A method and system for estimating the remaining life of cable insulation considering multi-factor aging

Abstract

The present specification provides a method and system for estimating the remaining life of cable insulation considering multi-factor aging, and relates to the field of cable testing technology. The method includes respectively determining the multi-factor test data of unaged cables and the multi-factor test data of in-service cables; determining the weight of influence of each aging factor on the aging of in-service cables according to the multi-factor test data of unaged cables and the multi-factor test data of in-service cables; determining the remaining life of in-service cables under the influence of each aging factor according to the multi-factor test data of unaged cables and the multi-factor test data of in-service cables; normalizing the remaining life of in-service cables under the influence of each aging factor according to the weight of influence of each aging factor on in-service cables, and obtaining the estimated remaining life of in-service cables. It can clarify the magnitude of the influence of different aging factors on the insulation of currently in-service cables, so as to further accurately calculate the remaining life of in-service cables.

Description

Technical Field

[0001] The present specification relates to the field of cable testing technology, and in particular to a method and system for estimating the remaining life of cable insulation taking into account multi-factor aging. Background Art

[0002] Generally, the life of power cables in a normal environment is about 30 years. Since the cables are laid in trenches, pipes, tunnels, etc., or buried directly underground, the above laying environment and the working state of the cables will greatly affect the life of the cables. Furthermore, there may be local defects in the manufacture or installation of cables. Therefore, the cable system is usually subjected to multiple aging stresses such as electrical, thermal, and mechanical stresses during operation. The resulting degradation of insulation performance will inevitably lead to cable breakdown and other failures, resulting in power outages and other phenomena. At present, the high-voltage cables with a voltage level of 66kV and above put into operation in China have entered the late loss stage of their expected service life. The performance of some cable insulation may be seriously deteriorated due to various aging factors, which means that a large number of cables in operation have the hidden danger of frequent failures due to insulation aging. Therefore, it is necessary to establish a cable insulation aging evaluation method and a life estimation model based on the understanding of the cable insulation aging mechanism to improve the reliability and economy of the operation of the cables in operation.

[0003] At present, the existing technologies at home and abroad mainly construct single-factor aging models under the action of electrical and thermal aging factors to evaluate the aging status of cable insulation and estimate the remaining service life. When estimating the remaining service life of cable insulation, the estimation results of different single-factor aging models may have large deviations. In addition, it is difficult to meet consistency when conducting aging status evaluation and remaining service life estimation of in-service cables, which makes it easy to be affected by personnel subjectivity when estimating the remaining service life of cable insulation, and the estimation results have large errors. Summary of the invention

[0004] The purpose of this specification is to provide a method for estimating the remaining life of cable insulation taking into account multi-factor aging, which can solve the problem in the prior art that the single-factor aging model has large errors in estimating the remaining life of the operating cable.

[0005] The embodiments of this specification are implemented as follows:

[0006] In the first aspect, this specification provides a method for estimating the remaining life of cable insulation considering multi-factor aging, mainly including:

[0007] Determine multi-factor test data of unaged cables and multi-factor test data of in-service cables, wherein the multi-factor test data is data obtained by testing the cables under multiple aging factors, wherein the multiple aging factors at least include electrical aging factors, thermal aging factors, moisture intrusion factors, radiation factors, and mechanical vibration factors;

[0008] According to the multi-factor test data of the unaged cable and the multi-factor test data of the in-service cable, by constructing an aging life influence function corresponding to each aging factor, the influence weight of each aging factor on the aging of the in-service cable is determined, and the aging life influence function is constructed by fitting the multi-factor test data of the unaged cable and the multi-factor test data of the in-service cable; according to the multi-factor test data of the unaged cable and the multi-factor test data of the in-service cable, by constructing a remaining life equation corresponding to each aging factor, the remaining life of the in-service cable under the influence of each aging factor is determined, and the remaining life equation is constructed according to the multi-factor test data of the unaged cable and the multi-factor test data of the in-service cable;

[0009] According to the influence weights of various aging factors on the cables in operation, the remaining life of the cables in operation under the influence of various aging factors is normalized to obtain the estimated remaining life of the cables in operation.

