Large-scale complex systems have the feature of including large amount of variables that have complex relationships, for which signed directed graph （SDG） model could serve as a significant tool by describing the ca...Large-scale complex systems have the feature of including large amount of variables that have complex relationships, for which signed directed graph （SDG） model could serve as a significant tool by describing the causal relationships among variables. Although qualitative SDG expresses the causing effects between variables easily and clearly, it has many disadvantages or limitations. Probabilistic SDG proposed in the article describes deliver relationships among faults and variables by conditional probabilities, which contains more information and performs more applicability. The article introduces the concepts and con- struction approaches of probabilistic SDG, and presents the inference approaches aiming at fault diagnosis in this framework, i.e. Bayesian inference with graph elimination or junction tree algorithms to compute fault probabilities. Finally, the probabilistic SDG of a typical example of 65t/h boiler system is given.展开更多
This paper puts forward a new fault diagnosis model based on Petri net.In this new fault diagnosis method,an associated tree is f irst defi ned to describe the logic according to the protections and circuit breakers.A...This paper puts forward a new fault diagnosis model based on Petri net.In this new fault diagnosis method,an associated tree is f irst defi ned to describe the logic according to the protections and circuit breakers.After that a Petri net diagnosis model comes into being and the precise diagnosis of power grid elements can be realized at the same time.The simulation results given in this paper illustrate that this fault diagnosis method can make a rapid diagnosis in complex fault situation and give accurate results to power grid fault diagnosis.展开更多
文摘Large-scale complex systems have the feature of including large amount of variables that have complex relationships, for which signed directed graph （SDG） model could serve as a significant tool by describing the causal relationships among variables. Although qualitative SDG expresses the causing effects between variables easily and clearly, it has many disadvantages or limitations. Probabilistic SDG proposed in the article describes deliver relationships among faults and variables by conditional probabilities, which contains more information and performs more applicability. The article introduces the concepts and con- struction approaches of probabilistic SDG, and presents the inference approaches aiming at fault diagnosis in this framework, i.e. Bayesian inference with graph elimination or junction tree algorithms to compute fault probabilities. Finally, the probabilistic SDG of a typical example of 65t/h boiler system is given.
文摘This paper puts forward a new fault diagnosis model based on Petri net.In this new fault diagnosis method,an associated tree is f irst defi ned to describe the logic according to the protections and circuit breakers.After that a Petri net diagnosis model comes into being and the precise diagnosis of power grid elements can be realized at the same time.The simulation results given in this paper illustrate that this fault diagnosis method can make a rapid diagnosis in complex fault situation and give accurate results to power grid fault diagnosis.
