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Method and system for identifying instantaneous fault of overhead DC line

A transient fault, DC line technology, applied in fault location, fault detection according to conductor type, measurement device, etc., can solve problems such as unfavorable DC grid stable operation, improve identification reliability, ensure accuracy, and eliminate secondary impact effect

Inactive Publication Date: 2018-04-13
CHINA ELECTRIC POWER RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The inaccurate judgment will cause the DC circuit breaker to overlap when a permanent fault occurs, which will make the DC grid and the fault point form a current path, and the fault current will form a secondary impact on the DC circuit breaker and DC converter, which is not conducive to the DC grid stable operation of

Method used

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  • Method and system for identifying instantaneous fault of overhead DC line
  • Method and system for identifying instantaneous fault of overhead DC line
  • Method and system for identifying instantaneous fault of overhead DC line

Examples

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Embodiment 1

[0054] The present invention provides a method for identifying instantaneous faults of overhead DC lines, the working principle of which is as follows:

[0055] The DC circuit breaker isolates the fault line during transient faults. The process after the DC circuit breaker is disconnected is divided into two parts: transient state and steady state. The transient process is divided into before and after the transient fault is eliminated, and the fault characteristics before the transient fault is eliminated The same as the permanent fault characteristics, the fault characteristics after the transient fault disappears are significantly different from those before the disappearance.

[0056] (1) After the DC circuit breaker is disconnected, the traveling wave path of the fault voltage before the instantaneous fault disappears is as follows: figure 2 As shown, it appears as a series of frequency components on the spectrum, such as image 3 shown.

[0057] (2) After the DC circu...

Embodiment 2

[0083] Based on the same idea, the present invention provides a transient fault identification system for overhead DC lines, which may include:

[0084] Calculation module, used to collect the DC line voltage, and calculate the voltage spectrum of different data windows;

[0085] The judging module is used to judge whether the amplitude of the transient component of the voltage spectrum is less than a preset first fixed value according to the voltage spectrum, and if it is less than, calculate the voltage amplitude; otherwise, calculate the correlation degree of the voltage spectrum of different data windows;

[0086] A determining module, configured to determine whether it is a transient fault according to the voltage amplitude or the voltage spectrum correlation.

[0087] The determination module includes:

[0088] The first calculation sub-module is used to calculate the voltage amplitude when the amplitude of the transient component of the voltage spectrum is less than a ...

Embodiment 3

[0105] Based on the same inventive concept, the present invention also provides a transient fault handling method for overhead DC lines, which may include the following steps:

[0106] When the overhead DC line fails, collect the DC line voltage and calculate the voltage spectrum of different data windows;

[0107] Determine whether it is a transient fault according to the voltage spectrum;

[0108] When it is determined that the fault is a transient fault, the DC circuit breaker is closed; otherwise, the DC circuit breaker is not closed.

[0109] The fault handling method provided by the present invention judges before the DC circuit breaker recloses after the fault, and recloses the DC circuit breaker according to the judgment result. If the fault is a transient fault, recloses the DC circuit breaker; if the fault is a permanent fault, does not reclose the DC circuit breaker. breaker. The present invention can eliminate the secondary impact on the DC system caused by the c...

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Abstract

The invention provides a method and a system for identifying an instantaneous fault of an overhead DC line, including steps that: when an overhead DC line fails, a DC line voltage is collected to calculate a voltage spectrum of different data windows; and the instantaneous fault is determined according to the voltage spectrum. The technical solution provided by the present invention utilizes the transient state component of the voltage spectrum and voltage characteristics to identify instantaneous faults, and improves the reliability of the instantaneous fault recognition of soft DC overhead lines.

Description

technical field [0001] The invention belongs to the field of relay protection, and in particular relates to a method and system for identifying instantaneous faults of overhead DC lines. Background technique [0002] When the flexible DC grid adopts overhead transmission lines, the probability of transient faults on the transmission lines increases significantly. The causes of faults include lightning strikes, foreign objects, strong winds, etc. After a fault, the faulty line is isolated by a DC circuit breaker. The circuit breaker restores DC line power. [0003] At present, the identification method of the transient fault of the DC line is to reclose the DC circuit breaker after a fixed delay after the trip of the DC circuit breaker. If the fault disappears, it is judged as a transient fault; if the fault still exists, it is judged as a permanent fault and the DC circuit breaker is tripped again. breaker. [0004] This identification method has the following defects: ...

Claims

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Application Information

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IPC IPC(8): G01R31/08
CPCG01R31/085G01R31/088
Inventor 王兴国杜丁香郭雅蓉王江天
Owner CHINA ELECTRIC POWER RES INST
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