Uniform pressure control in water distribution networks including location of control points

Abstract

It is recommended, in Japan, to keep the water head (pressure) within the range from 20m (2atm.) to 40m (4atm.) at any point in water distribution networks. If the pressure becomes lower than 20m, the water does not come out smoothly at end terminals (demand nodes), while if it goes up above 40m, leakage and waste of the water increase and, moreover, possibility of pipe break also increases.

In order to keep such a water head condition, under given levels of the water in reservoirs and consumptions at all demand nodes, we have to apply a control to the network by means of pumps and valves. This is simply called a uniform pressure control.

This paper investigates a control scheme including location of the pumps and valves. The problem is formulated into a nonlinear programming problem, and for its solution, two algorithms are constructed. The first one, the basic algorithm, adopts the idea of reducing the solution procedure to that of a chain of linear programs. The second one, a revised version, is equipped with some modifications to overcome a computational difficulty due to nondifferentiability of a function, and it succeeds for getting a nice convergence ability. Due to the linearization, the solution procedure is endowed with an excellent applicability to large-scale networks, as is shown in some examples of practical size.