The incoming line source of 10 kV substation and distribution substation is generally an isolated neutral system.The feeder and through lines inside the substation and distribution substation of high-speed railway are mostly full cable lines,in the event of a single-phase grounding fault,the zero-sequence protection of the feeder cable does not trip but only alarms,allowing the faulty feeder to operate with faults.However,the insulation margin of power cables is much smaller than that of overhead lines,and their ability to withstand overvoltage is low.Once a single-phase grounding fault occurs,it is easy to cause permanent insulation breakdown,which can develop into a phase-phase fault and expand the range of fault.The paper proposes a small current selection method for faulty feeder lines in substation and distribution substation of high-speed railway,it is able to accurately identify the feeder lines on which single-phase grounding faults occur and is able to avoid expansion of scope of fault.For high resistance grounding faults,a comprehensive line selection method based on transient variables is proposed.In addition to comparing the amplitude and phase of zero sequence current between fault and non-fault lines,accurate line selection is also carried out by application of the direction of transient reactive power.
10 kV substation and distribution substation of high-speed railwaysingle phase grounding faultoptimization of protection scheme
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