Abstract

The presence of nonlinearities, e.g., stiction, and deadband in a control valve limits the control loop performance. Stiction is the most commonly found valve problem in the process industry. In spite of many attempts to understand and model the stiction phenomena, there is a lack of a proper model, which can be understood and related directly to the practical situation as observed in real valves in the process industry. This study focuses on the understanding, from real-life data, of the mechanism that causes stiction and proposes a new data-driven model of stiction, which can be directly related to real valves. It also validates the simulation results generated using the proposed model with that from a physical model of the valve. Finally, valuable insights on stiction have been obtained from the describing function analysis of the newly proposed stiction model.