Cascade-controlled CSTR for Fault Simulation

A 4-state CSTR process dynamic simulation under 2 cascade control loops with fault simulation

This is a Simulink model of a CSTR under closed-loop control, where the process is represented by 4 ODEs (ordinary differential equations) which are mass and energy balances around the system. The CSTR (continuous stirred-tank reactor) carries out a hypothetical first-order exothermic reaction, where the tank temperature (T) is maintained using a cooling jacket. Liquid hold-up (h) is also being maintained by manipulating the tank outlet stream flow rate (F). Process conditions are being perturbed around the nominal operating point by random disturbances on 4 input variables, namely, Fi, Ti, Ci, and Tci.

In addition, faults can be simulated for process monitoring research purposes. When no faults are simulated, one can gain process understanding of the system dynamics under normal operation. Abrupt sensor bias faults may be added in each of the 10 measured variables. Incipient faults include sensor bias ramp changes and input disturbance ramp changes. Multiplicative faults include catalyst deactivation and heat transfer fouling by exponential decay. Any combination of these faults may also be simulated together. Additive white noise is present in all output measurements.

Note: Since this model is edited in MATLAB R2018a, change the Simulink preferences to run in an older version of MATLAB.

References:
Liu (2012), "Fault diagnosis using contribution plots without smearing effect on non-faulty variables," Journal of Process Control, Vol. 22, No. 9., 1609-1623.