CN110530972B - Ultrasonic detection evaluation method and device for cable aging state evaluation and device using method - Google Patents
Ultrasonic detection evaluation method and device for cable aging state evaluation and device using method Download PDFInfo
- Publication number
- CN110530972B CN110530972B CN201910684557.4A CN201910684557A CN110530972B CN 110530972 B CN110530972 B CN 110530972B CN 201910684557 A CN201910684557 A CN 201910684557A CN 110530972 B CN110530972 B CN 110530972B
- Authority
- CN
- China
- Prior art keywords
- cable
- amplitude value
- running
- aging
- maximum amplitude
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/12—Analysing solids by measuring frequency or resonance of acoustic waves
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
The invention provides an ultrasonic detection evaluation method, a device and a device using method for cable aging state evaluation, wherein echo signals on the inner surface of a main insulation of a cable are collected through an accelerated aging test, the echo signals on the inner surface of the main insulation of the cable are analyzed by a wavelet analysis method to obtain the maximum amplitude value and the average amplitude value of frequency response under different scales, so that a relation curve of the maximum amplitude value and the average amplitude value of the frequency response under different scales of the echo signals on the inner surface of the main insulation of the cable and the equivalent operating age limit under 90 ℃ of the cable is established, the equivalent operating age limit under 90 ℃ of the cable can be judged according to the maximum amplitude value and the average amplitude value of the actual operating cable and the relation curve, and the aging thinnest point and the whole aging state of the cable are evaluated according to the comparison of the actual operating age limit and the equivalent operating age limit under 90 ℃. The invention can simultaneously detect the whole aging state and the local aging state, has higher reliability and can be used for real-time detection.
Description
Technical Field
The invention belongs to the technical field of cable detection, and relates to an ultrasonic detection evaluation method and device for cable aging state evaluation and a device using method.
Background
XLPE of a three-dimensional network structure is widely used in power cable insulation due to its good mechanical properties, heat resistance, insulation properties and stable chemical properties. However, in actual operation, the cable is subjected to long-term combined action of water, heat, electricity and mechanical stress factors, and the physical, chemical and electrical properties of the cable are degraded, so that the stability and the economical efficiency of the operation of a power grid are affected. At present, in the existing service cables in China, the service time exceeds 30 years, the design service life of the earliest cables is generally 30-40 years, and how to accurately and effectively evaluate the aging state of cable insulation becomes a problem which is urgently needed to be solved by the power department. Scholars at home and abroad have a great deal of research on how to evaluate the aging state of cable insulation, and the research is mainly developed from the correlation between a micro molecular structure and macroscopic properties and the aging state.
Due to different electric-heat-force combined actions borne by the cables under different operation working conditions, the sizes, the types and the quantities of defects generated by the cables in operation are different, and the aging states are also different. In addition, even if the cable runs under the same working condition, the temperature of the main insulation inner side of the cable is higher than that of the outer side due to the fact that the cable wraps the high-temperature conductive copper conductor, the inner side of the cable is seriously aged than the outer side of the cable, and the defects are densely distributed on the outer side of the cable. With the increase of the working life of the cable, a part of defects develop from the inner side to the outer side, the defects are in the development trend from small to large and from small to large, and the local aging states of different positions of the cable also change along with the operation life. Therefore, both the overall aging state of the cable and the state where aging is most severe have an impact on the normal operation of the cable, i.e. the aging state assessment of the cable should include: (1) the overall aging state; (2) local aging state.
Most of domestic and overseas researches are based on laboratory researches, such as breakdown tests, thermogravimetric experiments and SEM electron microscope experiments (samples need to be corroded), all detection means have certain destructiveness, and the method cannot be used for field real-time monitoring and analysis of power cables. Previously, the researchers proposed to test the aging state of the cable by using an ultrasonic sound velocity method, but the method only can reflect the overall aging state of the cable, cannot simultaneously reflect the state of the most serious aging position, and cannot be applied to the field real-time movement detection of the whole cable.
Disclosure of Invention
The invention aims to provide an ultrasonic detection evaluation method and device for cable aging state evaluation and a device using method, which solve the problem that the overall and local aging states cannot be detected simultaneously by one method and can realize real-time continuous nondestructive detection.
The invention is realized by the following technical scheme:
an ultrasonic detection evaluation method for cable aging state evaluation comprises the following steps:
s1, taking an unused cable with the same type as the running cable to be evaluated, setting accelerated aging temperature, and carrying out accelerated aging test on the cable;
s2, sampling according to periods, sampling once in each period, placing the cable taken out on the surface of the cable to transmit pulse waves and receive echo signals after the cable is cooled to room temperature by using an ultrasonic probe, and obtaining cable echo signals corresponding to different aging times;
s3, intercepting the cable main insulation inner surface echo signal from the cable echo signal, performing wavelet transformation on the cable main insulation inner surface echo signal to obtain time and amplitude value data under different scales, finding out the maximum amplitude value under different scales and calculating to obtain an average amplitude value, and obtaining the corresponding relation between the aging time and the maximum amplitude value and the average amplitude value under different scales;
s4, obtaining equivalent operation years at 90 ℃ corresponding to different aging times through inverse extrapolation of accelerated aging temperature, obtaining maximum amplitude values and average amplitude values corresponding to the equivalent operation years at 90 ℃ at different scales, and drawing a relation curve of the equivalent operation years at 90 ℃ at different scales with the maximum amplitude values and the average amplitude values;
and S5, testing echo signals of the running cables of the same model on site, processing the echo signals according to S3 and S4 to obtain maximum amplitude values and average amplitude values under different scales, comparing the maximum amplitude values and the average amplitude values with the relation curve obtained by S4 to obtain the equivalent running life of the running cables at 90 ℃, comparing the equivalent running life of the running cables at 90 ℃ with the actual running life of the running cables, judging the running history of the running cables, and evaluating the state of the most serious cable aging part and the overall aging state.
