Development of a new methodology to obtain the characteristic pump curves that minimize the total cost at pumping stations

In this paper, a new methodology to obtain the optimal characteristic and efficiency curves (Q–H and Q–η) at pumping stations is presented. The design flow, the design pressure head, and the discharge distribution throughout the irrigation season are the three main parameters to design pumping stations. The purpose of this study is to develop a decision support tool to obtain the theoretical characteristic and efficiency curves of the pumps, the number of pumps, and the number of frequency speed drives that minimize the total cost (investment and operation costs) for a specific pumping station demand (design flow, pressure head, and frequency of the discharges). The results obtained in this paper make evident that the optimal shape (slope) of the Q–H curve varies depending on the discharge distribution throughout the irrigation season, mainly when there are few pumps installed at the pumping station. When there is a high frequency of low discharges, the desired slope of the Q–H curve is higher. In cases when the discharge distribution is unknown, increasing the number of pumps ensures high energy efficiency. When installing a pump with an optimal characteristic curve, it is not necessary to increase the number of frequency speed drives.