Fault detection for pipelines: a nonlinear observer approach

This paper considers a problem associated with the transportation of oil through a pipeline, possibly from an oil rig. A hydraulic hose, known as a sub-sea umbilical, is used to open or close a valve which controls the oil flow in a larger pipeline. A linear state-space model is described, including model terms for the faults. A general linear unknown input observer is then proposed and an example is given for the rig-system. An input-output model for the lamina case is then derived which facilitates identification of three important parameters. Finally, a nonlinear model for the nonlaminar flow case is proposed which includes certain quadratic nonlinearities. Fault modelling is also included.