Controllability analysis of two-phase pipeline-riser systems at riser slugging conditions

Storkaas, Espen; Skogestad, Sigurd

doi:10.1016/j.conengprac.2006.10.007

Cited by 64 publications

(48 citation statements)

References 19 publications

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“…It has been shown that it is difficult to stabilize flow in pipeline-riser systems when using only the top-side pressure measurement [3]. The reason is that the Right Half-Plane (RHP) zeros of the system with this measurement are relatively close to the RHP-poles of the system, and consequently the sensitivity transfer function of the system shows a large peak.…”

Section: Introductionmentioning

confidence: 99%

“…Based on a controllability analysis in [3] [14], it is much easier to stabilize the system by using the subsea pressure compared to the top-side pressure. The system could be stabilized up to 40% valve opening by controlling the subsea pressure with a simple PI controller (Fig.…”

Section: B Measuring Subsea Pressurementioning

confidence: 99%

“…• K h : correction factor for level of liquid in pipeline • K pc : choke valve constant • K G : coefficient for gas flow through low point • K L : coefficient for liquid flow through low point Bifurcations diagrams, describing the steady-state and the dynamics of this system, are used to compare the model to experiments [3]. Fig.…”

Section: B Simplified Modelmentioning

confidence: 99%

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Anti-slug control experiments using nonlinear observers

Jahanshahi

Skogestad

Grøtli

2013

2013 American Control Conference

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Abstract-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 used the top-side pressure as measurement for different observers to estimate state variables of the system, and then used the estimated states for control. This scheme was tested in experiments using three types of observers. A simple Luenberger observer with a large gain was found to be more robust than the standard Unscented Kalman Filter (UKF). We modified the UKF to a Fast UKF for time-scale separation of the closed-loop system. The resulting observer was robust, also less sensitive to measurement noise compared to the simple Luenberger observer when measuring the top-side pressure. Surprisingly, the nonlinear observers were not able to work in closed-loop when the subsea pressure was used as the measurement. On the other hand, a linear observer worked very well for this case with a larger operating range compared to that of the top-side pressure.

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Section: Introductionmentioning

confidence: 99%

Section: B Measuring Subsea Pressurementioning

confidence: 99%

Section: B Simplified Modelmentioning

confidence: 99%

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Anti-slug control experiments using nonlinear observers

Jahanshahi

Skogestad

Grøtli

2013

2013 American Control Conference

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“…However, the pressure at the bottom is often not measured, so it is tempting to switch and control the pressure at the top of the riser instead. However, this does not work because of the presence of unstable (RHP) zeros in the response from the valve position (input u) to the top pressure (output y), Storkaas and Skogestad (2007). This is due to the main fundamental limitation of feedback control: High feedback gains cannot be applied in the presence of time delays (Figure 3) and RHPzeros because it results in closed-loop instability; see also Chapters 5 and 6 in Skogestad and Postlethwaite (2005).…”

Section: Stabilization Using Feedbackmentioning

confidence: 99%

Feedback: Still the Simplest and Best Solution

Skogestad

2009

MIC

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“…• Feedback PID control strategy of a pipeline-riser, controlling the riser base pressure with the topside choke as control input, in Ogazi AI (2010), Jahanshahi and Skogestad (2015), Storkaas and Skogestad (2007), Storkaas et al (2001) and Skogestad (2009).…”

Section: Introductionmentioning

confidence: 99%

Model-free optimal anti-slug control of a well-pipeline-riser in the K-Spice/LedaFlow simulator

Dalen¹,

Ruscio²,

Nilsen³

2015

MIC

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Simplified models are developed for a 3-phase well-pipeline-riser and tested together with a high fidelity dynamic model built in K-Spice and LedaFlow. These models are developed from a subspace algorithm, i.e. Deterministic and Stochastic system identification and Realization (DSR), and implemented in a Linear Quadratic optimal Regulator (LQR) for stabilizing the slugging regime. We are comparing LQR with PI controller using different performance measures.

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Controllability analysis of two-phase pipeline-riser systems at riser slugging conditions

Cited by 64 publications

References 19 publications

Anti-slug control experiments using nonlinear observers

Anti-slug control experiments using nonlinear observers

Feedback: Still the Simplest and Best Solution

Model-free optimal anti-slug control of a well-pipeline-riser in the K-Spice/LedaFlow simulator

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