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HVDC transmission line protection method based on initial voltage traveling wave frequency domain attenuation rate

A DC transmission line, initial voltage technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the problems of reduced protection sensitivity, inability to accurately identify high-resistance faults, etc., and achieve the effect of high sensitivity

Active Publication Date: 2021-02-23
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above methods operate quickly, but there is a problem that the protection sensitivity decreases significantly with the increase of the transition resistance, and the high-resistance fault in the area cannot be accurately identified.

Method used

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  • HVDC transmission line protection method based on initial voltage traveling wave frequency domain attenuation rate
  • HVDC transmission line protection method based on initial voltage traveling wave frequency domain attenuation rate
  • HVDC transmission line protection method based on initial voltage traveling wave frequency domain attenuation rate

Examples

Experimental program
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Effect test

Embodiment 1

[0034] Based on the analysis of the attenuation rate of the fault initial voltage traveling wave frequency domain, the present invention concludes that when the following conditions are met: the current-limiting reactor is not less than 50mH, the transition resistance of the fault in the zone is less than 1500Ω, and the transition resistance of the unipolar fault outside the zone is less than 325Ω , the transition resistance of bipolar faults outside the zone is less than 650Ω, and the fault distance is less than 800km. In the frequency band 1k ~ 10kHz, the rate of initial voltage traveling wave decay with the increase of frequency under faults inside and outside the zone can be approximated as a constant, and the zone The frequency domain attenuation rate of the initial voltage traveling wave under external faults is twice that of internal faults.

[0035] figure 1 It is a schematic diagram of a ±400kV flexible direct current transmission system. figure 1 Middle L ij (i, j=...

Embodiment 2

[0079] The purpose of this embodiment is to provide a computing device, including a memory, a processor, and a computer program stored in the memory and operable on the processor. When the processor executes the program, the specific steps in Embodiment 1 are implemented. .

Embodiment 3

[0081] The purpose of this embodiment is to provide a computer-readable storage medium.

[0082] A computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the specific steps in the first implementation example are executed.

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Abstract

The invention discloses a DC transmission line protection method based on the attenuation rate of the initial voltage traveling wave frequency domain, which is characterized in that it includes: measuring the voltage at the installation place of the positive pole and the negative pole head end protection of the DC line, and constructing a low-voltage start-up criterion; if the protection starts, Measure the current at the installation place of the positive and negative poles of the DC line, and identify the fault direction according to the sign of the integral value of the positive or negative current fault component; if it is a positive fault, calculate the line-mode voltage traveling wave of the DC line, and make different scales for it Stationary wavelet transform, and extract the maximum value of the wavelet transform modulus at the corresponding scale; calculate the equivalent attenuation rate in the frequency domain of the initial voltage traveling wave, and identify faults inside and outside the line according to the absolute value of the rate. The invention satisfies the requirement of the fast main protection of the DC line, and can reliably identify high-resistance faults in the area and faults outside the area with high sensitivity.

Description

technical field [0001] The invention belongs to the field of relay protection of electric power systems, in particular to a DC transmission line protection method based on the attenuation rate of the initial voltage traveling wave in the frequency domain. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] DC transmission has significant technical advantages in large-scale renewable energy grid connection, asynchronous AC system connection and long-distance large-capacity transmission, and its application will become more and more extensive. Due to the low inertia characteristics of the DC power grid, a DC fault will generate a large short-circuit current in a very short period of time, which will cause great damage to the semiconductor devices in the converter station, and even cause the converter station to be blocked and the entire network...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
CPCH02H7/265H02H7/268
Inventor 丛伟张韵琦
Owner SHANDONG UNIV
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