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Method of boundary element utilizing polar wave S transform energy ratio to determine ultra high-voltage direct current transmission line fault

A DC transmission line, UHV DC technology, applied in the direction of emergency protection circuit devices, electrical components, etc.

Active Publication Date: 2012-10-31
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005]3: Voltage variables and ground mode waves are affected by fault distance
[0006] Therefore, based on the rate of change criterion, DC line protection is easily affected by the above factors, resulting in malfunction

Method used

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  • Method of boundary element utilizing polar wave S transform energy ratio to determine ultra high-voltage direct current transmission line fault
  • Method of boundary element utilizing polar wave S transform energy ratio to determine ultra high-voltage direct current transmission line fault
  • Method of boundary element utilizing polar wave S transform energy ratio to determine ultra high-voltage direct current transmission line fault

Examples

Experimental program
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Embodiment Construction

[0084] Simulation model such as figure 1 As shown, a positive ground fault occurs at a distance of 100km from the protection installation, the fault transition resistance is 0.1Ω, the time window length is 2ms, and the sampling frequency is 100kHz.

[0085] (1) After the DC line fails, the starting element starts immediately, according to the formula:

[0086] P 1 (k)=Z p × i 1 (k)-u 1 (k) (10)

[0087] P 2 (k)=Z p × i 2 (k)-u 2 (k) (11)

[0088] Find the positive line polar wave and the negative line polar wave, and the polar wave waveform is shown in Figure (4);

[0089] (2) According to the formula

[0090] S [ m , n ] = Σ k = 0 N - 1 X [ n + k ] e - ...

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Abstract

The invention relates to a method of a boundary element utilizing polar wave S transform energy ratio to determine ultra high-voltage (UHV) direct current (DC) transmission line faults, belonging to the technical field of power system relay protection. The method is as follows: a starting element is started when a DC line breaks down, the polar wave voltages of the positive and negative lines arecalculated according to dipolar DC voltages and DC currents measured at a protective installation part; a discrete polar wave voltage signal the sampling sequence length of which is 200 after faults is subjected to S transform, the transform result is a 101*200 time-frequency complex matrix, and mode operation is carried out on each element in the complex matrix. High-frequency component and low-frequency component of the polar wave voltage are extracted according to the obtained modular matrix, and then the ratio of the high-frequency energy to the low-frequency energy of the polar wave voltage is figured out; and whether the fault is interior or exterior is distinguished according to the value of the ratio of the high-frequency energy to the low-frequency energy. A large number of simulation results show that the invention has good effect.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for using a polar wave voltage S to convert energy ratios to UHV DC transmission line fault boundary elements. Background technique [0002] The existing DC line protection is mainly provided by ABB and SIEMENS. Their fast single-ended protection is based on the sudden change of voltage traveling wave, the rate of change of voltage traveling wave and the gradient of current change as criteria. Although traveling wave protection has ultra-high-speed action characteristics, it is not affected by current transformer saturation, system oscillation, and long-line distributed capacitance. However, according to the relevant data of actual operation at home and abroad, the traveling wave protection of the currently used DC line is affected by the following factors: [0003] (1) The voltage traveling wave is affected by the smoothing reactor and D...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
Inventor 束洪春田鑫萃彭仕欣
Owner KUNMING UNIV OF SCI & TECH
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