Stability and Robustness of Real-Time Pressure Control in Water Distribution Systems

This paper deals with the fundamental requirement of stability of real-time control algorithms for water distribution systems. Loss of stability may in fact generate strong pressure waves that cause damages to the structure and increase leakage and maintenance costs. In addition, since the system under control is characterized by complex, nonlinear dynamic behavior, it is very important to guarantee that stability is preserved even when the water distribution system is working very far from its nominal working point. The aim of this work is therefore to apply tools and methodologies of control system theory to analyze both nominal and robust stability of real-time control algorithms in a case study framework. This allows quantitative understanding of the cause of possible instability of the control scheme and suggests how to prevent it. Finally, this work proposes a possible way to improve the design of the control algorithms under investigation, to reduce the risk of instability events, and, at the same time, reduce the cost of control.