Search

The photovoltaic solar energy becomes more and more one of the most abundant and an alternative source of electric energy. But its efficiency is very low. For this reason, several Maximum Power Point Tracking algorithms are used to track de maximum power. This paper proposes a modified Perturb and Observe (P&O) algorithm using a boost chopper. That algorithm was implemented under Matlab/Simulink/Simpowersystems/Simelectronics platform. Results obtained showed that the proposed algorithm gives better results compared to the conventional P&O algorithm. In fact, the extracted power’s ripple factor using the conventional P&O method varies from 3.35 % to 5.30 %. Whereas the extracted power’s ripple factor using the 'modified P&O' varies from 1.41 % to 2.86 %.

The problem of stabilizing a boost converter in small-signal situations using linear control laws is derived by the means of oriented circuit procedure. After establishing a small-signal circuit model for the boost regulator including state-feedback, conditions for the stability of circuit are studied. Thereafter, a linear analysis is performed in order to design the desired dynamics and robust behavior of the boost converter. The linear analysis assumed shows that only a state feedback gain matrix is necessary, provided that the coordinates of the equilibrium point are known. This operation is done by using the root locus methodto choose the eigenvalue of this gain vector. It aims at presenting how boost converter averaged behavior can be tailored by means of feedback control structures. Various control structures with different design methods have become classical in control systems theory with a similar degree of efficiency. It is generally assumed that the obtained control input is applied to boost converter by using pulse-width modulation. Performance of the proposed pole placement method is evaluated by Simpower/Matlab simulation at the equilibrium operating points chosen. To verify a feasibility of the proposed method, set parameters of system is implemented. The control scheme is verified through Matlab simulation, which is present to verify the performance of proposed method and simulation results validate the analytical predictions. The circuit studied is an element of the wind energy conversion system (WECS).

In this work, each components of the photovoltaic water pumping system have been modeled in the Matlab/Simulink platform using meteorological data obtained from the field for the specific month corresponding to the hottest one of the year and for different total heads or pump loads. Optimization is done using the incremental conductance MPPT techniques which help to track the maximum power available in the photovoltaic module at each time and then feed the pump with optimal power. The results of this simulations show the effectiveness of the optimized system compare to the direct-coupled one. For the considered water pumps, daily flow rates are predicted and permit to calculate monthly total volume of water which is in the range of 122 m3 to 200 m3 for the total heads in the range of 60 m to 24 m with optimization and in the range of 12 m3 to 43 m3 for the same range of total heads without optimization. This study also shows the relevance of the optimized system compare to the direct-coupled system for providing water in rural areas of soudano-sahelian zone of Cameroon.

With the decline in price of the photovoltaic’s (PVs) and the increase in greenhouse gases due to the use of fossil fuels the use of photovoltaic as a power source for water pumping is becoming the more attractive solution instead of using diesel/gasoline generators. This paper deal with the optimal sizing of the water pumping system instead of gasoline generator for the irrigation of the onion farms in Cameroon it also discusses a share of greenhouse gas emitted from the cultivation of onions. The study uses the data generated from a survey carried out between 2014 and 2015 of consumption gasoline/lubrificant and water production from generators on the duration of the culture in the main production Area ''10°35’N, 14°18’E''. The results of the analysis indicates that the Life Cycle Cost, 'LCC' of the photovoltaic water pumping system depends on its capital costs (67 % of LCC) while the LCC of gasoline pumping system depends largely on recurring costs (79 % of LCC). The CO2 emissions depend not only on the type of land but on the stage of plant growth. This research work also demonstrates that using the PV water pumping system can improve living conditions of farmers.

This paper studies the behavior of three types of photovoltaic panels operating under partial shading conditions in the three climatic regions of Cameroon. The phenomenon of partial shading constitutes one of the factors which drastically disrupt the electric power produced by the photovoltaic generators. It is to contribute to solve this problem that we modelled the PV panels operating in partial shading conditions under the climatic parameters of the study area. The analytical method combined with the iterative method are used for the determination of PV module parameters under partial shading conditions. Studies were carried out over a period of one year in three cities, respectively: Yagoua for the sudano-sahelian region, Tchollire in the sudanese region and Tibati in the southern equatorial region. Three types of PV panels were used {polycrystalline (MSX-60), monocrystalline (Shell SP70) and CIS thin film (Shell ST40)}. The electrical power losses of each type of panel were evaluated.

