1 research outputs found
Design of an event-based early warning system for process operations
This thesis proposes a new methodology to design an event-based warning system as an
alternative to the conventional variable-based alarm system.
This study initially explores the options for grouping process variables for alarm
allocation. Several grouping methods are discussed and an event-based grouping
procedure is detailed. Selection of the key variables for a group is performed considering
the information that the variables contain to distinguish between an abnormal and a
normal condition. The information theory is used to quantify the information content of a
variable about an event to select the key variables. The cross-correlation analysis between
pairs of key variables is used to identify the redundant variables. Simulation study using
the model of a continuous stirred tank reactor (CSTR) is used to demonstrate the
methodology.
The proposed event-based early warning system utilizing online measurements is detailed
in the thesis. In this approach, warnings are assigned to plant abnormal events instead of
individual variables. To assess the likelihoods of undesirable events, the Bayesian
Network is used; the event likelihoods are estimated in real time utilizing online
measurements. Diagnostic analysis is conducted to identify root-causes of events. By
assigning warning to events, the methodology results in significantly lower number of
warnings compared to traditional variable-based warning (alarms) system. It also enables
early warning of a possible event along with an efficient diagnosis of the root-causes of
the event. Experimental testing using a level control system is presented to demonstrate
the efficacy of the proposed method. Simulation study using the model of a CSTR is also
presented to demonstrate the performance of the algorithm. Both, experimental and
simulation studies, have shown promising results