain deterministic ones that can be solved by using the MTL model. Therefore, the effects of the uncertainties of the parameters on the common mode and the differential mode currents are investigated in details, where, in each case, the probability density function is given. The results are validated in comparison with Monte Carlo (MC) method, where a very good agreement is obtained. It is shown that the PC-SGM simulation time is much smaller than that of the MC method as the number of random variables is relatively small.