Fault location approach based on fuzzy five-range SDG and hierarchical method

Conventional fault location method based on signed directed graph (SDG) can reflect the occurrence of the fault by node state. However, it is unable to explain the severity of fault. The conventional method has low inference efficiency due to the complexity of model structure, and it has a difficulty in identifying the real fault origin. In order to solve the above-metioned problems, a hybrid fault location method is developed from three aspects (model, structure and inference). Firstly, an improved five-range SDG model based on fuzzy set theory is proposed to reveal potential cause relationship of variables, to increase quantitative information and to reflect the harm extent of fault. Moreover, a structure simplification method is used to reduce model complexity, and the set of fault origin candidates can be obtained subsequently. In addition, the consistent path priority which includes the fault magnification, the fault support degree and the fault propagation speed is developed to identify fault origin from the candidates. Finally, the reactor of Tennessee Eastman process is modeled with the proposed method, and the result shows that this method has excellent fault location capacity in fault diagnosis.