22-10-2014, 12:11 PM
Abstracts: The performance of a solar water pumping system is discussed in this paper; the system consists of a photovoltaic (PV) array, a permanent magnet (PM) DC motor and a helical rotor pump. The operation of the PV array is analyzed using PSPICE. The efficiency of the system is improved with a maximum power point tracker (MPPT) and a sun-tracker. Simulation and field test results are This paper suggests how an optimal operation of a photovoltaic pumping system based on an induction motor driving a centrifugal pump can be realized. The optimization problem consists in maximizing the daily pumped water quantity via the optimization of the motor efficiency for every operation point, which has led to an optimum ‘ v-f ’ relationship useful in controlling the motor. This is reached via the control of a natural PWM VS inverter feeding the motor. The effectiveness of the proposed algorithm is described by simulation and the obtained results are compared to those of a system working with a constant air gap flux. The obtained results allow the improvement of the daily pumped water quantity and the pump efficiency. In addition, the influence of changing array temperature is also discussed. Two basic thermodynamic conversion techniques of solar water pumping are recognized. In the first technique, a high internal energy fluid heated in a solar collector is used to power a conventional heat engine which drives a conventional pump. The second technique involves specially designed solar pumps, for example the Bold, Rae and Michaels designs. The study reveals that an engine working on the organic Ranking cycle and having an output of a few kilowatts (maximum 20KW) would be most suitable for pumping purposes. It is also concluded that a pumping rate of 2-3 cubic meters per hour is obtainable for every square meter of the flat plate collector area in an engine employing Freon-11 as the working fluid.