Fault diagnosis method based on sign directed graph models

The application problem of sign directed graph (SDG) models under varying load conditions of industrial processes is being analyzed according to the processes particularities. Some industrial processes are subjected to frequent load variations, and each typical mode of operation has its own stable state, which also corresponds to a particular node pattern of the SDG model with all the node patterns being different from one-another. The mathematical expression of under varying load conditions of node patterns, as well as the SDG way of fault diagnosing, are given; where with the processes' degree of stability under varying load condition can be on-line ascertained with the help of a stability factor. Taking a deaerator as an example, the influence of load varying condition on SDG diagnosing is being discussed.