Preferably, in S1, before the cable is subjected to the accelerated aging test, the surface of the cable is wiped and cleaned with absolute ethyl alcohol and then dried.
Preferably, in S2, a plurality of echo signals at different positions of the cable are tested in each period, in S3, the maximum amplitude value of each period test is an average of the maximum amplitude values at different positions of the cable, and the average amplitude value of each period test is an average of the average amplitude values at different positions of the cable.
Preferably, in S2, the number of cycles is 5 or more.
Preferably, in S3, the specific step of performing wavelet transform on the echo signal of the inner surface of the main insulation of the cable is as follows: and performing zero processing on the echo signal of the inner surface of the main insulation of the cable, and then performing wavelet transformation on the echo signal of the inner surface of the main insulation of the cable after the zero processing.
Preferably, in S4, the equivalent operating life at 90 ℃ corresponding to different aging times at accelerated aging temperature is obtained by reverse reasoning according to the rule that the lifetime of the insulating material is reduced by half for each temperature increase of 8 ℃.
Preferably, in S5, the specific steps of determining the operation history of the operation cable and evaluating the state of the operation cable are:
if the equivalent operation years of the operation cable at 90 ℃ obtained by comparing the maximum amplitude value and the average amplitude value are larger than the actual operation years, the operation cable is indicated to have an overload operation condition in the operation process, the defect condition of main insulation and the integral aging state of the operation cable are more serious than those of the normal operation cable, and the actual service life of the operation cable is designed to be shorter than that of the operation cable at 90 ℃ under the condition that the integral operation condition is not changed;
if the equivalent operation years of the operation cable at 90 ℃ obtained by comparison according to the maximum amplitude value and the average amplitude value are equal to the actual operation years, the operation state of the operation cable is normal, and the service life of the operation cable can be designed at 90 ℃ under the condition that the whole operation condition is not changed;
if the equivalent operation years of the operation cable at 90 ℃ obtained by comparison of the maximum amplitude value and the average amplitude value are smaller than the actual operation years, the operation state of the operation cable is good, and the service life of the operation cable can reach or exceed the design service life at 90 ℃ under the condition that the whole operation condition is not changed;
if the equivalent operation years of the running cable at 90 ℃ obtained by comparison according to the maximum amplitude value are greater than the actual operation years of the running cable, and the equivalent operation years of the running cable at 90 ℃ obtained by comparison according to the average amplitude value are less than the actual operation years of the running cable, the integral aging state of the running cable is good, but individual severe aging points exist, and the actual service life of the running cable is lower than the design service life at 90 ℃ under the condition that the integral operation condition is not changed;
if the equivalent operation years of the running cable obtained by comparison according to the maximum amplitude value at 90 ℃ are smaller than the actual operation years of the running cable, and the equivalent operation years of the running cable obtained by comparison according to the average amplitude value at 90 ℃ are larger than the actual operation years of the running cable, the running cable does not have individual serious aging points, but the whole aging state is more serious than that of the normal running cable, and the actual service life of the running cable is shorter than the design service life of the running cable at 90 ℃ under the condition that the whole running condition is not changed.
An ultrasonic detection evaluation device for cable aging state evaluation comprises an ultrasonic detection module and a signal processing module;
the ultrasonic detection module is used for transmitting pulse waves to the surface of the running cable, receiving cable echo signals and transmitting the cable echo signals to the signal processing module;
and the signal processing module is used for intercepting the received cable echo signals to obtain cable main insulation inner surface echo signals, and performing wavelet transformation on the cable main insulation inner surface echo signals to obtain maximum amplitude values and average amplitude values of the running cable in different scales.
Preferably, the device further comprises a comparison module and an indication module;
the signal processing module is also used for transmitting the obtained maximum amplitude value and the average amplitude value of the running cable under different scales to the comparison module;
a comparison module, which stores the maximum amplitude value and the average amplitude value corresponding to the equivalent operation age at 90 ℃ under different scales obtained in any one of claims 1 to 7, sets a plurality of aging state levels according to the actual service life of the running cable to be tested and the maximum amplitude value and the average amplitude value corresponding to the equivalent operation age at 90 ℃ under different scales, compares the maximum amplitude value and the average amplitude value under different scales of the running cable with the maximum amplitude value and the average amplitude value corresponding to the equivalent operation age at 90 ℃ under different scales, determines the aging state level of the running cable, and sends a corresponding instruction to the indication module according to the aging state level;
and the indicating module is used for indicating the aging state level according to the received instruction.
