In this paper, nonlinear modeling and control of a typical drum steam generator are studied. At first, dynamics equations governing the steam generator are derived using physical principles and parameters. In fact, it is intended to combine some models presented in existing literature in order to construct a stronger model, which is to be based only on physical parameters, of steam generator dynamics. Next, these equations are simulated using numerical methods and open-loop responses of the steam generator system, which is inherently unstable, are obtained and investigated. Furthermore, considering boiler-follow mode as the main control mode, two PID controllers are designed using Ziegler–Nichols tuning rules. The Controllers are individually applied to the main steam pressure and the drum water level loops. During design process, the interaction between the steam pressure and the water level is well investigated and explained. This model can be used in researches and studies on the steam generator dynamics optimization and also on the different modern control theories applications.

Keywords: Nonlinear modeling, steam generator, steam pressure, drum water level, PID control

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