Esmaeil Jahanshahi

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In order to prevent the severe slugging flow regime in multiphase transport pipelines, active feedback control is the recommended solution. Instead of elaborated models such as CFD and OLGA models, a simple dynamical model with few state variables is required in a model-based control system. We propose a new simplified dynamical model for severe slugging(More)
Anti-slug control of multiphase risers involves stabilizing an open-loop unstable operating point. PID control is the preferred choice in the industry, but appropriate tuning is required for robustness. In this paper, we define PIDF as a PID with a low-pass filter on its derivative action where the low-pass filter is crucial for the dynamics. We compared a(More)
Active control of the production choke valve is the recommended solution to prevent severe slugging flow conditions at offshore oilfields. The focus of this work is to find the structure of a simple, yet robust anti-slug control system. In order to find suitable control variables for stabilization, a controllability analysis of the system with different(More)
To prevent slug-flow on offshore oil production units, controlling a subsea pressure is the recommended solution. However, the subsea pressure is not often available as a measurement. The top-side pressure is usually measured but it is difficult to use for stabilizing control, because of its Right Half-Plane zero dynamics combined with nonlinearity. We have(More)
Active control of the production choke valve is the recommended solution to prevent severe slugging flow at offshore oilfields. This requires operation in an open-loop unstable operating point. It is possible to use PI or PID controllers which are the preferred choice in the industry, but they need to be tuned appropriately for robustness against plant(More)
Instability and inverse response behaviour make anti-slug control at offshore oil-fields an interesting control problem where a robust solution considering the nonlinearity of the system is required. We tested three control solutions by experiments in this paper. First, we used state-feedback with state estimation by a nonlinear high-gain observer.(More)
Although many PID tuning approaches are available, it is not easy to find a method that does not require any engineer/operator interference. In this work, we present a fully automated approach for PID tuning based on relay feedback. This method involves sending the relay feedback test data from PLCs (Programmable Logic Controller) into a historian,(More)
Active control of the production choke valve is the recommended solution to prevent severe slugging flow conditions at offshore oilfields. The slugging flow constitutes an unstable and highly nonlinear system; the gain of the system changes drastically for different operating points. Although PI and PID controllers are the most widely used controllers in(More)
Active control of the production choke valve is the recommended solution to prevent casing-heading instability in gas-lifted oil wells. Focus of this work is to find a simple yet robust control structure for stabilization of the system. In order to find suitable control variables, a controllability analysis of the system with different candidate control(More)
This paper introduces an approach to fault detection and diagnosis scheme which uses fuzzy reference models to describe the symptoms of both faulty and fault-free plant operation. Recently, some approaches have been combined with fuzzy logic to enhance its performance in particular applications such as fault detection and diagnosis. The reference models are(More)