The Influence of the Object Model Choice on the Automatic Control System Efficiency

Using the example of the oxygen content in the boiler exhaust gases automatic regulation system of, the problem of the influence the object approximating model choice on the efficiency operation is considered. It is based on the experimental transient characteristic of the channel “position of the fan guide - oxygen content” For it, the least squares approximation was performed by five different models, differing in order and the presence of a delay. Optimal settings of the PID controller are obtained for each model and transients of the real system are modeled. It was revealed that the choice of the object model approximating structure significantly affects on the efficiency of the automatic control system. The first-order model with a delay is not suitable for describing the real object dynamics, as it leads to a noticeable decrease in the system stability margin. However, models of the second or third order with a delay may well be used in an adaptive control system with identification.