Analysis Of Current Characteristics Of Cable Metal Sheath In Small Current Grounding System

With the progress of electric power technology and the rapid development of urban modernization,cable line to the affected by external factors of small,high power supply reliability gradually replace the original overhead power lines,cable wire substation gradually become the main way of substation outlet,especially in cities,the application of high voltage distribution network transformer substation is becoming more and more widely.Due to the cable in the cable trench line,engineering hidden,in order to ensure the power supply reliability and fault fast positioning,this makes the analysis of wire cable insulation fault of more and more important role.Therefore,this article in view of the small current grounding system cable metal sheath current characteristics were analyzed,and the summary analysis the transient characteristics of the power cable grounding line current.According to the grounding line current can realize cable line fault line selection.This article mainly done the following work:1.The basic structure of cable outlet of 35 k V substation is analyzed,and the grounding method of metal sheath is introduced.The grounding method of metal sheath is selected,and the simulation parameters of cable core and metal sheath are given.The basic model of the overhead line is analyzed,and the simulation parameters and simulation model of the overhead line are given.2.Based on the structural characteristics of the cable,the steady-state characteristics of the single-phase earth fault of the 35 k V small current grounding system are analyzed,and the influence of the grounding mode of the small current grounding system is fully considered.Furthermore,the single-Wave characteristic theory.3.On the basis of 1 and 2,the 35 k V cable-overhead line model was es Tab.lished by using PSCAD4.5 simulation software,and the single-core cable-overhead line and three-core cable-overhead line simulation model were es Tab.lished respectively.Aiming at the single-phase cable-overhead line,the characteristics of the cable metal layer current and the cable ground line are analyzed for the single-phase cable-overhead line single-phase-to-ground fault and the bus position fault.Core cable-overhead line for cable ground line current characteristics of the analysis.4.Based on the characteristics of the transient traveling wave of the cable,the method and criterion of the small current grounding fault line are obtained by using the grounding current of the cable sheath,and the fault initial angle,fault location and fault transition Resistance and other factors to verify the simulation.In this paper,the characteristics of the current of the cable metal sheath under the single-phase grounding fault of the small current grounding system are analyzed,and the fault line of the small current grounding fault is analyzed by using the grounding current of the cable sheath.