[0010] In the second aspect, this specification provides a cable insulation remaining life estimation system considering multi-factor aging, mainly including:

[0011] A first determination module is used to determine multi-factor test data of unaged cables and multi-factor test data of in-service cables, wherein the multi-factor test data is data obtained by testing the cables under multiple aging factors, wherein the multiple aging factors at least include electrical aging factors, thermal aging factors, moisture intrusion factors, radiation factors, and mechanical vibration factors;

[0012] A second determination module is used to determine the influence weight of each aging factor on the aging of the in-service cable by constructing an aging life influence function corresponding to each aging factor according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, wherein the aging life influence function is constructed by fitting the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable;

[0013] A calculation module, for determining the remaining life of the in-service cable under the influence of each aging factor by constructing a remaining life equation corresponding to each aging factor according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, wherein the remaining life equation is constructed according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable;

[0014] The acquisition module is used to normalize the remaining life of the operating cable under the influence of each aging factor according to the influence weight of each heavy aging factor on the operating cable, so as to obtain the estimated remaining life of the operating cable.

[0015] The embodiments of this specification have at least the following advantages or beneficial effects:

[0016] This cable insulation remaining life estimation method can obtain the specific influence weights of each aging factor on the current operating cable through the aging test data of non-aged cables and cables in operation with the same insulation type under various influencing factors, thereby clarifying the influence of different aging factors on the insulation of the current operating cable. The remaining life of the cable in operation can be further accurately calculated through the above-defined influence weights. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of this specification, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present specification and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A flow chart of a method for estimating the remaining life of cable insulation considering multi-factor aging provided for this specification;

[0019] Figure 2 The step-by-step voltage rise curve for the voltage withstand test provided in this manual;

[0020] Figure 3 This is the trend curve of the elongation at break of the unaged cable versus the aging time at different aging temperatures provided in this manual;

[0021] Figure 4 The breakdown field strength of the unaged cable varies with the aging time at different aging temperatures provided in this manual;

[0022] Figure 5 The logarithmic variation trend curve of the elongation at break decrease rate of the unaged cable at different aging temperatures provided in this manual over time;

[0023] Figure 6 Schematic diagram of a cable insulation remaining life estimation system considering multi-factor aging provided for this specification. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of this specification more clear, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are part of the embodiments of this specification, not all of the embodiments. Generally, the components of the embodiments of this specification described and shown in the drawings here can be arranged and designed in various different configurations.

[0025] Please refer to Figure 1 An embodiment of the present specification provides a method for estimating the remaining life of cable insulation considering multi-factor aging, which mainly includes:

[0026] Step 102: determining multi-factor test data of unaged cables and multi-factor test data of cables in operation, wherein the multi-factor test data is data obtained by testing the cables under multiple aging factors, wherein the multiple aging factors at least include electrical aging factors, thermal aging factors, moisture intrusion factors, radiation factors, and mechanical vibration factors;

[0027] Step 104: Determine the influence weight of each aging factor on the aging of the in-service cable by constructing an aging life influence function corresponding to each aging factor according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, wherein the aging life influence function is constructed by fitting the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable;

[0028] Step 106: Determine the remaining life of the in-service cable under the influence of each aging factor by constructing a remaining life equation corresponding to each aging factor according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, wherein the remaining life equation is constructed according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable;

[0029] Step 108: According to the weights of the influence of each heavy aging factor on the in-service cable, the remaining life of the in-service cable under the influence of each aging factor is normalized to obtain the estimated remaining life of the in-service cable.

[0030] Specifically, the above-mentioned cable insulation remaining life estimation method can obtain the influence weight of each aging factor on the current operating cable through the aging test data of non-aged cables and cables in operation with the same insulation type under various influencing factors, thereby clarifying the influence of different aging factors on the insulation of the current operating cable. The remaining life of the cable in operation can be further accurately calculated through the above-defined influence weights.

[0031] In this embodiment, one implementation of step 102 is as follows:

[0032] Step 112, performing a step-by-step voltage withstand breakdown test on at least two groups of unaged cables until the unaged cables are in a breakdown state, and recording the voltage withstand level, the step-by-step voltage withstand test time, the breakdown voltage, and the duration under the breakdown voltage, respectively, to obtain the step-by-step voltage withstand breakdown test data;

[0033] Step 114, subjecting at least three groups of insulation samples of unaged cables to a heat aging test in a naturally ventilated environment until the elongation at break of the unaged cables drops to 40%-60% of their initial elongation at break, obtaining the time when the elongation at break of each group of unaged cables drops to 40%-60% of their initial elongation at break, which is the aging life of the unaged cables, setting the aging temperatures of at least three groups of insulation samples in a gradient manner, and recording the elongation at break, the corresponding aging temperature and the heat aging time of the insulation samples, respectively, to obtain the heat aging test data;

[0034] Step 116, performing the step-by-step withstand voltage breakdown test on the in-service cable to obtain the withstand voltage level of the in-service cable, the breakdown voltage of the in-service cable, and the duration under the breakdown voltage;

[0035] Step 118: Perform heat aging tests at various temperatures on the in-service cable to obtain the elongation at break, the corresponding aging temperature and the heat aging time of the in-service cable.