La situation énergétique au Nord Cameroun est caractérisée par un faible taux d’accès à l’électricité. Au vu du potentiel énergétique éolien existant sur le Mont Tinguelin, son utilisation pour le développement de l’énergie électrique de la région semble favorable. Une solution avantageuse pour le Nord Cameroun est la récupération et la transformation de l’énergie éolienne en énergie électrique. Ce travail présente à partir des données obtenues auprès de l’ASECNA et par RETScree.net en utilisant la distribution de Weibull [1], la densité de distribution du vent et exprime l’estimation statistique du potentiel énergétique éolien à des différentes altitudes sur le Mont Tinguelin à Garoua. Ensuite, la direction du vent est établie pour l’orientation des éoliennes dans le site. Enfin, l’évaluation de la prédiction de l’énergie électrique produite est faite tout en nous appuyant sur la prise en compte des choix judicieux des aérogénérateurs et de leurs facteurs de charge.

This paper presents a simple method of optimizing the photovoltaic (PV) generator based on the one diode electrical model. The method consists in solving a second degree equation representing the derivative of the power function. The maximum current and voltage are determined, and the maximum power is deduced. Two popular types of photovoltaic panels constructed with different materials have been considered for the test: the multi-crystalline silicon (Shell S75), and the mono-crystalline silicon (Shell SP70). For various environmental conditions, a comparative study is done between the simulated results and the product manufacturer data. The obtained results prove the efficiency of the proposed method.

The wind power is well adapted nowadays as solution to the production of electricity or for mechanical use. But wind is a very fluctuating source of energy; it generates a non-permanent and variable power to the loads. This paper presents a strategy to improve the quality of the electric power produced by a wind turbine under variable speed. The mathematical modeling of the various elements of the conversion system is performed. Two control strategies are developed to improve the quality of the energy produced by the wind turbine. The first consists to a judicious management of the DC bus and the second to control the inverters with a corrective proportional resonant. The results obtained after implementation and simulation under Matlab/Simulink platform are presented.

This paper presents a field study of indicators of the performance of absorption refrigerating systems in the Sudano-Sahelian region of Cameroon. A modeling of various components of the system is performed in order to choose the technology best adapted for the region. Based on the characteristics from the manufacturers, four absorption chillers were studied; namely: EAW Schüco LB 15 and 30; Rotartica Solar 045 and Sonnenklima Suninverse. The model of Kühn and Ziegler and meteorological data of the city of Maroua ((14.33 °E, 10.58 °N) were used to assess the coefficient of the performance (COP) of these machines. Results showed that the Sonnenklima Suninverse technology is best suited for the climatic conditions of the Sudano-Sahelian region with COP values between 1.5 and 3.5.

In this paper, we consider a photovoltaic silicon solar cell in which the charge carriers are moved solitary. To evaluate the number of charge carriers in the solar cell, the proposed nonlinear reaction-diffusion equation describing the phenomena of carriers transport in solar cell under the effect of band-trap impact ionization has been solved. The results from this equation are solitary solutions. The maximum efficiency of the proposed model has been evaluated for various photo-generation coefficients. The range of the external applied electric field Eo to be avoided has been carried out. The conditions to reach the peak of the maximum efficiency have been also identified. The interest of the obtained results is firstly economical since it could be useful in avoiding strong and undesirable external applied electric field on solar cells. The second interest is that they permit to identify the approximate maximum efficiency value of solar cell band-trap impact ionization working in dynamical regime.

