Universität Stuttgart
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Item Open Access Multivariable controller design for an industrial distillation column(1992) Allgöwer, Frank; Raisch, JörgIn this paper, we report our experience with the design of linear multivariable controllers for a staged binary distillation column with 40 trays. Controller design methods include H∞-minimization, DNA-design, CL-design and H2minimization. Results obtained at the real plant are shown.Item Open Access Validation and analysis of linear distillation models for controller design(1993) Amrhein, Michael; Allgöwer, Frank; Marquardt, WolfgangIt is a nontrivial task to decide whether a model describes the main dynamic characteristics of a process and to determine which model is to be preferred for controller design. Techniques for examining lineal models for controller design are described in Section 2. One focus of this paper is on tools for analysing multivariable processes in the frequency domain, for example, condition number and dynamic relative gain array (RGA) analysis. The latter tool is extended by the phase information of the RGA. A novel evaluation tool involving the singular directions over frequency of the respective processes is introduced. In Section 3, a new linear low-order model is compared to five models from the literature using the analysis tools introduced in Section 2. The new model directly exploits wave propagation phenomena, and, therefore, will be called the wave model. Finally, Section 4 shows briefly result of the H∞-coutrolled column where the controller is designed on the basis of the wave model. Simulations with a detailed nonlinear distillation model show that very good control action can be achieved with this model. Moreover, the linear model allows to predict the nonlinear closed loop behavior quite accurately.Item Open Access Chemical process control: a german perspective(1992) Allgöwer, FrankThis paper focuses on developments in controller design that we think can have a significant impact on the solution of practical process control problems, and try to summarize the discussion in Germany on this subject.Item Open Access Nonlinear control of an industrial distillation column by exact linearization(1989) Allgöwer, Frank; Sax, Antonius; Gilles, Ernst Dieter-Item Open Access Nichtlinearer Reglerentwurf auf der Grundlage exakter Linearisierungstechniken(1993) Allgöwer, Frank; Gilles, Ernst DieterDem nichtlinearen Reglerentwurf mittels exakter Linearisierung liegt eine Zweischritt-Philosophie zugrunde: zuerst wird die nichtlineare Regelstrecke durch eine nichtlineare Rückführung exakt in ein lineares System überführt. Das exakt linearisierte System kann im zweiten Schritt mit linearen Reglerentwurfsverfahren so geregelt werden, daß Stabilität und gutes Regelverhalten erreicht werden. In diesem Übersichtsbeitrag wird eine Einführung und ein Überblick über das Gebiet der exakten Linearisierung gegeben. Anhand von Beispielen werden die Vorteile und Grenzen der Verfahren diskutiert.Item Open Access Chemical process control : present status and future needs ; the view from European industry(1991) Schuler, Hans; Allgöwer, Frank; Gilles, Ernst DieterNot only in Europe, chemical process control is characterized by a broad invasion of distributed control systems into chemical plants. The information integration from process control up to business management is a great challenge of today which follows from the overall computerization of production. Most of the recent progress in process automation results from the application of computer science paradigms to control systems, and of advanced developments in field instrumentation. Despite these advances and the considerable progress made in process control theory, there is only limited acceptance and application of modern advanced process control methodologies in industrial practice. This paper is an attempt to summarize the European discussion on the reasons for these facts.Item Open Access Influence of the wall on the dynamic behavior of homogeneous tubular reactors with a highly exothermic reaction(1974) Eigenberger, GerhartThe influence of the tube wall on the behavior of tubular reactors with a highly exothermic reaction was studied. The effect of heat accumulation in the wall has a considerable influence upon the transient behavior of the reactor. Because of this influence excess temperatures can occur if the feed temperature is lowered or the flow velocity is raised. For a gas phase reaction the transient behavior is determined almost completely by the heat capacity of the wall. An example of multiple steady states caused by axial heat conduction in the wall is given, and the influence of heat conduction in the wall is compared with that in the reaction mixture.Item Open Access An engineering perspective on nonlinear H∞ control(1994) Allgöwer, Frank; Rehm, Ansgar; Gilles, Ernst DieterThe focus is on the question whether meaningful practical control problems for nonlinear systems can be expressed and solved in the nonlinear H∞ framework. Approximate I/O-linearization of a realistic chemical reactor, that cannot be I/O-linearized exactly, is given.Item Open Access Look-ahead cyclic pitch control using LIDAR(2010) Schlipf, David; Schuler, Simone; Grau, Patrick; Allgöwer, Frank; Kühn, MartinLIDAR (Light detection and ranging) systems are able to provide preview information of wind disturbances at various distances in front of wind turbines. This information can be used to improve the control of wind turbines. This paper compares a predictive feedforward control structure combined with common PI controllers to a baseline controller and to an H∞ approach showing the advantage of look-ahead control to reduce wind turbine loads. The control design is verified by simulations with a turbulent wind field and a full nonlinear model of the wind turbine.Item Open Access Design of robustly performing controllers for a class of practical control problems(1993) Amann, Notker; Allgöwer, FrankThe design of robustly performing controllers for a class of practical control problems is considered, involving both parametric and unstructured uncertainty. The problem is dealt with in the structured singular value (μ)-framework. An iterative approach comprising both μ-analysis of the detailed problem and D-K-iteration for a modified problem is proposed, as no direct solution to the detailed μ-synthesis problem is known to date. With a practical MIMO process control example it is shown that this approach leads to controllers that exhibit robust performance.