Control Loop Performance Monitoring -: Stiction Detection and Compensation

Controller Performance Monitoring involves the following three routine activities: (1) monitor the performance of each loop, (2) isolate poorly performing loops and (3) diagnose the cause of poor performance. A typical processing industry installs several hundreds of control loops to achieve the desired process performance. Recent studies reveal that only about one-third of controllers provide acceptable performance, indicating significant commercial benenfits exist in diagnosing and improving the remaining two thirds of the control loops. Recent surveys indicate that 20% to 30% of all control loops oscillate due to valve problems caused by static friction (also referred as stiction). Two different techniques for diagnosing stiction using routine operating data have been proposed. The success of these approaches is built on a new technique that detects and characterizes oscillations in control loops. An integrated solution strategy to compensate stiction is provided. Stiction detection and diagnosis techniques are validated on a large industrial data set.