In this study, five numerical Weibull distribution methods, namely, the maximum likelihood method, the modified maximum likelihood method (MLM), the energy pattern factor method (EPF), the graphical method (GM), and the empirical method (EM) were explored using hourly synoptic data collected from 1985 to 2013 in the district of Maroua in Cameroon. The performance analysis revealed that the MLM was the most accurate model followed by the EPF and the GM. Furthermore, the comparison between the wind speed standard deviation predicted by the proposed models and the measured data showed that the MLM has a smaller relative error of -3.33% on average compared to -11.67% on average for the EPF and -8.86% on average for the GM. As a result, the MLM was precisely recommended to estimate the scale and shape parameters for an accurate and efficient wind energy potential evaluation.

In this study, five numerical Weibull distribution methods, namely, the maximum likelihood method, the modified maximum likelihood method (MLM), the energy pattern factor method (EPF), the graphical method (GM), and the empirical method (EM) were explored using hourly synoptic data collected from 1985 to 2013 in the district of Maroua in Cameroon. The performance analysis revealed that the MLM was the most accurate model followed by the EPF and the GM. Furthermore, the comparison between the wind speed standard deviation predicted by the proposed models and the measured data showed that the MLM has a smaller relative error of -3.33% on average compared to -11.67% on average for the EPF and -8.86% on average for the GM. As a result, the MLM was precisely recommended to estimate the scale and shape parameters for an accurate and efficient wind energy potential evaluation.

Au vu des potentiels énergétiques solaires, géothermiques et éoliens existants au Tchad, leurs utilisations pour le développement économique de certaines zones semblent favorables. Dans ce papier, les caractéristiques du vent sont analysées en utilisant les données de la vitesse du vent recueillies pour chacune des trois zones agro-climatiques du Tchad et disponibles pour au moins 19 ans (19 ans pour la Zone Saharienne, 21 ans pour la Zone Sahélienne et 21 ans pour la Zone Soudanienne). La distribution de Weibull est utilisée pour modéliser la vitesse du vent à ces trois zones du Tchad. Les paramètres de forme et d’échelle ont été estimés en utilisant la méthode de densité de puissance ou facteur d’énergie. L’objectif de cet article est de comparer les potentialités énergétiques éoliennes des trois zones du Tchad. Il a été observé que les paramètres de forme et d’échelle varient considérablement au cours d’un mois. Ainsi, ces paramètres pour les trois zones sont respectivement 3.746 et 3.598 m/s en Zone Saharienne, 4.233 et 3.572 m/s en Zone Sahélienne et 3.101 et 3.008 m/s en zone Soudanienne. On remarque que les zones les plus ventées sont les zones Saharienne et Sahélienne avec une vitesse moyenne du vent de l’ordre de 3.25 m/s. L’extrapolation de la vitesse du vent et des paramètres de Weibull augmente avec l’altitude et par conséquent, la densité de puissance également.

Wind data analysis and accurate wind energy potential assessment are critical factors for suitable development of wind power application at a given location. This paper explores wind speed distribution to select the two-parameter Weibull methods that provide accurate and efficient estimation of energy output for Wind Energy Conversion Systems (WECS).The dimensionless shape parameter k and the scale parameter C are determined based on measured hourly mean wind speed data in times-series from 2007 to 2012, collected at the Garoua International Airport, main meteorological station, in Garoua, Cameroon. Six numerical methods, namely Empirical Method (EM), Energy Pattern Factor method (EPF), Graphical Method (GM), Maximum Likelihood Method (MLM), Moment Method (MM) and Modified Maximum Likelihood Method (MMLM) are examined to estimate the Weibull parameters. To analyze the efficiency of the methods and to ascertain how closely the measured data follow the Weibull methods, goodness of fit tests were performed using the chi-square test (X2), correlation coefficient (R2), root mean square error (RMSE) and Kolmogorov-Smirnov test (KOL). The results revealed that the EPF followed by the MM were the most accurate and efficient methods for determining the value of C and k to approximate wind speed distribution. The statistical tests rejected the GM as an adequate method and revealed as well that the EM, MLM and MMLM ranked respectively third, fourth and fifth. Furthermore, the potential for wind energy development in Garoua is not fitted for generating electricity and a very fruitful result would be achieved if windmills were installed for producing community water supply, livestock watering, and farm irrigation.