An approach for stiction compensation in industrial process control valves

Abstract

In the process industry, control valve stiction causes oscillations in the control loop, and this results in deterioration of control performance. Therefore, the sticking control valves are repaired during a scheduled plant shutdown maintenance. Until such permanent solutions are used, it is expected that the oscillations can be reduced with a low-cost approach; PID control parameter re-tuning is a suitable approach in this case. This study involves a method of compensating for control valve stiction. In particular, it aims to improve the control performance by tuning the parameters of normal PID controllers. We propose a method to search for the optimal PID parameter values based on control simulation using a stiction model. First, the stiction model and the process model are identified. Next, simulation is performed using a combination of the stiction model, process model and PID controller. Finally, the PID parameter values are optimized based on the assessment.