Method and apparatus for evaluating insulation performance of submarine cable, and medium

Abstract

A method and apparatus for evaluating the insulation performance of a submarine cable, and a medium. The method comprises: acquiring a first actually measured dissipation factor value of a submarine cable, and a first current limiting resistance and a first insulating resistance of same (S1); substituting the above parameters into a first actually measured dissipation factor value expression, and performing calculation to obtain a first actual dissipation factor value, wherein the first actually measured dissipation factor value expression is obtained by means of performing calculation on the basis of a preset overall dissipation factor value expression, and the overall dissipation factor value expression comprises a first product and the first actual dissipation factor value to be calculated, the first product being calculated by means of a preset model performing under an n-order condition, which represents that the submarine cable has n branches, n being a natural number (S2); and evaluating the insulation performance of the submarine cable on the basis of the first actual dissipation factor value, so as to obtain an insulation performance evaluation result (S3). In the method, by means of eliminating a data deviation in an actually measured dissipation factor value to obtain an actual dissipation factor value, and then using the actual dissipation factor value to evaluate the insulation performance of a submarine cable, the problem of the reliability of an insulation performance evaluation result of a submarine cable being low can be solved.

Description

A method, device and medium for evaluating insulation performance of submarine cables Technical Field

[0001] The present invention relates to the technical field of cable insulation status evaluation, and in particular to a method, device and medium for evaluating the insulation performance of a submarine cable. Background Art

[0002] Submarine cables play a crucial role in the transmission of electrical energy in power systems. As submarine cables age and are corroded by the harsh submarine environment, their insulation performance gradually degrades, potentially causing their operating life to fall short of their designed lifespan. Therefore, evaluating the insulation condition of submarine cables is crucial. Existing techniques for evaluating the insulation performance of submarine cables based on their dielectric loss value primarily employ the polarization-depolarization current (PDC) method, applying a voltage similar to a step signal to the submarine cable to obtain the measured dielectric loss value, which is then used to evaluate insulation performance.

[0003] However, the length of submarine cables usually ranges from several kilometers to tens of kilometers, and the capacitance is relatively large. As the cable length increases, the cable capacitance gradually increases, so that the voltage applied to the submarine cable during the test is not a voltage that can be approximated as a step signal, but a voltage that is approximate to an exponential signal, resulting in an overestimation of the measured dielectric loss value, causing the insulation performance evaluation results of the submarine cable to have large deviations and be unreliable.

[0004] Summary of the Invention

[0005] The present invention provides a method, device and medium for evaluating the insulation performance of a submarine cable, so as to solve the problem that when evaluating the insulation performance of a submarine cable, the dielectric loss value measurement result is too large, resulting in inaccurate insulation performance evaluation results of the submarine cable.

[0006] In order to solve the above problems, the present invention provides a method for evaluating the insulation performance of a submarine cable, comprising:

[0007] Obtaining a first measured dielectric loss value, a first current limiting resistance, and a first insulation resistance of the submarine cable;

[0008] Substituting the first measured dielectric loss value, the first current-limiting resistor, and the first insulation resistance into a first measured dielectric loss value expression to calculate a first actual dielectric loss value; wherein the first measured dielectric loss value expression is calculated based on a preset overall dielectric loss value expression, the overall dielectric loss value expression including a first product and the first actual dielectric loss value to be solved, the first product being calculated using a preset model under an n-th order situation, where the n-th order situation indicates that there are n branches of the submarine cable, and n is a natural number;

[0009] The insulation performance of the submarine cable is evaluated according to the first actual dielectric loss value to obtain an insulation performance evaluation result.

[0010] The present invention substitutes the first measured dielectric loss value, the first current limiting resistor and the first insulation resistance into the first measured dielectric loss value expression obtained in advance to obtain the first measured dielectric loss value, and then uses the first measured dielectric loss value to evaluate the insulation performance of the submarine cable to obtain an evaluation result. This evaluation method is simple, fast, efficient and convenient. Among them, the overall dielectric loss value expression includes the first product and the first actual dielectric loss value to be solved. The first product is calculated by the preset model and substituted into the overall dielectric loss value expression to obtain the first measured dielectric loss value expression. At this time, the first measured dielectric loss value expression contains the first actual dielectric loss value to be solved. The first measured dielectric loss value expression is actually a combination of the first actual dielectric loss value and the "parameter that causes the measured dielectric loss value to be too large". Therefore, as long as the relevant data is substituted in, the first actual dielectric loss value can be inversely solved. This solution is simple and fast, and after eliminating the biased data, the accuracy of the first actual dielectric loss value is guaranteed, thereby making the evaluation result obtained by using the first actual dielectric loss value to evaluate the insulation performance of the submarine cable highly accurate. Compared with the existing technology, the present invention obtains a first actual dielectric loss value by eliminating the data deviation in the first measured dielectric loss value, and then uses the first actual dielectric loss value to evaluate the insulation performance of the submarine cable. This can ensure that the first actual dielectric loss value has high accuracy. On this basis, a high-precision insulation performance evaluation result of the submarine cable is obtained, thereby solving the problem of low reliability of the insulation performance evaluation result of the submarine cable.

[0011] As a preferred solution, the first measured dielectric loss value expression is calculated based on a preset overall dielectric loss value expression, specifically:

[0012] Establishing a frequency domain impedance expression based on first preset data, and performing a formula transformation on the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the first preset data includes a preset first measured dielectric loss value of the submarine cable, a preset total cable resistance, a preset total cable capacitance, a preset current limiting resistance, an imaginary unit, an angular frequency of the submarine cable under direct current, and a preset insulation resistance;

[0013] Transforming the initial frequency-domain admittance expression into an algebraic form of a complex number to obtain a first frequency-domain admittance expression including a first real part and a first imaginary part;

[0014] Calculate the overall dielectric loss value expression according to the first real part and the first imaginary part, substitute the value of the first product into the overall dielectric loss value expression, and calculate the first measured dielectric loss value expression;

[0015] The first product is the product of the first real part and the preset current limiting resistance.

