Central Flow Control in Sewer Networks

Abstract

Control methods are applied to sewer network flow in the aim of reducing pollution of receiving waters. A multilayer control structure consisting of an adaptation, an optimization, and a direct control layer may be used for the solution of the complex control problem. Several approaches have been proposed with regard to the optimization layer. This paper focuses on the comparison of two methods, the nonlinear optimal control and the multivariable feedback control. For the numerical solution of the nonlinear optimal control problem a feasible direction algorithm is used, and for the design of the linear multivariable feedback regulator a linear-quadratic approach is applied. A detailed study of the central control problem for a particular sewer network is presented using these two methods and comparing their respective efficiency. Results indicate a slight superiority in terms of efficiency of the nonlinear optimal control approach for the price of an increased, but real-time, feasible computational effort.