A SDG-based method is proposed in this paper to qualitatively predict the effects of one or more fault propagating in a multi-loop process system. The conventional version of qualitative simulation techniques (Chen and Chang, 2006) is modified to differentiate not only the locations of fault origins but also their magnitudes. A computer algorithm is also presented to generate the IF-THEN inference rules automatically according to the anticipated fault propagation behaviors. Effectiveness and feasibility of this approach has been tested with two case studies. One is concerned with a single-tank level control system and the other an exothermic CSTR reactor with temperature and level control loops.

Reference: Chen, J. Y., and Chang, C. T., “Fuzzy Diagnosis Method for Control Systems with Coupled Feed Forward and Feedback Loops,” Chem. Eng. Sci. 61, 3105-3128 (2006).