A method for scheduling of multi-source, multi-reservoir water supply systems containing only fixed speed pumps

Consideration is given to the problem of evaluating overall optimized control schedules for multi-source, multi-reservoir (MSMR) water supply schemes. The system sources supply consumers and storage reservoirs via highly interactive and nonlinear networks of pipes and valves. For these systems the major operating costs are due to electricity charges for pumped source operations. The pump stations contain only fixed speed pumps so that the pump control is purely discrete. A new method for solving the problem is proposed. This constitutes a natural extension of an algorithm, developed by Brdys (1988), for single-source, single-reservoir systems (SSSR). The extension, to cover MSMR systems, is based on Lagrangian relaxation of the hydraulic constraints which couple the pump stations to the network. The method has been applied to a practical MSMR system, containing two sources and two storage reservoirs, and the paper concludes with a presentation and discussion of the results