Study On Fault Diagnosis And Location Technology Of High Voltage Cable Based On Sheath Current Method

Power cables have become widely used in power systems due to their superior electrical,chemical and mechanical properties.During the operation of the cable,main insulation faults and sheath insulation faults may occur.This paper mainly studies the diagnosis and location methods of insulation faults in cable sheath cross-connect systems.By analyzing the circulating data,the fault can be diagnosed and located quickly to the possible area.This greatly reduces the workload.Firstly,the formation mechanism of circulation is studied.Research indicates that the sheath circulation is generated the combination of electromagnetic induction and electrostatic induction.The electromagnetic induction is main part of the sheath circulation.The cross-connected sheath simulation model of the normal operation system is established.The correctness of the simulation model is verified by theoretical model.Based on that,the simulation model of the double-circuit cable is established.The circulation of the double-circuit cable is calculated.It is compared to the circulation of a single loop cable.Research indicates that the circulation difference is small between the double-circuit and the single-circuit.Secondly,a simulation model of the main insulation fault is established.It is used to study the circulation distribution of main insulation faults.The influence of laying method,grounding resistance,uneven cable laying need to consider.Research indicates that the circulating current data can be used for fault location when the main insulation fault occurs.It could find the small segment where the fault point is located.When the main insulation fault occurs,the above influence factors have less influence on the main insulation fault location.Finally,a simulation model of the insulation fault is established.It is used to study the circulation distribution under the insulation failure of the sheath.The effects of laying method,grounding resistance and uneven cable laying on fault diagnosis and positioning are also considered.Research indicates that the diagnosis and location of the insulation failure of the cable sheath can be realized by monitoring and analyzing the circulation of the sheath.There is a blind spot in the fault diagnosis and location of the insulation of the sheath.This is related to cross-connected grounding resistance and fault point grounding resistance.Different laying methods and uneven laying of cables have less influence on the diagnosis and position.