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Yacef R.,Jijel University | Mellit A.,Jijel University | Belaid S.,Unite de Recherche Appliquee en Energies Renouvelables | Sen Z.,Technical University of Istanbul
Energy Conversion and Management | Year: 2014

In this paper, combined empirical models and a Bayesian neural network (BNN) model have been developed to estimate daily global solar radiation (GSR) on a horizontal surface in Ghardaïa, Algeria. An experimental database of daily GSR, maximum and minimum air temperatures of the year 2006 has been used to estimate the coefficients of the empirical models, as well as to train the BNN model. Six months of the year 2007 (summer period: May, June, July, and winter period: October, November, December) have been used to test the calibrated models, while six months of the year 2012 (from 1st February to 31th July) have been used to check generalisation capability of the developed models as well as the BNN model. Results indicate that the new calibrated models are able to estimate the global solar radiation with an excellent accuracy in this location. Calibrated models are also compared with the developed BNN model to show their effectiveness. © 2014 Elsevier Ltd. All rights reserved.

Belaid S.,Unite de Recherche Appliquee en Energies Renouvelables | Mellit A.,Jijel University
Energy Conversion and Management | Year: 2016

Prior knowledge of solar radiation in situ is very important, for better management, sizing and control of solar energy installations. In this paper, an application of a support vector machine (SVM) for the prediction of daily and monthly global solar radiation on horizontal surface in Ghardaïa (Algeria) is presented. Different combinations of measured ambient temperatures, calculated maximum sunshine duration and calculated extraterrestrial solar radiation have been considered for one-step ahead prediction (one day or one month). The obtained results showed a good agreement between measured and predicted global solar radiation data. A comparative study is conducted with the developed neural networks based model and some models published in the literature. The main advantage is that the proposed SVM based models require few simple parameters to get good accuracy. © 2016 Elsevier Ltd. All rights reserved.

Gairaa K.,Université Ibn Khaldoun | Khellaf A.,Renewable Energy Development Center Algeria | Messlem Y.,Université Ibn Khaldoun | Chellali F.,Unite de Recherche Appliquee en Energies Renouvelables
Renewable and Sustainable Energy Reviews | Year: 2016

In this paper, a new combined model coupling the linear autoregressive moving average (ARMA) model and the nonlinear artificial neural network (ANN) model has been proposed in order to estimate the daily global solar radiation. The main feature of this approach lies in the fact that has the strength to capture the advantages containing in both models. The combined method have been developed and tested using global solar radiation data recorded during two years (2012-2013) for two different climate sites in Algeria. The obtained results showed an improvement of the combined model over ARMA and ANN models in term of mean absolute error (MPE) of about 18.1% and 2.7%, for the first site, of about 27.26% and 1.39% for the second site. Moreover, compared to the ARMA and ANN models, a decrease in the RMSE values of about 17.1% and 3.59% compared to the ARMA and ANN models has been observed. © 2015 Elsevier Ltd. All rights reserved.

Yaiche M.R.,Renewable Energy Development Center Algeria | Bouhanik A.,Renewable Energy Development Center Algeria | Bekkouche S.M.A.,Unite de Recherche Appliquee en Energies Renouvelables | Malek A.,Renewable Energy Development Center Algeria | Benouaz T.,Abou Bekr Belkaid University Tlemcen
Energy Conversion and Management | Year: 2014

Solar irradiation data is generally required in modelling a system's thermal performance, and evaluation of long-term effects of climatological changes. In Algeria, measurements of solar irradiation have been carried out for a few locations because the measuring instruments are expensive to purchase and install. The only alternative to obtain solar irradiation data is to estimate it by use of an appropriate solar irradiation model. The present study attempted to draw global solar irradiation maps for Algeria, witch are generated for all types of sky. The incident solar radiation on a horizontal surface, on a surface tilted at the latitude angle and for a vertical plane facing east, south, west, south-east, south-west was determined using numerical models. To obtain a solar radiation map of a certain zone it is necessary to know the solar radiation of a huge number of sites spread wide across the zone. The comparison between the measured and the computed values is satisfactory; the relative error is less than 7%. The results allow to view information about 48 provinces of Algeria, and are presented in the form of an annual solar radiation map. The solar maps developed in this paper provide information about the levels of total solar radiation which can be used as a database for future investments in the solar sector in Algeria. © 2014 Elsevier Ltd. All rights reserved.

