Method for testing biochemical erosion axial distribution imbalance degree of cable outer sheath

Abstract

The invention discloses a method for testing the biochemical erosion axial distribution imbalance degree of a cable outer sheath. Comprising the following steps: (1) inputting a test excitation signal to a to-be-tested cable; (2) collecting a test signal reflection wave; (3) calculating a time domain reflection energy space distribution ratio; (4) calculating a time domain reflection energy space distribution imbalance degree; the method has the advantages that excitation test signals are injected into the head end of a to-be-tested cable sheath and a cable core loop, reflected wave signals are collected synchronously, the time-domain reflected energy space distribution imbalance degree of the reflected wave signals is calculated, the axial distribution imbalance degree of biochemical erosion of the cable outer sheath is evaluated, and the method is simple, efficient and high in reliability. And the axial distribution imbalance degree of the biochemical erosion of the cable outer sheath can be well evaluated.

Description

Technical Field

[0001] This invention belongs to the field of testing and evaluation of biochemical erosion of cable outer sheath, and specifically relates to a method for testing the axial distribution unevenness of biochemical erosion of cable outer sheath. Background Technology

[0002] Since the beginning of the 21st century, my country's rapid economic development has driven the continuous expansion of its power grid. Power cables, due to their advantages such as reliable power supply and minimal impact on the urban environment, have gradually replaced overhead lines and become the core equipment of urban power transmission and distribution networks. However, cables face the risk of insulation damage due to various factors during operation. In the southern coastal areas, cables are susceptible to biochemical corrosion, leading to sheath failure and damage. Biochemical corrosion refers to the destructive behavior of biological or chemical factors on the cable substrate. Under buried laying conditions, the cable sheath is in direct contact with the soil, making it vulnerable to biological corrosion. Termites are a major source of damage; during foraging or nest building, they can bite through the cable sheath, leading to further corrosion of the internal metal sheath and water-blocking strip by formic acid, microorganisms, and moisture, damaging the cable's original performance, causing insulation aging, and in severe cases, insulation breakdown and power outages. In addition, rodent gnawing can also cause sheath damage, accelerating cable aging and insulation failure, threatening cable operation safety.

[0003] Currently, there are no testing methods related to the uneven axial distribution of biochemical erosion on the outer sheath of cables. Therefore, it is urgent to find a testing method to assess the uneven axial distribution of biochemical erosion on the outer sheath of cables, providing a scientific basis for developing operation and maintenance management measures for the biochemical erosion status of the outer sheath of cables in operation. This is of great significance for ensuring the safe and reliable operation of power cables and extending their service life. Summary of the Invention

[0004] This method is a test method for the axial distribution unevenness of biochemical erosion of cable outer sheath. The method is simple and convenient to operate, and can effectively evaluate the axial unevenness of biochemical erosion of cable outer sheath by calculating the spatial distribution unevenness of time-domain reflected energy of the cable under test.

[0005] The technical solution of the present invention is as follows:

[0006] 1. A method for testing the axial distribution unevenness of biochemical erosion on the outer sheath of cables, comprising the following steps:

[0007] Step 1: Inject an excitation test signal into the cable under test and collect the reflected wave.

[0008] A linear frequency modulated pulse excitation signal is injected into the cable sheath and core circuit under test at the first end, and the reflected wave signal is acquired simultaneously. ;

[0009] Step 2: Calculate the spatial distribution ratio of reflected energy in each time domain of the reflected wave signal.

[0010] The entire reflected wave signal is determined based on the signal time length. Divide the region into 100 equal areas, and ensure the dominance and sensitivity of biochemical erosion fault reflection pulses under noisy conditions. Calculate the normalized spatial distribution ratio of temporal reflection energy in each region:

[0011]

[0012]

[0013] in, , , The maximum value in the original signal. The minimum value in the original signal. The average value of the original signal. The length of the cable to be measured is... The wave speed of the signal in the cable. The reflected energy values ​​for each region, The spatial distribution ratio of temporal reflectance energy in each region;

[0014] Step 3: Calculate the spatial distribution non-uniformity of temporal reflectance energy.

[0015]

[0016] in, To divide the area into regions, The mean of the spatial distribution ratio of time-domain reflectance energy;

[0017] Step 4: Based on the spatial distribution unevenness of time-domain reflective energy Assessing the uneven axial distribution of biochemical erosion on the cable outer sheath.