[0016] In this preferred embodiment, the first preset data is used to establish the frequency domain impedance expression because the frequency domain impedance expression is transformed to obtain the initial frequency domain admittance expression, and many of the parameters therein will be eliminated after the subsequent transformation processing. Therefore, by using the first preset data to establish the frequency domain impedance expression, the human resources consumed in obtaining data can be saved.

[0017] As a preferred solution, the first product is calculated by a preset model in the nth order case, specifically:

[0018] Calculating the first product in the n-th order case by using the Debye model;

[0019] The first product is:

[0020] Where A is the first real part, R0, R, ω and R 直流 are respectively the preset total cable resistance, the preset current limiting resistance, the angular frequency and the preset insulation resistance in the first preset data, C i and R i are the equivalent capacitance and equivalent resistance of the i-th branch in the submarine cable respectively.

[0021] The preferred solution is to calculate the first product of the first real part and the preset current limiting resistor in the nth order case through the Debye model. At this time, the Debye model is equivalent to an equivalent model of a submarine cable, which can be used to cover all possible branch conditions of the submarine cable, and thus can quickly and accurately calculate the first product of the first real part and the preset current limiting resistor in different branch conditions.

[0022] As a preferred solution, the overall dielectric loss value expression is specifically:

[0023] Among them, tanδ total is the preset first measured dielectric loss value, AR is the first product, and tanδ is the first actual dielectric loss value to be solved. As a preferred solution, the initial frequency domain admittance expression is specifically:

[0024] Among them, R0, C0, R, ω and j are respectively the preset total cable resistance, the preset total cable capacitance, the preset current limiting resistance, the angular frequency and the imaginary unit in the first preset data.

[0025] As a preferred solution, before obtaining the first measured dielectric loss value, the first current limiting resistance, and the first insulation resistance of the submarine cable, the method further includes:

[0026] Determine whether there is a branch in the submarine cable;

[0027] When a branch exists, obtaining a first measured dielectric loss value, a first current limiting resistance, and a first insulation resistance of the submarine cable;

[0028] When no branch exists, obtaining a second measured dielectric loss value, a second current limiting resistor, and a second cable resistance of the submarine cable;

[0029] Substituting the second measured dielectric loss value, the second current limiting resistor, and the second cable resistance into a second measured dielectric loss value expression to calculate a second actual dielectric loss value; wherein the second measured dielectric loss value expression is calculated based on a preset second frequency domain admittance expression;

[0030] The insulation performance of the submarine cable is evaluated according to the second actual dielectric loss value to obtain an insulation performance evaluation result.

[0031] Based on the original solution, this preferred solution provides another method for solving the measured dielectric loss value when there is no branch in the submarine cable. The second measured dielectric loss value, the second current limiting resistor and the second cable resistance of the submarine cable are substituted into the pre-calculated second measured dielectric loss value expression to obtain the second actual dielectric loss value. The second actual dielectric loss value is then used to evaluate the insulation performance of the submarine cable to obtain an evaluation result. This evaluation method is simple, fast, efficient and convenient.

[0032] As a preferred solution, the second measured dielectric loss value expression is calculated based on a preset frequency domain admittance expression, specifically:

[0033] Establishing a frequency domain impedance expression based on second preset data, and performing a formula transformation on the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the second preset data includes a preset second measured dielectric loss value of the submarine cable, a preset cable resistance, a preset cable capacitance, a preset current limiting resistor, an angular frequency of the submarine cable under direct current, and an imaginary unit;

[0034] Converting the initial frequency-domain admittance expression into a functional expression in which one part does not have an imaginary unit and the other part has an imaginary unit, to obtain the second frequency-domain admittance expression including a second real part and a second imaginary part;

[0035] The second measured dielectric loss value expression is calculated based on the second real part and the second imaginary part.

[0036] As a preferred solution, the second measured dielectric loss value expression is specifically:

[0037] Among them, tanδ system, R and R0 are respectively the preset second measured dielectric loss value, the preset current limiting resistor and the preset cable resistance in the second preset data, and tanδ' is the second actual dielectric loss value to be solved.

[0038] The present invention also provides an insulation performance evaluation device for a submarine cable, comprising an information acquisition module, a data solution module and a first evaluation module;

[0039] Wherein, the information acquisition module is used to obtain a first measured dielectric loss value, a first current limiting resistance and a first insulation resistance of the submarine cable;

[0040] The data solving module is configured to substitute the first measured dielectric loss value, the first current-limiting resistor, and the first insulation resistance into a first measured dielectric loss value expression to calculate a first actual dielectric loss value; wherein the first measured dielectric loss value expression is calculated based on a preset overall dielectric loss value expression, the overall dielectric loss value expression including a first product and the first actual dielectric loss value to be solved, the first product being calculated using a preset model under an n-th order condition, where the n-th order condition indicates that there are n branches of the submarine cable, and n is a natural number;

[0041] The first evaluation module is used to evaluate the insulation performance of the submarine cable according to the first actual dielectric loss value to obtain an insulation performance evaluation result.