Chellali F.,Unite de recherche appliquee en energies renouvelables | Chellali F.,Polytechnic School of Algiers | Khellaf A.,Center de recherche et developpement des energies renouvelables | Belouchrani A.,Polytechnic School of Algiers
Renewable Energy | Year: 2010

Spectra of many meteorological data such as wind speed and temperature are time variable. Thus a Fourier analysis is not sufficient. In the present work, the wavelet transform is applied as a time-frequency analysis to the meteorological data for the region of Adrar (27.9°N, 0.3°W, 263 m), Algeria. This analysis is carried out in order to investigate the power spectra behaviors of both temperature and wind speed and their variations with time. To determine the relationship between these two meteorological parameters, the cross wavelet analysis is also applied. The study is carried out using data extending over a period of four years. The analysis is applied over a frequency range from 0.002 to 0.5 cycles per day. The results show that significant synoptic oscillations of periods between 2 and 16 days occur mainly in the cold season in both wind and temperature time series. Those oscillations are characterized by short life durations of one to few weeks. Wavelet power spectrum has also revealed the presence of intra-seasonal oscillations of periods between 30 and 60 days. These intra-seasonal oscillations have been observed mainly in the warm seasons. This study reveals also that temperature and wind speed co-vary especially at the synoptic and the intra-seasonal frequencies. © 2009 Elsevier Ltd. All rights reserved.

Irbah A.,University of Versailles | Meftah M.,University of Versailles | Hauchecorne A.,University of Versailles | Djafer D.,Unite de Recherche Appliquee en Energies Renouvelables | And 3 more authors.
Astrophysical Journal | Year: 2014

The PICARD spacecraft was launched on 2010 June 15 with the scientific objective of studying the geometry of the Sun. It is difficult to measure solar oblateness because images are affected by optical distortion. Rolling the satellite, as done in previous space missions, determines the contribution of the telescope by assuming that the geometry of the Sun is constant during the observations. The optical response of the telescope is considered to be time-invariant during the roll operations. This is not the case for PICARD because an orbital signature is clearly observed in the solar radius computed from its images. We take this effect into account and provide the new space value of solar oblateness from PICARD images recorded in the solar continuum at 535.7 nm on 2011 July 4-5. The equator-pole radius difference is 8.4 ± 0.5 mas, which corresponds to an absolute radius difference of 6.1 km. This coincides with the mean value of all solar oblateness measurements obtained during the last two decades from the ground, balloons, and space. It is also consistent with values determined from models using helioseismology data. © 2014. The American Astronomical Society. All rights reserved.

Khelifa A.,University of Batna | Touafek K.,Unite de Recherche Appliquee en Energies Renouvelables | Ben Moussa H.,University of Batna | Tabet I.,Unite de Recherche Appliquee en Energies Renouvelables
Solar Energy | Year: 2016

A vast evolution to renewable energy resources such as solar energy is the best option for alleviating poverty in developing countries where the majority of people do not have access to modern forms of energy. Renewable energy resources, due to their inherent decentralized nature can largely contribute to resolve the energetic problems. Among these techniques and technologies for the exploitation of this solar energy, the Photovoltaic conversion is known to produce electricity; and thermal collectors that provide heating energies.The two systems are independent and different, but there are not compatible, that can be completed using a hybrid design that allows using both techniques, thermal and electrical, in the process called (PV/T). The hybrid solar photovoltaic thermal (PV/T) offers an interesting option now because the absorbed solar radiation is converted into electric energy and heat (the conversion can be done simultaneously or separately). In this paper, the mathematical model is presented; the studied system consists of a photovoltaic panel for the production of electricity, with a thermal system for water heating. It is constituted by a sheet and tube placed below the surface on which the solar cells are assembled to extract heat from the photovoltaic module, in order to cool the cells and to increasing their electric efficiency. This phenomenon is due to the unobserved part by cells. This model is based on the equations of the energy balances written for the various nodes of the system, and the coupled differential equations obtained are solved by using the finite difference method. The temperatures of the various layers of solar PV/T Collector and the coolant temperature are predicted. The objective of this work is to study theoretically and experimentally the hybrid (PV/T) Collector. The fluid flow and heat transfer in the module are studied using the ANSYS14 Software. The heat transfer phenomenon conjugate between the photovoltaic cells and the coolant is modeled using the FLUENT Software. The transfer of heat by the solar radiation is not modeled; however, the effects of radiation are taken into consideration when calculating the conditions for heat flux limit for the Collector layers. The geometric model and fluid domain for the CFD analysis is generated using ANSYS software Design Modeler, mesh geometry is carried out by ANSYS Meshing Software. © 2016.

