Comprehensive evaluation method for ultrahigh-voltage cable factory joint performance

Abstract

The invention discloses a comprehensive evaluation method for ultrahigh-voltage cable factory joint performance, and the method comprises the following steps: 1, carrying out the sampling of an ultrahigh-voltage submarine cable factory joint sample section, and carrying out the performance test, and obtaining a performance parameter; 2, selecting the obtained performance parameters to obtain performance evaluation indexes; 3, constructing a hierarchical structure of evaluation indexes, and comparing to obtain a judgment matrix; performing consistency verification to obtain the subjective weight of each evaluation index; 4, performing standardization processing on each evaluation index, and calculating a standard deviation of each index and a correlation coefficient between the indexes; 5, calculating the information amount contained in each index, and normalizing the information amount to obtain the objective weight of each evaluation index; and 6, calculating to obtain a comprehensive weight of the subjective weight and the objective weight, and carrying out comprehensive evaluation on the ultrahigh-voltage submarine cable factory joint. According to the invention, the performance of the ultrahigh-voltage cable factory joint can be comprehensively and accurately evaluated from a multi-dimensional comprehensive angle.

Description

Technical Field

[0001] The present invention belongs to the field of material science and engineering technology, and in particular to a comprehensive evaluation method for the performance of ultra-high voltage cable factory joints. Background Art

[0002] With the increasing demand for offshore wind power and island power supply, considering the extremely harsh operating environment of ultra-high voltage cable joints, natural factors such as seawater, organisms, waves, and currents, human factors such as ship anchor damage, and long-term operation of ultra-high voltage cable joints caused by electrical, thermal aging and mechanical strain will cause damage to ultra-high voltage cable joints, leading to insulation failure. The insulation failure of ultra-high voltage cable joints will bring huge economic losses to offshore wind power platforms, and will also affect the stable production of other platforms in the power grid. Traditional ultra-high voltage cable joint performance evaluation often focuses on a single performance indicator, such as only focusing on the DC breakdown field strength of insulation performance. However, ultra-high voltage cable joints are affected by a variety of factors in actual operation, and a single indicator cannot fully reflect their performance. The Chinese invention patent with publication number CN114966338 A describes a TOPSIS model for evaluating cable insulation materials with different voltage stabilizing components. It comprehensively evaluates cable insulation materials with different voltage stabilizing components while considering electrical and thermal properties, which can ensure that the cable insulation materials have more comprehensive insulation performance. Although this method provides a comprehensive evaluation method for insulation performance taking into account electrical and thermal properties, in actual operation, cables are also affected by a variety of other factors, and this method cannot fully reflect their performance status. Summary of the invention

[0003] The purpose of the present invention is to provide a comprehensive evaluation method for the performance of ultra-high voltage cable factory joints. The present invention can comprehensively and accurately evaluate the performance of ultra-high voltage cable factory joints from a comprehensive perspective of multiple dimensions.

[0004] The technical solution of the present invention is a comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, comprising the following steps:

[0005] Step 1: Take samples of the ultra-high voltage submarine cable factory joint sample section, and perform performance tests on the samples to obtain performance parameters;

[0006] Step 2: Select the obtained performance parameters according to the principal component analysis method to obtain the evaluation index of the ultra-high voltage submarine cable factory joint performance;

[0007] Step 3: Construct a hierarchical structure of evaluation indicators according to the hierarchical analysis method, compare the importance of each evaluation indicator, and obtain a judgment matrix; perform consistency check on the judgment matrix to obtain the subjective weight of each evaluation indicator;

[0008] Step 4: Standardize the evaluation indicators of the ultra-high voltage cable factory joints, and calculate the standard deviation of each indicator and the correlation coefficient between the indicators;

[0009] Step 5: Calculate the amount of information contained in each indicator based on the correlation coefficient, and normalize the amount of information to obtain the objective weight of each evaluation indicator;

[0010] Step 6: Calculate the comprehensive weight of subjective weight and objective weight according to the combined weighting method; and based on the obtained comprehensive weight, establish a comprehensive evaluation model, and conduct a comprehensive evaluation of the ultra-high voltage submarine cable factory joints according to the comprehensive evaluation model.

