Optimal Control of Large-Scale Combined Sewer Systems

Abstract

Optimal control methods are applied to combined sewer systems in order to reduce pollution of receiving waters through maximum utilization of existing storage capacity. Because of the high dimension and complexity of the control problem, a multilayer methodology is proposed leading to a horizontal and vertical decentralization of the overall control structure. A constrained discrete dynamical optimal control problem for a simplified sewer network is solved on-line in the optimization layer using variational calculus and gradient techniques. Optimal state and control trajectories are used as reference trajectories for the local control of small subnetworks. Prediction of runoff-trajectories are provided by a supremal adaptation layer. Efficacy of the control system is demonstrated by application to the combined sewer system of the city of Munich.