Fault location algorithm based on the qualitative and quantitative knowledge of signed directed graph

In term of multivariate operating conditions, complex dynamic performance and steady qualitative logic relation between variables in power plant thermal process, signed directed graph (SDG) is first presented to apply in fault diagnosis of the power plant thermal system, this method has good completeness, and detailed explanation facility. First, the fault patterns can be primary diagnosed by using the qualitative model of SDG, then the patterns with the same qualitative characteristics can be changed to form a qualitative and quantitative model by using fuzzy knowledge, and then can be distinguished effectively by comparing the membership grade of the patterns need be diagnosed to the given fault patterns. The case studies show the qualitative and quantitative model has better resolution in fault diagnosis, even if the system having unmeasurable nodes