The paper discusses the detectability and the location problem of simultaneous leaks in a pipeline when only pressure and flow rate are measured at the extremes of the line. Despite the strong detectability property of the leaks, it is shown that the distinguishability problem is not feasible for simultaneous leaks with the residual evaluation in steady state. This fact can be explained because each leak introduces two unknown parameters in the fluid model, and there not exist a unique solution for the set of relationships involving the unknown parameters and the measurement at the extremes of the line; even if the flow in steady state between the two leaks is known. Then, any fault detection and identification method, based on steady state conditions of the flow rate loss at the extremes when two leaks appear simultaneously in a pipeline, diagnoses incorrect results. To characterize the subset of indistinguishable leaks a new parameter zeq is defined in this contribution which corresponds with the leak position value obtained if one leak is assumed. This novel parameter zeq allows to reformulate the FDI problem in such a way that the leaks transient response complements the information of the system behavior to fix the four unknown parameters. Since reduced order models are not appropriated to describe precise transient behavior, from the analysis introduced here remains as open problem, the generation of suitable models to tackle the isolation task for two leaks.
Multi-leaks location problem in a fluid pipeline
Das Problem der Lokalisation von Mehrfachlecks in Rohrfernleitungen für Flüssigkeiten
2003
6 Seiten, 5 Bilder, 1 Tabelle, 9 Quellen
Conference paper
English
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