OPTIMAL OPERATION OF MULTIQUALITY NETWORKS .1. STEADY-STATE CONDITIONS

A model is developed for optimal operation of a multiquality water-supply system, under steady-state conditions. The system contains: sources of different qualities, treatment facilities, pipes, and pumping stations. The objective is to minimize total cost, while delivering to all consumers the required quantities, at acceptable qualities and pressures. A special approximation of the equation for water quality in pipes is used, which enables the model to select the flow directions in pipes as part of the optimization. The steady-state operation of an example system is optimized: it supplies six consumers from three sources, two of them with treatment plants, and has three pumping stations and 10 pipes. The optimization is carried out with GAMS/MINOS, which employs a projected augmented Lagrangian algorithm. The example system has been analyzed through a base run and four additional runs, aimed at studying the effects of modifications in key data. The optimal solutions of the five cases demonstrate the response to changes in economic and operational conditions.