Optimisation of Pump and Valve Schedules in Complex Large-scale Water Distribution Systems Using GAMS Modelling Language

Abstract

This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN). An optimisation model is automatically generated in GAMS language from a hydraulic model in EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduc- tion algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model. The proposed approached was tested on a large-scale WDN model provided in EPANET format. The considered WDN included complex structures and interactions between pump stations. Solving of several scenarios considering different horizons, time steps, operational constraints and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for variety of requirements.