The road to plant validation

Effective production requires serviceable unit processes, under stable control with credible sensed data and precise actuation. Validation of these components is not just an aid to safe operation, but can also enhance the availability of the plant. Cost-effective validation uses standard metrics for the intercommunication of results via a network and starts at the sensor and actuator level. In particular, greater availability comes from limp-home features that provide a degree of operability even in the presence of faults. This can be achieved at the device level, by adjusting a loop´s PID regulator, by using auxiliary variables and data fusion, or by the reconfiguration of a model predictive controller (MPC). Examples are given of self-validating (SEVA) field instruments and the effect of adjusting a control loop using SEVA data. Plant validation is a combination of SEVA devices and of change detection based on the residuals derived from an MPC model.