The use method of the ultrasonic detection evaluation device for cable aging state evaluation moves the ultrasonic detection evaluation device along the length direction of the cable, and the ultrasonic detection module is always aligned with the cable in the moving process.
Compared with the prior art, the invention has the following beneficial technical effects:
the method of the invention carries out accelerated aging test, collects the echo signal of the inner surface of the main insulation of the cable, and utilizes wavelet analysis method to analyze the echo signal of the inner surface of the main insulation of the cable to obtain the maximum amplitude value and the average amplitude value of the frequency response under different scales of the echo signal of the inner surface of the main insulation of the cable, thereby establishing the relation curve of the maximum amplitude value and the average amplitude value of the frequency response under different scales of the echo signal of the inner surface of the main insulation of the cable and the equivalent operation age limit under 90 ℃, indicating the change relation that the maximum amplitude value and the average amplitude value of the frequency response of the echo signal of the inner surface of the main insulation of the cable decrease along with the increase of the aging degree of the main insulation of the cable, associating the maximum amplitude value of the frequency response of the ultrasonic echo signal with the most serious aging point, and associating the; according to the maximum amplitude value and the average amplitude value of the actual running cable and the relation curve, the equivalent running life of the running cable at 90 ℃ can be judged, and according to the comparison between the actual running life and the equivalent running life at 90 ℃, the weakest point of the aging and the overall aging state of the running cable are evaluated. The invention establishes a time-scale (frequency) -amplitude value relation curve of an ultrasonic echo based on a wavelet analysis method, and the method can be used for continuously detecting the local and overall aging degrees of a whole cable in real time on site and accurately positioning the position of the most severe aging point according to time information because the wavelet analysis method has accurate frequency and time resolution (for understanding the frequency resolution and the time resolution, the frequency resolution accurately represents that component information of different frequency points in a signal can be accurately obtained, the frequency resolution difference represents that only component information of a certain frequency band can be obtained, the time resolution accurately represents that information corresponding to a certain time point can be accurately obtained, and the time resolution difference represents that only information appearing in a certain time band can be obtained and the specific time point appearing in the information cannot be judged). The invention utilizes the real-time wavelet analysis method of the ultrasonic signal to analyze the echo signal at the inner side of the main insulation of the cable, compared with the sound velocity analysis method, the echo signal penetrating through the whole main insulation not only carries the whole information of the main insulation of the cable, but also carries the information of the most seriously aged part of the inner surface of the main insulation, and can simultaneously detect the whole aging state and the local aging state. Compared with the sound velocity method, the method can reflect the aging state of the cable more comprehensively and accurately, and has higher reliability; and the wavelet analysis method carries time information, so that the method can be used for real-time detection.
When the device is used, the device is enabled to move along the cable at a certain speed, so that the maximum amplitude value and the average amplitude value at different positions along the length direction of the cable can be obtained, the local and overall aging degree of the whole cable can be continuously detected on site in real time, and the position of the most severe aging point can be accurately positioned according to time information.
Furthermore, by arranging the comparison module and the indication module, the aging state of the whole cable can be continuously detected on site in real time, and the aging states of different positions can be judged and indicated by the device, so that a worker can find a serious aging point quickly.
Drawings
FIG. 1 is a graph of scale (frequency) -time-amplitude of the echo signal of the primary insulation inner surface.
FIG. 2 is a graph showing the relationship between 90 ℃ equivalent operating life and maximum amplitude at different scales.
FIG. 3 is a graph of 90 ℃ equivalent operating life and average amplitude at different scales.
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
The invention transmits pulse ultrasonic waves and receives echo signals reflected from the inner surface of the main insulation of the power cable, utilizes software to perform wavelet analysis on the echo signals in a time-frequency domain to obtain time and amplitude trend graphs under different scales (frequencies), and draws a relation curve between the maximum amplitude and the average amplitude of the echo signals on the inner surface of the main insulation of the cable under different scales and the equivalent operation life of the cable at 90 ℃. And then, acquiring echo signals of the inner surface of the main insulation of the cable on site, analyzing the echo signals, obtaining maximum amplitude and average amplitude values under different scales, comparing the maximum amplitude and the average amplitude values with a drawn relation curve, judging the running state of the cable, and evaluating the aging state of the cable.