[0042] As a preferred solution, the data solution module further includes a first transformation unit, a second transformation unit and a third transformation unit;

[0043] The first conversion unit is configured to establish a frequency domain impedance expression based on first preset data, and perform formula conversion on the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the first preset data includes a preset first measured dielectric loss value of the submarine cable, a preset total cable resistance, a preset total cable capacitance, a preset current limiting resistance, an imaginary unit, an angular frequency of the submarine cable under direct current, and a preset insulation resistance;

[0044] The second transformation unit is configured to transform the initial frequency-domain admittance expression into an algebraic form of a complex number to obtain a first frequency-domain admittance expression including a first real part and a first imaginary part;

[0045] The third transformation unit is configured to calculate the overall dielectric loss value expression based on the first real part and the first imaginary part, substitute the value of the first product into the overall dielectric loss value expression, and calculate the first measured dielectric loss value expression;

[0046] The first product is the product of the first real part and the preset current limiting resistance.

[0047] As a preferred solution, the data solving module further includes a first product unit;

[0048] The first product unit is used to calculate the first product in the nth order case through a Debye model;

[0049] The first product is:

[0050] Where A is the first real part, R0, R, ω and R 直流 are respectively the preset total cable resistance, the preset current limiting resistance, the angular frequency and the preset insulation resistance in the first preset data, C i and R i are the equivalent capacitance and equivalent resistance of the i-th branch in the submarine cable respectively.

[0051] As a preferred solution, the overall dielectric loss value expression is specifically:

[0052] Among them, tanδ total is the preset first measured dielectric loss value, AR is the first product, and tanδ is the first actual dielectric loss value to be solved. As a preferred solution, the initial frequency domain admittance expression is specifically:

[0053] Among them, R0, C0, R, ω and j are respectively the preset total cable resistance, the preset total cable capacitance, the preset current limiting resistance, the angular frequency and the imaginary unit in the first preset data.

[0054] As a preferred solution, the insulation performance evaluation device for a submarine cable further includes a judgment module, a data acquisition module and a second evaluation module;

[0055] Wherein, the judgment module is used to judge whether there is a branch in the submarine cable;

[0056] The data acquisition module is used to obtain a first measured dielectric loss value, a first current limiting resistance, and a first insulation resistance of the submarine cable when a branch exists;

[0057] The second evaluation module is configured to obtain a second measured dielectric loss value, a second current limiting resistor, and a second cable resistance of the submarine cable when no branch exists;

[0058] The second evaluation module is further configured to substitute the second measured dielectric loss value, the second current limiting resistor, and the second cable resistance into a second measured dielectric loss value expression to calculate a second actual dielectric loss value; wherein the second measured dielectric loss value expression is calculated based on a preset second frequency-domain admittance expression;

[0059] The second evaluation module is further configured to evaluate the insulation performance of the submarine cable according to the second actual dielectric loss value to obtain an insulation performance evaluation result.

[0060] As a preferred solution, the second evaluation module further includes a fourth transformation unit, a fifth transformation unit and a sixth transformation unit;

[0061] The fourth transformation unit is configured to establish a frequency domain impedance expression based on second preset data, and perform formula transformation on the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the second preset data includes a preset second measured dielectric loss value of the submarine cable, a preset cable resistance, a preset cable capacitance, a preset current limiting resistance, an angular frequency of the submarine cable under direct current, and an imaginary unit;

[0062] The fifth transformation unit is configured to transform the initial frequency-domain admittance expression into a functional expression, part of which does not have imaginary units and another part of which has imaginary units, to obtain the second frequency-domain admittance expression including a second real part and a second imaginary part;

[0063] The sixth transformation unit is used to calculate the second measured dielectric loss value expression according to the second real part and the second imaginary part.

[0064] As a preferred solution, the second measured dielectric loss value expression is specifically:

[0065] Among them, tanδ system , R and R0 are respectively the preset second measured dielectric loss value, the preset current limiting resistor and the preset cable resistance in the second preset data, and tanδ' is the second actual dielectric loss value to be solved.

[0066] The present invention also provides a storage medium having a computer program stored thereon. The computer program is called and executed by a computer to implement the above-mentioned method for evaluating the insulation performance of a submarine cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] FIG1 is a schematic flow chart of a method for evaluating the insulation performance of a submarine cable provided by an embodiment of the present invention;

[0068] FIG2 is a diagram showing the calculation error of low-frequency dielectric loss at different sampling intervals provided by an embodiment of the present invention;

[0069] FIG3 is a first-order circuit model diagram of a PDC provided in an embodiment of the present invention;

[0070] FIG4 is a comparison diagram of the correction of dielectric loss calculation results provided by an embodiment of the present invention;

[0071] FIG5 is a schematic structural diagram of a submarine cable insulation performance evaluation device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0072] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0073] In the description of this application, it should be understood that the terms "first," "second," "third," "fourth," "fifth," and "sixth" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first," "second," "third," "fourth," "fifth," and "sixth" may explicitly or implicitly include one or more of the features.

[0074] Referring to FIG1 , an embodiment of the present invention provides a method for evaluating the insulation performance of a submarine cable, including: S1 to S3:

[0075] S1. Obtain a first measured dielectric loss value, a first current limiting resistance, and a first insulation resistance of a submarine cable.

[0076] In an embodiment of the present invention, a polarization-depolarization current method (PDC) is used to apply a voltage approximately equivalent to a step signal to the submarine cable to test and obtain a first measured dielectric loss value; the resistance value of the first current limiting resistor can be calculated according to Ohm's law; and the submarine cable can be tested using a DC resistance insulation resistance tester ZZJ3D or a high resistance meter method to obtain a first insulation resistance.

[0077] S2. Substitute the first measured dielectric loss value, the first current limiting resistor, and the first insulation resistance into the first measured dielectric loss value expression to calculate the first actual dielectric loss value; wherein, the first measured dielectric loss value expression is calculated based on a preset overall dielectric loss value expression, and the overall dielectric loss value expression includes a first product and the first actual dielectric loss value to be solved. The first product is calculated by a preset model under the n-order case, and the n-order case indicates that there are n branches of the submarine cable, and n is a natural number.

