Jean-François Dulhoste

Real-time leak isolation based on state estimation in a plastic pipeline

A Leak Detection and Isolation (LDI) algorithm based on a State Estimation Observer is designed and tested in real-time to locate a water-leak on a plastic pipeline prototype. In order to tackle the problem of friction variations in such a pipeline, the explicit so-called Swamee-Jain equation is implanted for the friction, instead of a constant parameter as in other studies. The observer is then designed as an Extended Kalman filter on the basis of a discretized model both in time and in space. The space discretization is nonuniform depending on the unknown leak location, and the time variable is discretized with the Heuns method. The approach assumes only flow and pressure sensors at the ends of the duct, and experimental results with data obtained from the pipeline prototype are presented to assess the method efficiency.

About friction modeling for observer-based leak estimation in pipelines

A study of the friction model for the leak detection with a nonlinear observer is presented. Classically the friction model in leak detection algorithms only relies on a constant parameter. In the present work, the use of a more elaborate friction model is considered, with a coefficient explicitly depending on the flow, either algebraically, or even differentially. Those friction formulations are implemented within a nonlinear-observer-based algorithm for detection and location of leaks, which is analyzed, and tested with real measurements on some experimental pipeline prototype. Some conclusions and recommendations about this extended friction modeling are finally given.

Finite-Difference Modeling Improvement for Fault Detection in Pipelines

This paper comes in continuation of former studies on finite-difference modeling for pipelines dynamics with a purpose of model-based fault detection. The finite-difference model is here revisited, and enhanced with extremal instrumentation modeling. It is then emphasized how such a model can indeed be useful for fault detection, in particular including instrumentation faults in addition to leaks for instance.

Leak detection and location based on improved pipe model and nonlinear observer

This paper proposes a new contribution to observer-based approaches for detection and location of leaks in pipelines. In previous studies for such approaches, the observer is most of the time designed for a model obtained from hydraulic dynamical equations and finite difference techniques, using pressures at both ends of the pipe as boundary conditions; in the present work, the finite difference model is modified by using other boundary conditions, which are the pressure in the inlet pump and the pressure at the end of the pipe system. This modification provides a better representation of the pipeline dynamics, as illustrated by comparing the behavior simulated in this way with real data. It is then emphasized that this improved model may be used for an observer-based direct estimation of a possible leak flow in the pipe - together with its position, only using two measured variables (instead of four in former studies): one pressure at one end of the pipe, and one flow at the other pipe side. The other two variables, to be known by the observer - related to the boundary conditions, can indeed be taken here as constant values, since they correspond to the inlet pump pressure and the atmospheric pressure respectively. Results obtained with an Extended Kalman observer designed on this basis are finally presented, both in simulation and with real data.

A decentralized optimal LQ state observer based on an augmented Lagrangian approach

Abstract This paper is devoted to the design of a decentralized optimal batch LQ state observer for state estimation of large-scale interconnected systems, well suited for implementation on a sensor network. The here-proposed approach relies on both the use of an augmented Lagrangian formulation and a price-decomposition–coordination algorithm. The state estimation of an open-channel hydraulic system illustrates the effectiveness of this approach and is used to provide a comparison with alternative methods.

Pipeline partial blockage modeling and identification

Abstract This paper proposes an extension of former finite-difference-based models for pipelines dynamics to a case including possible partial blockages in the pipe. Model equations are first established, and a simple application to the detection – and location – of such faults is then presented via an identification-like procedure. Simulation results finally illustrate the proposed methodology.

Comparacion de controladores de nivel para canales abiertos basados en un modelo por colocacion

This paper proposed a comparative study between different nonlinear control techniques for level regulation in an open channel. Flow dynamics in a canal can be modeled by Saint-Venant equations. In this paper three control laws derived from a collocation model are presented. These laws are: input output linearization, dynamic input output linearization, and backstepping. A one-dimensional simulator that solves Saint-Venant’s equations was implemented, allowing to study the controlled system. The results showed that the dynamic input output linearization control technique was the best among the studied control techniques, and that these techniques are reliable in the cases studied.