Grounding line selection device

Abstract

The invention discloses a grounding line selection device comprising the following units connected in series between a bus terminal (A-B-C) and a grounding terminal (D): a three-phase synchronous operation switch (K3) and a ground transformer (B), a phase separation control switch (K1), an impedor (R1) and a second current transformer (CT2), a phase selection switch (K2) connected in parallel on two ends of the impedor (R1), a voltage sensor (PT), and a controller (KZQ) electrically connected with a branch zero sequence current sensor (CT3-CTn); when single phase grounding faults happen, the controller (KZQ) firstly soft closes a soft switch branch, than closes a grounding transformer branch; when the controller determines the grounding fault is an instant singlephase earth fault according to conditions in which the output of the second current transformer is <=1A, cuts off the soft switch branch and the grounding transformer branch, otherwise, combines with the branch zero sequence current sensor output determination so as to realize line selection and positioning, and disconnects the grounding transformer branch. The grounding line selection device is easily and widely applied to commercialization earth fault processing and line selection fields.

Description

technical field [0001] The invention relates to a line selection device, in particular to a grounding line selection device. Background technique [0002] At present, my country's distribution network based on the neutral point non-effective grounding method has the advantages of high power supply reliability, and most of them adopt this power supply and distribution method. Single-phase ground fault is a common fault in this method. People have made unremitting efforts to determine the faulty branch and deal with it in time. For example, the Chinese utility model patent CN 202275132 U was announced on June 13, 2012 A pulse current line selection device of the applicant. The device is composed of a controller electrically connected to the secondary side of the zero-sequence current transformer on the branch, a grounding transformer connected in series between the busbar and the ground, an insulated gate bipolar transistor, and a voltage transformer, wherein the insulated ga...

AI Technical Summary

Problems solved by technology

Although this device can quickly and accurately determine the branch circuit and phase where the ground fault occurs, it also has shortcomings. Impact damage to the insulation of each component in the transformer is likely to cause secondary interference to the distribution network; secondly, for the frequent or long-term operation of the grounding transformer, a large margin needs to be left, resulting in an excessively large volume and increasing the manufacturing cost. cost; finally, when a permanent single-phase-to-earth fault occurs, it is easy to reignite the fault point

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