Study And Implementation Of A Portable Vibration Monitoring And Fault Diagnosis System For Power Transformers

The large-scale power transformer is one of the key equipments in the power industry,and its safe operation is highly significant to ensure the safety and reliability of the electrical power networks.Therefore,it is a vital research topic to monitor the online condition of power transformers.Recent years adopting the vibration analysis for state monitoring and fault diagnosis has become a hot issue of research.Compared with the traditional method,the transformer fault diagnosis method based on the vibration signal analysis is sensitive to the internal mechanical structure of the transformer,and has no electrical connection with the whole power system,and can be safely and reliably used for the condition monitoring of the transformer.At present,research of vibration monitoring system is basically used for experimental analysis,while those that are used in the actual site monitoring and diagnosis system are very rare.At the same time,neither the accuracy nor the practicality is satisfying.Not to mention that there is basically no portable form of the vibration monitoring system in China or abroad.This paper is on the basis of vibration analysis.Features which can reflect the vibration distribution of the transformer oil tank has been extracted for transformer fault diagnosis,and on this foundation,a set of portable vibration monitoring and fault diagnosis system for power transformers has been designed in this paper.The main contents of this paper are summarized as follows:First of all,through the study of transformer vibration mechanism,features that can reflect the vibration distribution of oil tank surface have been put forward.And the vibration amplitude center and vibration centre trajectory what is used in featuring the mechanical center of gravity of the vibration amplitude and its variation trajectory in a vibration cycle.In this paper,an experiment of simulated failure has been conducted with a real transformer to comparing the features of vibrational distribution before and after the transformer failure,proving that features can be effectively used in fault diagnosis of transformers.Based on what has been mentioned above,this paper mainly studies the system of portable vibration monitoring and fault diagnosis system for power transformers,and at the same time,a signal acquisition subsystem based on embedded Linux is developed which includes the circuit of hardware and signal acquisition of software.Hardware circuit which has the functions of signal conditioning,signal acquisition,network communication,system timing and power supply,includes the embedded core board,signal conditioning module,signal acquisition module,network communication module,real-time clock module and power module.Signal acquisition software is capable of signal sampling,data storage and data management,including the modules of signal sampling function based on PRU,data storage function and data management function.Finally,the test of the whole portable system in the laboratory environment and the actual site environment has been completed.The results show that the portable system can work steadily and reliably in the actual site,as well as effectively achieve the vibration monitoring and fault diagnosis for power transformers.