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A method for single-pole grounding fault location suitable for true bipolar flexible straight system

A technology of unipolar ground fault and fault distance, which is applied to the fault location, detects faults according to conductor types, and measures electricity. It can solve problems such as complex and diverse terrain, transient faults and permanent faults, and low correct rate of protection actions.

Active Publication Date: 2022-08-02
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

DC transmission lines are often very long, and the terrain across the region is complex and diverse and has a high failure rate
Due to the current low protection action rate of DC transmission lines, transient faults can easily develop into permanent faults

Method used

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  • A method for single-pole grounding fault location suitable for true bipolar flexible straight system
  • A method for single-pole grounding fault location suitable for true bipolar flexible straight system
  • A method for single-pole grounding fault location suitable for true bipolar flexible straight system

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Embodiment Construction

[0019] Based on the frequency model of the DC transmission line, the invention deduces the ground mode component and the differential mode component, the propagation coefficient and the characteristic impedance of the voltage and current measured by the positive and negative lines at the head end of the DC transmission line when the metallic single-pole ground fault occurs according to the propagation formula of the traveling wave. The relationship between the fault distance is realized by assuming the fault distance and judging whether the relationship is satisfied, which has a high ranging accuracy.

[0020] The invention is based on the frequency model of the DC transmission line, the characteristic impedance Z of the DC transmission line c (f) and the propagation coefficient A(f) are calculated as follows:

[0021]

[0022]

[0023] In the formula, l represents the total length of the DC transmission line, R(f) and L(f) are the resistance and inductance of the line p...

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Abstract

The present invention provides a method for single-pole grounding fault location suitable for true bipolar flexible DC system. component; assume the distance to fault is l mki =i·Δl; calculate the assumed fault distance l mki Each sampling point corresponds to the ranging criterion Dif i (t) value, and then calculate the variance and S of the ranging criterion values ​​of all sampling points under the assumed fault distance i 2 And record; continuously increase the value of i with 1 as the unit length and repeat steps (3) and (4) until l mki The cycle ends when =i·Δl≥l; in all assumed fault distances, the variance and S are calculated i 2 The assumed fault distance l corresponding to the minimum mki is the actual fault distance.

Description

technical field [0001] The invention belongs to the technical field of electric power systems and automatic relay protection thereof, and relates to a method for distance-finding of metallic unipolar grounding faults in a true bipolar flexible direct current transmission system. Background technique [0002] Large-capacity flexible DC transmission systems or flexible DC transmission systems using overhead lines are widely used in the form of true bipolar wiring. Under normal operating conditions, the flexible DC transmission system operates bipolarly. DC transmission lines often have long distances, complex and diverse terrains and high failure rates. Due to the low accuracy of the protection action of the current DC transmission line, transient faults are very easy to develop into permanent faults. When a permanent fault occurs, it needs to be cleared manually. At this time, accurate and reliable fault location technology is particularly important to reduce the workload of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08G01R31/52
CPCG01R31/085G01R31/088G01R31/52
Inventor 李博通黄旭华李春波李斌温伟杰陈晓龙
Owner TIANJIN UNIV