Model-based estimation techniques for oil and gas rotating equipment

The analysis and the techniques proposed in this thesis have highlight the potential of the model-based approach in oil and gas applications. A mathematical model based on a deep knowledge of the system physics leads to the improvement of existing oil and gas plants without requiring the modification of already installed equipment. A reliable modelling of the particular subsystem under analysis unlocks the full capabilities of the available equipment. By introducing proper models focused on specic behaviour of the system it is possible to develop suitable methods which are aimed to the enhancement of the system reliability, operability and robustness. Thanks to these models it is possible to compensate and overcome system lacks or limitations without introducing expensive or overkill solutions. In particular specific models have been proposed both to estimate the power required to drive a centrifugal compressor and to estimate the steady-state response and the dynamical evolution of a specific two-shaft gas turbine. Furthermore, the mathematical modelization both of the mechanical and the electric part of a power generation plant has drawn the attention to the real features of the plant that are at the basis of torsional instability. Nowadays, in order to keep pace with the scientific and technological practices, it is clear that it is necessary to lean forward to embrace, develop and rapidly adopt these new solutions. Model-based techniques indeed represent a unique opportunity to unleash the whole potential of the available equipment without requiring additional and expensive installations.