[0018] Based on the uneven spatial distribution of time-domain reflectance energy To assess the unevenness of the axial distribution of biochemical erosion of the cable outer sheath in the cable under test. and The smaller the value, the more unbalanced the distribution.

[0019] The beneficial effect of this invention is that by injecting an excitation test signal into the cable sheath and core circuit under test at the first end and simultaneously acquiring the reflected wave signal, the spatial distribution unevenness of the time-domain reflected energy of the reflected wave signal is calculated to evaluate the axial distribution unevenness of the biochemical erosion of the cable outer sheath. This method is simple and efficient and can provide a good evaluation of the axial distribution unevenness of the biochemical erosion of the cable outer sheath. Attached Figure Description

[0020] Figure 1 This invention relates to a flowchart of a method for testing the axial distribution unevenness of biochemical erosion on the outer sheath of cables; Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific implementation process.

[0022] Figure 1 A flowchart of a test method for the axial distribution unevenness of biochemical erosion on the outer sheath of a cable, including the following steps:

[0023] 1. A method for testing the axial distribution unevenness of biochemical erosion on the outer sheath of cables, comprising the following steps:

[0024] Step 1: Inject an excitation test signal into the cable under test and collect the reflected wave.

[0025] A linear frequency modulated pulse excitation signal is injected into the cable sheath and core circuit under test at the first end, and the reflected wave signal is acquired simultaneously. ;

[0026] Step 2: Calculate the spatial distribution ratio of reflected energy in each time domain of the reflected wave signal.

[0027] The entire reflected wave signal is determined based on the signal time length. Divide the region into 100 equal areas, and ensure the dominance and sensitivity of biochemical erosion fault reflection pulses under noisy conditions. Calculate the normalized spatial distribution ratio of temporal reflection energy in each region:

[0028]

[0029]

[0030] in, , , The maximum value in the original signal. The minimum value in the original signal. The average value of the original signal. The length of the cable to be measured is... The wave speed of the signal in the cable. The reflected energy values ​​for each region, The spatial distribution ratio of temporal reflectance energy in each region;

[0031] Step 3: Calculate the spatial distribution non-uniformity of temporal reflectance energy.

[0032]

[0033] in, To divide the area into regions, The mean of the spatial distribution ratio of time-domain reflectance energy;

[0034] Step 4: Based on the spatial distribution unevenness of time-domain reflective energy Assessing the uneven axial distribution of biochemical erosion on the cable outer sheath.

[0035] Based on the uneven spatial distribution of time-domain reflectance energy To assess the unevenness of the axial distribution of biochemical erosion of the cable outer sheath in the cable under test. and The smaller the value, the more unbalanced the distribution.

Claims

1. A method for testing the axial distribution unevenness of biochemical erosion on the outer sheath of a cable, comprising the following steps: Step 1: Inject an excitation test signal into the cable under test and collect the reflected wave. A linear frequency modulated pulse excitation signal is injected into the cable sheath and core circuit under test at the first end, and the reflected wave signal is acquired simultaneously. ; Step 2: Calculate the spatial distribution ratio of reflected energy in each time domain of the reflected wave signal. The entire reflected wave signal is determined based on the signal time length. Divide the region into 100 equal areas, and ensure the dominance and sensitivity of biochemical erosion fault reflection pulses under noisy conditions. Calculate the normalized spatial distribution ratio of temporal reflection energy in each region: in, , , The maximum value in the original signal. The minimum value in the original signal. The average value of the original signal. The length of the cable to be measured is... The wave speed of the signal in the cable. The reflected energy values ​​for each region, The spatial distribution ratio of temporal reflectance energy in each region; Step 3: Calculate the spatial distribution non-uniformity of temporal reflectance energy. in, To divide the area into regions, The mean of the spatial distribution ratio of time-domain reflectance energy; Step 4: Based on the spatial distribution unevenness of time-domain reflective energy Assessing the uneven axial distribution of biochemical erosion on the cable outer sheath. Based on the uneven spatial distribution of time-domain reflectance energy To assess the unevenness of the axial distribution of biochemical erosion of the cable outer sheath in the cable under test. and The smaller the value, the more unbalanced the distribution.

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