[Design,and,Description,of,a,Photovoltaic,Pumping,System:,Application,in,the,Site,of,Adrar] both of a and b

　　Ahmed Mehdaoui1, Amar Hadj Arab2 and Djaafar Semmar3 　　1. Research Unit for Renewable Energies in the Saharan Medium, Photovoltaic Conversion Department, Route de Reggane, Adrar 01000, Algeria
　　2. Development Center for Renewable Energies, Department of Photovoltaic Solar Energy, Route de l’observatoire, Bouzaréah, Algiers 16340, Algeria
　　3. Department of Mechanial Engineering, Saad Dahlab University, Route de Soumaa, Blida 09000, Algeria
　　Received: February 15, 2011 / Accepted: June 14, 2011 / Published: February 20, 2012.
　　Abstract: The Saharan areas and in particular the isolated sites are characterized by low levels of population, in dispersed cores, which suffer from serious problems of water supply for consumption and the irrigation. The photovoltaic pumping systems (PV) are an ideal solution for these problems. Despite the presence of several photovoltaic pumping systems (PVPS) projects, data acquisition system is still missing in most cases. In this work, the authors will present the PVPS installed at the unit of research in renewable energies in Saharan medium (URERMS, Algeria). This system will enable us to better analyze the performances of a photovoltaic pumping system in Saharan medium. The principal elements of the chain of the photovoltaic pumping system are: a photovoltaic generator, the power conditioning system, a motor-driven pump immersed group, an electric wiring, a hydraulic infrastructure which comprises a water tank.
　　Key words: Photovoltaic pumping, dimensioning, optimization, system of irrigation, performances.
　　 1. Introduction??
　　In spite of the availability of the PVPS during the last years, it allowed a notable improvement of the living conditions in the Saharan areas. The experiment of the ground with these systems is not always entirely satisfactory, because it lacks of reliable experimental data.
　　Generally, in the photovoltaic pumping system, two configurations present themselves:
　　PVPS with batteries using the latter is to store the electricity produced by the photovoltaic modules (PV). These batteries make it possible to be freed from the risks of the sun and the problems of adaptation between the photovoltaic generator and the electric pomp. However, their use comprises more components which influence the reliability and the overall costs of the system. Moreover, they are fragile and are often the first elements which will need to be changed. They require moreover a constant maintenance and a rigorous control of their load and discharges.
　　The PVPS without batteries, more commonly called“pumping systems with the wire of the sun”, make it possible to have a photovoltaic system simpler, more reliable and less expensive than a system with batteries. Storage is done in a hydraulic way in a water tank and then distributed by gravity to the need or a system for water evacuation [1-3].
　　Taking into account the additional costs of systems PVPS with batteries and the problems of maintenance of these last, the solution with the wire of the sun is preferred at present.
　　In the unit of research in renewable energies in Saharan medium (site of Adrar), the authors carried out a photovoltaic pumping system in collaboration with the Development Center of Renewable Energies(CDER, Algiers).
　　 2. Description of the Photovoltaic Pumping System
　　The photovoltaic generator is installed in the east part of the unit. The orientation is full south. It is tilted with the latitude of the place of the site of Adrar, i.e. 27.8°, thus supporting an optimal production of the annual energy.
　　Thus the PVPS consists of photovoltaic generator and an inverter at variable frequency which converts the D.C. current produced into alternative course, thus supplying the motor-driven pump. The use of a motor-driven pump which plays a role of a frequency variator driver allows the system to work over the sun, and consequently the flow generated by the electric pomp immersed depends on the irradiance received by the PV modules.
　　Following the needs really expressed by the local users and after a study the authors proposed the following PVPS [1, 4-6]:
　　A photovoltaic generator of 2.25 kWC;
　　A power conditioning system of 3 kVA;
　　A solar electric pomp of 2 kw;
　　A water well of 16 m in depth;
　　A basin of a water storage with a capacity of 80 m3.
　　2.1 The Photovoltaic Generator
　　The power of an installed photovoltaic is 2250 WC(Fig. 1). To obtain this power, the authors use two branches of 15 standard photovoltaic modules Isofoton I-75/12 (Table 1 and Fig. 2).
　　It should be noted that in the Saharan areas, a shelter(Fig. 3) protects the well and the system from data acquisition against bad weather (sands, high temperatures, etc.) [5-8].
　　Pumped water is intended primarily for the irrigation of the unit (Fig. 4).
　　The generator of 30 photovoltaic modules consists of two parallel branches, including each one of them with 15 modules PV in series. The exit of this generator is connected to a converter DC/AC. This last is of the three-phase type supplying the electric pomp (Fig. 5)[3, 6, 9].
　　
　　Fig. 1 Sight of a part of a photovoltaic generator and basin of water storage.
　　Table 1 Electric characteristics of photovoltaic module.
　　
　　
　　Fig. 2 PV Module type Isofoton I-75/12.
　　
　　Fig. 3 A well shelter and basin of water.
　　
　　Fig. 4 System of evacuation of water destined for irrigation of the unit.
　　
　　Fig. 5 Controller and solar electric pomp.
　　The main features of the controller are: Controller PS1800 and Engine ECDRIVE 1200 C. 2.2 Controller PS1800
　　It controls the system of pumping and the indication of the operating conditions assembly on the surface (no immersed electronics). It presents two entries for gauge level water (protection against dry operation), a liquid-level switch, a pressure controller, a remote control, etc..
　　The restarting is automatic in 20 minutes after the stopping of the pomp by gauge level protection against the inversions of polarity, overloads and temperatures excessive.
　　2.3 Engine ECDRIVE 1200 C
　　The engine uses D.C. ( direct current), without brush and electronics inside the engine filled with water,
　　 3. Results and Discussions
　　The various stages for the realization of this system of photovoltaic pumping are [7-9]:
　　geotechnical study for the realization of the basin water storage of 80 m3;
　　tests of water leaks from the basin;
　　choice of the site of photovoltaic generator to avoid shade (palm trees, walls, antennas, etc.);
　　design and the realization of photovoltaic generator (carrying structure, inking, wiring, etc.);
　　design and realization of the shelter well.
　　In the same way, the principal considerations and technical specifications concerning the connection of the elements of the chain of the PVPS are:
　　choice of the tension of the branch of photovoltaic generator in adequacy with the tension of the controller;
　　installation of a system of evacuation of water of basin destined for the irrigation of the unit;
　　put at the ground.
　　 4. Conclusion
　　The realization of the various elements of the chain of the PVPS (photovoltaic generator; basin of water, well, etc.) was made under good conditions.
　　In Algeria, the priority is to develop such demonstration projects in order to familiarize the different specialist in electronic and hydraulic field, and other actors, with the concepts of PVPS provided with a system which includes a data acquisition for performances evaluation.
　　The authors can say that the advantages of this type of installation are:
　　control of transfer of energy entering the elements of the chain of the PVPS;
　　optimization of the PVPS and thus reduction of the invoice of m3 of pumped water;
　　use of clean energy and nonpolluting;
　　control of the techniques of irrigations using the systems of photovoltaic pumping the next stage consists of the realization of the system of data acquisition will allow the follow-up of the system in real-time for the evaluation of the PVPS performances.
　　 Acknowledgments
　　The authors would like to thank Mr. A. Touzi, as well as Mr. D. Draou from the URERMS-MS, Adrar. The authors also thank all the people who contributed to this study and to the realization of photovoltaic pumping system, particularly Mr. Mammeri, Mr. Yaichi.
　　 References
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