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Study On The Method Of Fault Type Identification And Fault Segment Location For Distribution Lines Based On Distributed Non-contact Measurement

Posted on:2021-04-24Degree:MasterType:Thesis
Country:ChinaCandidate:T HeFull Text:PDF
GTID:2492306107981739Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
With the rapid development of social economy,social production and people’s life demand higher and higher reliability of power supply system.The distribution system is directly facing the vast number of users,and its safe and stable operation will have a direct impact on the reliability of power supply and the interests of users.The operation environment of distribution lines is complex and prone to faults.Identifying fault types and locating fault sections reliably can help isolate fault areas and restore power supply to non fault areas,narrow the scope of line patrol,shorten the time for emergency repair personnel to eliminate faults,and reduce many adverse effects caused by faults.Most of the existing methods of fault type identification and fault section location use fault voltage and current signals as information sources,while the traditional voltage and current transformers are limited in geometry sizes,insulation strength and transient response speed because they need to be measured in direct contact with the line.In addition,the installation and maintenance of voltage and current transformers along the line are inconvenient,and there are potential ferromagnetic resonance hazards,which is not conducive to the promotion and use of the methods.Considering that the electromagnetic field around the line is its inherent property,the electromagnetic field also has fault information after the fault occurs,and the electromagnetic field measurement does not need to contact with the line directly,so it is convenient to arrange measurement devices along the line and obtain fault information.Therefore,this paper provides a new idea for the distribution system fault automation by extracting and analyzing the electromagnetic field characteristics differences along the fault line for fault type identification and section location.The main research contents of this paper are as follows:(1)According to the quasi-static characteristics of transient electromagnetic field after distribution line fault,the calculation model of electric field and magnetic field of distribution line is established.By comparing with other methods to verify the accuracy of the model.(2)Four kinds of typical faults(single-phase grounding fault,two-phase shortcircuit grounding fault,two-phase short-circuit fault and three-phase short-circuit fault)of distribution lines are modeled and simulated.The transient voltage and current data are extracted after the fault occurs,and the differences of electric and magnetic field characteristics of different types of faults are calculated and analyzed.A fault type based on the differences of electromagnetic field characteristics is proposed in combination with k nearest neighbor algorithm(KNN)Pattern recognition algorithm.(3)According to the results of fault type identification algorithm,four typical faults are divided into two types: the grounding fault(single-phase ground fault and two-phase short-circuit grounding fault)and the short-circuit fault(two-phase short-circuit fault and three-phase short-circuit fault).For the grounding fault,by setting several electric field measurement points along the line,extracting the electric field characteristics along the line after the fault occurs,and combined with the dynamic time warping algorithm(DTW),this paper propose a fault section location method based on distributed electric field information.(4)For the short-circuit fault,the magnetic field characteristics along the line are extracted by setting multiple magnetic field measurement points along the lines.Based on the section location algorithm of the grounding fault and combined with the action time of relay protection,a fault section location method based on distributed magnetic field information is proposed.
Keywords/Search Tags:Distribution lines, electromagnetic field features, fault type identification, fault section location
PDF Full Text Request
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