Self tuning control applied to heating systems.

Abstract

The use of self tuning control to aid the commissioning and to improve the performance of environmental heating controls is investigated. The theory of self tuning control is well developed, this study considers its application to air conditioning plant, and in particular the measures necessary to devise a controller that is sufficiently robust to be competitive with conventional controllers. Nonlinearities peculiar to air conditioning plant are considered in detail and the effect on the self tuning control is investigated. The commissioning of heating controls can be simplified by using self tuning control, as its predictive nature compensates for the large phase lag present in most heating plant. Commissioning of controls is described in detail, and a novel commissioning procedure is presented for use with self tuning control. An important feature of heating plant is the air mixing process. A test facility that exhibits the major characterics of a practical air mixing process, such as an occupied air space (room) is constructed and its thermal characteristics modelled. Modelling of practical heating plant is described and techniques based on crosscorrelation and least squares methods are presented as a means of obtaining optimal estimates of the model parameters. The results of parameter identification of the test facility highlight several of the problems of applying self tuning control in practice, and in particular to heating plant. The self tuning control presented is shown to have a less sensitive commissioning procedure and better, long term performance than conventional PI control both in simulation and in real time control of the test facility.

Date of Award	1985
Original language	English
Awarding Institution	University of Bath