[0078] In this embodiment of the present invention, S2 includes S2.1 to S2.5:

[0079] S2.1. Establish a frequency domain impedance expression based on the first preset data, and transform the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the first preset data includes a preset first measured dielectric loss value tanδ of the submarine cabletotal , preset total cable resistance R0, preset total cable capacitance C0, preset current limiting resistor R, imaginary unit j, angular frequency ω of the submarine cable under DC, and preset insulation resistance R 直流 ;

[0080] The frequency domain impedance expression is:

[0081] The initial frequency domain admittance expression is:

[0082] In this embodiment, the first preset data is used to establish the frequency domain impedance expression because the frequency domain impedance expression is transformed to obtain the initial frequency domain admittance expression, and many of the parameters therein will be eliminated after the subsequent transformation processing. Therefore, establishing the frequency domain impedance expression through the first preset data can save the human resources consumed in obtaining data.

[0083] S2.2. Transform the initial frequency-domain admittance expression into a complex algebraic form (A + Bi) to obtain a first frequency-domain admittance expression including a first real part A and a first imaginary part B;

[0084] The first frequency domain admittance expression is:

[0085] Wherein, A, B and i are the first real part, the first imaginary part and the imaginary unit respectively.

[0086] In this embodiment, considering that if the circuit of the submarine cable has a first-order response or a multi-order response, that is, there is no branch or there are many branches, the circuit frequency domain impedance transformation can be performed, and the initial frequency domain admittance expression can be converted into a general A+Bi form to solve the equation. This method can ensure that the branch range of the submarine cable applicable to this solution is wider.

[0087] S2.3. Divide the first real part A by the first imaginary part B to obtain the overall dielectric loss expression;

[0088] The overall dielectric loss value expression is:

[0089] S2.4. Calculate, using the Debye model, a first product of a first real part A and a preset current-limiting resistor R in an n-order case; wherein the n-order case indicates that there are n branches of the submarine cable, and n is a natural number;

[0090] In the 0th order case,

[0091] In the first-order case,

[0092] …

[0093] In the case of order n,

[0094] Among them, A is the first real part, R0, R, ω and R 直流 are respectively the preset total cable resistance, preset current limiting resistance, angular frequency and preset insulation resistance in the first preset data, C i and R i are the equivalent capacitance and equivalent resistance of the i-th branch preset in the submarine cable respectively.

[0095] In this embodiment, the first product of the first real part and the preset current limiting resistor in the n-th order case is calculated through the Debye model. At this time, the Debye model is equivalent to an equivalent model of a submarine cable, which can be used to cover all possible branch conditions of the submarine cable, and thus can quickly and accurately calculate the first product of the first real part and the preset current limiting resistor in different branch conditions.

[0096] S2.4. Substitute the value of the first product (AR) into the overall dielectric loss value expression to obtain the first measured dielectric loss value expression;

[0097] The first measured dielectric loss value expression is:

[0098] S2.5. Substitute the first measured dielectric loss value, the first current limiting resistor, and the first insulation resistance into the first measured dielectric loss value expression to calculate the first actual dielectric loss value tanδ. Specifically: Substitute the first measured dielectric loss value into the preset first measured dielectric loss value tanδ total , substitute the first current limiting resistor into the preset current limiting resistor R, substitute the first insulation resistance into the preset insulation resistance R 直流 , calculate and obtain the first actual dielectric loss value tanδ.

[0099] Please refer to Figure 2. In order to apply the embodiment of the present invention, the embodiment of the present invention also provides a calculation error diagram of low-frequency dielectric loss under different sampling intervals. The horizontal axis of Figure 2 represents the frequency of the current flowing through the submarine cable, and the vertical axis represents the theoretical error of the first actual dielectric loss value tanδ. For the first actual dielectric loss value tanδ, it can be seen that after the sampling interval is less than 0.04, the algorithm accuracy is relatively high in the low-frequency band near 0.1Hz, and the average error is less than 0.0002%. It can be considered that this result can be well fitted. Therefore, it can be analyzed that for submarine cables with longer lengths and larger capacitances, in the process of performing polarization-depolarization current tests to obtain measured dielectric loss values, it is more reasonable to take a sampling interval of 0.04s, which can obtain an accurate first actual dielectric loss value tanδ.

[0100] S3. Evaluate the insulation performance of the submarine cable according to the first actual dielectric loss value to obtain an insulation performance evaluation result.

[0101] In an embodiment of the present invention, the insulation performance of the submarine cable is evaluated based on the first actual dielectric loss value tanδ to obtain an insulation performance evaluation result. The smaller the first actual dielectric loss value tanδ, the better the insulation performance of the submarine cable.

[0102] In the embodiment of the present invention, S3 further includes S10:

[0103] S10, determining whether there is a branch in the submarine cable;

[0104] Case 1: When there is a branch, execute steps S1 to S3;

[0105] Case 2: When there is no branch, obtain the second measured dielectric loss value, the second current limiting resistor, and the second cable resistance of the submarine cable, and perform the following steps (S10.1 to S10.5):

[0106] S10.1. Establish a frequency domain impedance expression based on the second preset data, and transform the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the second preset data includes a preset second measured dielectric loss value tanδ of the submarine cable system , preset cable resistance R0, preset cable capacitance C0, preset current limiting resistor R, angular frequency ω of the submarine cable under DC and imaginary unit j;

[0107] The frequency domain impedance expression is:

[0108] The initial frequency domain admittance expression is:

[0109] Referring to Figure 3 , for application of the present invention, a first-order circuit model diagram of a PDC is also provided. The equivalent model of the submarine cable circuit when no branches exist can be represented by a first-order RC parallel model, where R0 and C0 are the preset cable resistance and capacitance, respectively, and R is the preset current-limiting resistor.