[0011] In the aforementioned comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, in step 2, based on the selected performance parameters, the evaluation indexes of the ultra-high voltage submarine cable factory joint performance in macro and micro dimensions are calculated:

[0012]

[0013] F1=2 11 x1+2 12 x2+L+2 1m x m

[0014] F2=2 21 x1+l 22 x2+L+l 2m x m

[0015] M

[0016] F t = l t1 x1+l t2 x2+L+l tm x m ;

[0017] Among them, x am is the mth performance parameter of sample a, F t is the tth principal component; l tm is the mth coefficient of the tth principal component, t is the number of principal components, m is the number of performance parameters, x m is the mth performance parameter comprehensive of all samples; X represents the evaluation index; L, M and O all represent ellipsis.

[0018] In the aforementioned comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, in step 2, the performance parameters are reasonably selected, and the process of obtaining the performance evaluation index is to standardize the performance parameters:

[0019]

[0020] Among them, x′ am is the mth performance parameter of sample a after standardization, min(x ，m ) is the minimum value of the mth performance parameter of all samples, max(x m ) is the maximum value of the mth performance parameter of all samples;

[0021] Then calculate the correlation coefficient r of the standardized performance parameters ij and partial correlation coefficient The formula is as follows:

[0022]

[0023]

[0024] Where cov(ij) is the covariance between the i-th performance parameter and the j-th performance parameter, var|i| is the covariance of the i-th performance parameter, var|j| is the variance of the j-th performance parameter, and r ij represents the correlation coefficient between the i-th performance parameter and the j-th performance parameter, ri k represents the correlation coefficient between the i-th performance parameter and the k-th performance parameter, and k represents the correlation coefficient between the j-th performance parameter and the k-th performance parameter. represents the partial correlation coefficient between the i-th performance parameter and the j-th performance parameter;

[0025] The calculation formula for obtaining the KMO value is as follows:

[0026]

[0027] Among them, when When KMO≈1; when When , KMO≈0, and the value of KMO is between 0 and 1;

[0028] Finally, the evaluation index of the ultra-high voltage submarine cable factory joint performance is selected by adjusting the KMO value.

[0029] In the aforementioned comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, in step three, when constructing multi-layer indicators according to the hierarchical analysis method, the ultimate goal is to determine the comprehensive performance of the ultra-high voltage cable factory joints, and the comprehensive performance of the ultra-high voltage cable factory joints is used as the target layer of the hierarchical structure; the ultra-high voltage cable factory joint performance is divided into macroscopic performance and microscopic performance, and the macroscopic performance and microscopic performance are used as the criterion layer of the hierarchical structure, and the volume resistivity, dielectric strength, thermal shrinkage rate, volume resistivity, dielectric constant, dielectric loss factor, thermal weight loss temperature in the macroscopic performance and the crystallinity, maximum crystal ring diameter, number of crystal rings, and spherulite size in the microscopic performance are used as the indicator layer of the staggered structure.

[0030] In the aforementioned comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, in step 3, the quantitative judgment matrix is ​​obtained as follows:

[0031]

[0032]

[0033] in, c ij is the evaluation index T i Compared with the indicator T j The importance of.

[0034] In the aforementioned comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, in step 3, a random consistency index is used to check the consistency of the judgment matrix:

[0035]

[0036] CR = CI / RI;

[0037] Among them, λ m is the maximum eigenvalue of the judgment matrix, n is the number of evaluation indicators, CI is the consistency index, and RI is the random consistency index obtained by table lookup; if CR is less than 0.1, the matrix consistency is considered good, otherwise the judgment matrix is ​​adjusted;

[0038] The subjective weights of various evaluation indicators are solved through the judgment matrix:

[0039]

[0040]

[0041] in, is the average value of each row of the judgment matrix, W i It is the subjective weight obtained after normalizing each evaluation index.

