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Fault discrimination method of UHV DC line based on frequency band measurement impedance

A technology of UHV DC and impedance measurement, which is applied in the direction of detecting faults according to conductor types, measuring electricity, measuring devices, etc., can solve the problem of loss of selectivity, etc., and achieve the effects of reducing hardware costs, easy engineering implementation, and simple calculations

Active Publication Date: 2018-07-27
SHANGHAI JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • Fault discrimination method of UHV DC line based on frequency band measurement impedance
  • Fault discrimination method of UHV DC line based on frequency band measurement impedance
  • Fault discrimination method of UHV DC line 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

A fault discrimination method for UHV DC lines based on frequency band measurement impedance. Firstly, the voltage and current on both sides of the DC line are sampled to obtain the voltage and current in a specific frequency band, and then the measured impedance and its sudden change in the frequency bands on both sides are calculated. The mutation amount is compared with the set fault discrimination threshold value to distinguish line faults. The present invention uses the ratio of frequency band voltage to current, that is, frequency band measurement impedance as the fault criterion. The frequency band measurement impedance when faults occur in the zone is determined by system parameters and topology. Theoretically, it is not affected by transient voltage and current amplitude, and can overcome the traditional transient harmonic protection that is easily affected by transition resistance and line attenuation, and is insensitive to changes in parameters such as line impedance parameters, line length, and smoothing reactors.

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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Patent Type & Authority Patents(China)
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 JIAOTONG UNIV