The method comprises the following specific implementation steps:
step 3, sampling once every accelerated aging period, immediately placing a 1-2.5MHz ultrasonic probe on the surface of the cable to transmit pulse waves and receive echo signals after the sample is naturally cooled to room temperature, determining echo signals of the inner surface of the main insulation of the cable in the echo signals according to the number of layers in the cable structure, intercepting the received echo signals to obtain the echo signals of the inner surface of the main insulation of the cable, testing not less than 5 echo signals at different positions of the sample per period, and continuously placing the sample back into an oven for aging after the test is finished so as to carry out experiments of the next period;
step 4, performing zero adding processing on the echo signals of the inner surface of the main insulation of the cable measured in the step 3;
Step 6, storing data of time and amplitude values under different scales (frequencies) and drawing a frequency-time-amplitude relation graph according to the data obtained after wavelet transformation in the step 5, finding out maximum amplitude values under different scales (frequencies), calculating an average amplitude value, and then recording; obtaining the relation between different aging times and the maximum amplitude value and the average amplitude value under different scales;
step 7, obtaining equivalent operation years at 90 ℃ corresponding to different aging times through reverse deduction of accelerated aging temperature and aging time, and drawing a relation curve of the equivalent operation years at 90 ℃ at different scales and the maximum amplitude value and the average amplitude value;
and 8, testing echo signals of cables with the same model and different operation ages on site, intercepting to obtain echo signals of the inner surface of the main insulation of the operation cable, processing according to the steps 4, 5 and 6 to obtain maximum amplitude values and average amplitude values under different scales, comparing with a relation curve of equivalent operation ages at 90 ℃ under different scales, the maximum amplitude values and the average amplitude values, judging the equivalent operation age at 90 ℃ of the main insulation of the cable, and judging the operation history of the cable and evaluating the state of the most serious aging part of the cable and the overall aging state according to the comparison of the equivalent operation age at 90 ℃ with the actual operation age.
Some embodiments of the invention are as follows:
example 1
Carrying out 186 ℃ accelerated aging on XLPE cables of certain models according to a formula T1T + N × 8, acceleration multiple of 2NMultiple, T is working temperatureDegree, T1To accelerate the aging temperature, the acceleration factor of this embodiment is 212The unaged and aged samples were tested at 10.69h per cycle (equivalent to 5 years at 90 ℃) with 5 cycles of aging. According to the technical scheme, the echo signals of the inner surface of the main insulation of the cable are processed according to the steps 4-6, a scale (frequency) -time-amplitude relation graph (shown in figure 1) of the echo signals of the inner surface of the main insulation of the sample under different aging times is obtained, and the maximum amplitude values of the frequency response of the echo signals of the inner surface of the main insulation of the sample in different periods are respectively recorded and the average amplitude value is calculated. Tables for establishing the relationship between the aging time at 186 ℃ and the maximum amplitude value and the average amplitude value of the frequency response of the echo signal on the inner surface of the main insulation of the cable are shown in tables 1 and 2. According to the accelerated aging law, the equivalent operation age at 90 ℃ is obtained by reverse extrapolation, and a relation curve of the equivalent operation age at 90 ℃ and the maximum amplitude value and the average amplitude value of the frequency response at different scales is drawn, as shown in fig. 2 and 3 (by adopting piecewise linear fitting).
TABLE 1186 relationship between aging time at C and frequency response maximum amplitude at scale (frequency)
TABLE 2186 deg.C aging time and frequency response average amplitude relationship table under scale (frequency)
Comparing the tested and processed data of a certain type of cable actually operated on site with the curves of fig. 2 and 3, the operation history of the cable can be judged, and the local aging state and the overall aging state of the cable can be evaluated.
Example 2
According to the relevant steps in the technical scheme, a certain model (same as the model of the embodiment 1) of XLPE cable which runs for 5 years at a certain place is tested, and the maximum frequency response amplitude values of the XLPE cable at the scales of 1,5,10,50,100,200 and 500 are recorded as 0.0046249, 0.0242547, 0.029273, 0.0365282, 0.0445753, 1.7322649 and 2.1759119 respectively, and the average amplitude values are recorded as 0.000675, 0.003674, 0.004461, 0.007816, 0.012951, 0.419216 and 0.620941 respectively. Compared with fig. 2 and 3, the equivalent operating life of the cable at 90 ℃ can be judged to be between 5 and 10 years. Calculated according to the piecewise linear fitting curves of fig. 2 and fig. 3, when the scale is 1, the equivalent operation time at 90 ℃ is respectively 10-5 (0.0046249-0.00456)/(0.00467-0.00456) to 7.05 years, 10-5 (0.000675-0.00064)/(0.0007-0.00064) to 7.083, and similarly, the maximum amplitude value and the average amplitude value of the frequency response at other scales are respectively 7.05 and 7.08. The equivalent operation age at 90 ℃ is more than 5 years, which shows that the cable has long-term electricity-heat-force combined action in the operation process, the overall aging state of the main insulation of the cable is more serious than that of the cable in normal operation after long-term overload operation, and individual and serious aging points exist, so the equivalent operation age at 90 ℃ is more than 5 years. The actual service life of the cable is lower than the theoretical service life designed at 90 ℃, local aging points and the overall aging state need to be noticed, but the cable can be periodically checked in a sampling mode considering that the service life is short.
Example 3
According to the relevant steps in the technical scheme, a certain model (same as the model of the embodiment 1) of an XLPE cable which runs for 15 years at a certain place is tested, the maximum amplitude values of the XLPE cable at the scales of 1,5,10,50,100,200 and 500 are recorded as 0.004515, 0.02396, 0.028355, 0.03427, 0.039745, 1.246295 and 1.58907 respectively, the average amplitude values are 0.00061, 0.003145, 0.004395, 0.00664, 0.0126, 0.33586 and 0.44896 respectively, and compared with the comparison between the graph in figure 2 and the graph in figure 3, the equivalent operation year limit of the cable at 90 ℃ can be judged to be between 10 and 15 years. According to the piecewise linear fit curve comparison of fig. 2 and fig. 3, when the scale is 1, the equivalent operation years at 90 ℃ are respectively 15-5 (0.004515-0.00447)/(0.00456-0.00447) to 12.5 years, 15-5 (0.00061-0.00058)/(0.00064-0.00058) to 12.5, and the maximum amplitude value and the average amplitude value of the frequency response at other scales are obtained by the same method and are 12.5. Therefore, the equivalent service life at 90 ℃ is shorter than the actual service life, and the local aging condition and the overall aging condition are better than those of a normally-operated cable, which shows that the cable has a good operation state. Under the condition that the whole operation condition is not changed, the actual service life of the cable exceeds the design service life at 90 ℃.
