Automatic Control Strategies for Combined Sewer Systems

Abstract

Automatic 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 control structure is developed taking into account practical requirements like moderate computational effort and real‐time evaluation. A constrained discrete dynamical optimal control problem for a simplified form of the overall network is solved online in an optimization layer using the discrete maximum principle and gradient techniques. Resulting optimal state and control trajectories are used as reference trajectories for the decentralized 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 a practical problem.