[0036] In this embodiment, the in-service cable used for the step-by-step voltage breakdown test and the in-service cable used for the thermal aging test are different parts of the in-service cable.

[0037] In this embodiment, the detailed implementation of step 112 is as follows:

[0038] The thickness of the insulation sample of the unaged cable used for the step-by-step voltage withstand test is 0.3mm~0.5mm. Please refer to the step-by-step voltage withstand test process. Figure 2 .

[0039] Taking polypropylene insulation as an example, the thickness of the insulation sample is specifically set to 0.3 mm, and its short-time breakdown voltage is about 24 kV.

[0040] The unaged cables were divided into two groups. The starting voltage of the step-by-step withstand voltage test of each group of insulation samples was selected as 40% of the short-time breakdown voltage, i.e. 9.6 kV. The step-by-step withstand voltage test time of the two groups of insulation samples was set to 10 min (the first group) and 15 min (the second group) for each level. The insulation samples were placed in a constant temperature oil cup at 90 °C. Figure 2 As shown, the voltage is increased step by step for the withstand voltage test until the insulation sample undergoes voltage breakdown, and the withstand voltage level, breakdown voltage, and duration under the breakdown voltage of each group of step-by-step withstand voltage tests are recorded, that is, the withstand voltage breakdown test data is obtained through the step-by-step withstand voltage breakdown test.

[0041] In other embodiments, the number of groups of insulation samples can be set as needed, and the time of the step-by-step voltage withstand test can be determined according to the short-time breakdown voltage.

[0042] In this embodiment, the detailed implementation of step 114 is as follows:

[0043] The insulation specimens of the unaged cables used for the heat aging test were prepared as dumbbell specimens in accordance with the provisions of GB / T 2951.11-2008, with a thickness of 1 mm, a length of 75 mm, and an average width of 4 mm in the middle.

[0044] In this embodiment, the initial elongation at break of the unaged dumbbell specimens is first measured, and then the unaged dumbbell specimens are divided into at least 3 groups. Each group of dumbbell specimens is placed in a natural ventilation aging test box that meets the requirements of GB / T 2951.12-2008 for heat aging. Sampling is performed regularly, and the elongation at break of the insulation specimens after heat aging is tested until the elongation at break of the insulation specimens after aging drops to about 50% of the initial elongation at break. The heat aging test is stopped, and the regular sampling time and the corresponding elongation at break of each group of insulation specimens are recorded. Figure 3 shown.

[0045] It should be noted here that the test temperature of thermal aging should be at least 5°C lower than the melting temperature of the insulated cable, and the test temperature of thermal aging should be more than 15°C higher than the maximum allowable operating temperature. The test temperature difference between different groups of insulation samples should be 5~15°C.

[0046] Taking polypropylene insulation as an example, its melting point is about 160℃. The insulation samples are divided into 4 groups, and the test temperatures of thermal aging are set at 125℃, 135℃, 140℃ and 155℃ respectively. Figure 3 Shown are the elongation at break test results of dumbbell specimens at different aging times at the corresponding heat aging specimen temperature.

[0047] The sampling interval is set according to the test temperature of heat aging and the chemical reaction rate of thermal oxidative decomposition of polypropylene insulation at this temperature. In this example, the specific setting method of the sampling interval is shown in Table 1.

[0048]

[0049] In this embodiment, the detailed implementation of step 116 is as follows:

[0050] The insulation of the operating cable (part of the section of the operating cable) is cut into slices with a thickness of 0.3 mm and subjected to a step-by-step voltage breakdown test (the step-by-step voltage breakdown test proposed in step 112), and the breakdown voltage of the insulation of the operating cable in the current state is obtained, such as Figure 4 Considering the randomness and error of one set of samples, two sets of insulation samples of in-service cables were subjected to step-by-step withstand voltage tests, with the voltage increased step by step until the cable samples broke down, and the withstand voltage level, breakdown voltage, and duration under the breakdown voltage of each set of samples were recorded.

[0051] In this embodiment, the detailed implementation of step 118 is as follows:

[0052] According to the test method of step 114, the insulation of the in-service cable (different from the portion of the in-service cable used for the withstand voltage test) is made into a dumbbell specimen, and the elongation at break of the insulation of the in-service cable in the current state is measured.

[0053] That is, the heat aging test is carried out in two groups (considering the randomness and error of one group of samples), and the elongation at break of the dumbbell samples after heat aging is tested regularly. The sampling interval refers to the recommendations in Table 1. Based on the test data of the heat aging test, such as Figure 5 As shown, the thermal aging remaining life of the in-service cable insulation under two groups of aging temperatures can be obtained.

