Power transmission line protection method and system based on frequency spectrum characteristic of transient component

A technology of spectrum characteristics and transmission lines, applied in emergency protection circuit devices, electrical components, fault detection according to conductor type, etc., can solve problems such as difference in operating current, slow attenuation of current transient components, and refusal of protection to operate, and achieves the computational complexity of Small, criterion-adaptive effect

Active Publication Date: 2018-05-01
CHINA ELECTRIC POWER RES INST +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when there is a fault in the zone, the line model will change due to the existence of the fault point, so that the action current after taking compensation measures is different from the fault point current. When the line length reaches a certain level, it may cause the protection to refuse to operate.
Since the effective resistance of large-capacity generators and transmission lines with split conductors is very small, the decay time constant of the network is very large, so that the transient components of current and voltage decay very slowly during short circuit, so the transient transition process will last for a long time For a period of time, it will seriously affect the waveform and phase of the power frequency electrical quantity, which may cause protection malfunction. The current measure is to use a filter to filter it out, but the transient component contains a lot of useful fault information. Through effective Utilizing the information of transient components can improve the action performance of protection
[0003] At present, the protection research based on transient components mainly focuses on the utilization of time-domain characteristics, and there are few protection principles based on the frequency-domain characteristics of transient components.

Method used

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  • Power transmission line protection method and system based on frequency spectrum characteristic of transient component
  • Power transmission line protection method and system based on frequency spectrum characteristic of transient component
  • Power transmission line protection method and system based on frequency spectrum characteristic of transient component

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0098] Example 1: figure 2 The fault outside the F1 point of the system shown

[0099] (1) Collect the three-phase current on both sides of the transmission line Calculate the β mode component of the current on both sides of the line, the calculation formula is Using the Fourier algorithm to calculate the β-mode current spectrum ( image 3 shown).

[0100] Calculate according to the formula

[0101]

[0102] In the formula, I(f N ) represents: current amplitude; N represents: frequency spectrum; i β Indicates: current β modulus value; n indicates: sampling value.

[0103] (2) Carry out differential calculation on the spectrum signal, set the threshold value Iset, and set the frequency value whose amplitude is smaller than Iset in the current spectrum to zero. Reserve the frequency value whose amplitude is greater than Iset in the spectrum, and set its amplitude to 1A, and set the rest to 0. The processed spectrum is as follows Figure 4 shown.

[0104] (3) Calcu...

Embodiment 2

[0105] Example 2: figure 2 Fault in the F2 point area of ​​the system shown

[0106] (1) Collect the three-phase current on both sides of the transmission line Calculate the β mode component of the current on both sides of the line, the calculation formula is Calculate the β-mode current spectrum ( Figure 5 shown).

[0107] (2) Carry out differential calculation on the spectrum signal, set the threshold value Iset, and set the frequency value whose amplitude is smaller than Iset in the current spectrum to zero. Reserve the frequency value whose amplitude is greater than Iset in the spectrum, and set its amplitude to 1A. The processed spectrum is as follows Figure 6 shown.

[0108] (3) Calculate the frequency difference Δf at the protection point 1 1 , transmitted to protection 2, the frequency difference at protection 2 is Δf 2 , and Δf 2 -Δf 2 > fset, it is judged as an internal failure.

[0109] The present invention proposes a transmission line protection sys...

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Abstract

The invention relates to a power transmission line protection method and system based on a frequency spectrum characteristic of a transient component. The method comprises that three-phase currents atthe two sides of a line after a fault are obtained, and beta-mode currents taking the three phases as reference are calculated; when all the beta-mode currents of the three phases do not equal 0, aninter-phase fault occurs, and the type of the inter-phase fault is determined via preset inter-phase fault protection criteria; when the inter-phase fault is an internal fault, a protection motion iscarried out rapidly; and when the inter-phase fault is an external fault, the protection motion is not carried out. The preset inter-phase fault protection criteria comprises that internal and external faults are determined according to frequency spectrums of beta-mode currents at the two sides of the line and a difference between the frequency spectrums. According to technical schemes of the invention, the criteria are highly adaptive, and the method and system are suitable for ultra / extra high voltage power transmission lines with relatively high distributive capacitance as well as series compensated lines, and transmission lines with parallel reactors.

Description

technical field [0001] The invention relates to the field of electrical technology, in particular to a transmission line protection method and system based on transient component spectrum characteristics. Background technique [0002] For high-voltage lines, especially EHV and UHV transmission lines, due to the large distributed capacitance of the line, the capacitive current after a fault will affect the action performance of power frequency protection. The current conventional method is to compensate the capacitive current. However, when there is a fault in the zone, the line model will change due to the existence of the fault point, so that the operating current after taking compensation measures is different from the current at the fault point. When the line length reaches a certain level, the protection may refuse to operate. Since the effective resistance of large-capacity generators and transmission lines with split conductors is very small, the decay time constant of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26G01R31/08
CPCH02H7/26G01R31/085
Inventor 王兴国杜丁香郭雅蓉周泽昕曹虹
Owner CHINA ELECTRIC POWER RES INST
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