Research On Diagnosis Theory And Key Technology For The Operating State Of Insulator

The working environment of insulator is critical and there are many complicated factors influence its running. It is difficult to monitor those comprehensive variables which influence the running of insulator and which indicate the running state of insulator. Now, it is an important task for the domain of power transmission to research the diagnosis and prediction system of the running state of insulator. After the research of the formation mechanism and the developing process of insulator's flashover and the intelligent diagnosis technology, a diagnosis expert system is designed for the insulator which can diagnose the operating state of insulator outright. The integrating theory based on expert system, fuzzy reasoning system, Petri net, and neural network is put forward to be used to diagnose the running state of insulator. The diagnosis strategies and theory of diagnosis expert system are presented. The reasoning system based on fuzzy neural Petri net has been thoroughly discussed.In order to design the diagnosis expert system of the running state of insulator commendably, the formation mechanism, the developing process and reason of insulator's flashover is analyzed and researched. After analyzing the complicated relation of some factors, effective diagnosis and prediction method is summarized. Flashover physical and mathematical models are used to analyze critical current, critical arc voltage and the critical length, which provides a theoretical basis for designing the intelligent expert diagnosis system.In order to resolve the problem that the resource of knowledge and reasoning rules of diagnostic expert system of the insulator's running state, some effective factors and correlation are detail analysised and some characteristic variables are summed. The idea that the running state of insulator is diagnosed synthetically based on those characteristic variables is presented and the advanced monitoring and diagnosing system for insulator and the positioning system for insulator's flashover are given. In order to eliminate the noise signal of leakage current, wavelet denoising method based on the threshold value is used to eliminate the noise signal of sampled signal.Based on the analysis of diagnostic methods and strategies for insulator's running, the expert diagnostic system based on fuzzy neural Petri network is proposed to diagnose the operating state of insulator. Fuzzy Petri net and neural network are integrated to optimize system, which makes expert system have the ability of fuzzy reasoning, learning and optimization. In the design of expert diagnostic system, the modularized structure is designed and synthetical method is used to express knowledge. After summing the key technology and judging basis, the expert diagnostic reasoning system is designed for the diagnosis of insulator. Fuzzy Petri net are also extended in its concept and theory, which makes the net's express of reasoning system relations between input and output is easier. A lot of works have been done for designing system in formation and expression. In expert diagnostic system, continuous function is made for reasoning, which makes the reasoning process more accurate. The improved learning method is used to optimize reasoning system. The diagnostic results validate the reasonableness and accuracy of reasoning system. This research provides effective diagnostic technologies and valuable experience for expert diagnostic system of insulator running.Finally, the dissertation summarizes all the works and results achieved in this dissertation. The further research works to be developed are also put forward.