[0054] In this embodiment, the test data of the unaged cables and the cables in operation are obtained in the above manner, which can further improve the accuracy of the remaining life calculation when multiple factors such as electrical aging factors and thermal aging factors affect the cable aging.

[0055] In this embodiment, the implementation of step 102 further includes:

[0056] The dielectric loss and the voltage breakdown field strength of the non-aged cable and the cable in operation are determined respectively, and the test data of the moisture intrusion factor of the non-aged cable and the cable in operation are obtained.

[0057] The elongation at break of the non-aged cable and the cable in operation under mechanical fatigue conditions are determined respectively, and test data of mechanical vibration factors of the non-aged cable and the cable in operation are obtained.

[0058] According to the above method, the influence weights of moisture intrusion factor and mechanical vibration factor on cable aging can be determined.

[0059] In this embodiment, test data of the radiation factor of the cable is obtained through testing to further determine the influence weight of the radiation factor when the cable is located in an environment such as nuclear radiation or strong radiation.

[0060] In this embodiment, the influence of electrical aging factors and thermal aging factors are taken into consideration, and the electrical aging factors and thermal aging factors are used as examples for explanation:

[0061] One implementation of step 104 is as follows:

[0062] Step 122: construct an electrical aging life influence function according to the breakdown voltage of the in-service cable and the breakdown voltage of the non-aged cable;

[0063] Step 124: construct a thermal aging life influence function according to the elongation at break of the in-service cable and the initial elongation at break of the unaged cable;

[0064] Step 126: Determine the electrical aging impact weight and the thermal aging impact weight of the in-service cable according to the electrical aging life impact function and the thermal aging life impact function.

[0065] In this embodiment, the electrical aging life influence function and the thermal aging life influence function They are:

[0066] in, is the breakdown voltage of the unaged cable, is the breakdown voltage of the cable in operation, is the initial elongation at break of the unaged cable, is the elongation at break of the cable in operation, Is the life expectancy index.

[0067] In this embodiment, the above life index Determined by the method proposed in step 152.

[0068] In this embodiment, the insulation breakdown voltage The fitting result function of aging temperature and aging time is The form of expression can be referred to Figure 4 .

[0069] Based on the above fitting function, the electrical aging life influence function is constructed by considering the electrical aging cumulative effect and the voltage inverse power law. , that is, the mathematical relationship model between the insulation breakdown field strength and the remaining life of the insulation material electrical aging is

[0070] in, is the breakdown voltage of the unaged cable, is the breakdown voltage of the cable in operation, Is the life index. Breakdown voltage The closer to the initial breakdown voltage, the greater the electrical aging life effect function The closer it is to 1, the smaller the influence of electrical aging on insulation life is, and the smaller the weight factor is when estimating the remaining insulation life is.

[0071] In this embodiment, the elongation at break decreases by a ratio of The fitting result function of the aging temperature and the logarithm of the aging time is The form of expression (fitting can refer to Figure 5 ), the elongation at break decreases by The expression is:

[0072]

[0073] Based on the above fitting function, the thermal aging life influence function can be constructed , that is, the mathematical relationship model between the elongation at break and the remaining life of the insulation material after thermal aging is:

[0074]

[0075] is the initial elongation at break of the unaged cable, is the elongation at break of the cable in service.

[0076] The closer to the initial value Thermal aging life effect function The closer it is to 1, the smaller the influence of thermal aging on insulation life is, and the smaller the weight factor is when estimating the remaining insulation life.

[0077] Specifically, the weight of the influence of electrical aging on life can be clearly determined through the above-mentioned step-by-step voltage test data and life index, wherein the life index can be calculated through the constructed electrical aging single-factor cable insulation life equation.

[0078] Moreover, the above electrical aging life influence function and thermal aging life influence function both conform to the cumulative effect and exponential law of insulating materials.

[0079] In this embodiment, one implementation of step 126 is as follows:

[0080] Step 132: Taking the electrical aging life influence function as , the thermal aging life influence function is , the electrical aging influence weight and thermal aging influence weight of the in-service cable are:

[0081] in, is the breakdown voltage of the cable in operation, is the elongation at break of the cable in operation, is the influence weight of electrical aging factors on the cables in operation, is the weight of the impact of thermal aging factors on the cable in operation.

[0082] In this embodiment, the sum of the electrical aging influence weight and the thermal aging influence weight is 1.