[0110] S10.2. First, convert the initial frequency-domain admittance expression into a functional expression, partly without imaginary units and partly with imaginary units, to obtain a second frequency-domain admittance expression including a second real part and a second imaginary part.

[0111] Then, the second real part is divided by the second imaginary part to obtain the third measured dielectric loss value expression;

[0112] The third measured dielectric loss value expression is:

[0113] S10.3, use tanδ' to express the third measured dielectric loss value expression Obtain a fourth measured dielectric loss value expression; after ignoring the second term in the fourth measured dielectric loss value expression, obtain a second actual dielectric loss value expression;

[0114] The fourth measured dielectric loss value expression is:

[0115] The second measured dielectric loss value expression is:

[0116] It should be noted that tanδ' is used to represent the third measured dielectric loss value expression. Because through the formula The result is the second actual dielectric loss value, but due to the formula The parameters in are difficult to obtain, so the parameter tanδ' is used to express the formula By inversely solving the value of the parameter tanδ' using the method described in this embodiment, the second actual dielectric loss value can be obtained. The second term in the fourth measured dielectric loss value expression is ignored because R / R0 depends on the ratio of the current-limiting resistor to the cable resistance in the circuit. Even if the length of the submarine cable reaches more than 7500m, its cable resistance should be significantly greater than the current-limiting resistor. Therefore, the coefficient of the second term does not actually affect the final result.

[0117] S10.4. Substitute the second measured dielectric loss value, the second current limiting resistor, and the second cable resistance into the second measured dielectric loss value expression to calculate the second actual dielectric loss value. Specifically: Substitute the second measured dielectric loss value into the preset second measured dielectric loss value tanδ system , substitute the second current limiting resistor into the preset current limiting resistor R, substitute the second cable resistance into the preset cable resistance R0, and calculate the second actual dielectric loss value tanδ'.

[0118] Please refer to Figure 4. For the application of the embodiment of the present invention, the embodiment of the present invention also provides a comparison chart of the correction of the dielectric loss calculation results. The cable resistance Rx can be calculated by conductivity. When the cable resistance R0 is 15.55GΩ and the current limiting resistor R is 5MΩ, the above parameters are substituted into the second measured dielectric loss value expression, and then by selecting different first measured dielectric loss values ​​tanδ system , the second actual dielectric loss value (after the improved algorithm) obtained by this embodiment and the actual dielectric loss value can be plotted. The horizontal axis of Figure 4 represents the frequency of the current flowing through the submarine cable, and the vertical axis represents the first measured dielectric loss value tanδ system It can be seen that the low-frequency response fitting effect is good, and the improvement effect basically coincides with the actual effect. It can be considered that the calculated value at this time is the actual dielectric loss value. Therefore, the second measured dielectric loss value obtained by this embodiment is reliable.

[0119] S10.5. Evaluate the insulation performance of the submarine cable based on the second actual dielectric loss value tan δ' to obtain an insulation performance evaluation result. The smaller the second actual dielectric loss value tan δ', the better the insulation performance of the submarine cable.

[0120] This embodiment, based on the existing solution, provides another method for calculating the actual dielectric loss value when a submarine cable does not have a branch. The second measured dielectric loss value, the second current-limiting resistor, and the second cable resistance of the submarine cable are substituted into a pre-calculated expression for the second measured dielectric loss value to calculate the second actual dielectric loss value. This second actual dielectric loss value is then used to evaluate the insulation performance of the submarine cable to obtain an evaluation result. This evaluation method is simple, fast, efficient, and convenient.

[0121] This embodiment takes into account that the circuit of the submarine cable is a first-order response and does not have a multi-order response, that is, there is no branch. Therefore, there is no need to perform circuit frequency domain impedance conversion, that is, there is no need to convert the initial frequency domain admittance expression into a general A+Bi form to solve the equation. Instead, the initial frequency domain admittance expression is directly converted into a function containing a second real part and a second imaginary part, and the second real part and the second imaginary part are used to solve the equation. This makes the process of obtaining the second measured dielectric loss value expression more convenient.

[0122] In general, the embodiments of the present invention have the following beneficial effects:

[0123] The present invention substitutes the first measured dielectric loss value, the first current limiting resistor and the first insulation resistance into the first measured dielectric loss value expression obtained in advance to obtain the first measured dielectric loss value, and then uses the first measured dielectric loss value to evaluate the insulation performance of the submarine cable to obtain an evaluation result. This evaluation method is simple, fast, efficient and convenient. Among them, the overall dielectric loss value expression includes the first product and the first actual dielectric loss value to be solved. The first product is calculated by the preset model and substituted into the overall dielectric loss value expression to obtain the first measured dielectric loss value expression. At this time, the first measured dielectric loss value expression contains the first actual dielectric loss value to be solved. The first measured dielectric loss value expression is actually a combination of the first actual dielectric loss value and the "parameter that causes the measured dielectric loss value to be too large". Therefore, as long as the relevant data is substituted in, the first actual dielectric loss value can be inversely solved. This solution is simple and fast, and after eliminating the biased data, the accuracy of the first actual dielectric loss value is guaranteed, thereby making the evaluation result obtained by using the first actual dielectric loss value to evaluate the insulation performance of the submarine cable highly accurate.

