Analysis of nonlinearities compensation for control valves

Control valves have an important function in many industry processes, such as power generation plants, chemical industries, refinery industries, etc. Unfortunately, the control valve has inherent nonlinearities characteristics, e.g. static friction (stiction), backlash, and dead-band. The presence of nonlinearities in a control valve limits the control loop performance and also causes a stability problem of the system. Moreover, this condition renders the design of control system more complex and very hard to be handled. Based on this phenomenon, it is desirable to improve the control systems to compensate for these inherent nonlinear characteristics of the control valve. In this paper, a procedure to compensate for the stiction phenomenon of control valve for a pneumatic control valve type is presented. A computational simulation is also presented to verify the proposed method. (authors)