[0083] Specifically, the electrical aging influence weight and the thermal aging influence weight calculated in the above manner can further accurately determine the remaining life of the cable insulation under the influence of multiple factors, and can effectively reduce the error of the remaining life calculated by a single factor cable insulation.

[0084] In this embodiment, one implementation of step 106 is as follows:

[0085] Step 142: construct an electrical aging single factor cable insulation life equation and a thermal aging single factor cable insulation life equation respectively according to the step-by-step voltage breakdown test data and the thermal aging test data;

[0086] Step 144: According to the multi-factor aging test data, the remaining life of the in-service cable under the electrical aging factor and the remaining life under the influence of the thermal aging factor are obtained through the electrical aging single-factor cable insulation life equation and the thermal aging single-factor cable insulation life equation.

[0087] In this embodiment, one implementation of step 142 is as follows:

[0088] Step 152: Calculate the life index according to the withstand voltage level, step-by-step withstand voltage test time, breakdown voltage and duration under the breakdown voltage of the non-aged cable by using the cumulative effect of electrical aging and the inverse power law, which is:

[0089]

[0090] E 11 、E 21 They represent the voltage applied to the first stage of the first group of samples and the voltage applied to the first stage of the second group of samples, respectively. 1N1 、E 2N2 They represent the voltage applied at level N1 of the first group of samples and the voltage applied at level N2 of the second group of samples, t1 and t2 represent the duration of each level of the withstand voltage test of the first group of samples and the second group of samples, respectively. N1 ,t N2 Respectively represent the breakdown voltage E 1N1 、E 2N2 The duration under this condition is as follows: const represents a constant, n represents a life exponent, and the sample is an unaged cable.

[0091] Step 154: construct the electrical aging single factor cable insulation life equation according to the life index, which is:

[0092]

[0093] Among them, E N represents the voltage applied to the Nth level of the in-service cable, t represents the time of the in-service step-by-step voltage withstand test, t N Indicates the breakdown voltage E N E0 represents the duration under the long-term operating voltage of the tested sample, and t0 represents the remaining life under the long-term operating voltage E0.

[0094] Specifically, test data is obtained from at least two groups of insulation specimens of unaged cables, the life index is calculated, and then the above-mentioned electrical aging single-factor cable insulation life equation is constructed based on the life index and the withstand voltage test data of the cables in operation. It can be seen that when the operating voltage of the cables in operation is determined, the remaining life of the cables in operation under the influence of electrical aging factors can be calculated using the above formula.

[0095] In this embodiment, the two sets of step-by-step withstand voltage test data of the in-service cable obtained in step 116 are used as the calculation basis, and the remaining life t of the in-service cable under the long-term operating voltage E0 is calculated according to the above-mentioned electrical aging single factor cable insulation life equation. d1 ,t d2 .

[0096] In this embodiment, one implementation of step 142 is as follows:

[0097] Step 162, obtaining coefficients of the Arnius equation by least squares linear fitting according to the aging temperatures and aging lives of at least three groups of the non-aged cables;

[0098] Step 164: construct the thermal aging single factor cable insulation life equation according to the coefficients of the Arnius equation and the Arnius equation, which is:

[0099]

[0100] Among them, Y r is the service life of the insulating sample at the aging temperature, T is the aging temperature, and A and B are the coefficients of the Arnius equation.

[0101] Specifically, according to the thermal aging test data of the insulation sample of the unaged cable obtained in step 114, A and B are fitted by the least square method to construct the above-mentioned thermal aging single-factor cable insulation life equation. According to the thermal aging test data of the in-service cable obtained in step 118, the thermal aging remaining life of the in-service cable can be calculated by the above-mentioned thermal aging single-factor cable insulation life equation.

[0102] In detail, the thermal aging test data of the unaged cable is used to obtain the fitting function of the aging time and the decrease ratio of the elongation at break of the unaged cable insulation at different aging temperatures. The τ corresponding to each aging temperature is obtained through the fitting function at different temperatures. τ is related to the activation energy of the material.

[0103] The aging temperature and τ corresponding to each aging temperature are fitted to obtain a fitting function about τ. According to the fitting function, τ at a specific aging temperature can be obtained.

[0104] According to τ at the specific aging temperature, the fitting function of the aging time and the decrease ratio of the elongation at break at the current specific aging temperature (for example, 90°C) can be determined. According to the fitting function, when the decrease ratio of the elongation at break is known to be 50% (the life of the cable is deemed to have ended when the decrease ratio is 50%), the service life of the non-aged cable (that is, the total life of the non-aged cable insulation) can be calculated.

