Method for faulty indication and subsection of power system low current grounding

Abstract

An indication and sectionalizing method of the small current grounding fault of the power system relates to the detecting field of the grounding fault of the power system. The method is characterized in that the back zero sequence equivalent capacity of the detecting point is estimated, simultaneously the related information of the transient phase voltage and the transient zero sequence current caused by the fault is utilized as the basis of the fault indication and sectionalizing. The back zero sequence equivalent capacity of the detecting point is estimated according to the collected transient phase voltage and the transient zero sequence current after the fault, and whether the fault detecting device is actuated to alarm is determined according the value of the zero sequence capacitor. The method has the advantages of only need of one phase voltage transformer for realization, effective decrease of the production cost, obtaining the phase voltage signal for the cable line via the sheet iron that is covered on the line and grounded via the RC circuit, being simple and feasible, higher amplitude of the transient signal than that of the stationary signal and easy detecting, and no influence from the grounding mode of the neutral point of the system.

Description

technical field

[0001] The invention belongs to the field of detection and processing of grounding faults in electric power systems, and in particular relates to a single-phase grounding fault indication and segmentation method of a medium-voltage distribution network in a neutral point ungrounded, grounded through an arc suppressing coil, or a high-resistance grounded system. Background technique

[0002] Most of my country's power distribution system adopts the neutral point grounding method of ungrounded neutral point or resonant grounded (grounded through arc suppression coil). Due to the small fault current and the unstable grounding process caused by arc light, single-phase ground fault detection has been difficult to solve completely.

[0003] In the neutral point ungrounded power grid, when the single phase is grounded, the power frequency zero-sequence current of the fault line is equal to the sum of the capacitance currents of all healthy lines to the ground, and t...

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