[0124] In addition, based on the original solution, this embodiment provides another method for solving the measured dielectric loss value when there is no branch in the submarine cable. The second measured dielectric loss value, second current limiting resistor, and second cable resistance of the submarine cable are substituted into the pre-calculated second measured dielectric loss value expression to calculate the second actual dielectric loss value. The second actual dielectric loss value is then used to evaluate the insulation performance of the submarine cable to obtain an evaluation result. This evaluation method is efficient and fast.

[0125] Referring to FIG5 , an embodiment of the present invention provides a molecular insulation strength prediction device based on a neural network, comprising an information acquisition module 10 , a data solution module 20 , and a first evaluation module 30 ;

[0126] The information acquisition module 10 is used to obtain a first measured dielectric loss value, a first current limiting resistor, and a first insulation resistance of the submarine cable;

[0127] a data solving module 20 for substituting the first measured dielectric loss value, the first current-limiting resistor, and the first insulation resistance into a first measured dielectric loss value expression to calculate a first actual dielectric loss value; wherein the first measured dielectric loss value expression is calculated based on a preset overall dielectric loss value expression, the overall dielectric loss value expression including a first product and the first actual dielectric loss value to be solved, the first product being calculated using a preset model under an n-th order condition, where the n-th order condition indicates that there are n branches of the submarine cable, where n is a natural number;

[0128] The first evaluation module 30 is configured to evaluate the insulation performance of the submarine cable according to the first actual dielectric loss value to obtain an insulation performance evaluation result.

[0129] In one embodiment, the data solution module further includes a first transformation unit, a second transformation unit, and a third transformation unit;

[0130] The first conversion unit is configured to establish a frequency domain impedance expression based on first preset data, perform formula conversion on the frequency domain impedance expression, and obtain an initial frequency domain admittance expression; wherein the first preset data includes a preset first measured dielectric loss value of the submarine cable, a preset total cable resistance, a preset total cable capacitance, a preset current limiting resistance, an imaginary unit, an angular frequency of the submarine cable under direct current, and a preset insulation resistance;

[0131] a second transform unit, configured to transform the initial frequency-domain admittance expression into an algebraic form of a complex number, to obtain a first frequency-domain admittance expression including a first real part and a first imaginary part;

[0132] a third transformation unit, configured to calculate an overall dielectric loss value expression based on the first real part and the first imaginary part, substitute the value of the first product into the overall dielectric loss value expression, and calculate a first measured dielectric loss value expression;

[0133] The first product is the product of the first real part and the preset current limiting resistance.

[0134] In one embodiment, the data solving module further includes a first product unit;

[0135] A first product unit, used for calculating the first product in the n-th order case through a Debye model;

[0136] The first product is:

[0137] Among them, A is the first real part, R0, R, ω and R 直流 are respectively the preset total cable resistance, preset current limiting resistance, angular frequency and preset insulation resistance in the first preset data, C i and R i are the equivalent capacitance and equivalent resistance of the i-th branch in the submarine cable respectively.

[0138] In one embodiment, the overall dielectric loss value expression is specifically:

[0139] Among them, tanδ total is the preset first measured dielectric loss value, AR is the first product, and tanδ is the first actual dielectric loss value to be solved.

[0140] In one embodiment, the initial frequency domain admittance expression is specifically:

[0141] Among them, R0, C0, R, ω and j are respectively the preset total cable resistance, the preset total cable capacitance, the preset current limiting resistance, the angular frequency and the imaginary unit in the first preset data.

[0142] In one embodiment, a submarine cable insulation performance evaluation device further includes a judgment module, a data acquisition module, and a second evaluation module;

[0143] The judgment module is used to judge whether there is a branch in the submarine cable;

[0144] a data acquisition module, configured to acquire a first measured dielectric loss value, a first current limiting resistance, and a first insulation resistance of the submarine cable when a branch line exists;

[0145] a second evaluation module, configured to obtain a second measured dielectric loss value, a second current limiting resistor, and a second cable resistance of the submarine cable when no branch exists;

[0146] The second evaluation module is further configured to substitute the second measured dielectric loss value, the second current limiting resistor, and the second cable resistance into a second measured dielectric loss value expression to calculate a second actual dielectric loss value; wherein the second measured dielectric loss value expression is calculated based on a preset second frequency domain admittance expression;

[0147] The second evaluation module is further used to evaluate the insulation performance of the submarine cable according to the second actual dielectric loss value to obtain an insulation performance evaluation result.

[0148] In one embodiment, the second evaluation module further includes a fourth transform unit, a fifth transform unit, and a sixth transform unit;

[0149] The fourth transformation unit is configured to establish a frequency domain impedance expression based on second preset data, perform formula transformation on the frequency domain impedance expression, and obtain an initial frequency domain admittance expression; wherein the second preset data includes a preset second measured dielectric loss value of the submarine cable, a preset cable resistance, a preset cable capacitance, a preset current limiting resistor, an angular frequency of the submarine cable under direct current, and an imaginary unit;

[0150] a fifth transform unit, configured to transform the initial frequency-domain admittance expression into a functional expression having a portion without imaginary units and another portion with imaginary units, to obtain a second frequency-domain admittance expression including a second real part and a second imaginary part;

[0151] The sixth transformation unit is used to calculate the second measured dielectric loss value expression according to the second real part and the second imaginary part.

[0152] In one embodiment, the second measured dielectric loss value expression is specifically:

[0153] Among them, tanδ system , R and R0 are respectively the preset second measured dielectric loss value, the preset current limiting resistor and the preset cable resistance in the second preset data, and tanδ' is the second actual dielectric loss value to be solved.