[0105] According to the constructed thermal aging single-factor cable insulation life equation, the service life of the insulation sample of the cable in operation at a specific aging temperature can be calculated; by subtracting the service life of the cable in operation at the same specific temperature from the service life of the non-aged cable at a specific temperature, the remaining life of the cable in operation under the thermal aging factor can be obtained.

[0106] In this embodiment, one implementation of step 108 is as follows:

[0107] Step 172: The remaining life of the in-service cable under the electrical aging factor is t d , the remaining life of the cable in operation under the thermal aging factor is t r ;

[0108] Step 174: The estimated remaining life Y of the in-service cable is:

[0109]

[0110] Among them, c1 is the influence weight of the electrical aging factor on the cable in operation, and c2 is the influence weight of the thermal aging factor on the cable in operation.

[0111] In this embodiment, the estimated remaining life of the in-service cable can be calculated using two groups of insulation samples of the in-service cables to further reduce the error, specifically:

[0112] Among them, t d1 ,t d2 Electrical aging test is performed on two groups of insulation samples of the in-service cables to obtain the remaining life under the influence of electrical aging factors, t r1 ,t r2 Thermal aging tests were carried out on two groups of insulation samples of the cables in operation to obtain the remaining life under the influence of thermal aging factors.

[0113] Specifically, by performing normalization processing in the above manner, the errors of single-factor electrical aging life and thermal aging life can be eliminated, and the accuracy of the above-mentioned remaining life calculation can be further improved according to the influence weight.

[0114] Please refer to Figure 6 Another embodiment of the present specification provides a cable insulation remaining life estimation system considering multi-factor aging, mainly comprising:

[0115] A first determination module 202 is used to determine multi-factor test data of an unaged cable and multi-factor test data of an in-service cable, wherein the multi-factor test data is data obtained by testing the cable under multiple aging factors, wherein the multiple aging factors at least include electrical aging factors, thermal aging factors, moisture intrusion factors, radiation factors, and mechanical vibration factors;

[0116] A second determination module 204 is used to determine the influence weight of each heavy aging factor on the aging of the in-service cable by constructing an aging life influence function corresponding to each heavy aging factor according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, wherein the aging life influence function is constructed by fitting the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable;

[0117] A calculation module 206, configured to determine the remaining life of the in-service cable under the influence of each aging factor by constructing a remaining life equation corresponding to each aging factor according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, wherein the remaining life equation is constructed according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable;

[0118] The obtaining module 208 is used to normalize the remaining life of the operating cable under the influence of each aging factor according to the influence weight of each heavy aging factor on the operating cable, so as to obtain the estimated remaining life of the operating cable.

[0119] Specifically, the above system can obtain the influence weights of various aging factors of the current operating cables through the aging test data of non-aged cables and cables in operation with the same insulation type under various influencing factors, thereby clarifying the influence of different aging factors on the insulation of the current operating cables. The remaining life of the cables in operation can be further accurately calculated through the above-defined influence weights.

[0120] In this embodiment, the first determination module 202 is used to perform a step-by-step voltage withstand breakdown test on at least two groups of unaged cables until the unaged cables are in a breakdown state, and respectively record the voltage withstand level, the step-by-step voltage withstand test time, the breakdown voltage, and the duration under the breakdown voltage to obtain the step-by-step voltage withstand breakdown test data, which is the test data of the electrical aging factor of the unaged cables; perform the step-by-step voltage withstand breakdown test on the in-service cables to obtain the voltage withstand level, the step-by-step voltage withstand test time, the breakdown voltage of the in-service cables, and the duration under the breakdown voltage, which is the test data of the electrical aging factor of the in-service cables; place the insulation samples of at least three groups of unaged cables in a naturally ventilated The heat aging test is carried out under the environment until the elongation at break of the unaged cable drops to 40%-60% of its initial elongation at break, and the time when the elongation at break of each group of unaged cables drops to 40%-60% of its initial elongation at break is obtained, which is the aging life of the unaged cable. The aging temperatures of at least three groups of the insulation samples are set in a gradient, and the elongation at break, the corresponding aging temperature and the heat aging time of the insulation samples are recorded respectively, which are the test data of the heat aging factor of the unaged cable; the heat aging test is carried out on the in-service cable to obtain the elongation at break, the corresponding aging temperature and the heat aging time of the in-service cable, which are the test data of the heat aging factor of the in-service cable. The dielectric loss and voltage breakdown field strength of the unaged cable and the in-service cable are determined respectively, and the test data of the moisture intrusion factor of the unaged cable and the in-service cable are obtained. The elongation at break of the unaged cable and the in-service cable under mechanical fatigue conditions are determined respectively, and the test data of the mechanical vibration factor of the unaged cable and the in-service cable are obtained. By obtaining the test data of non-aged cables and cables in operation under various aging factors in the above manner, the influence weight of each aging factor can be further determined.

