ISSN : 1796-203X
Volume : 3    Issue : 11    Date : November 2008

Sensor Location Strategy in Large-Scale Systems for Fault Detection Applications
Fan Yang and Deyun Xiao
Page(s): 51-57
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Fault detection in large-scale systems is conducted by the use of sensors, thus the sensor location
influences the performances of fault detection directly. As the scale of systems increases, traditional
input-output models may not work well or may even not be applicable. The Signed Directed Graph
(SDG) model is used to describe large-scale complex systems and the cause-effect relationships
among variables. However, SDG cannot express the dynamic propagation properties when
describing the fault propagation phenomena. In this paper, time parameters are taken into account
within the branches of an SDG, in order to approximately denote the propagation time of the variable
changes in the systems. An SDG constructed this way is called a dynamic SDG. As to sensor
location, because of the economic and technical limitations, the number of sensors should be
limited while meeting the demands of fault detection. We analyzed the main criteria of the
fundamental demand such as reachability, detectability and identifiability of faults in the framework
of dynamic SDG, and presented an algorithm to describe the fault propagation process using
forward inference and obtained a way to locate sensors. These indices guarantee that the faults can
be detected in time and identified from each other. The criteria change when the faults propagate;
they are much closer to the reality than those in the framework of a traditional SDG. Some general
results, which extend the results obtained in the framework of a traditional SDG, were presented. An
algorithm was presented to describe the fault propagation process using forward inference and a
way to locate the sensors was obtained. Finally, two examples were used to illustrate the proposed
method and results.

Index Terms
sensor location, signed directed graph, largescale complex system, fault detection