Example 4
According to the relevant steps in the technical scheme, a certain model (same as the model of the embodiment 1) of XLPE cable which runs for 16 years at a certain place is tested, the maximum amplitude values of the frequency response of the XLPE cable under the scales of 1,5,10,50,100,200 and 500 are recorded to be 0.004415, 0.02357, 0.027435, 0.03366, 0.037515, 0.89064 and 1.081635 respectively, the average amplitude values are 0.000601, 0.0031, 0.004387, 0.006603, 0.012544, 0.320552 and 0.431085 respectively, and compared with the comparison of the graph in the figure 2 and the graph in the figure 3, when the scale is judged to be 1 according to the maximum amplitude value, the 90 ℃ equivalent operating age of the cable is between 15 and 20 years, when the scale is judged to be 1 according to the average amplitude value, the 90 ℃ equivalent operating age of the cable is between 10 and 15 years. The equivalent operation time at 90 ℃ is 20-5 (0.004415-0.00436)/(0.00447-0.00436) to 17.5 years according to the piecewise linear fit curve of fig. 2, and the equivalent operation time at 90 ℃ is 15-5 (0.000601-0.00058)/(0.00064-0.00058) to 13.25 years according to the piecewise linear fit curve of fig. 3, and the maximum amplitude value and the average amplitude value are respectively 17.5 years and 13.25 years in other scales. The service life obtained according to the maximum amplitude is longer than the actual service life, and the service life obtained according to the average amplitude is shorter than the actual service life, so that the cable is good in overall aging state, but individual severe aging points exist, and important monitoring and attention are required. Under the condition that the whole operation condition is unchanged, the service life of the cable can be shortened due to the existence of individual serious aging points.
Example 5
According to the relevant steps in the technical scheme, a certain model (same as the model of the embodiment 1) of XLPE cable which runs for 20 years at a certain place is tested, and the maximum amplitude values of the XLPE cable at different frequency scales are recorded as 0.004412, 0.023554, 0.027412, 0.033654, 0.037506, 0.879432 and 1.069614 respectively, and the average amplitude values are recorded as 0.000495, 0.002331, 0.004175, 0.006297, 0.011372, 0.178884 and 0.253252 respectively. The 90 ℃ equivalent operating time of the cable can be judged to be between 15 and 20 years in comparison with fig. 2, and the 90 ℃ equivalent operating time of the cable can be judged to be between 20 and 25 years in comparison with fig. 3. The equivalent operation time at 90 ℃ is 20-5 (0.004412-0.00436)/(0.00447-0.00436) to 17.64 years according to the piecewise linear fit curve of fig. 1, the equivalent operation time at 90 ℃ is 25-5 (0.000495-0.00048)/(0.00052-0.00048) to 23.125 years according to the piecewise linear fit curve of fig. 2, and the maximum amplitude value and the average amplitude value are respectively 17.64 years and 23.13 years under the same principle of obtaining other scales. The service life obtained according to the maximum amplitude is shorter than the actual service life, and the service life obtained according to the average amplitude is longer than the actual service life, so that the cable does not have individual severe aging points, but the overall performance of the cable is poorer than that of the cable in actual use, and the overall aging state needs to be monitored and paid attention to. Under the condition of unchanged overall operation conditions, the cable may become deteriorated due to the existence of excessive defects or less serious aging points, and finally the service life is shortened.