[0121] In this embodiment, the determination module 204 is used to construct an electrical aging life influence function based on the test data of the electrical aging factors of the unaged cable and the test data of the electrical aging factors of the in-service cable; to construct a thermal aging life influence function based on the test data of the thermal aging factors of the unaged cable and the test data of the thermal aging factors of the in-service cable; and to determine the electrical aging influence weight and thermal aging influence weight of the in-service cable based on the electrical aging life influence function and the thermal aging life influence function. , the thermal aging life influence function is , the electrical aging influence weight and thermal aging influence weight of the in-service cable are: ;in, E x is the breakdown voltage of the cable in operation, L xis the elongation at break of the cable in operation, c1 is the influence weight of the electrical aging factor on the cable in operation, and c2 is the influence weight of the thermal aging factor on the cable in operation.

[0122] Specifically, the electrical aging influence weight and the thermal aging influence weight calculated in the above manner can further accurately determine the remaining life of the cable insulation under the influence of multiple factors, and can effectively reduce the error of the remaining life calculated by a single factor cable insulation.

[0123] In this embodiment, the obtaining module 208 is used to take the remaining life of the in-service cable under the electrical aging factor as , the remaining life of the cable in operation under the thermal aging factor is ; The estimated remaining life Y of the cable in operation is: ; Among them, c1 is the influence weight of electrical aging factor on the said cable in operation, and c2 is the influence weight of thermal aging factor on the said cable in operation.

[0124] Specifically, by performing normalization processing in the above manner, the errors of electrical aging life and thermal aging life under the influence of a single factor can be eliminated, and the accuracy of the above remaining life calculation can be further improved according to the influence weight.

[0125] Based on the same invention, another embodiment of the present specification further provides a computer-readable storage medium, wherein the computer-readable storage medium stores one or more programs, and when the one or more programs are executed by an electronic device including multiple application programs, the electronic device executes Figure 1 The corresponding embodiment provides a method for estimating the remaining life of cable insulation taking into account multi-factor aging.

[0126] In this specification, each embodiment is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0127] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0128] Those skilled in the art will appreciate that the embodiments of this specification may be provided as methods, systems, or computer program products. Therefore, this specification may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this specification may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0129] This specification is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of this specification. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that has the function specified in a box.

[0130] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0131] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0132] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0133] Memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

[0134] The above is only an embodiment of the present application and is not intended to limit this specification. For those skilled in the art, this specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification should be included in the scope of the claims of this specification.

Claims

1. A method for estimating the remaining life of cable insulation considering multi-factor aging, characterized in that: include: Determine multi-factor test data of unaged cables and multi-factor test data of in-service cables, wherein the multi-factor test data is data obtained by testing the cable insulation under multiple aging factors, wherein the multiple aging factors at least include electrical aging factors, thermal aging factors, moisture intrusion factors, radiation factors, and mechanical vibration factors; According to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, by constructing the aging life influence function corresponding to each heavy aging factor, the influence weight of each heavy aging factor on the insulation aging of the in-service cable is determined, and the aging life influence function is constructed by fitting the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, including: Constructing an electrical aging life influence function according to the test data of the electrical aging factors of the non-aged cable and the test data of the electrical aging factors of the in-service cable; Constructing a thermal aging life influence function according to the test data of the thermal aging factor of the unaged cable and the test data of the thermal aging factor of the in-service cable; The test data of the electrical aging factor includes the breakdown voltage of the cable, the test data of the thermal aging factor includes the breaking elongation of the cable, the electrical aging life influence function f(Ex) and the thermal aging life influence function f(L X ) are: Among them, E N is the breakdown voltage of the unaged cable, E x is the breakdown voltage of the cable in operation, L0 is the initial elongation at break of the unaged cable, L x is the elongation at break of the cable in service, and n is the life index; Determining the electrical aging influence weight and the thermal aging influence weight of the in-service cable according to the electrical aging life influence function and the thermal aging life influence function, including: The electrical aging life influence function is f(Ex), and the thermal aging life influence function is f(L X ), the electrical aging influence weight and thermal aging influence weight of the in-service cable are: Among them, E x is the breakdown voltage of the cable in operation, L x is the elongation at break of the cable in operation, c1 is the influence weight of the electrical aging factor on the cable in operation, and c2 is the influence weight of the thermal aging factor on the cable in operation; According to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, the remaining life of the in-service cable under the influence of each aging factor is determined by constructing a remaining life equation corresponding to each aging factor, wherein the remaining life equation is constructed according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable; According to the influence weights of various aging factors on the in-service cable, the remaining life of the insulation of the in-service cable under the influence of various aging factors is normalized to obtain the estimated remaining life of the insulation of the in-service cable.