[0042] In the aforementioned comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, in step 4, the process of the standardization process is as follows:

[0043]

[0044] Among them, X′ ij is the jth evaluation index after the i-th sample is processed; X ij is the jth evaluation index before the i-th sample is processed, X j It is the jth evaluation index comprehensive before all samples are processed;

[0045] The calculation of the standard deviation of each indicator and the correlation coefficient between the indicators is specifically as follows:

[0046]

[0047] ρ ij = cov(X′ i , X′ j ) / (σ i , σ j ) i=1,2,Ln;

[0048] Among them, cov(X′ i , X′ j ) is the covariance between the i-th index and the j-th index in the standardized matrix, σ i is the standard deviation of the i-th evaluation index, σ j is the standard deviation of the jth evaluation index.

[0049] In the above-mentioned comprehensive evaluation method of the performance of the ultra-high voltage cable factory joint, in step 5, the formula for calculating the amount of information contained in each evaluation index through the standard deviation of each evaluation index and the correlation coefficient between the evaluation indexes is as follows:

[0050]

[0051] Based on the calculated amount of information, the objective weight βi of the i-th evaluation index is obtained:

[0052]

[0053] In the aforementioned comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, in step 6, the comprehensive weight formula of the subjective weight and the objective weight is calculated according to the combined weighting method as follows:

[0054] E i =kW i +(1-k)β i ;

[0055] Among them, E i is the comprehensive weight of the i-th evaluation index, W i is the subjective weight of the i-th indicator, β i is the objective weight; k is the coefficient, and its value range is 0<k<1.

[0056] In the aforementioned comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, in step 6, the cable factory joint performance comprehensive evaluation model established based on the obtained comprehensive weight is specifically:

[0057]

[0058] Among them, y a is the comprehensive score of the a-th evaluated object, X aiis the value of the i-th evaluation index of the a-th evaluated object, E i is the comprehensive weight of the i-th evaluation index.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The present invention selects multiple performance parameters, establishes an evaluation method for the subjective weight and objective weight of ultra-high voltage cable factory joints, and constructs a quantitative evaluation index system, which comprehensively and accurately reflects the performance of ultra-high voltage cable factory joints from a comprehensive perspective of multiple dimensions, overcomes the problem of inaccurate evaluation in the prior art, and further improves the quality standards of ultra-high voltage cable factory joints, thereby ensuring the safe and reliable operation of ultra-high voltage submarine cables. In addition, when the present invention selects performance parameters using the principal component analysis method, it is screened by calculating the KMO value, which is helpful for the screening of performance parameters. The present invention constructs a hierarchical structure of evaluation indicators according to the hierarchical analysis method, which is helpful for in-depth research on the mutual influence relationship between performance indicators at different levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a flow chart of the method of the present invention;

[0062] Figure 2 The analytic hierarchy process evaluation hierarchy provided for the implementation of the present invention. DETAILED DESCRIPTION

[0063] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0064] Embodiment: A comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, such as Figure 1 As shown, the following steps are included:

[0065] Step 1: Take samples of the ultra-high voltage submarine cable factory joint sample section, and perform performance tests on the samples to obtain performance parameters;

[0066] In this embodiment, the ultra-high voltage cable factory joint is sliced ​​by the ring cutting method. The ultra-high voltage submarine cable factory joint sample to be tested is placed on a lathe, the tool is pressed against the outside of the factory joint sample, and the ultra-high voltage submarine cable factory joint sample is rotated to start ring cutting. The distance between the tool and the ultra-high voltage submarine cable factory joint sample is controlled so that the thickness of the cut sample is about 0.2 mm. The ultra-high voltage submarine cable factory joint is divided into two parts: the main insulation and the recovery insulation. The recovery insulation sample is prepared according to the position of the sample cut during ring cutting.

