This chapter relaxes the assumption of availability of a redundant control configuration and presents a “safe-parking” approach to handle faults. The safe-parking approach dictates driving the system to a (appropriately chosen) temporary operating point (the so-called safe-park point) until the fault is rectified. The choice of the safe-park point is based on stability and performance considerations, and also necessitates fault diagnosis (estimating the magnitude of the fault), going beyond FDI. A comprehensive mechanism for Fault-detection and Diagnosis (FDD) and safe-parking is presented and illustrated through chemical process examples.
KeywordsManifold Enthalpy Steam Polystyrene Styrene