Industrial & Engineering Chemistry Research, Vol.58, No.26, 11316-11325, 2019
Control Valve Stiction Compensation - Part I: A New Method for Compensating Control Valve Stiction
Valve stiction is a hidden menace in process control loops. The presence of stiction in control valves limits the control loop performance. Compensation of its effect is beneficial before the sticky valve can be sent for maintenance. This work is the first of a two part study on control valve stiction compensation. This part proposes a novel stiction compensation method, while the second part compares the performance of this proposed stiction compensation method with some of other compensation methods appeared in the literature. The proposed compensator is developed based on reduction of control action and addition of an extra pulse of finite energy as required. A method for estimating an appropriate parameter for reducing controller action has been developed. The proposed stiction compensator has been extensively evaluated using the MATLAB Simulink environment. The compensator has also been implemented in a pilot plant experimental setup. It has been found to be successful in removing valve stiction-induced oscillations from process variables both in simulation and pilot plant experimentation. The compensator developed in this study has the capability of reducing process variability with a minimum number of valve reversals.