Borni A.,Unite de Recherche Appliquee en Energies Renouvelables | Zaghba L.,Unite de Recherche Appliquee en Energies Renouvelables
Proceedings of 2014 International Renewable and Sustainable Energy Conference, IRSEC 2014 | Year: 2014

This paper presents a simulation of the operation of a chain of photovoltaic energy connected to a low voltage grid. Starting with the modeling phase of the components of the conversion system, where we modeled the photovoltaic cell (elementary of the solar panel) and the parallel converter DC-DC (Boost) that allows the variation of the value of the capacitor voltage placed to the output of the photovoltaic panel. Then we study the optimization phase with sliding mode control for tracking the maximum power point (VMPP) for extracting maximum power panel solar. In the end, we proceed with the injection of the power grid operated via the inverter, the inverter injects the electric active power operated by controlling the value of the DC bus voltage through a corrector 'IP'. Because of the random waveform of the output current of the inverter we are studied the various current controller: PI, Fuzzy and Fuzzy PI the objective is to obtain current inverter output faithfully following a prescribed reference The output current should be as sinusoidal as possible with low harmonic distortion as required by the standards of a system of network connection. © 2014 IEEE.

Djafer D.,Unite de Recherche Appliquee en Energies Renouvelables | Irbah A.,University of Versailles
Atmospheric Research | Year: 2013

The atmospheric turbidity expresses the attenuation of the solar radiation that reaches the Earth's surface under cloudless sky and describes the optical thickness of the atmosphere. We investigate the atmospheric turbidity over Ghardaïa city using two turbidity parameters, the Linke turbidity factor and the Angström turbidity coefficient. Their values and temporal variation are obtained from data recorded between 2004 and 2008 at Ghardaïa. The results show that both parameters have the same trend along the year. They reach their maximum around summer months and their minimum around winter months. The monthly average value varies between 1.3 and 5.6 for the Linke turbidity factor and between 0.02 and 0.19 for the Angström turbidity coefficient. We find that 39.8% of the Linke turbidity factor values are less than 3, 47.5% are between 3 and 5 and only 12.7% are greater than 5. For the Angström turbidity coefficient, 9.4% of the values are less than 0.02, 75.4% are between 0.02 and 0.15 and 15.2% exceed 0.15. © 2013.

Chellali F.,Unite de Recherche Appliquee en Energies Renouvelables | Chellali F.,Polytechnic School of Algiers | Khellaf A.,Center de Recherche et Developpement des Energies Renouvelables | Belouchrani A.,Polytechnic School of Algiers | Khanniche R.,Unite de Recherche Appliquee en Energies Renouvelables
Renewable and Sustainable Energy Reviews | Year: 2012

The knowledge of the probability density function of wind speed is of paramount importance in many applications such as wind energy conversion systems and bridges construction. An accurate determination of the probability distribution of wind speed allows an efficient use of wind energy, thus rendering wind energy conversion system more productive. In the present paper, the maximum entropy principle (MEP) is used to derive a family of pre-exponential distributions in order to fit wind speed distributions. Using averaged hourly wind speed of six different regions in Algeria, it has been found that the proposed pre-exponential distributions fit the wind speed distributions better than the conventional Weibull distributions in terms of root mean square error. However, it has been found also that MEP based distributions have shown some practical limitations such as the choice of pre-exponential order and interval of definition. © 2011 Elsevier Ltd. All rights reserved.

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