Active Fault Tolerant Control System in Sensors and Actuators: Application in a Distillation Column

This work presents the simulation results of an active fault tolerant control system on a distillation column. The aim of the control system is to maintain the binary distillation process (ethanol-water) in continuous operation even if both sensors or actuator fault occurs. To develop the active fault tolerant control system, it was designed a fault detection and diagnosis system by using a full-order high-gain observer to estimate the temperatures and concentrations on the distillation column; the estimation of the temperatures and concentrations was made by using only one measured temperature. Also, there were employed three adaptive observers, one is used to estimate the vapor pressure, the other two observers are used to estimate a parameter in each actuator, in that way is estimated the size, instant and magnitude of the fault. The active fault tolerant system is based on the compensation of the fault based on the information given by the fault detection and diagnosis system. The fault tolerant in sensor is based in the reconfiguration of the faulty sensor. The main contribution of this work is that proposed scheme is able to detect and diagnosis, multiple and simultaneous failures in sensors and at least in one actuator. The simulation test shows that the control law allows that the liquid molar concentrations required in distillates, follow the reference properly, even in presence of faults.