[0067] The performance of the ultra-high voltage submarine cable factory joint is divided into macroscopic performance and microscopic performance. Performance tests include mechanical, chemical, thermal and electrical performance tests. Performance parameters include DC breakdown field strength, dielectric loss, dielectric constant, volume resistivity, melting temperature, crystallinity, crystal plane spacing, lamellar crystal thickness, and spherulite size. The DC breakdown field strength is tested according to the national standard GB / T1408.1-2016A, and the breakdown electric field of the polypropylene sample under DC voltage is tested using a ball-column electrode. The diameter of the ball electrode is 20mm, the diameter of the column electrode is 25mm, the ball electrode is connected to the capacitor, the column electrode is grounded, the sample is placed between the two electrodes, and the voltage increase speed is 1kV / s. The pressure increase method during the test adopts a uniform speed increase, and the test voltage drop is used as the breakdown criterion, which is set to 0.2kV. The same sample is tested 15 times effectively and the breakdown voltage value is recorded. The volume resistivity was tested by the three-electrode method, the polarization time was 30 minutes, a data point was recorded every 1 second, and the volume resistivity of the sample was calculated by taking the average value of the data of the last 30 seconds; the dielectric loss and dielectric constant were tested by Novocontrol Concept 80 broadband and wide-temperature dielectric spectrometer, and the test frequency range was 1-106 Hz; the crystallinity and the thickness of the lamellae were studied and analyzed by TA-Q200 differential scanning calorimeter; when testing the gel content, the test sample was heated at 120°C for 12 hours in xylene, and the mass change before and after heating was calculated; the interplanar spacing and spherulite size were tested by D2 PHASER X-ray diffractometer of Bruker, Germany;

[0068] Table 1 Macro reference performance test results established by the embodiment of the present invention

[0069]

[0070] Table 2 Microscopic reference performance test results established by the embodiment of the present invention

[0071]

[0072] Step 2: Select the obtained performance parameters according to the principal component analysis method to obtain the evaluation index of the ultra-high voltage submarine cable factory joint performance;

[0073] In this embodiment, based on the selected performance parameters, the evaluation index of the ultra-high voltage submarine cable factory joint performance in the macro and micro dimensions is calculated:

[0074]

[0075] F1=l 11 x1+l 12 x2+L+l 1m x m

[0076] F2=l 21 x1+l22 x2+L+l 2m x m

[0077] M

[0078] F t = l t1 x1+l t2 x2+L+l tm x m ;

[0079] Among them, x am is the mth performance parameter of sample a, F t is the tth principal component; l tm is the mth coefficient of the tth principal component, t is the number of principal components, m is the number of performance parameters, x m is the mth performance parameter comprehensive of all samples; X represents the evaluation index; L, M and O all represent ellipsis.

[0080] Then, the performance parameters are reasonably selected to obtain the performance evaluation index, which is the process of standardizing the performance parameters:

[0081]

[0082] Among them, x′ am is the mth performance parameter of sample a after standardization, min(x ，m ) is the minimum value of the mth performance parameter of all samples, max(x m ) is the maximum value of the mth performance parameter of all samples;

[0083] Then calculate the correlation coefficient r of the standardized performance parameters ij and partial correlation coefficient The formula is as follows:

[0084]

[0085]

[0086] Among them, cov(ij) is the covariance between the ith performance parameter and the jth performance parameter, bar|i| is the covariance of the ith performance parameter, var|j| is the variance of the jth performance parameter, r ij represents the correlation coefficient between the i-th performance parameter and the j-th performance parameter, ri k represents the correlation coefficient between the i-th performance parameter and the k-th performance parameter, and k represents the correlation coefficient between the j-th performance parameter and the k-th performance parameter. represents the partial correlation coefficient between the i-th performance parameter and the j-th performance parameter;

[0087] The calculation formula for obtaining the KMO value is as follows:

[0088]

[0089] Among them, when When KMO≈1; when When , KMO≈0, and the value of KMO is between 0 and 1;

[0090] Finally, the evaluation index of the ultra-high voltage submarine cable factory joint performance is selected by adjusting the KMO value.

[0091] If the KMO value is higher than 0.5, it means that the group of indicators can be used for principal component analysis; if the KMO value is less than 0.5, it is not suitable for principal component analysis, that is, there are no evaluation indicators that can be combined.

