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.