Real-time control of a PRV in water distribution networks for pressure regulation: Theoretical framework and laboratory experiments

Pressure-reducing valves (PRVs) are often used in water distribution networks (WDNs) to regulate pressure for leakage reduction. Optimal management would require the pressure to be constant and as low as possible at the WDN critical node. Such operating conditions can be achieved by means of real-time control (RTC) of the PRVs. Because the pressure RTC of PRVs in WDNs is still an uncommon application, this paper first provides the theoretical framework of control systems and also discusses the benefits of a feedback control over a feedforward scheme. A closed-loop controller was developed, allowing RTC of pressure at the critical node in a WDN by changing the pressure set point in the PRV at the network inlet. To this end, a diaphragm-actuated control valve coupled to an actuator for remote control of the pilot spring was used. Laboratory experiments were carried out to characterize PRV operation and effectiveness of the algorithms. A simplified model of the PRV and numerical simulations to reproduce the pressure transient were also developed. Results show that (1)the algorithm is able to control pressure also in case of abrupt variations of the set point pressure and finite delays; and (2)the numerical model is in good agreement with relevant experiments.