I. Introduction
Substations play an important role in power systems. When a fault occurs in a substation, a flood of alarm information could be displayed without any analysis on the console in the control center, and lead to the difficulty for dispatchers to identify the faulted section in a short time. Therefore, an accurate and efficient method of fault diagnosis in substation is significant for rapid fault location and hence assures the stability and security of power system. So far, the presented approaches mainly includes Expert Systems (ES) [1]–[2], analytic model based approaches [3]–[6], Artificial Neural Networks (ANN) [7]–[9], Petri Nets[10], [11], Rough Set [12] and so on.