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Multi-fractal spectrum ultra-high voltage direct current line fault identification method based on filter branch current

A multi-fractal spectrum, UHV DC technology, applied in the direction of fault location, fault detection according to conductor type, instrument, etc., can solve DC blocking accidents, cannot reliably respond to high-impedance faults, and longitudinal differential protection cannot achieve backup protection Function and other issues, to achieve the effect of strong ability

Inactive Publication Date: 2017-02-22
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Through the analysis of the action of traveling wave protection in engineering practice, it is found that traveling wave protection with du / dt as the core often cannot respond reliably to high impedance faults (High impedance fault, HIF), and as a longitudinal Differential protection relies on time delay to avoid transient response during AC system faults to ensure that it does not malfunction
At the same time, in order to avoid misoperation during power adjustment, the SIMENS differential protection has added a blocking logic, so the exit delay of the longitudinal differential protection is too long, which may cause the longitudinal differential protection to often fail to function as a backup protection. It may even cause the protection of the DC control system to act first, causing unnecessary DC blocking accidents

Method used

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  • Multi-fractal spectrum ultra-high voltage direct current line fault identification method based on filter branch current
  • Multi-fractal spectrum ultra-high voltage direct current line fault identification method based on filter branch current
  • Multi-fractal spectrum ultra-high voltage direct current line fault identification method based on filter branch current

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] Example 1: Establish as attached figure 1 The Yun-Guang ±800kV UHV DC transmission system is shown as the simulation model. The reactive power compensation capacities of the rectifier side and the inverter side are 3000 and 3040Mvar respectively. Each pole commutation unit is composed of two 12-pulse converters connected in series. The total length of the DC transmission line is 1500km. 400mH smoothing reactors are installed on both sides of the line, and the DC filter is a 12 / 24 / 36 three-tuned filter. The total length of the grounding electrode line on the rectification side is 109km, and the total length of the grounding electrode line on the inverter side is 80km. Now assume that the positive line is 100km away from the M terminal and a ground fault occurs, and the transition resistance is 100Ω.

[0060] According to step 1, the current i(t) is obtained by using the filter branch measurement terminal Q; according to step 2 and formula (1), the mass distribution prob...

Embodiment 2

[0061] Example 2: Establish as attached figure 1 The Yun-Guang ±800kV UHV DC transmission system is shown as the simulation model. The reactive power compensation capacities of the rectifier side and the inverter side are 3000 and 3040Mvar respectively. Each pole commutation unit is composed of two 12-pulse converters connected in series. The total length of the DC transmission line is 1500km. 400mH smoothing reactors are installed on both sides of the line, and the DC filter is a 12 / 24 / 36 three-tuned filter. The total length of the grounding electrode line on the rectification side is 109km, and the total length of the grounding electrode line on the inverter side is 80km. Assume now that a ground fault occurs 1000km away from the M terminal on the negative pole line, and the transition resistance is 100Ω.

[0062] According to step 1, the current i(t) is obtained by using the filter branch measurement terminal Q; according to step 2 and formula (1), the mass distribution pr...

Embodiment 3

[0063] Example 3: Establish as attached figure 1 The Yun-Guang ±800kV UHV DC transmission system is shown as the simulation model. The reactive power compensation capacities of the rectifier side and the inverter side are 3000 and 3040Mvar respectively. Each pole commutation unit is composed of two 12-pulse converters connected in series. The total length of the DC transmission line is 1500km. 400mH smoothing reactors are installed on both sides of the line, and the DC filter is a 12 / 24 / 36 three-tuned filter. The total length of the grounding electrode line on the rectification side is 109km, and the total length of the grounding electrode line on the inverter side is 80km. Assume now that a ground fault occurs at the outlet of the rectifier side, and the transition resistance is 10Ω.

[0064] According to step 1, the current i(t) is obtained by using the filter branch measurement terminal Q; according to step 2 and formula (1), the mass distribution probability p is obtained...

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Abstract

The invention relates to a multi-fractal spectrum ultra-high voltage direct current line fault identification method based on filter branch current and belongs to the technical field of direct current line protection. When a direct current line has a fault, a sampling frequency is 6.4kHz, and a filter branch measurement end is used for obtaining current data; and k (k>=2) squares of proper edges of [Epsilon] 1, [Epsilon] 2, ...[Epsilon] k are selected to over current i(t), so as to obtain the quality distribution probability pk ([Epsilon]) and the non-uniform degree index [delta][alpha], and finally faults inside and outside a direct current line area are identified according to that whether the non-uniform degree index [delta][alpha] is larger than a fixed value [delta][alpha]set or not. The invention generates time domain waveforms in case of faults inside and outside the direct current line area based on the multi-fractal spectrum, constructs protection criteria hereby, and achieves the stronger traveling wave protection transition-resisting resistance capability.

Description

technical field [0001] The invention relates to a fault identification method of an ultra-high voltage direct current line based on a filter branch current multi-fractal spectrum, and belongs to the technical field of direct current line protection. Background technique [0002] The distance of DC transmission lines is long, the environment across regions is complex, and the probability of failure is high. Actual operating data shows that DC line failures account for about 50% of DC transmission system failures. However, actual engineering shows that the protection rate of DC line protection is only 50%, and nearly half of the DC line faults are activated by the control system, directly blocking the DC transmission system, which will cause unnecessary DC outages. The DC line fault leads to the blocking of the DC system, which not only causes a large amount of load loss, but also has a great impact on the power grid, and even affects the stable operation of the power grid. A...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08
CPCG01R31/085G01R31/088
Inventor 束洪春范黎涛杨晨曦王璇宋晶田鑫萃
Owner KUNMING UNIV OF SCI & TECH
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