Positioning method for single-phase earth fault sections of isolated neutral system

A single-phase-to-ground fault, neutral point ungrounded technology, applied in the fault location and other directions, can solve the problems of inaccurate fault location, long fault line, large influence of "S" injection method transition resistance, etc., and the accuracy requirements are not high. , the effect of improving the accuracy

Active Publication Date: 2015-02-04
STATE GRID CORP OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Several fault location methods are provided in the prior art, such as the steady-state zero-sequence current comparison method and the "S" injection method, etc., but the steady-state zero-sequence current comparison method is very long for th

Method used

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  • Positioning method for single-phase earth fault sections of isolated neutral system
  • Positioning method for single-phase earth fault sections of isolated neutral system
  • Positioning method for single-phase earth fault sections of isolated neutral system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] Please refer to figure 1 , figure 1 A flow chart of the process of a method for locating a single-phase ground fault section in a neutral point ungrounded system provided by the present invention, the method includes:

[0053] Step s101: selecting a test area on the line to be tested;

[0054] It can be understood that at first a line is selected as the line to be tested, and a test area is selected on the line to be tested, where the line to be tested and the selection of the test area on the line can be an important area on the important line, or can be It is randomly selected from multiple lines, and is not specifically limited here.

[0055] In addition, the test area mentioned here refers to the area between the two ends when the double-terminal detection device collects the synchronous steady-state zero-sequence current at both ends. It is worth noting that the double-terminal detection device here refers to a device capable of synchronously collecting the stea...

Embodiment 2

[0083] Please refer to image 3 , image 3 It is a flow chart of the process of another method for locating the single-phase ground fault section of the neutral point ungrounded system provided by the present invention. On the basis of the method provided in Embodiment 1, the method also includes:

[0084] Step s307: Judging whether all tests are completed, if yes, proceed to step s308; otherwise, proceed to step s304;

[0085] Step s308: Judging whether the instantaneous values ​​of the steady-state zero-sequence current collected on the line to be tested are all positive values, if yes, proceed to step s309; if not, proceed to step s310;

[0086] It can be understood that firstly judge whether all tests are completed, if not, then return to step s304 to continue fault diagnosis; if yes, then judge whether the instantaneous values ​​of the steady-state zero-sequence current collected on the line to be tested are all positive values, If both are positive, it means that the f...

Embodiment 3

[0099] The invention also provides another method for locating the single-phase ground fault section of the neutral point ungrounded system.

[0100] Because the principle of this method is the same as the method provided by the first embodiment above, the difference from the above method is emphasized here. The only difference is the specific process of judging the area where the fault point is located by combining the current conditions at both ends of the area. different, please refer to Figure 7 , Figure 7 The flow chart of another process for judging the area where the fault point is located in combination with the current situation at both ends of the area provided by the present invention, the process is:

[0101] Step s401: collecting the instantaneous value i of the synchronous steady-state zero-sequence current at both ends of the region A2 i B2 , and calculate i B2 -i A2 Get the difference △i B2A2 ;

[0102] Step s402: Judging △i B2A2 polarity, if △i B2A2...

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Abstract

The invention discloses a positioning method for single-phase earth fault sections of an isolated neutral system. The method comprises the following steps: firstly, collecting synchronous stable zero sequence current instantaneous values at two ends of the previous section of a to-be-detected line; calculating the difference value of the two synchronous stable zero sequence current instantaneous values; and determining the fault position regions by virtue of the polarity of the difference value and polarities of the two zero sequence current instantaneous values. The method disclosed by the invention can be used for positioning the fault regions for the condition that a transitional resistance is relatively great and the change of length of the line is inconsistent in the system and has a low requirement on the precision of equipment, so that the accuracy of positioning the fault regions is improved.

Description

technical field [0001] The invention relates to the field of relay protection of electric power systems, in particular to a method for locating a single-phase ground fault section of a neutral point ungrounded system. Background technique [0002] At present, most of the distribution network adopts a small current grounding system, among which, the small current grounding system can be divided into three types: neutral point ungrounded, arc suppression ring grounded and high impedance grounded. When a single-phase ground fault occurs in a small-current neutral point ungrounded system, since no short-circuit loop is formed, the ground short-circuit current is much smaller than the load current, the fault phase voltage decreases, and the phase voltage of the non-fault two phases increases, but the line voltage However, it is still symmetrical, so it does not affect the continuous power supply to users, and the system can continue to run for a period of time. However, if a sin...

Claims

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Application Information

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IPC IPC(8): G01R31/08
Inventor 雒文博李大兴袁绍军孙荣富夏革非陈广宇程林袁靖
Owner STATE GRID CORP OF CHINA
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