Physical-Based Modeling of Nonlinearities in Process Control Valves

Nonlinear failures of control valves, such as valve stiction, are often encountered in process industries. This degrades the performance of control loops and systems. Modeling and analyzing various valve nonlinearities are essential for either failure prevention or fault diagnosis. The physical model of a typical pneumatic control valve is introduced and modeled by using object-oriented AMESim toolkit in this paper. Four common failures of valves are simulated by setting specific physical model parameters. Operating data are obtained through the closed-loop feedback control system simulations. Nonlinearities are successfully verified with the existing nonlinear testing methods. The testing results validate the proposed physical model. The generated faulty operation data can be utilized for further study, especially for control valve fault diagnosis and nonlinear compensations.