The general structure and purposes of the distributed control systems (DCS) are reminded in connection with the capability to use them for on-line optimization of the load distribution in large, multiunit power stations. The basic assumptions, equations and structure of a model of backpressure extraction turbine are presented. The tasks, realized using this model in collaboration with the DCS’s measuring and archive systems, are defined. The principles of using and correcting the input data for the considered tasks are described. Model calculation results and recorded measuring data are compared. The input data quality and influence of the DCS record mode on the abilities to use the model appropriately are discussed.