Study On The Fault Diagnostic Method Of Equipments Based On Extension Theory

The internal and international progresses as well as the problems in the condition monitoring and fault diagnostics of rotating machinery and pressurized equipments are reviewed. The foundation of extension theory, which is based on matter element model, is introduced. The expressions of matter element for things are described, while the extension theory is applied to the condition monitoring and fault diagnostics of rotating machinery and pressurized equipments. In order to overcome the restriction on the fault diagnosis in classical set theory, the multiple faults are analyzed quantitatively and qualitatively with the help of the concept of correlation degree instead of the concept of yes-no. The divergence, extensibility, relativity and conjugate of fault characteristics of equipments are analyzed from the point of view of extension theory. Rhombus thought of matter elements is put forward and the idea of multiple matter elements is used to fault diagnosis, which supplies a new approach to describe the characteristics of the faults. The matter element model of the fault characteristics and fault situation are established. By introducing the concepts of the difference field and the recognition field, the biggest dependence rule and the smallest close field rule are brought forward, and a new multiple faults diagnostic method based on extension theory is deduced which can determine the type of faults qualitatively and the possibility quantitatively. The multiple faults diagnosing of a gas turbine is illustrated by using the deduced method, which shows that the method is effective on multiple faults diagnosis of the gas turbine.In order to solve the problem that the recognition ability weakens badly when the ranges of the characteristics of faults with multiple parameters superpose or overlap, the factors affecting the recognition ability to faults are investigated. It is supposed that the relations between characteristic parameters of the faults can be regarded as secondary parameters which are the characteristic parameters too. The concept of secondary characteristic parameters is put forward and the ratio method to extract the secondary characteristic parameters is deduced. The parametric difference ratio method is investigated with emphasis to extract the secondary characteristic parameters, and the relative root mean square method and correlative degree method of mean admittable field are put forward to find the best secondary characteristic parameters. The corresponding algorithms are deduced and realized. According to the characteristic of the acoustic emission from pressurized special equipments, Three-parameter-patio pethod is brought forward used to diagnose the faults of pressurized special equipments, and the recognition ability is improved obviously, solving the problem of the fault diagnosis with multiple parameters while the ranges of the characteristics of faults superpose or overlap.