Example 6
The data of table 1 and table 2 in example 1 are stored in the comparison module of the ultrasonic detection and evaluation device, and the operation age of the operation cable to be detected is 22 years, so the indication module of the ultrasonic detection and evaluation device performs the following settings: when the maximum amplitude value of each scale in the collected signal is lower than corresponding values of equivalent operation age of 25 years at 90 ℃ in table 1, namely 0.00338, 0.01407, 0.01575, 0.01713, 0.02885, 0.43369 and 0.47447, and the average amplitude value of each scale in the collected signal is lower than corresponding values of equivalent operation age of 25 years at 90 ℃ in table 2, namely 0.00048, 0.00204, 0.00411, 0.00627, 0.01110, 0.16716 and 0.21977, the device flashes red light and gives an alarm; similarly, when the maximum amplitude value of each scale in the collected signal is 20 years below the equivalent operation time limit of 90 ℃ in table 1 and 25 years above 90 ℃, and the average amplitude value is 20 years below 90 ℃ and 25 years above 90 ℃, the device flashes the yellow light; when the maximum amplitude value of each scale in the collected signal is 15 years below the equivalent operation year at 90 ℃ and 20 years above 90 ℃, the average amplitude value is 15 years below 90 ℃ and 20 years above 90 ℃, the device flashesA green light; when the maximum amplitude value of each scale in the collected signal is 10 years below the equivalent operation time limit of 90 ℃ in the table 1 and 15 years above the equivalent operation time limit of 90 ℃, and the average amplitude is 10 years below the equivalent operation time limit of 90 ℃ and 15 years above the equivalent operation time limit of 90 ℃, the device flashes a blue lamp; when the maximum amplitude of each scale in the collected signal is 5 years below the equivalent operation time limit of 90 ℃ in the table 1 and 10 years above the equivalent operation time limit of 90 ℃, and the average amplitude value is 5 years below the equivalent operation time limit of 90 ℃ and 10 years above the equivalent operation time limit of 90 ℃, the device flashes the purple light; when the maximum amplitude value of each scale in the collected signal is 0 year below the equivalent operation time limit of 90 ℃ in the table 1 and 5 years above the equivalent operation time limit of 90 ℃, and the average amplitude value is 0 year below the equivalent operation time limit of 90 ℃ and 5 years above the equivalent operation time limit of 90 ℃, the white light is flashed by the device; according to the relevant steps in the technical scheme, a certain type of cable running for 22 years is subjected to whole cable test, the handheld ultrasonic detection evaluation device moves along the cable at the speed of 1m/s, and the ultrasonic emission frequency is 104S, sample rate 109And s. Before 5.8s, the lamp corresponding to the maximum amplitude value and the average amplitude value of the device is yellow all the time, and when 5.8s, the lamp corresponding to the maximum amplitude value is changed into red and gives an alarm to indicate that a serious aging point exists in a cable part corresponding to the time, and after that, regular monitoring needs to be paid attention to during the operation of the cable, and once the safe operation of a serious dangerous power grid is found, the cable part needs to be replaced in time. The color of the indicator light and the setting interval density can be changed according to actual needs so as to realize more accurate detection.
The laboratory also carries out cable state evaluation based on a Fourier analysis method, and because the accuracy of Fourier transform depends on the signal duration and the selected window width, the amplitude of the harmonic component with relatively low frequency is easy to distort, and the laboratory is more suitable for independently researching the state of the most serious cable aging; and it is difficult to compromise between frequency resolution and time resolution, while wavelet analysis can compromise at the same time. Therefore, compared with the wavelet analysis method, the method is more suitable for simultaneously evaluating the overall and local aging states and is also more suitable for real-time detection.
Compared with a sound velocity method and a Fourier analysis maximum amplitude method, the method has the advantages that the state of the most serious aging part and the whole aging state can be evaluated at the same time; the second advantage is that the time resolution and the frequency resolution are higher, and the test is more accurate; the three advantages are that three kinds of information of more accurate time-frequency-amplitude are provided at the same time, and the on-site real-time detection is facilitated.
Claims (10)
1. An ultrasonic detection evaluation method for cable aging state evaluation is characterized by comprising the following steps:
s1, taking an unused cable with the same type as the running cable to be evaluated, setting accelerated aging temperature, and carrying out accelerated aging test on the cable;
s2, sampling according to periods, sampling once in each period, placing the cable taken out on the surface of the cable to transmit pulse waves and receive echo signals after the cable is cooled to room temperature by using an ultrasonic probe, and obtaining cable echo signals corresponding to different aging times;
s3, intercepting the cable main insulation inner surface echo signal from the cable echo signal, performing wavelet transformation on the cable main insulation inner surface echo signal to obtain time and amplitude value data under different scales, finding out the maximum amplitude value under different scales and calculating to obtain an average amplitude value, and obtaining the corresponding relation between the aging time and the maximum amplitude value and the average amplitude value under different scales;
s4, obtaining equivalent operation years at 90 ℃ corresponding to different aging times through inverse extrapolation of accelerated aging temperature, obtaining maximum amplitude values and average amplitude values corresponding to the equivalent operation years at 90 ℃ at different scales, and drawing a relation curve of the equivalent operation years at 90 ℃ at different scales with the maximum amplitude values and the average amplitude values;
and S5, testing echo signals of the running cables of the same model on site, processing the echo signals according to S3 and S4 to obtain maximum amplitude values and average amplitude values under different scales, comparing the maximum amplitude values and the average amplitude values with the relation curve obtained by S4 to obtain the equivalent running life of the running cables at 90 ℃, comparing the equivalent running life of the running cables at 90 ℃ with the actual running life of the running cables, judging the running history of the running cables, and evaluating the state of the most serious cable aging part and the overall aging state.
2. The ultrasonic testing and evaluating method for cable aging status evaluation according to claim 1, wherein in S1, before the cable is subjected to the accelerated aging test, the surface of the cable is wiped with absolute ethyl alcohol and then dried.
3. The ultrasonic testing and evaluating method for cable aging status evaluation according to claim 1, wherein in S2, a plurality of echo signals at different positions of the cable are tested in each period, in S3, the maximum amplitude value of each period test is the average of the maximum amplitude values at different positions of the cable, and the average amplitude value of each period test is the average of the average amplitude values at different positions of the cable.
