Optimizing Energy Costs and Water Whithdrawal in a Prototype Water Supply System

Water requirements in many large water supply systems are provided by mixing water withdrawal from surface and underground resources with different quantity and quality.Water supply from underground sources requires energy consumption and surface water resources are limited and unstable.The aim of this research is managing optimal supply of required water of system with minimum energy cost and minimum water withdrawal from surface sources, meanwhile maintaining quantitative and qualitative stability of the system.This goal is achieved by optimizing operation schedule of pumps by managing energy consumption and optimizing changes in harvest discharge and mixing ratio of water sources.Differences between this study and similar studies, is the definition of multiple objectives, adding constraints like water quality in stability of the system, and assumption of harvest discharge and mixing ratio of water sources as variable.By considering continuity and energy rules and features of the system, system hydraulic is modeled mathematically and then by simulation in Vensim software with mathematical model assistance, model validation based on comparison with the actual data has evaluated.A multi-objective optimization is solved by using GAMS software.Finally, based on the goals of system administrators, sensitivity analysis on input data and results performed ,and optimal scenarios for managing the water supply system are presented.According to research findings,optimizing the water supply system can lead to 21% reduction in peak load consumption and 5% in energy costs .By considering just pumping stations, we save 37% in peak load consumption and 13% in energy costs.