The Establishment Of Fault Model And The Research Of Diagnosis Method For Generator

The power industry as the leading industry for sustainable development of the national economy developed very fast.Many large units have been put into operation.However, the increase of the unit capacity make the structure and system more and more complex,how to ensure the unit to work safe,reliable,economical and efficient is vital to the security and stability of the whole power system.Due to rapid rotation of the large generators rotor in operation,suffering considerable mechanical stress and thermal loads,also by the great action of the electromagnetic force,so part of the rotor fault diagnosis is particularly important.The rotor winding one-point grounding and inter turn short circuit is common electrical fault.This paper from the traditional test method and electrical secondary relay protection,made a detailed discussion on the generator rotor one-point grounding fault diagnosis.Also analyzed the change of electrical parameters after the rotor winding interturn short circuit.The main work of this paper consists of four parts:The first part discuss the generator rotor one-point grounding fault and the analysis of measured data.Introduces the structure of generator rotor,rotor system fault causes and rotor ground fault hazards.And the actual power plant rotor circuit grounding alarm fault,for example,elaborate the explanation of one-point earth fault,monitoring,diagnosis and treatment of cases,made the appropriate electrical tests,analysis the possible reasons of the fault,take appropriate action and put forward the preventive measures.The second part study the low-frequency square wave injection type on rotor one-point ground protection and its application.Analyzed the characteristics of the square-wave voltage injection type on rotor one point ground protection,derived the protection criterion,and use simulation results to verify the correctness of theoretical analysis.Third part research on generator rotor winding inter-turn short circuit.Introduced the classification of generator rotor winding inter turn short circuit,advantages and disadvantages of various traditional detection methods and applications.Analysis the electromagnetic properties of turn to turn short circuit and typical fault-related parameters were determined.Part IV investigate artificial neural network apply to fault diagnosis of inter-turn shortcircuit of rotor.Introduced the basics of artificial neural network and its advantages and disadvantages.According to rotor of generator rotor winding inter-turn short circuit would cause the current increases but the relative reduction in the reactive,get the learning samples of neural networks, by means of the generator monitoring data to build a prediction model of BP neural network based on LM algorithm, and diagnosed the existence and severity of the rotor winding inter-turn short circuit fault.