Direct Grid Connection of a Prototype with Real-Time Control for Energy Recovery and Pressure Control in a Water Distribution Network through Hydraulic Regulation

Abstract

Although pressure regulation valves (PRVs) are commonly used for reducing leakage in water distribution networks (WDNs), in recent years, many studies have highlighted the opportunity of using pumps as turbines (PATs) so as to couple pressure reduction (and thus leakage reduction) with hydropower generation. Unlike in water transmission systems however, flow discharge in a WDN varies continuously, consequently requiring real-time control (RTC) of pressure. Nevertheless, RTC of a PAT in a WDN remains an open issue, due to the lack of information and knowledge about PAT operation in a real environment. Whereas previous experimental studies have described PAT installation with a frequency converter in which the power produced gets dissipated through electrical resistance, in the hydraulic regulation layout, impeller speed depends on the electrical grid. Consequently, this paper proposes a comprehensive algorithm to both control the pressure at the control node of a WDN and produce power through a PAT directly connected to the electrical grid. The operation of the prototype was considered under hydraulic regulation, demonstrated by several studies to represent the most effective trade-off between costs and benefits. Further testing by means of laboratory experiments designed to simulate the operation of a grid-connected PAT installed in a WDN effectively validated the robustness of the proposed method. The results proved the ability of the prototype and algorithm to couple hydropower generation with pressure control even when the flow varied suddenly.