[0154] This device has the following beneficial effects:

[0155] This device substitutes the first measured dielectric loss value, the first current limiting resistor, and the first insulation resistance into the pre-calculated first measured dielectric loss value expression to obtain the first measured dielectric loss value, and then uses the first measured dielectric loss value to evaluate the insulation performance of the submarine cable to obtain an evaluation result. This evaluation method is simple, fast, efficient, and convenient. Among them, the overall dielectric loss value expression includes the first product and the first actual dielectric loss value to be solved. The first product is calculated by the preset model and substituted into the overall dielectric loss value expression to obtain the first measured dielectric loss value expression. At this time, the first measured dielectric loss value expression contains the first actual dielectric loss value to be solved. The first measured dielectric loss value expression is actually a combination of the first actual dielectric loss value and the "parameter that causes the measured dielectric loss value to be too large". Therefore, as long as the relevant data is substituted in, the first actual dielectric loss value can be inversely solved. This solution is simple and fast, and after eliminating the biased data, the accuracy of the first actual dielectric loss value is guaranteed, thereby making the evaluation result obtained by using the first actual dielectric loss value to evaluate the insulation performance of the submarine cable highly accurate.

[0156] Accordingly, an embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device containing the computer-readable storage medium is controlled to execute the method for evaluating the insulation performance of a submarine cable;

[0157] Among them, if a method for evaluating the insulation performance of a submarine cable is implemented in the form of a software functional unit and used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, it can implement the steps of the above-mentioned various method embodiments. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form. Computer-readable media can include: any entity or device that can carry computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0158] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for evaluating the insulation performance of a submarine cable, characterized in that: include: Obtaining a first measured dielectric loss value, a first current limiting resistance, and a first insulation resistance of the submarine cable; Substituting the first measured dielectric loss value, the first current limiting resistor and the first insulation resistance into a first measured dielectric loss value expression, and calculating a first actual dielectric loss value; wherein the first measured dielectric loss value expression is calculated according to a preset overall dielectric loss value expression, and the overall dielectric loss value expression includes a first product and the first actual dielectric loss value to be solved, and the first product is calculated by a preset model in an n-order case, and the n-order case indicates that there are n branches of the submarine cable, and n is a natural number; The insulation performance of the submarine cable is evaluated according to the first actual dielectric loss value to obtain an insulation performance evaluation result.

2. A method for evaluating the insulation performance of a submarine cable according to claim 1, characterized in that: The first measured dielectric loss value expression is calculated based on a preset overall dielectric loss value expression, specifically: Establish a frequency domain impedance expression according to first preset data, and transform the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the first preset data includes a preset first measured dielectric loss value of the submarine cable, a preset total cable resistance, a preset total cable capacitance, a preset current limiting resistance, an imaginary unit, an angular frequency of the submarine cable under direct current, and a preset insulation resistance; Transforming the initial frequency-domain admittance expression into an algebraic form of a complex number to obtain a first frequency-domain admittance expression including a first real part and a first imaginary part; The overall dielectric loss value expression is calculated according to the first real part and the first imaginary part, and the value of the first product is substituted into the overall dielectric loss value expression to calculate the first measured dielectric loss value expression; The first product is the product of the first real part and the preset current limiting resistance.

3. A method for evaluating the insulation performance of a submarine cable as claimed in claim 2, characterized in that: The first product is calculated by a preset model in the nth order, specifically: Calculate the first product in the n-th order case by using the Debye model; The first product is: Where A is the first real part, R0, R, ω and R 直流 are respectively the preset total cable resistance, the preset current limiting resistance, the angular frequency and the preset insulation resistance in the first preset data, C i and R i are the equivalent capacitance and equivalent current of the i-th branch of the submarine cable respectively. Resistance.

4. A method for evaluating the insulation performance of a submarine cable as claimed in claim 2, characterized in that: The overall dielectric loss value expression is specifically: Among them, tanδ total is the preset first measured dielectric loss value, AR is the first product, and tanδ is the first actual dielectric loss value to be solved.

5. The method for evaluating the insulation performance of a submarine cable according to claim 2, characterized in that: The initial frequency domain admittance expression is specifically: Among them, R0, C0, R, ω and j are respectively the preset total cable resistance, the preset total cable capacitance, the preset current limiting resistance, the angular frequency and the imaginary unit in the first preset data.

6. The method for evaluating the insulation performance of a submarine cable according to claim 1, characterized in that: Before obtaining the first measured dielectric loss value, the first current limiting resistance and the first insulation resistance of the submarine cable, the method further includes: Determine whether there is a branch in the submarine cable; When a branch exists, obtaining a first measured dielectric loss value, a first current limiting resistance, and a first insulation resistance of the submarine cable; When there is no branch, obtaining a second measured dielectric loss value, a second current limiting resistor, and a second cable resistance of the submarine cable; Substituting the second measured dielectric loss value, the second current limiting resistor and the second cable resistance into a second measured dielectric loss value expression to calculate a second actual dielectric loss value; wherein the second measured dielectric loss value expression is calculated according to a preset second frequency domain admittance expression; The insulation performance of the submarine cable is evaluated according to the second actual dielectric loss value to obtain an insulation performance evaluation result.

7. A method for evaluating the insulation performance of a submarine cable as claimed in claim 6, characterized in that: The second measured dielectric loss value expression is calculated based on a preset frequency domain admittance expression, specifically: Establish a frequency domain impedance expression according to second preset data, and transform the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the second preset data includes a preset second measured dielectric loss value of the submarine cable, a preset cable resistance, a preset cable capacitance, a preset current limiting resistance, an angular frequency of the submarine cable under direct current, and an imaginary unit; Converting the initial frequency-domain admittance expression into a functional expression in which one part does not have an imaginary unit and the other part has an imaginary unit, to obtain the second frequency-domain admittance expression including a second real part and a second imaginary part; The second measured dielectric loss value expression is calculated based on the second real part and the second imaginary part.

