Application of Variable- speed Pumps in Design and Operation of on- Demand Irrigation Systems

In more irrigation systems in our country، pumping stations equipped with fixed speed pump are implemented. These pumps in addition to waste water، consume excessive energy. Providing a method for adjusting the pumps functioning with obligations of operation can improve efficiency of water distribution and also productivity of energy. One of the choice toward this aim، is employing the variable speed pumps which consistent themselves with variable demand of system. In this study، by coding in MATLAB software، design of pumping stations equipped with variable- speed pumps was done for a drip irrigation system. Then regarding to variable demand of discharge and pressure during irrigation season، the designed system was evaluated and compared with some ordinary operation methods based on constant speed pumps. The results show that the utility of variable- speed pumps to supply the pressure head and discharge is definitely acceptable; while the water losses in ordinary pumping stations، depending on the type of station، is 16 to 36 percent.