A study on fault detection and diagnosis for VAV air handling units of real buildings

Research on fault detection and diagnosis of variable air volume (VAV) air-conditioning systems is of great significance for energy conservation and stable operation of the air-conditioning systems. A fault detection and diagnosis (FDD) strategy using a hybrid method is presented for VAV air handling units in this paper. The Cumulative sum (CUSUM) control charts are used to detect faults in air handling units. The CUSUM control charts are used to monitor the temperature errors between the supply air temperature and its setpoint. Faults are detected when the CUSUM values exceed the chart limits. The fault detection method is robust enough to cope with the non-stationary characteristics of the VAV air handling units. Three rule-based fault classifiers consisting of expert rules and fault isolation algorithms are developed to isolate fault sources. The FDD strategy was tested and validated using in real time data from real VAV air-conditioning systems.