Fault tolerant control (FTC) is essential nowadays in the automation industry. It provides a means for higher equipment availability. Fault in dynamical systems can occur due to the deviation of the system parameters from the normal operating range. Alternatively, it can be a structural change from the normal situation of continuous operation such as the blocking of an actuator due to the mechanical stiction. In this research project, a fault tolerant controller is designed with Matlab Simulink for a feedwater system.
The feedwater system components are modified to work under embedded controller design with FTC attached to it. Feedwater systems usually consist of a de-aerator or simply a water storage tank, feedwater pumps, control valves, piping and support fitting elements such as chock valves, anges, hoses and relief valves, beside instrumentation devices like level transmitters, flow transmitters, pressure regulators. The faults are injected separately for each device. Fault diagnostic is used to detect and identify the faults by Limit-checking method. Then a controller is reconfigured to take the action of correcting the hardware failures in the control valve, level sensor, and feedwater pump.
The simulation results revealed that the redundant components can take over and handle the process operation when the fault occurs at the duty components. Level sensors are set to work in on-line mode, while the control valves are set to work in off-line mode, due to the mechanical parts movement. Setting the control valves in on-line mode reduces the probability of valve stiction and elongates the component availability.
The results reveal the operation of feedwater system is not stopped when a hardware failure takes place in all feedwater system major components. Moreover, the disturbances are not considered in this research as there are many control techniques that can be used to handle the disturbance in a robust way.
Fault Tolerant Control Design for Feedwater System