Rolling-horizon optimal control of sewer networks

The problem considered addresses the optimal wastewater distribution to several retention reservoirs in an urban sewer network during rainfall in the aim of protecting the quality of waters that receive the network outflows. The main task of the corresponding control system is the minimization of overflows during rainfall events. The proposed solution of this complex control problem employs nonlinear constrained optimal control concepts while the rolling horizon method is used for the real-time application of the optimal control algorithm with updated inflow predictions and updated initial conditions. A detailed study of the control problem for a particular large-scale real combined sewer network using this method is presented on the basis of a realistic simulation model. Results demonstrate the efficiency of the developed methodology as well as its low sensitivity with regard to modeling and prediction errors.