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The Research On Single-Phase Grounding Fault Line Selection And Section Location Of Distribution Network

Posted on:2021-04-25Degree:MasterType:Thesis
Country:ChinaCandidate:L Y LiFull Text:PDF
GTID:2392330620978878Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
The distribution network is an important part of the transmission and distribution of electrical energy,the operation quality of which directly affects the economic development of the society and the well-being of thousands of people.Among distribution network faults,single-phase ground fault probability accounts for the largest proportion.After a single-phase ground fault occurs,timely,fast,and accurate fault line selection and location are of great significance to improve power supply reliability.Most of China's distribution networks use small-current grounding systems to operate,which results in single-phase grounding fault conditions with small fault currents and complex fault conditions,which brings many obstacles to accurate selection of fault line and section location.This article firstly analyzes and summarizes by reading a large number of domestic and foreign literatures,and compares the advantages and disadvantages of the existing route selection and positioning methods.Then the steady-state and transient theoretical models of the small current system are established to analyze the variation rules of steady-state and transient fault signals.This thesis focuses on the analysis of the steadystate characteristics of the two neutral point grounding methods of the small current system and the transient characteristics of the neutral indirectly earthed system when different grounding resistance faults.It provides a theoretical basis for studying singlephase ground fault line selection and section location.This thesis firstly conducts an in-depth analysis of the voltage and current extraction fault components during single-phase ground fault.The signal characteristics of the fault component of line-mode current at the time of fault are analyzed by means of Karenbauer phase-mode transformation,it is concluded that the line-mode current fault component has a clear difference between the fault characteristic area and the nonfault characteristic area.Then apply the improved Hausdorff distance to obtain the characteristic coefficient of the linear mode current increment matrix.Finally,the characteristic coefficient is used to establish the criterion of single-phase ground fault line selection and section location.A distribution network model is built in PSCAD/EMTDC for single-phase ground fault simulation under different fault conditions,which verifies the correctness of the new method.The new method has obvious fault characteristics and has good applicability to the mixture of overhead line and cable line.When the transition resistance is large,the fault line selection and section location can be completed,which is not subject to the constraint of the initial phase angle and fault location.In this thesis,the detection device and the supporting experimental platform are developed at last,and the design ideas of the experimental device are introduced in detail from the aspects of hardware and software.Simulation tests were conducted under laboratory conditions to verify the feasibility of the terminal detection device and algorithm flow.The thesis has 78 figures,21 tables,and 81 references.
Keywords/Search Tags:distribution network, single-phase ground fault, line-mode current fault component, PSCAD, fault line selection and section location
PDF Full Text Request
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