2. The method for estimating the remaining life of cable insulation considering multi-factor aging according to claim 1 is characterized in that: The multi-factor test data for determining the non-aging cables and the multi-factor test data for the cables in operation include: Performing a step-by-step voltage withstand breakdown test on at least two groups of unaged cables until the unaged cables are in a breakdown state, recording the voltage withstand level, the step-by-step voltage withstand test time, the breakdown voltage, and the duration under the breakdown voltage, respectively, to obtain the step-by-step voltage withstand breakdown test data, i.e., the test data of the electrical aging factor of the unaged cables; The step-by-step voltage withstand breakdown test is performed on the in-service cable to obtain the voltage withstand level, step-by-step voltage withstand test time, breakdown voltage of the in-service cable and duration under the breakdown voltage, which are the test data of the electrical aging factor of the in-service cable.

3. The method for estimating the remaining life of cable insulation considering multi-factor aging according to claim 1, characterized in that: The multi-factor test data for determining the non-aging cables and the multi-factor test data for the cables in operation include: Conducting heat aging tests on at least three groups of unaged cables in a naturally ventilated environment until the elongation at break of the unaged cables drops to 40%-60% of their initial elongation at break, obtaining the time when the elongation at break of each group of unaged cables drops to 40%-60% of their initial elongation at break, which is the aging life of the unaged cables; setting the aging temperatures of at least three groups of insulation samples in a gradient manner, and recording the elongation at break, the corresponding aging temperature and the heat aging time of the insulation samples, which are the test data of the heat aging factor of the unaged cables; A heat aging test is performed on the in-service cable to obtain the elongation at break, the corresponding aging temperature and the heat aging time of the in-service cable, which are the test data of the heat aging factor of the in-service cable.

4. The method for estimating the remaining life of cable insulation considering multi-factor aging according to claim 1, characterized in that: The multi-factor test data for determining the non-aging cables and the multi-factor test data for the cables in operation include: The dielectric loss and the voltage breakdown field strength of the non-aged cable and the cable in operation are determined respectively, and the test data of the moisture intrusion factor of the non-aged cable and the cable in operation are obtained.

5. The method for estimating the remaining life of cable insulation considering multi-factor aging according to claim 1, characterized in that: The multi-factor test data for determining the non-aging cables and the multi-factor test data for the cables in operation include: The elongation at break of the non-aged cable and the cable in operation under mechanical fatigue conditions are determined respectively, and test data of mechanical vibration factors of the non-aged cable and the cable in operation are obtained.

6. The method for estimating the remaining life of cable insulation considering multi-factor aging according to claim 1, characterized in that: The method of normalizing the remaining life of the insulation of the cable in operation under the influence of each aging factor according to the influence weight of each aging factor on the cable in operation to obtain the estimated remaining life of the insulation of the cable in operation includes: The remaining life of the cable in operation under electrical aging factors is t d , the remaining life of the cable in operation under the thermal aging factor is t r ; The estimated remaining life Y of the cable in operation is: Y=c1t d + c2t r Among them, c1 is the influence weight of the electrical aging factor on the cable in operation, and c2 is the influence weight of the thermal aging factor on the cable in operation.

7. A cable insulation remaining life estimation system considering multi-factor aging, applying the method described in any one of claims 1 to 6, characterized in that: include: A first determination module is used to determine multi-factor test data of unaged cables and multi-factor test data of in-service cables, wherein the multi-factor test data is data obtained by testing the cables under multiple aging factors, wherein the multiple aging factors at least include electrical aging factors, thermal aging factors, moisture intrusion factors, radiation factors, and mechanical vibration factors; A second determination module is used to determine the influence weight of each aging factor on the aging of the in-service cable by constructing an aging life influence function corresponding to each aging factor according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, wherein the aging life influence function is constructed by fitting the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable; A calculation module, for determining the remaining life of the in-service cable under the influence of each aging factor by constructing a remaining life equation corresponding to each aging factor according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable, wherein the remaining life equation is constructed according to the multi-factor test data of the non-aged cable and the multi-factor test data of the in-service cable; The acquisition module is used to normalize the remaining life of the operating cable under the influence of each aging factor according to the influence weight of each heavy aging factor on the operating cable, so as to obtain the estimated remaining life of the operating cable.

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