[0092] Table 3 KMO analysis results

[0093]

[0094] The results show that the KMO values ​​of both macro and micro performance are less than 0.5, which indicates that the correlation between the selected performance parameters is low and the evaluation indicators cannot be reduced.

[0095] Step 3: Construct a hierarchical structure of evaluation indicators according to the hierarchical analysis method, compare the importance of each evaluation indicator, and obtain a judgment matrix; perform consistency check on the judgment matrix to obtain the subjective weight of each evaluation indicator;

[0096] like Figure 2 As shown in the figure, when the hierarchical analysis method is used to evaluate the performance of ultra-high voltage cable factory joints, the ultimate goal is to determine the comprehensive performance of ultra-high voltage cable factory joints. Therefore, the comprehensive performance of ultra-high voltage cable factory joints is used as the target layer of the hierarchical structure, and the performance of ultra-high voltage submarine cable factory joints is divided into macroscopic performance and microscopic performance. The macroscopic performance and microscopic performance are used as the criterion layers of the hierarchical structure, and the volume resistivity, dielectric strength, thermal shrinkage rate, volume resistivity, dielectric constant, dielectric loss factor, thermal weight loss temperature in the macroscopic performance and the crystallinity, maximum crystal ring diameter, number of crystal rings and spherulite size in the microscopic performance are used as the indicator layers of the staggered structure.

[0097] In this embodiment, the quantized judgment matrix is ​​obtained as follows:

[0098]

[0099]

[0100] in, c ij is the evaluation index T i Compared with the indicator T jThe importance of.

[0101] Then the random consistency index is used to check the consistency of the judgment matrix:

[0102]

[0103] CR = CI / RI;

[0104] Among them, λ m is the maximum eigenvalue of the judgment matrix, n is the number of evaluation indicators, CI is the consistency index, and RI is the random consistency index obtained by table lookup; if CR is less than 0.1, the matrix consistency is considered good, otherwise the judgment matrix is ​​adjusted;

[0105] The subjective weights of various evaluation indicators are solved through the judgment matrix:

[0106]

[0107]

[0108] in, is the average value of each row of the judgment matrix, W i It is the subjective weight obtained after normalizing each evaluation index.

[0109] In this embodiment, the macro-index and micro-index judgment matrix are constructed using the hierarchical analysis method (1-9 scaling method):

[0110] The macro performance judgment matrix is:

[0111]

[0112] The micro-performance judgment matrix is:

[0113]

[0114] According to the calculation process, the calculation results of the macro-indicators and micro-indicators, macro-performance and micro-performance weights of the 1-9 scale method can be obtained as follows:

[0115] Table 4 Performance weights of macro and micro indicators

[0116]

[0117] Table 5 Macro performance weights

[0118]

[0119] Table 6 Micro performance weights

[0120]

[0121] From the above table, we can see that the AHP hierarchical analysis method is used to study the first-level judgment matrix established for macro indicators and micro indicators, and the corresponding weight values ​​are 75.188% and 24.812% respectively.

[0122] A secondary judgment matrix was constructed for a total of seven items, including gel content, breakdown field strength, thermal shrinkage, volume resistivity, melting temperature, dielectric constant, and dielectric loss factor, and the AHP hierarchical analysis method was used for research. The corresponding weight values ​​were 13.314%, 35.822%, 5.103%, 16.170%, 10.797%, 7.511%, and 14.281%, respectively.

[0123] A secondary judgment matrix was constructed for the interplanar spacing, lamellar thickness, crystallinity, and spherulite size to conduct AHP analysis, and the corresponding weight values ​​were 45.453%, 27.27%, 18.183%, and 9.088%, respectively.

[0124] The smaller the CR value, the better the consistency of the judgment matrix. Generally, if the CR value is less than 0.1, the judgment matrix satisfies the consistency test; if the CR value is greater than 0.1, it means that there is no consistency, and the judgment matrix should be appropriately adjusted and analyzed again. The CI values ​​calculated by the two judgment matrices are 0, 0.097, and 0, respectively. The RI values ​​are 0, 1.360, and 0.89, which means that the judgment matrix of this study satisfies the consistency test and the calculated weights are consistent.

