Method and device for positioning single-phase ground faults in star-shaped three-phase ungrounded system

A single-phase grounding fault and grounding system technology, applied in fault location, fault detection by conductor type, signal transmission system, etc., can solve problems such as low ground fault accuracy, and achieve faster positioning time, accurate positioning, and accelerated feedback and Aggregated effects

Inactive Publication Date: 2017-05-31
DEZHOU POWER SUPPLY COMPANY OF STATE GRID SHANDONG ELECTRIC POWER +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In view of the low price of the fault finder and the low accuracy rate of judging the ground fault, most ground faults still need to be found by on-site operation and maintenance personnel along the line to inspect and observe with the naked eye

Method used

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  • Method and device for positioning single-phase ground faults in star-shaped three-phase ungrounded system
  • Method and device for positioning single-phase ground faults in star-shaped three-phase ungrounded system
  • Method and device for positioning single-phase ground faults in star-shaped three-phase ungrounded system

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Effect test

Embodiment 1

[0036] A method for locating a single-phase ground fault point in a star-shaped three-phase ungrounded system: when a ground fault occurs in the line, a different-frequency current signal different from the frequency of the power grid is injected into the midpoint of the three-phase line in sequence, and the two-phase current signal of the injection point is detected. If no current signal is detected in the other two phases, and the current signal strength on one side of the injection point is greater than the current signal strength on the other side, it is determined that the current phase is a faulty phase;

[0037] Continue to inject the different-frequency current signal at the end of the faulty phase, if the different-frequency current signal can be detected at the midpoint A of the faulty phase line, it means that the single-phase grounding fault point is still at the other end of A and the faulty phase line between A and B; take the midpoint B from A to the other end of...

Embodiment 2

[0041] Embodiment 2: On the basis of the method for locating the single-phase ground fault point in the above-mentioned star-shaped three-phase ungrounded system, record the time and the position of the fault point from when the circuit breaks down to the location of the fault point, and use wireless communication to report to the target Terminal sends. Its beneficial effect is that the detection results can be sent to the target terminal through the nearest local area network or 4G network in time by using the information network, which effectively accelerates the feedback and aggregation of information.

Embodiment 3

[0043] Such as image 3 As shown, a device for locating a single-phase ground fault point in a star-shaped three-phase ungrounded system includes a signal generating device for generating different frequency current signals; a signal conducting device connected with the output of the signal generating device for sending to The transmission line injects different frequency current signals; the signal detection device is used for detecting different frequency current signals. The device has the advantages of simple structure, convenient use, fast and accurate detection and positioning.

[0044] Wherein the signal detection device can be a hand-held signal detection device. The signal generating device also includes a liquid crystal display module, a dedicated metering chip, a signal generating device box, and a storage battery. The liquid crystal display module is used to display the frequency and amplitude of the different frequency current signal. The beneficial effect is t...

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Abstract

The invention relates to a method and a device for positioning single-phase ground faults in a star-shaped three-phase ungrounded system. The method includes sequentially injecting abnormal-frequency current signals different from a power grid frequency into a midpoint of a three-phase line when the line is in ground fault, and detecting current signal intensities on two sides of the injection point so as to determine a fault phase; continuing to inject the abnormal-frequency current signals at the end of the fault phase, and indicating that a single-phase fault point is positioned between A and the other end of a fault-phase line if the abnormal-frequency current signals can be detected at the midpoint A of the fault-phase line; acquiring a midpoint B between the A and the other end of the fault-phase line, and indicating that the single-phase ground fault point is positioned between the A and the B if the abnormal-frequency current signals cannot be detected; repeating the above steps until the single-phase ground fault point is positioned within a visual range distance of human eyes. The method is capable of accelerating positioning of single-phase ground fault points effectively and accurate in positioning.

Description

technical field [0001] The invention relates to a method and a device for locating a single-phase ground fault point in a star-shaped three-phase ungrounded system. Background technique [0002] In my country's star-shaped three-phase ungrounded system, since the neutral point is not effectively grounded, after a single-phase ground fault occurs, the fault signal is weak, which makes it difficult to automatically locate the fault point. [0003] Take Dezhou Power Grid as an example: Dezhou Power Grid uses a large number of fault finders as the main means of detecting single-phase ground fault points in star-shaped three-phase ungrounded systems. The structure of this device is simple, and the cost of a single set is low. It is usually installed at the rear section of the switch and the T interface of the branch line, and one set is installed about every 300 meters. figure 1 List the line lengths of Zhaohu Station and Zhaozhai Station in Dezhou Direct Supply District and the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08G08C17/02
CPCG01R31/086G08C17/02
Inventor 李仟成刘志刚沙超毕美妍张振民鞠浩李娜陈成蛟孙海洋张勇胡建伟
Owner DEZHOU POWER SUPPLY COMPANY OF STATE GRID SHANDONG ELECTRIC POWER
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