Analysis of possible reasons of erronious identificationof the dynamic parameters of a controlled thermal plant

Abstract

For optimal adjustment of the temperature regulator, it is necessary to know the dynamic properties of the controlled plant, which are mainly obtained from an experimen, in the procedure of identifying the dynamic parameters of the controlled plant. The purpose of the study is to analyze possible causes of erronious identification of dynamic parameters of the plant. A possible mistake may be an unsuccessful selection of parameters, being identified. Their necessary and sufficient list includes static coefficient of transmission, the main and additional time constants, time delay. Possible strong nonlinearity of the actuator should be taken into account to compensate it in calculations. During the experiment, it is desirable not  to allow large temperature deviations from the normal operating mode, to avoid the influence of possible small nonlinearity of the controlled plant. To process the results of the experiment, verified universal automatic optimization algorithms should be used. As a minimization criterion, it is recommended to use the logarithm of the mean square deviation between the experimental temperature oscillogram and the corresponding calculated oscillogram on the model. If, as the result of identification, equal or close values of the main time constants are obtained, this may be the result of a fault of the automatic search procedure, which is "stuck" in a local minimax. The values should be divercified, to help the automatic optimizer.