Selection and Operation of Pumping Stations of Water Distribution Systems

摘要

The energy cost is one of the most important cost components in the water supply systems. Since large amounts of electricity are required to pump, transport and apply water, the profitability of some business, as irrigation districts or fishfarms, which use the water as production resource, is heavily dependent upon energy costs. Methodologies that can maximize energy cost savings while satisfying system performance criteria should be sought for the design and management of the water distribution systems. Some of these methods can be: (a) to improve the selection and/or operation of pumping stations; and (b) to include a regulating reservoir between the water supply source and the delivery system. The alternative (a), related with the optimal designof pumping stations, refers to the selection of pump type, capacity and number of pump groups that results in minimum design and operating costs for a given water demand. With the alternative (b), if time-of-day energy tariff is available, the reservoircan be used for storing water that is pumped during off-peak hours to be used during peak hours. Also, the inclusion of reservoirs allows an equalization of pumping schemes that is not possible by pumping directly into the water delivery system. This allows pumping stations to operate near optimum energy efficiency. In this chapter, one model that includes both alternatives was presented. To implement this optimization process, two algorithms were developed: (a) Algorithm for selection of least cost oroptimum pump combinations in water supply systems and to evaluate the system's energy costs; and (b) Algorithm to determine the reservoir storage capacity that permits water to be pumped when energy tariffs are lowest and establish an annual pumping schedule in accordance with time-of-use energy tariffs. This model was applied to the water distribution systems of one irrigation district and one fishfarm located in southern Spain. The analysis indicated that the optimal selection of pump groups and/or the addition of a regulating reservoir was/were energy cost effective.