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P/Pd Types Of Override Control Systems
Author(s) -
Tsai YawYing,
Cheng YuChang,
Yu ChengChing
Publication year - 2002
Publication title -
asian journal of control
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.769
H-Index - 53
eISSN - 1934-6093
pISSN - 1561-8625
DOI - 10.1111/j.1934-6093.2002.tb00090.x
Subject(s) - control engineering , control system , engineering , control theory (sociology) , constraint (computer aided design) , control (management) , process (computing) , computer science , process control , artificial intelligence , mechanical engineering , electrical engineering , operating system
The override control provides protective action against abnormal operation and/or incipient process failure. In terms of control theory, it is a logic‐based switching system and, in terms of operation, it is usually activated between the soft constraint and the hard constraint. It is used in all process industries, and most PID control loops are patched with some type of override system. Despite widespread application, little research has been done to analyze override control systems. In this work, the properties of the override control are explored. The stability of the override control is also studied. Counter to intuition, many well‐known override systems may exhibit instability and lead to oscillatory responses as the process approaches constraints. Approaches are proposed for the design of override control systems to ensure inherent safe operation.