Active Sensor Configuration Validation in Refrigeration Systems

This master’s thesis presents an approach to validation of the sensor con-figuration in control systems. Major faults in the commissioning phase of refrigeration systems are caused by defects related to sensors. With a num-ber of similar sensors that differ only by spatial location and their use in the control system, fault-finding is not trivial and it often results in expensive delays. Validation and handling of faults in the sensor configuration are therefore essential to cut costs during commissioning. With passive fault-diagnosis methods falling short on this problem, this thesis describes an ac-tive diagnosis procedure to isolate sensor faults at the commissioning stage, before normal operation has started. Using statistical methods, residuals are evaluated versus multiple hypothesis models in a minimization process to uniquely identify the sensor configuration. The method as such is generic and is shown in the sequel to work convincingly on refrigeration systems with both nonlinear behaviors and significant mutual differences. The thesis includes sections concerning the target system with respect t