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Control System Performance (control + system_performance)

Distribution by Scientific Domains
Engineering75%

Selected Abstracts

Adaptive transfer function-based control of nonlinear process.

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2007
Case study: Control of temperature in industrial methane tank
Abstract The state model-based transfer function models are applied for adaptation of linear controller and disturbance compensator in a feedback/feed-forward control system of nonlinear process. An advantage of the presented adaptation method is the avoidance of artificial disturbances or iterative identification procedures for on-line estimation of process dynamic parameters. The adaptation is based on linearization of the process model at each sampling time about the current state point, independent of the process being at steady-state or transient conditions. The linear time-varying dynamics model is updated on-line using measured values of process variables and reduced to the first-order plus time delay transfer function models in order to directly apply well-developed controller tuning rules. Computational aspects of the adaptation method are discussed and computation algorithms are presented. The adaptive feedback/feed-forward control system was applied for controlling temperature in industrial methane tank, dynamic parameters of which vary in a wide range due to variations of methane-tank process load and external conditions. The heat balance-based process state model is developed and validated using observation data of real plant. Computer simulation of the proposed control system performance under extreme operating conditions demonstrates fast adaptation of controller parameters, robust behaviour and significant improvement in the controllers' performance compared to that of fixed-gain controllers. Copyright © 2007 John Wiley & Sons, Ltd. [source]

An analytical and experimental analysis of a very fast thermal transient

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2001
C. Aprea
Abstract According to some international standards, some products, developed for use under heavy thermal conditions, have to be tested by subjecting them for a short time to a particular heating and cooling thermal stress to allow them an acceptable future operative life. It is possible to obtain these fast thermal gradients in confined environments, called climatic chambers where the air is heated by an electrical resistance and is cooled with a finned evaporator which is linked to a vapour compression system subjected to a particular control system of the refrigerating power. In particular, in this paper the air and object tested thermal transients are studied from an analytical and experimental point of view. The study of the mathematical model is realized assuming simplified hypotheses about the air, the object and the air cooled evaporator temperature. The most complex circumstances are related to a very fast temperature decrease because under this working condition the mathematical model is characterized by a nonlinear differential system. The nonlinear term is represented by the refrigerating power that varies in a definite range with the evaporator temperature according to a sinusoid trend. For this power a suitable analytical expression, derived by the control system performance and by the compressor characteristic, has been found. The analytical,experimental comparison during a cooling thermal stress of typical products subjected to international standard tests as the electronic boards, has been carried out showing acceptable results. The model presented is useful to foresee the climatic chamber performances in the presence of a specific refrigerating power trend; this is the start-point for the design of the vapour compression plant and its control system. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Control of a high-purity ethylene glycol reactive distillation column with insights of process dynamics

AICHE JOURNAL, Issue 8 2009
Kejin Huang
Abstract Inventory control is often regarded as less important than product quality control in the operation of reactive and nonreactive distillation columns (i.e., often detuned considerably in control system design). For the high-purity ethylene glycol reactive distillation column, the inventory control of top condenser is, however, an exception and plays actually a crucial role in the stable and effective process operation, reminding the necessity to thoroughly investigate the intricate dynamic mechanism and its complicated implications on control system synthesis and design. In this article, the dynamics of a high-purity ethylene glycol reactive distillation column is examined, and it is found that the complicated dynamics, for example, the nonminimum phase behavior and process nonlinearity, can be suppressed considerably with the tight inventory control of the top condenser. Moreover, an extremely low controllability is detected, implying the potential difficulties in process operation and thus the need of process design modification. In terms of these insights obtained, two control schemes are devised and studied. It is demonstrated that sharp improvement could be acquired in control system performance when the tight inventory control has been implemented in the top condenser. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

A study on a new AVR parameter tuning concept using on-line measured data with the real-time simulator

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2006
Joong-Moon Kim
Abstract Automatic voltage regulator (AVR) parameter tuning for voltage control of power system generators has generally been performed with the analytic methods and the simulation methods, which mostly depend on off-line linear mathematical models of power system. However, due to the nonlinear nature of power system, the mathematical models of the excitation system may not be correct. So the excitation control system performances with the parameter set that is tuned by using the mathematical model, may not be appropriate for some operating conditions. This paper presents an AVR parameter tuning method using on-line measured data of the excitation control system with parameter optimization technique. As this method utilizes on-line operating data, it can overcome the limitation of model uncertainty problems of conventional method. To validate the proposed tuning concept, a scaled model excitation system is connected to the real-time power system simulator, and the proposed tuning concept is tested. Copyright © 2006 John Wiley & Sons, Ltd. [source]