8. A method for evaluating the insulation performance of a submarine cable as claimed in claim 7, characterized in that: The second measured dielectric loss value expression is specifically: Among them, tanδ system , R and R0 are respectively the preset second measured dielectric loss value, the preset current limiting resistor and the preset cable resistance in the second preset data, and tanδ' is the second actual dielectric loss value to be solved.

9. A submarine cable insulation performance evaluation device, characterized in that: It includes an information acquisition module, a data solution module and a first evaluation module; Wherein, the information acquisition module is used to obtain a first measured dielectric loss value, a first current limiting resistor and a first insulation resistance of the submarine cable; The data solving module is used to substitute the first measured dielectric loss value, the first current limiting resistor and the first insulation resistance into a first measured dielectric loss value expression to calculate a first actual dielectric loss value; wherein the first measured dielectric loss value expression is calculated according to a preset overall dielectric loss value expression, the overall dielectric loss value expression includes a first product and the first actual dielectric loss value to be solved, the first product is calculated by a preset model in an n-order case, the n-order case indicates that there are n branches of the submarine cable, and n is a natural number; The first evaluation module is used to evaluate the insulation performance of the submarine cable according to the first actual dielectric loss value to obtain an insulation performance evaluation result.

10. The insulation performance evaluation device for a submarine cable according to claim 9, characterized in that: The data solving module further includes a first transformation unit, a second transformation unit and a third transformation unit; The first transformation unit is used to establish a frequency domain impedance expression according to first preset data, and perform formula transformation on the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the first preset data includes a preset first measured dielectric loss value of the submarine cable, a preset total cable resistance, a preset total cable capacitance, a preset current limiting resistance, an imaginary unit, an angular frequency of the submarine cable under direct current, and a preset insulation resistance; The second transformation unit is used to transform the initial frequency domain admittance expression into an algebraic form of a complex number to obtain a first frequency domain admittance expression including a first real part and a first imaginary part; The third transformation unit is used to calculate the overall dielectric loss value expression according to the first real part and the first imaginary part, substitute the value of the first product into the overall dielectric loss value expression, and calculate the first measured dielectric loss value expression; The first product is the product of the first real part and the preset current limiting resistance.

11. The insulation performance evaluation device for a submarine cable according to claim 10, characterized in that: The data solving module further includes a first product unit; The first product unit is used to calculate the first product in the n-th order case through a Debye model; The first product is: Where A is the first real part, R0, R, ω and R 直流 are respectively the preset total cable resistance, the preset current limiting resistance, the angular frequency and the preset insulation resistance in the first preset data, C i and R i are the equivalent capacitance and equivalent resistance of the i-th branch in the submarine cable respectively.

12. The insulation performance evaluation device for a submarine cable according to claim 10, characterized in that: The overall dielectric loss value expression is specifically: Among them, tanδ total is the preset first measured dielectric loss value, AR is the first product, and tanδ is the first actual dielectric loss value to be solved.

13. The insulation performance evaluation device for a submarine cable according to claim 10, characterized in that: The initial frequency domain admittance expression is specifically: Among them, R0, C0, R, ω and j are respectively the preset total cable resistance, the preset total cable capacitance, the preset current limiting resistance, the angular frequency and the imaginary unit in the first preset data.

14. The insulation performance evaluation device for a submarine cable according to claim 9, characterized in that: The insulation performance evaluation device for a submarine cable also includes a judgment module, a data acquisition module and a second evaluation module; Wherein, the judging module is used to judge whether there is a branch in the submarine cable; The data acquisition module is used to obtain a first measured dielectric loss value, a first current limiting resistance and a first insulation resistance of the submarine cable when a branch exists; The second evaluation module is used to obtain a second measured dielectric loss value, a second current limiting resistor and a second cable resistance of the submarine cable when no branch exists; The second evaluation module is further used to substitute the second measured dielectric loss value, the second current limiting resistor and the second cable resistance into a second measured dielectric loss value expression to calculate a second actual dielectric loss value; wherein the second measured dielectric loss value expression is calculated according to a preset second frequency domain admittance expression; The second evaluation module is further used to evaluate the insulation performance of the submarine cable according to the second actual dielectric loss value to obtain an insulation performance evaluation result.

15. The insulation performance evaluation device for a submarine cable according to claim 14, characterized in that: The second evaluation module further includes a fourth transformation unit, a fifth transformation unit and a sixth transformation unit; The fourth transformation unit is used to establish a frequency domain impedance expression according to second preset data, and perform formula transformation on the frequency domain impedance expression to obtain an initial frequency domain admittance expression; wherein the second preset data includes a preset second measured dielectric loss value of the submarine cable, a preset cable resistance, a preset cable capacitance, a preset current limiting resistance, an angular frequency of the submarine cable under direct current, and an imaginary unit; The fifth transformation unit is used to transform the initial frequency domain admittance expression into a function expression in which a part does not have an imaginary unit and another part has an imaginary unit, so as to obtain the second frequency domain admittance expression including a second real part and a second imaginary part; The sixth transformation unit is used to calculate the second measured dielectric loss value expression according to the second real part and the second imaginary part.

16. The insulation performance evaluation device for a submarine cable according to claim 15, characterized in that: The second measured dielectric loss value expression is specifically: Among them, tanδ system , R and R0 are respectively the preset second measured dielectric loss value, the preset current limiting resistor and the preset cable resistance in the second preset data, and tanδ' is the second actual dielectric loss value to be solved.

17. A storage medium, characterized in that: The storage medium stores a computer program, which is called and executed by a computer to implement the insulation performance evaluation method of a submarine cable as claimed in any one of claims 1 to 8.

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