A fault monitoring method for substation cable outlets based on current initial traveling wave polarity

Abstract

The invention discloses a method for monitoring fault of cable outgoing lines of a transformer substation on the basis of current initial traveling wave polarity. Each outgoing line of the transformer substation is provided with a current transformer; and the current transformers are connected with a current initial traveling wave analyzing device. The method comprises the following steps of establishing a cable outgoing line fault simulation model of the transformer substation according to the cable outgoing lines and a distribution network model of the transformer substation; acquiring three-phase current of each outgoing line by using the corresponding current transformer so as to acquire current initial traveling wave of each outgoing line by using the current initial traveling wave analyzing device; and analyzing the current initial traveling wave to confirm a faulty line. By the method, the cable outgoing lines of the transformer substation and distribution lines can be selected, current initial traveling wave characteristics are different when single-phase earth faults occur at different positions, the problem that lines are selected difficultly in the existing small-current earth system is solved by polarity comparison of current initial traveling waves of various phases after single-phase earth faults of the system, and the method is reliable and economical.

Description

technical field [0001] The invention relates to a fault monitoring method for a cable outlet of a substation, in particular to a fault monitoring method for a cable outlet of a substation based on the current initial traveling wave polarity, and belongs to the technical field of cable fault line selection. Background technique [0002] The neutral point ineffective grounding method is widely used in my country's distribution network. This grounding method has the advantages of high power supply reliability, and its single-phase grounding fault has the highest incidence rate. When a single-phase ground fault occurs, the non-fault phase voltage rises to 1.732 times of the original. In some cases, the ground capacitive current may cause an arc to fly over the fault point, and an overvoltage 4-5 times greater than the phase voltage appears instantaneously, resulting in insulation Breakdown, further expanded into two or more points grounding short circuit; the arc at the fault po...

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the deficiencies in the above-mentioned existing technologies, the present invention provides a method for monitoring faults of substation cable outlets based on the initial current traveling wave polarity, which can solve the problem of difficult line selection in the current low-current grounding system, and effectively realize substation cable outlets. Fault line selection of its distribution lines

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