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Resonant grounding power distribution network high-resistance grounding fault line selection method and system and storage medium

A high-resistance grounding fault, resonant grounding technology, applied in the fault location, detecting faults by conductor type, short-circuit testing, etc., can solve the problems of high-resistance grounding fault detection and line selection, etc. long-running effects

Pending Publication Date: 2021-11-30
STATE GRID HUNAN ELECTRIC POWER +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention provides a method, system and storage medium for line selection of high-impedance grounding faults in a resonant grounding distribution network to solve the problem that the existing methods cannot realize the detection and line selection of high-impedance grounding faults

Method used

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  • Resonant grounding power distribution network high-resistance grounding fault line selection method and system and storage medium
  • Resonant grounding power distribution network high-resistance grounding fault line selection method and system and storage medium
  • Resonant grounding power distribution network high-resistance grounding fault line selection method and system and storage medium

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Effect test

Embodiment 1

[0047] like figure 1 , figure 2 As shown, this embodiment provides a method for line selection of a high-impedance ground fault in a resonant ground distribution network, including:

[0048] Step S1: Obtain the zero-sequence voltage of the busbar of the distribution network. Since the zero-sequence voltage of the busbar is greater than the zero-sequence voltage setting value (5% of the rated value of the phase voltage in this embodiment), go to step S2.

[0049] Step S2: Obtain the zero-sequence current sequence {x(n)} of a feeder on the bus; where the zero-sequence current sequence {x(n)} is a feeder on the bus with a sampling frequency of 10kHz after a delay of 0.2 seconds The zero-sequence current is obtained by continuous sampling for 0.03 seconds, n=1, 2, 3,...,300.

[0050] Step S3: Obtain the first local extremum point of the waveform after the first zero-crossing point of the zero-sequence current sequence - the extremum point x(n 1 ), where n 1 is the sampling va...

Embodiment 2

[0060] like figure 1 and image 3 As shown, the difference between this embodiment and embodiment 1 only lies in:

[0061] Step S3: Obtain the first local extreme point of the waveform after the first zero-crossing point of the zero-sequence current sequence—the maximum point x(n 1 ), where n 1 is the sampling value sequence number of the extremum point; obtain the second local extremum point of the waveform after the zero-sequence current waveform crosses the zero point again—the extremum point x(n 2 ), where n 2 is the sampling value sequence number of the extreme point; the zero-sequence current waveform between the two extreme points is as follows image 3 (a) shown.

[0062] Step S6: if image 3 The sequence GoL(k) shown in (c) is almost all positive, and the number of negative ones is less than 5, then it is judged that the line does not have a high-impedance ground fault (maybe the three-phase parameters of the line are unbalanced, or a low-impedance fault occurs...

Embodiment 3

[0064] like figure 1 and Figure 4 As shown, the difference between this embodiment and embodiment 1 only lies in:

[0065] Step S3: Obtain the first local extremum point of the waveform after the first zero-crossing point of the zero-sequence current sequence - the extremum point x(n 1 ), where n 1 is the sampling value sequence number of the extremum point; obtain the second local extremum point of the waveform after the zero-sequence current waveform crosses the zero point again—the maxima point x(n 2 ), where n 2 is the sampling value sequence number of the extreme point; the zero-sequence current waveform between the two extreme points is as follows Figure 4 (a) shown.

[0066] Step S6: if Figure 4 The number of positive and negative numbers in the sequence GoL(k) shown in (c) is roughly equal, and they are all far greater than 5. It is judged that a high-impedance grounding fault has occurred on the line.

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Abstract

The invention discloses a resonant grounding power distribution network high-resistance grounding fault line selection method and system and a storage medium, and the method comprises the steps: obtaining the bus zero-sequence voltage of a power distribution network, and carrying out preliminary judgment; then obtaining a zero-sequence current sequence of one feeder line on the bus; obtaining a first local extreme point of the waveform after the zero-sequence current sequence crosses the zero point for the first time, and a second local extreme point of the waveform after the zero-sequence current waveform crosses the zero point again; taking a central point of the two local extreme points as a time window center, and solving a zero-sequence current linearity sequence under different time window widths; solving a change rate sequence of the zero-sequence current linearity sequence; if the positive number and the negative number in the change rate sequence are both not smaller than the preset number, judging that the feeder line has a high-resistance grounding fault; otherwise, determining that the feeder line does not have the high-resistance grounding fault. A high-resistance fault line can be timely and accurately selected, fault elimination is facilitated, long-time operation of a distribution line under a high-resistance fault is avoided, and safe and reliable operation of a power distribution network is guaranteed.

Description

technical field [0001] The present invention relates to the field of intelligent power distribution technology, in particular to a method, system and storage medium for line selection of a high-impedance grounding fault in a neutral point resonant grounding distribution network. Background technique [0002] my country's medium-voltage distribution network widely adopts the grounding method of ungrounded neutral point or arc suppression coil, also called small current grounding. When a single-phase ground fault occurs in a low-current grounding system, no short-circuit loop will be formed, the ground fault current is very small, and the line voltage between the three phases of the system is basically kept symmetrical, which will not affect the load power supply, and the system can run with faults for a period of time , high power supply reliability. However, due to the small single-phase ground fault current, the difficulty of fault detection is increased. [0003] Due to ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08G01R31/52
CPCG01R31/086G01R31/52
Inventor 车红卫王哲刘啸
Owner STATE GRID HUNAN ELECTRIC POWER
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