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UHV DC line fault identification method with use of filter branch current and fractal box dimension

A technology of UHV DC and DC lines, which is applied in the direction of fault location and fault detection according to conductor type, and can solve the problem that DC protection cannot withstand high resistance

Active Publication Date: 2017-01-04
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The technical problem to be solved in the present invention is to propose a UHV DC line fault identification method using filter branch current and fractal box dimension in view of the problem that the current DC protection cannot withstand high resistance

Method used

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  • UHV DC line fault identification method with use of filter branch current and fractal box dimension
  • UHV DC line fault identification method with use of filter branch current and fractal box dimension
  • UHV DC line fault identification method with use of filter branch current and fractal box dimension

Examples

Experimental program
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Effect test

Embodiment 1

[0056] 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.

[0057] According to the first step, the current i(t) is obtained by using the filter branch measurement terminal Q; according to the second step and formula (1), the frac...

Embodiment 2

[0060] Example 2: On June 1, 2015, a ±800kV DC line had I-pole blocking. Before the abnormality occurred, the DC line operated in bipolar mode, and the bipolar power was 3500MW. The number of fault restarts is set to 1, and the traveling wave protection action criterion and setting value of the two pole protections are: d(UdH) / dt>112kV / 0.15ms&deltaU>240kV / 0.15ms&deltaI>1563A. At 18:12:05:659, du / dt in pole I satisfies d(UdH) / dt>112kV and then widens for 6ms. During this 6ms period, d(UdH) / dt, U, and I simultaneously meet the criteria, and pole I Start the DC line fault recovery sequence, and block 87DCLT (DC line lateral difference protection), 87DCLL (DC line longitudinal difference protection), WPDFL (traveling wave protection) and 27du / dt (DC low voltage protection) at the same time.

[0061] According to the first step, the current i(t) is obtained by measuring the terminal Q of the filter branch, such as figure 2 Shown; Find the fractal box dimension D=1.2775 of electr...

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Abstract

The invention relates to a UHV DC line fault identification method with the use of filter branch current and a fractal box dimension, belonging to the technical field of power system protection. When a DC line is failed, the filter branch measuring end is used to obtain current data. K (k is larger than or equal to 2) squares with the side length of epsilon 1, epsilon 2 to epsilon k are selected to cover current i(t), and the box dimension D of the current i(t) is obtained. Finally, DC line area inner and outer faults are identified according to a condition whether the box dimension D is larger than a fixed value Dset. According to the method of the invention, a 'relative mode' is used to measure the characteristic of a fault waveform, the ability of resisting transition resistance is strong, and the accuracy is high.

Description

technical field [0001] The invention relates to a method for identifying faults of UHV DC lines using filter branch currents and fractal box dimensions, and belongs to the technical field of power system protection. Background technique [0002] Through the analysis of the traveling wave protection action of the actual operating DC line in the field, it is found that for non-high-resistance faults, the fault waveform obtained by the 6.4kHz sampling rate at the observation end of the line shows that the time domain characteristics of the internal fault data of the line show similar The time-domain characteristics of the fault data under the external fault of the line are also similar, which reflects the modality of the fault data: similar within the same fault mode, and different among different fault modes. For the same fault mode, different fault distances and different transition resistances, the amplitude and slope of the time domain waveforms are different, but there is ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08
CPCG01R31/085
Inventor 束洪春何婕王璇宋晶田鑫萃
Owner KUNMING UNIV OF SCI & TECH
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