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High-resistance ground fault detection method based on zero-sequence current zero-crossing discontinuity discrimination

A high-resistance ground fault and zero-sequence current technology is applied in the direction of measuring electricity, measuring devices, and measuring electrical variables. It can solve problems such as difficult selection of amplitude and phase thresholds, and neglect of time-domain characteristics of electrical quantities. It achieves high sensitivity, harm reduction effect

Active Publication Date: 2014-10-22
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, the above methods all use frequency domain information to detect high-resistance grounding faults. Their limitations are that they completely ignore the time domain characteristics of electrical quantities, and the harmonic content and phase will change under different fault conditions, making it difficult to select a fixed amplitude. and phase threshold

Method used

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  • High-resistance ground fault detection method based on zero-sequence current zero-crossing discontinuity discrimination

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Experimental program
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Embodiment

[0026] This embodiment includes the following steps:

[0027] 1) Sampling the zero-sequence current of the feeder with a sampling frequency of 9kHz to obtain a cycle of sampling value sequence f(n) with a total of 180 points, and low-pass filtering the sampling value sequence with an FIR filter with a filter cutoff frequency of 900Hz to obtain Filtered 180-point sequence F(n), n=1,2,...180;

[0028] f(n)=

[0029][23.05,22.34,64,20.94,20.17,19.33,17.67,16.82,14.97,14.03,14,14,1.12,9.087,066.024,5.003,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103,103. ,0.6728,0.089,-0.3828,-0.7697,-1.066,-1.270,-1.395,-1.486,-1.563,-1.620,-1.641,-1.646,-1.666,-1.701,-1.739,-1.771,-1.821, -1.909,-2.047,-2.231,-2.492,-2.910,-3.623,-4.899,-7.307,-11.51,-16.33,-19.47,-21.04,-21.97,-22.94,-23.96,-25.02,-25.87 ,-26.40,-26.92,-27.30,-27.61,-28.05,-28.51,-28.81,-28.96,-29.08,-29.24,-29.43,-29.55,-29.55,-29.45,-29.44,-29.44,- 29.30,-29.09,-28.87,-28.66,-28.4...

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Abstract

The invention relates to a high-resistance ground fault detection method based on zero-sequence current zero crossing point interruption discrimination and belongs to the field of protection and control of power systems. The method comprises the following steps of: acquiring a zero-sequence current instantaneous value of a monitored feeder line of a substation, calculating the time of the zero-sequence current less than a set value after the zero-sequence current is subjected to zero crossing, and determining that the zero crossing point interruption occurs and determining the fault to be a suspected high-resistance ground fault if the time exceeds a threshold; and determining that a steady-state high-resistance ground fault occurs if the duration of the suspected high-resistance ground fault exceeds the threshold. The method is applicable to a three-phase medium-voltage distribution system with neutral point grounded through resistance, and only a zero-sequence current signal is utilized; and compared with the conventional high-resistance ground fault detection methods, the method has high sensitivity.

Description

technical field [0001] The invention belongs to the field of power system protection and control, in particular to the detection of high-resistance grounding faults in radially connected medium-voltage (6kV-66kV) power distribution lines whose neutral points are grounded through resistance. technical background [0002] Single-phase ground fault is the most common fault phenomenon in power distribution system, accounting for about 70-80% of all faults. In order to improve the reliability of power supply, the traditional domestic 6kV ~ 66kV distribution network generally adopts neutral point non-effective grounding, including: no grounding, arc suppression coil or high resistance grounding and other methods. When a single-phase ground fault occurs in the distribution line of the neutral point non-effectively grounded system, the triangular symmetry of the line voltage remains unchanged and does not affect the continuous power supply of the load; but the non-faulted phase volt...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/02
Inventor 王宾耿建昭董新洲
Owner TSINGHUA UNIV
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