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Ultrahigh voltage direct current line fault discrimination method based on frequency band measurement impedance

An ultra-high voltage DC, measuring impedance technology, applied in the direction of detecting faults, measuring electricity, measuring devices, etc. according to conductor type, can solve problems such as loss of selectivity, reduce hardware costs, overcome the effects of transition resistance and line attenuation, and is easy to use. The effect of engineering

Active Publication Date: 2016-08-24
SHANGHAI JIAO TONG UNIV
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Problems solved by technology

However, the amplitude of the specific frequency component of this technology is easily affected by the fault transition resistance and the attenuation of the DC line. When it is applied to an ultra-high DC system, it will lose selectivity for the discrimination of high-impedance faults and line-end faults.

Method used

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  • Ultrahigh voltage direct current line fault discrimination method based on frequency band measurement impedance
  • Ultrahigh voltage direct current line fault discrimination method based on frequency band measurement impedance
  • Ultrahigh voltage direct current line fault discrimination method based on frequency band measurement impedance

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Embodiment 1

[0031] Such as figure 1 As shown, M and N are the measurement points of the voltage and current at both ends of the DC line respectively, and A, B, C, and D respectively indicate the location of the fault point outside the DC line area, where A and B are located between the converter and the smoothing reactor At the connection line, C and D are located at the AC commutation bus on the rectifier side and the inverter side, and F indicates the location of the fault point of the DC line. figure 1 The schematic diagram of the DC filter is inside the dotted line box, such as figure 2 As shown, for the UHV DC transmission system, 12 / 24 double-tuned filters and 12 / 24 / 36 triple-tuned filters are generally configured.

[0032] When the DC transmission system is faulty, the fault point can be regarded as a transient harmonic source during the fault transient state. The transient harmonic source is located at the fault point of the DC line, and the transient harmonic current flows fro...

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Abstract

The invention discloses an ultrahigh voltage direct current line fault discrimination method based on frequency band measurement impedance. Voltage and current of two sides of a direct line can be sampled, and voltage and current in specific frequency band can be acquired, and then frequency band measurement impedance of two sides and break variable thereof can be calculated, and then the line fault can be discriminated by comparing the break variable with the set fault discrimination threshold value. The ultrahigh voltage direct current line fault discrimination method is advantageous in that by adopting the ratio between the frequency band voltage and the frequency band current, and the frequency band measurement impedance can be used as the fault criterion, and then the frequency band measurement impedance during the internal fault can be determined by the system parameter and the topology, and cannot be affected by the transient voltage and the current amplitude theoretically, and therefore the problem of the conventional transient harmonic protection being easily affected by the transition resistor and the line attenuation, and being not sensitive to the changes of the parameters such as the line impedance parameter, the line length, and the smoothing reactor, and other parameters can be overcome.

Description

technical field [0001] The invention relates to a technology in the field of fault diagnosis of electric power systems, in particular to a fault discrimination method of UHV DC lines based on frequency band measurement impedance. Background technique [0002] UHV DC transmission lines are often used as connection lines for large-area networking. DC lines are generally long, spanning a wide area, and operate in harsh environments. The probability of failure is high, and the reliability of fault discrimination is low. [0003] At present, the main protection of HVDC transmission line is equipped with traveling wave protection and differential undervoltage protection, and the differential undervoltage protection is also used as the backup protection of traveling wave protection. Backup protection is equipped with current differential protection, and some projects are also equipped with low voltage protection. However, traveling wave protection and differential undervoltage pro...

Claims

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Application Information

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IPC IPC(8): G01R31/08
CPCG01R31/085G01R31/088H02H3/40H02H3/44H02H5/105
Inventor 刘剑邰能灵范春菊杨亚宇郑晓冬
Owner SHANGHAI JIAO TONG UNIV
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