[0125] The comprehensive subjective weight values ​​of gel content, breakdown field strength, thermal shrinkage, volume resistivity, melting temperature, dielectric constant, and dielectric loss factor were obtained as follows: 0.133, 0.358, 0.0510, 0.1617, 0.107, 0.0751, 0.142, 0.454, 0.272, 0.182, and 0.091.

[0126] Step 4: Standardize the evaluation indicators of the ultra-high voltage cable factory joints, and calculate the standard deviation of each indicator and the correlation coefficient between the indicators;

[0127] In this embodiment, the process of using the Max-Min method to standardize each evaluation index is as follows:

[0128]

[0129] Among them, X′ ij is the jth evaluation index after the i-th sample is processed; X ij is the jth evaluation index before the i-th sample is processed, X j It is the jth evaluation index comprehensive before all samples are processed;

[0130] The calculation of the standard deviation of each indicator and the correlation coefficient between the indicators is specifically as follows:

[0131]

[0132] ρ ij = cov(X′ i , X′ j ) / (σ i , σ j ) i=1,2,Ln;

[0133] Among them, cov(X′ i , X′ j ) is the covariance between the i-th index and the j-th index in the standardized matrix, σ i is the standard deviation of the i-th evaluation index, σ j is the standard deviation of the jth evaluation index.

[0134] Step 5: Calculate the amount of information contained in each indicator based on the correlation coefficient, and normalize the amount of information to obtain the objective weight of each evaluation indicator;

[0135] In this embodiment, the formula for calculating the amount of information contained in each evaluation indicator is as follows, using the standard deviation of each evaluation indicator and the correlation coefficient between the evaluation indicators:

[0136]

[0137] Based on the calculated amount of information, the objective weight βi of the i-th evaluation index is obtained:

[0138]

[0139] The objective weight values ​​of macro-performance and micro-performance are calculated using the CRITIC weight analysis method. The CRITIC weight method is an objective weighting method. Its basic principle is to determine the indicator weights based on the judgment matrix composed of the indicator values ​​of the evaluated object. The calculation results are shown in Table 7 below:

[0140] Table 7 Objective weight values ​​of macro-performance and micro-performance

[0141]

[0142]

[0143] Step 6: Calculate the comprehensive weight of subjective weight and objective weight according to the combined weighting method; and based on the obtained comprehensive weight, establish a comprehensive evaluation model, and conduct a comprehensive evaluation of the ultra-high voltage submarine cable factory joints according to the comprehensive evaluation model.

[0144] The comprehensive weight formula of subjective weight and objective weight calculated by the combined weighting method is as follows:

[0145] E i =kW i +(1-k)β i ;

[0146] Among them, E i is the comprehensive weight of the i-th evaluation index, W i is the subjective weight of the i-th indicator, β i is the objective weight; k is the coefficient, and its value range is 0<k<1.

[0147] The comprehensive evaluation model of cable factory joint performance established based on the obtained comprehensive weight is as follows:

[0148]

[0149] Among them, y a is the comprehensive score of the a-th evaluated object, X ai is the value of the i-th evaluation index of the a-th evaluated object, E i is the comprehensive weight of the i-th evaluation index.

[0150] Selecting the subjective emphasis coefficient and the objective emphasis coefficient k = 0.7, the final weight values ​​of gel content, breakdown field strength, thermal shrinkage, volume resistivity, melting temperature, dielectric constant, and dielectric loss factor are calculated as shown in Table 8:

[0151] Table 8 Comprehensive weight values ​​of performance indicators

[0152] Performance Indicators Subjective weight Objective weight Comprehensive weight Gel content 0.133 0.057 0.110 Dielectric loss factor 0.358 0.057 0.268 Thermal shrinkage 0.051 0.057 0.053 Volume resistivity 0.1617 0.057 0.130 Melting temperature 0.107 0.057 0.092 Dielectric constant 0.0751 0.057 0.070 Dielectric loss factor 0.142 0.057 0.117 Interplanar spacing 0.454 0.057 0.335 Lamellar thickness 0.272 0.057 0.208 Crystallinity 0.182 0.057 0.145 Spherulite size 0.091 0.057 0.081