4. The ultrasonic detection evaluation method for cable aging state evaluation according to claim 1, wherein in S2, the number of cycles is 5 or more.
5. The ultrasonic testing and evaluating method for cable aging state evaluation according to claim 1, wherein in S3, the wavelet transformation of the echo signal of the cable main insulation inner surface is specifically: and performing zero processing on the echo signal of the inner surface of the main insulation of the cable, and then performing wavelet transformation on the echo signal of the inner surface of the main insulation of the cable after the zero processing.
6. The ultrasonic testing and evaluating method for cable aging status evaluation according to claim 1, wherein in S4, equivalent operating years at 90 ℃ corresponding to different aging times at accelerated aging temperature are obtained by reverse extrapolation according to the rule that the lifetime of the insulating material is reduced by half for each 8 ℃ rise in temperature.
7. The ultrasonic detection evaluation method for cable aging state evaluation according to claim 1, wherein in S5, the judging of the operation history of the operating cable and the evaluation of the state thereof are specifically:
if the equivalent operation years of the operation cable at 90 ℃ obtained by comparing the maximum amplitude value and the average amplitude value are larger than the actual operation years, the operation cable is indicated to have an overload operation condition in the operation process, the defect condition of main insulation and the integral aging state of the operation cable are more serious than those of the normal operation cable, and the actual service life of the operation cable is designed to be shorter than that of the operation cable at 90 ℃ under the condition that the integral operation condition is not changed;
if the equivalent operation years of the operation cable at 90 ℃ obtained by comparison according to the maximum amplitude value and the average amplitude value are equal to the actual operation years, the operation state of the operation cable is normal, and the service life of the operation cable can be designed at 90 ℃ under the condition that the whole operation condition is not changed;
if the equivalent operation years of the operation cable at 90 ℃ obtained by comparison of the maximum amplitude value and the average amplitude value are smaller than the actual operation years, the operation state of the operation cable is good, and the service life of the operation cable can reach or exceed the design service life at 90 ℃ under the condition that the whole operation condition is not changed;
if the equivalent operation years of the running cable at 90 ℃ obtained by comparison according to the maximum amplitude value are greater than the actual operation years of the running cable, and the equivalent operation years of the running cable at 90 ℃ obtained by comparison according to the average amplitude value are less than the actual operation years of the running cable, the integral aging state of the running cable is good, but individual severe aging points exist, and the actual service life of the running cable is lower than the design service life at 90 ℃ under the condition that the integral operation condition is not changed;
if the equivalent operation years of the running cable obtained by comparison according to the maximum amplitude value at 90 ℃ are smaller than the actual operation years of the running cable, and the equivalent operation years of the running cable obtained by comparison according to the average amplitude value at 90 ℃ are larger than the actual operation years of the running cable, the running cable does not have individual serious aging points, but the whole aging state is more serious than that of the normal running cable, and the actual service life of the running cable is shorter than the design service life of the running cable at 90 ℃ under the condition that the whole running condition is not changed.
8. An ultrasonic detection evaluation device for cable aging state evaluation is characterized by comprising an ultrasonic detection module and a signal processing module;
the ultrasonic detection module is used for transmitting pulse waves to the surface of the running cable, receiving cable echo signals and transmitting the cable echo signals to the signal processing module;
and the signal processing module is used for intercepting the received cable echo signals to obtain cable main insulation inner surface echo signals, and performing wavelet transformation on the cable main insulation inner surface echo signals to obtain maximum amplitude values and average amplitude values of the running cable in different scales.
9. The ultrasonic detection evaluation device for cable aging state evaluation according to claim 8, further comprising a comparison module and an indication module;
the signal processing module is also used for transmitting the obtained maximum amplitude value and the average amplitude value of the running cable under different scales to the comparison module;
a comparison module, which stores the maximum amplitude value and the average amplitude value corresponding to the equivalent operation age at 90 ℃ under different scales obtained in any one of claims 1 to 7, sets a plurality of aging state levels according to the actual service life of the running cable to be tested and the maximum amplitude value and the average amplitude value corresponding to the equivalent operation age at 90 ℃ under different scales, compares the maximum amplitude value and the average amplitude value under different scales of the running cable with the maximum amplitude value and the average amplitude value corresponding to the equivalent operation age at 90 ℃ under different scales, determines the aging state level of the running cable, and sends a corresponding instruction to the indication module according to the aging state level;
and the indicating module is used for indicating the aging state level according to the received instruction.
