COMPARATIVE ROBUSTNESS ANALYSIS OF TWO COAL PREPARATION TECHNOLOGICAL SYSTEMS TO PROCESS DISTURBANCES ANALIZA PORÓWNAWCZA ODPORNOŚCI DWÓCH UKŁADÓW TECHNOLOGICZNYCH PRZERÓBKI WĘGLA NA ZAKŁÓCENIA PROCESOWE

One of the basic tasks attributable to supervisory control systems is the aim to reach maximum effi ciency of production processes. Therefore objectives of the supervisory control can be considered as searching for the most favourable operating conditions (a operating point) of the system with consideration of anticipated dominant tasks and predictions of average values for disturbances. The operating point is determined by averaged values of input and output process variables. Therefore it is the robustness of system parameters to disturbances in the optimum operating point that decides on practical effects of optimization processes. The set of factors deciding on robustness degree of quantitative and qualitative parameters of products from coal preparation processes includes but is not limited to the following: selection of the technological structure, the objective function of the control process along with its boundaries as well as disturbances that are related to settings of decisive parameters within the system along with variability of raw coal characteristic parameters. In order to improve control robustness for systems with substantial nonlinearities (as in case of coal preparation systems) it is necessary to analyse disturbances occuring in the optimum set-point of the system. This paper presents comparative sensitivity analysis of two technological system for robustness problems of performance index of the supervisory control to process disturbances.