This paper addresses the problem of decentralised control of multivariable process systems. The postulation here is that disturbance observers can be used to reduce the interactions between controlloops, hence improv...
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ISBN:
(纸本)9788995003848
This paper addresses the problem of decentralised control of multivariable process systems. The postulation here is that disturbance observers can be used to reduce the interactions between controlloops, hence improving multiloopcontrol and allowing loopcontrollers to be tuned independently. Applications to a well known linear model of a distillation process show that marked servo and regulatory performances can be achieved without introducing excessive complexity to the control tuning process.
Two simple PID design methods, IMC and GPM, that use robustness as their main design criteria, as opposed to performance, are applied to a multi-loop PI control configuration which is being used to control a multivari...
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ISBN:
(纸本)4907764227
Two simple PID design methods, IMC and GPM, that use robustness as their main design criteria, as opposed to performance, are applied to a multi-loop PI control configuration which is being used to control a multivariable process model against load disturbances. Initially individual loopcontrol designs will be tested on the multivariable process. In addition to these studies on the LV multi-loop control configuration decouplers will then be added to try and reduce the controlloop interaction. Finally process model mismatch studies will be performed.
Main feature of one-cycle control method is its real time ability to reject line disturbance. Despite of this great feature it has not good load rejection ability and fast command tracking. It is possible to use anoth...
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ISBN:
(纸本)0780383044
Main feature of one-cycle control method is its real time ability to reject line disturbance. Despite of this great feature it has not good load rejection ability and fast command tracking. It is possible to use another controller as auxiliary controller to improve the performances of one-cycle controller. In this paper, an error dependent controller, which uses output error as measure to select reference value for one-cycle controller, has been proposed. When the error is big and positive it will select a pseudo reference bigger than actual reference and when it is big and negative it will select a pseudo reference smaller than actual reference. By this method, the one-cycle controller performance has been improved greatly.
In this paper, the development of relay-enhanced multi-loop PI controllers is described for multivariable processes. The control system employs a relay in series with the controller. The relay can ensure a satisfactor...
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In this paper, the development of relay-enhanced multi-loop PI controllers is described for multivariable processes. The control system employs a relay in series with the controller. The relay can ensure a satisfactory level of closed-loop performance and it also yields oscillations for tuning of the PI controller based on an equivalent process model for each loop. A simulation example [on a two-inputs-two-outputs (TITO) process] is provided to illustrate the effectiveness of the proposed method and to compare its performance to an existing method. (C) 2003 ISA-The Instrumentation, Systems, and Automation Society.
In this paper, a multi-loop version of the modified Ziegler-Nichols method (Astrom and Hagglund, 1988) is proposed for TITO (two input two output) processes. The key idea is to regard each loop together with its corre...
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In this paper, a multi-loop version of the modified Ziegler-Nichols method (Astrom and Hagglund, 1988) is proposed for TITO (two input two output) processes. The key idea is to regard each loop together with its corresponding interactions from all other loops as an equivalent SISO plant and design for it an SISO controller by shifting a given point on the Nyquist curve of the equivalent SISO plant to a desired position. This is however a nonlinear problem since the equivalent plants depend on unknown controllers. A novel approach is thus presented to obtain the controller parameters which achieve the above design objective. Simulation examples are provided to show the effectiveness of the proposed method.
his paper reports new design aspects of conventional cascade control systems and develops the basic cascade control structure into a multi-loop (single-input, multioutput or SIMO) topology to improve the system perfor...
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his paper reports new design aspects of conventional cascade control systems and develops the basic cascade control structure into a multi-loop (single-input, multioutput or SIMO) topology to improve the system performance for process control applications. This SIMO control structure has several advantages such as an easy and simultaneous controller design procedure, which considers the inner process dynamics and disturbance rejection for on-line operation. The paper includes a sequential reduction algorithm using additive and multiplicative uncertainties to provide low order controllers and to improve the system robustness. Subsequently SIMO self-tuning cascade control is developed. Different design methods such as polynomial LQG or H-infinity are used in different cascade controlloops. Parametrized dynamic weighting functions in the controller design theory are used to achieve stability robustness. Stability robustness theorems are applied to the model-order-reduced plant and the effect of strong inner process disturbance is attenuated. In the multi-loop explicit self-tuning control described, fast convergence and reliable parameter estimation is achieved using an unbiased recursive least squares algorithm. Simulated industrial examples, superheater temperature control and furnace temperature control show that the stability and time domain performance of conventional cascade and multi-loop processes are improved by the new design approaches and the use of adaptive control when appropriate.
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