An object oriented operator support system based on process models and an expert system shell

Abstract An operator support system for detection of process upsets and determining their cause is presented. An important part of the system is a total plant model where each process unit is represented as an attributed process object and where the process flows are modelled as relations between process objects in the form of process connections. For each process connection, a number of measured or calculated process variables are monitored for deviations. Once a deviation has been detected, the process object connected at the input of the process connection checks all incoming streams to see if the upset may have been caused by an upstream process object. If so, control is passed to the diagnoser associated with the upstream process unit, which in tum may pass control to a unit further upstream. This goes on until a diagnoser finds no relevant deviations in any of its upstream units. The diagnoser then decides that the cause of the upset is internal and an internal diagnosis of the process object is initiated. The diagnostic process can be controlled or overridden by the operator. The operator interaction is based on animated process flowsheet pictures where the diagnostic search is indicated by colour coded process object and process connections. The internal diagnostics of the system is based on quantitative techniques such as process models, fault tree models and Kaiman filtering methods. The topological search is rule based.