OPTIMAL PUMP SCHEDULING IN WATER-SUPPLY NETWORKS

The electricity cost of pumping accounts for a large part of the total operating cost for water-supply networks. This study presents a method based on linear programming for determining an optimal (minimum cost) schedule of pumping on a 24-br basis. Both unit and maximum demand electricity charges are considered. Account is taken of the relative efficiencies of the available pumps, the structure of the electricity tariff, the consumer-demand profile, and the hydraulic characteristics and operational constraints of the network. The use of extended-period simulation of the network operation in determining the parameters of the linearized network equations and constraints and in studying the optimized network operation is described. An application of the method to an existing network in the United Kingdom is presented, showing that considerable savings are possible. The method was found to bc robust and with low computation-time requirements, and is therefore suitable for real-time implementation.