The Research And Design Of Fault Diagnosis System For A Distribution Card Used In A Power Station

With China’s power system moving towards large capacity and ultra-high voltage,how to operate the power system stably,reliably and safely has become the focus problem.As an important card in the power station,the power distribution card is responsible for realizing the functions of battery charging mode switching,voltage monitoring and fault isolation.When it breaks down,it will directly affect the normal operation of the battery pack,and may cause relay protection equipment damage and power failure.At present,the main maintenance method of the card is that the operator replaces the card which is detected as a fault through live testing.This method not only requires high skills of operators,but also causes waste of cards.Therefore,this thesis takes this card as the research object,and designs and forms a fault diagnosis system that meets the needs of many kinds of users such as maintenance,diagnosis and management.First of all,the thesis makes a survey of the current fault diagnosis technology at home and abroad and the current fault diagnosis situation in the power system field.It points out that the existing fault diagnosis technology in the power system field is seldom applied to the diagnosis of precision circuits,thus clarifying the purpose and significance of the research in the thesis.Secondly,in order to deeply analyze the failure mechanism of the card,the card circuit is divided into functional modules such as high-voltage alarm,low-voltage alarm,floating charge switching,etc.,and the principle analysis and sensitivity analysis are carried out for each sub-circuit,and the functional monitoring points and sensitive components of each module are selected according to the analysis results.Thirdly,standard modeling and simulation,fault mode setting and fault modeling and simulation of the card are completed by PSPICE simulation software.Output waveforms of monitoring points of the card under normal and various fault states form a case library similar to a fault dictionary.Then,according to the characteristics of fault dictionary case base,various diagnostic methods are studied,and a diagnostic method combining waveform similarity and fuzzy mathematics is proposed.Finally,the detailed design process of the fault diagnosis system formed by applying the above theory is described.The system consists of testing device,communication network and upper computer platform software.After installation and debugging,the system can display the power-on test waveform of the card in real time and automatically give a diagnosis conclusion.In general,the fault diagnosis system designed in this thesis takes the power station distribution card as the research object,which can reduce the workload of maintenance personnel in the power station,implement preventive decision before the fault,realize rapid diagnosis during the fault,obtain optimization experience after the fault,and finally reduce the card maintenance,purchase cost and damage risk of power station equipment.