Discrete Event Modeling, Supervisor Control, and Fault Diagnosis of the Chlorinated Water Station of Delfino Based on the Sensor and Actuator Interaction

A chlorinated water station in Delfino, Greece, was studied from the control and fault diagnosis point of view, using the interaction of the devices installed to the station as well as rules resulting from the physical characteristics of the station. The DES models of the station’s devices (pumps, level sensors, flow sensors, and pressure sensors) are presented. The models of the pumps include both the activation/deactivation functionality and the regulation of the output flow of the pump. The models of the devices were validated using field data extracted from the monitoring system of the station. Towards protecting the pump from dry running and the tanks from overflow, a set of safety requirements were realized in the form of supervisor automata. Using field data, the effect of the supervisors in the activation/deactivation of the pumps was tested. A modular fault diagnosis system, where the number of fault diagnosers is equal to the number of pumps, was implemented to diagnose the faulty case of pump having stuck open despite deactivation command. A fault diagnosis system for a flow sensor of the station was developed and tested using the field data of the sensors and the pumping system. Supervisors and diagnosers were tested using one-week field data. The structured language code for PLC implementation of the diagnosers is presented.