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Direct-current self-injection type small-current grounding and route selecting system and method

A small current grounding and line selection technology, applied in the direction of the fault location, can solve the problems of not being able to identify the fault circuit and not being used for line selection

Inactive Publication Date: 2013-09-04
河北兆联电气设备科技有限公司
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  • Abstract
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  • Application Information

AI Technical Summary

Problems solved by technology

The method of injecting an additional DC source into the low-voltage IT system to detect the insulation resistance of the power grid, although the technology is mature, cannot identify faulty circuits and cannot be used for line selection

Method used

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  • Direct-current self-injection type small-current grounding and route selecting system and method

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Embodiment Construction

[0010] Such as figure 1 As shown, a system and method for DC self-injection small current grounding line selection according to the present invention is characterized in that the system includes a DC signal acquisition unit TA D , signal processing and display unit PC, DC signal automatic injection unit D and power transformer neutral point processing unit C 1 .

[0011] Installed on the DC signal acquisition unit TA D The signal acquisition of each feeder line in (TA D ), which is a cable through-type transformer, which has two annular iron cores with the same size and openings and external windings with the same number of turns and winding directions. The two windings are connected in parallel to eliminate AC magnetic flux; the annular iron Only the DC magnetic field is kept in the core; the Hall element is installed at the opening of the core, the DC signal is extracted by the external circuit and the voltage signal is output, and then processed by the PC to display the ...

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Abstract

The invention provides a commonly-known direct-current self-injection type small-current grounding and route selecting system and method, which are applicable to trouble shooting of single-phase earth faults of a non-effective grounding system of a radiation type middle-voltage power grid and a low-voltage power distribution IT (Information Technology) system. The system comprises a direct-current signal collection unit, a signal processing and displaying unit, a direct-current signal automatic injection unit and a power supply transformer neutral point processing unit. According to the commonly-known direct-current self-injection type small-current grounding and route selecting system and method disclosed by the invention, under the realization condition of applying an electromagnetic voltage transformer, an injection method of a direct-current signal is simplified; special direct-current power supply equipment does not need to be arranged and the direct-current signal is not injected into a power grid under a normal operation condition; and only if the single-phase earth faults happen, the direct-current signal is automatically injected into the power grid, and the injection is simple and reliable and is easy to realize. A self-injection manner after half-wave rectification of zero sequence voltage is ingeniously utilized.

Description

technical field [0001] The invention relates to a system and a method for selecting a small current grounding line, in particular to a system and a method for selecting a direct current self-injection type small current grounding line. Background technique [0002] Medium-voltage power grid neutral point non-effectively grounded system (including neutral point ungrounded, arc-suppression coil grounded and high-impedance grounded) and low-voltage power distribution IT system, which allow short-term operation with single-phase ground fault, uninterrupted The advantages of power supply, but the investigation of single-phase ground fault is difficult, which disturbs the safe operation of the system. [0003] The small current line selection device widely used at present applies the principles of fundamental wave, third harmonic current direction or amplitude comparison and the combination of the two. That is, the zero-sequence current of the fault circuit lags the zero-sequence...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08
Inventor 张春雷董智君马洪王振东慈润宁佟越波李晓志王化月李卫刘涛
Owner 河北兆联电气设备科技有限公司
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