It has been shown [1] that use of a ``fast feedback'' loop incorporating a plant model and a two-position controller results in better control of first-order thermal plants with inherent time delay In this paper such a control scheme is analyzed with a view of adapting it for process control Both steady-and unsteady-state analyses are carried out for the case where disturbance variations occur during regulatory control Based on the results obtained, criteria are evolved for the selection of suitable model parameters which result in zero offset in plant output, minimum period of steady-state cycling, and acceptable transient behavior

Use of Fast-Time Process Analogs in Two-Position Control

Some Problems of Automatic Control in Industrial Electroheat State and Needs - A Survey

Control of first-order thermal plants with inherent time lags by means of hystereitc ON?OFF controllers is investigated. Open-loop pulse-duration-modulation control of the same class of plants is briefly analyzed. A scheme is investigated where the plant is controlled on an open-loop basis by a controller which is included in a feedback loop containing a model of the plant. The parameters of the model can deliberately be made different than those of the process. By a suitable choice of these model parameters better performance criteria can be obtained, especially when they exist due to the distributed nature of thermal processes and to the location of temperature sensing units.

Guney Gonenc

Papers

Use of Models to Control Electroheat Processes