[0153] The final calculation results of the scores of different materials are:

[0154] Material Score A1 0.385 A2 0.527 A3 0.369 A4 0.642 A5 1.098 A6 0.482 A7 1.027 A8 0.919 A9 0.520

[0155] The present invention selects multiple performance parameters, establishes an evaluation method for the subjective weight and objective weight of ultra-high voltage cable factory joints, and constructs a quantitative evaluation index system, which comprehensively and accurately reflects the performance of ultra-high voltage cable factory joints from a comprehensive perspective of multiple dimensions, overcomes the problem of inaccurate evaluation in the prior art, and further improves the quality standards of ultra-high voltage cable factory joints, thereby ensuring the safe and reliable operation of ultra-high voltage submarine cables. In addition, when the present invention selects performance parameters using the principal component analysis method, it is screened by calculating the KMO value, which is helpful for the screening of performance parameters. The present invention constructs a hierarchical structure of evaluation indicators according to the hierarchical analysis method, which is helpful for in-depth research on the mutual influence relationship between performance indicators at different levels.

[0156] In summary, the present invention can comprehensively and accurately evaluate the performance of the ultra-high voltage cable factory joint from a comprehensive multi-dimensional perspective.

Claims

1. A comprehensive evaluation method for the performance of ultra-high voltage cable factory joints, characterized in that: The following steps are involved: Step 1: Take samples of the ultra-high voltage submarine cable factory joint sample section, and perform performance tests on the samples to obtain performance parameters; Step 2: Select the obtained performance parameters according to the principal component analysis method to obtain the evaluation index of the ultra-high voltage submarine cable factory joint performance; Step 3: Construct a hierarchical structure of evaluation indicators according to the hierarchical analysis method, compare the importance of each evaluation indicator, and obtain a judgment matrix; perform consistency check on the judgment matrix to obtain the subjective weight of each evaluation indicator; Step 4: Standardize the evaluation indicators of the ultra-high voltage cable factory joints, and calculate the standard deviation of each indicator and the correlation coefficient between the indicators; Step 5: Calculate the amount of information contained in each indicator based on the correlation coefficient, and normalize the amount of information to obtain the objective weight of each evaluation indicator; Step 6: Calculate the comprehensive weight of subjective weight and objective weight according to the combined weighting method; and based on the obtained comprehensive weight, establish a comprehensive evaluation model, and conduct a comprehensive evaluation of the ultra-high voltage submarine cable factory joints according to the comprehensive evaluation model.

2. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 1 is characterized by: In step 2, based on the selected performance parameters, the evaluation indexes of the ultra-high voltage submarine cable factory joint performance in macro and micro dimensions are calculated: F1=l 11 x1+l 12 x2+L+l 1m x m F2=l 21 x1+l 22 x2+L+l 2m x m M F t l t1 x1+l t2 x2+L+l tm x m ; Among them, x am is the mth performance parameter of sample a, F t is the tth principal component; l tm is the mth coefficient of the tth principal component, t is the number of principal components, m is the number of performance parameters, x m is the mth performance parameter comprehensive of all samples; X represents the evaluation index; L, M and O all represent ellipsis.

3. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 2 is characterized in that: In step 2, the performance parameters are reasonably selected to obtain the performance evaluation index, which is to standardize the performance parameters: Among them, x' am is the mth performance parameter of sample a after standardization, min(x ,m ) is the minimum value of the mth performance parameter of all samples, max(x m ) is the maximum value of the mth performance parameter of all samples; Then calculate the correlation coefficient r of the standardized performance parameters ij and partial correlation coefficient The formula is as follows: Where cov(ij) is the covariance between the i-th performance parameter and the j-th performance parameter, var|i| is the covariance of the i-th performance parameter, var|j| is the variance of the j-th performance parameter, and r ij represents the correlation coefficient between the i-th performance parameter and the j-th performance parameter, r ik represents the correlation coefficient between the i-th performance parameter and the k-th performance parameter, r jk represents the correlation coefficient between the jth performance parameter and the kth performance parameter, represents the partial correlation coefficient between the i-th performance parameter and the j-th performance parameter; The calculation formula for obtaining the KMO value is as follows: Among them, when When KMO≈1; when When , KMO≈0, the value of KMO is between 0 and 1; Finally, the evaluation index of the ultra-high voltage submarine cable factory joint performance is selected by adjusting the KMO value.

4. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 1 is characterized by: In step three, when constructing multi-layer indicators according to the hierarchical analysis method, the ultimate goal is to determine the comprehensive performance of the ultra-high voltage cable factory joints, and the comprehensive performance of the ultra-high voltage cable factory joints is used as the target layer of the hierarchical structure; the ultra-high voltage cable factory joint performance is divided into macroscopic performance and microscopic performance, and the macroscopic performance and microscopic performance are used as the criterion layer of the hierarchical structure, and the volume resistivity, dielectric strength, thermal shrinkage rate, volume resistivity, dielectric constant, dielectric loss factor, thermal weight loss temperature in the macroscopic performance and the crystallinity, maximum crystal ring diameter, number of crystal rings, and spherulite size in the microscopic performance are used as the indicator layer of the staggered structure.

5. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 1 is characterized by: In step 3, the quantized judgment matrix is ​​obtained as follows: in, c ij is the evaluation index T i Compared with the indicator T j The importance of.

6. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 5 is characterized by: In step 3, the consistency of the judgment matrix is ​​checked using a random consistency indicator: CR = CI / RI; Among them, λ m is the maximum eigenvalue of the judgment matrix, n is the number of evaluation indicators, CI is the consistency index, and RI is the random consistency index obtained by table lookup; if CR is less than 0.1, the matrix consistency is considered good, otherwise the judgment matrix is ​​adjusted; The subjective weights of various evaluation indicators are solved through the judgment matrix: in, is the average value of each row of the judgment matrix, W i It is the subjective weight obtained after normalizing each evaluation index.

7. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 6 is characterized by: In step 4, the process of the standardization is as follows: Among them, X' ij is the jth evaluation index after the i-th sample is processed; X ij is the jth evaluation index before the i-th sample is processed, X j It is the jth evaluation index comprehensive before all samples are processed; The calculation of the standard deviation of each indicator and the correlation coefficient between the indicators is specifically as follows: r ij =cov(X′ i ,X′ j ) / (s i ,s j ) i=1,2,L n; Among them, cov(X' i ,X' j ) is the covariance between the i-th index and the j-th index in the standardized matrix, σ i is the standard deviation of the i-th evaluation index, σ j is the standard deviation of the j-th evaluation index.

8. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 7 is characterized by: In step 5, the formula for calculating the amount of information contained in each evaluation indicator is as follows through the standard deviation of each evaluation indicator and the correlation coefficient between the evaluation indicators: Based on the calculated amount of information, the objective weight β of the i-th evaluation index is obtained. i :

9. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 1 is characterized by: In step 6, the comprehensive weight formula of subjective weight and objective weight is calculated according to the combined weighting method: E i =kW i +(1-k)β i ; Among them, E i is the comprehensive weight of the i-th evaluation index, W i is the subjective weight of the i-th indicator, β i is the objective weight; k is the coefficient, and its value range is 0<k<1.

10. The comprehensive evaluation method for the performance of ultra-high voltage cable factory joints according to claim 1 is characterized by: In step 6, the cable factory joint performance comprehensive evaluation model established based on the obtained comprehensive weight is as follows: Among them, y a is the comprehensive score of the a-th evaluated object, X ai is the value of the i-th evaluation index of the a-th evaluated object, E i is the comprehensive weight of the i-th evaluation index.

Images