10. The use of the ultrasonic testing and evaluation device for cable degradation state assessment according to claim 8 or 9, characterized in that the ultrasonic testing and evaluation device is moved along the length of the cable, during which the ultrasonic testing module is always aligned with the cable.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910684557.4A CN110530972B (en) | 2019-07-26 | 2019-07-26 | Ultrasonic detection evaluation method and device for cable aging state evaluation and device using method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910684557.4A CN110530972B (en) | 2019-07-26 | 2019-07-26 | Ultrasonic detection evaluation method and device for cable aging state evaluation and device using method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110530972A CN110530972A (en) | 2019-12-03 |
| CN110530972B true CN110530972B (en) | 2020-06-19 |
Family
ID=68661942
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910684557.4A Active CN110530972B (en) | 2019-07-26 | 2019-07-26 | Ultrasonic detection evaluation method and device for cable aging state evaluation and device using method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110530972B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111595810A (en) * | 2020-05-25 | 2020-08-28 | 云南电网有限责任公司电力科学研究院 | Insulating material evaluation method based on terahertz detection |
| CN112083294A (en) * | 2020-07-30 | 2020-12-15 | 西安交通大学 | Method for nondestructive evaluation of silicon rubber cable joint state by utilizing ultrasonic sound velocity |
| CN112710820B (en) * | 2020-12-17 | 2023-07-07 | 国网上海市电力公司 | Static contact angle-based rubber cable joint aging state evaluation method |
| CN117309624B (en) * | 2023-11-30 | 2024-02-06 | 天津天大求实电力新技术股份有限公司 | Temperature sensing cable performance evaluation method and system |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5517994A (en) * | 1994-11-16 | 1996-05-21 | Advanced Technology Laboratories, Inc. | Self diagnostic ultrasonic imaging systems |
| JP2010048762A (en) * | 2008-08-25 | 2010-03-04 | Takenaka Komuten Co Ltd | Method for diagnosing laminated rubber |
| WO2014197077A1 (en) * | 2013-03-15 | 2014-12-11 | Vibrant Corporation | Saw mode-based surface defect system/method |
| CN104076256A (en) * | 2014-06-23 | 2014-10-01 | 国家电网公司 | Ultrasonic positioning device and method for GIS withstand voltage breakdown fault |
| CN104330711B (en) * | 2014-10-27 | 2017-02-22 | 华北电力大学 | Saturated reactor insulation accelerated aging test device and test method |
| FR3029288B1 (en) * | 2014-11-27 | 2016-12-23 | Electricite De France | METHOD FOR ULTRASOUND DETECTION AND CHARACTERIZATION OF DEFECTS IN HETEROGENEOUS MATERIAL |
| JP6799982B2 (en) * | 2016-09-26 | 2020-12-16 | 神鋼検査サービス株式会社 | Abnormality detection method and abnormality detection device for linear body, and jig used for abnormality detection device for linear body |
| CN108627571A (en) * | 2018-03-15 | 2018-10-09 | 奥瑞视（北京）科技有限公司 | A kind of wheel ultrasonic detection equipment of rail vehicle, system and method |
| CN109358270A (en) * | 2018-08-22 | 2019-02-19 | 国网天津市电力公司电力科学研究院 | A method of for assessing crosslinking polyethylene-insulated cable insulation ageing state |
| CN109490730A (en) * | 2018-12-19 | 2019-03-19 | 国网北京市电力公司 | Cable discharge detection method, device, storage medium and processor |
-
2019
- 2019-07-26 CN CN201910684557.4A patent/CN110530972B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN110530972A (en) | 2019-12-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110530972B (en) | Ultrasonic detection evaluation method and device for cable aging state evaluation and device using method | |
| US9395279B2 (en) | Method for evaluation of cable aging degradation based on slice sampling | |
| RU2650717C2 (en) | Method and system for monitoring condition of electrical cables | |
| US20110241697A1 (en) | Insulation diagnosis method, insulation diagnosis system, and rotating electric machine | |
| CN1896760A (en) | Method for determining short circuit between windings of power generator rotor with load automatically | |
| CN110458248A (en) | Transformer exception condition detection method based on multi-measuring point vibration signal | |
| CN112763842A (en) | Cable local aging degree judging method and device based on impedance spectrum | |
| CN112858845A (en) | Partial discharge diagnosis method for gas insulated switchgear | |
| CN114252749B (en) | Transformer partial discharge detection method and device based on multiple sensors | |
| CN102680870A (en) | Insulation performance testing method of electric power devices | |
| CN112083294A (en) | Method for nondestructive evaluation of silicon rubber cable joint state by utilizing ultrasonic sound velocity | |
| CN110231547B (en) | Nondestructive testing evaluation method for cable state evaluation | |
| CN113075501A (en) | Cable fault positioning method and system based on impedance spectrum periodic characteristics | |
| CN106443388A (en) | Electric tree channel partial discharge analyzing system based on LabVIEW | |
| CN111025093B (en) | XLPE cable insulation life estimation method based on double-end balance factor | |
| KR20140033979A (en) | Apparatus for diagnosing a power transformer | |
| CN117517823A (en) | State evaluation method and device for reactor | |
| CN115468946A (en) | Transformer oil aging diagnosis method and device and storage medium | |
| KR101600698B1 (en) | System and Method for Predicting Life of Power Transformer | |
| CN115218777A (en) | Method and system for detecting deformation of transformer winding based on leakage magnetic field distribution | |
| CN114740292A (en) | Lightning arrester operation state assessment method | |
| CN110146772B (en) | Transformer core loose defect diagnosis method based on vibration frequency spectrum matrix | |
| CN207336435U (en) | A kind of transformer oil detector with humiture monitoring device | |
| CN113763679B (en) | Method and device for monitoring abnormal sound of gas insulated enclosed type combined electrical apparatus | |
| CN117232644B (en) | Transformer sound monitoring fault diagnosis method and system based on acoustic principle |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |