Method and device for determining direct current conductivity based on insulating material

Abstract

The present invention provides a method and device for determining the direct current conductivity of an insulating material. The method for determining the direct current conductivity of the insulating material includes: determining the conductivity slope according to the historical direct current conductivities at various electric fields and various temperatures; determining the conductivity activation energy according to the historical direct current conductivities at various temperatures; determining the conductivity constant according to the historical direct current conductivity, the conductivity slope, the conductivity activation energy, the electric field and the temperature corresponding to the historical direct current conductivity; and determining the current direct current conductivity according to the conductivity constant, the current electric field, the current temperature, the conductivity slope and the conductivity activation energy. The present invention can accurately calculate the direct current conductivity of the insulating material.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage insulating materials, and in particular, to a method and device for determining the direct current conductivity based on insulating materials. Background Art

[0002] To meet the requirements of modern power systems for economy and environmental protection, the emphasis on, promotion of, and the need for long-distance and high-power electric energy transmission of new energy have led to the rapid development of high-voltage direct current (HVDC) transmission technology. Polymer insulating materials used in DC transmission and transformation equipment such as HVDC cable insulation and DC overhead transmission line insulators are of great significance for the safe and stable operation of HVDC transmission.

[0003] The direct current conductivity of polymer insulating materials is a very important insulation performance index, and the insulation characteristics of polymer insulating materials are different under alternating current voltage and direct current voltage. When a polymer insulating material bears a power frequency alternating current voltage, its electric field strength is distributed inversely proportional to the dielectric constant; when it bears a direct current voltage, its electric field strength is distributed inversely proportional to the conductivity, and the conductivity of the polymer insulating material changes with temperature and electric field strength.

[0004] Figure 1 is a schematic diagram of the variation characteristics of the current density of polymer insulating materials with the electric field strength at different temperatures. As Figure 1 shown, the current density is the direct current conductance current flowing through the test sample of the polymer insulating material to be measured divided by the sample area; the electric field strength is the direct current voltage applied to the test sample of the polymer insulating material to be measured divided by the sample thickness. Figure 1 The straight line in is the regression straight line of the current density and the electric field strength in logarithmic coordinates.

[0005] Figure 1 The slope of the regression straight line in is approximately 1 at low electric field strengths, and the relationship between the current density and the field strength conforms to Ohm's law. The low electric field strength region can also be called the Ohm region; the slope at high electric field strengths is greater than 2, and the relationship between the current density and the field strength in the high electric field strength region does not conform to Ohm's law. The high electric field strength region can also be called the non-Ohm region. According to the research of domestic and foreign scholars on the conduction mechanisms of different types of polymer insulating materials, as long as the slope of the regression straight line in logarithmic coordinates in the high electric field strength region is greater than 2, there is a space charge limited current effect. At the same time, the magnitude of the slope in the high electric field strength region only indicates different material conduction mechanisms and cannot judge the quality of the material. In addition, from Figure 1 it can be seen that the slope of the regression straight line in the high electric field strength region gradually decreases with increasing temperature. Relevant research shows that the increase in electric field strength will lead to a decrease in the activation energy of the polymer, and thus the slope in the high electric field strength region decreases with increasing temperature.

[0006] In order to calculate and analyze the electric field distribution of polymer insulating materials under different DC conditions, it is necessary to calculate the DC conductivity of polymer insulating materials at different temperatures and electric field strengths. Most of the existing technologies do not consider the DC conductivity in segments, so the accuracy of the obtained DC conductivity is not high. Summary of the Invention

[0007] The main purpose of the embodiments of the present invention is to provide a method and device for determining the DC conductivity based on insulating materials to accurately calculate the DC conductivity of insulating materials.

[0008] To achieve the above object, the embodiments of the present invention provide a method for determining the DC conductivity based on insulating materials, including:

[0009] Determine the conductivity slope according to the historical DC conductivity at each electric field and each temperature;

[0010] Determine the conductivity activation energy according to the historical DC conductivity at each temperature;

[0011] Determine the conductivity constant according to the historical DC conductivity, conductivity slope, conductivity activation energy, electric field and temperature corresponding to the historical DC conductivity;

[0012] Determine the current DC conductivity according to the conductivity constant, current electric field, current temperature, conductivity slope and conductivity activation energy.

[0013] In one of the embodiments, determining the conductivity slope according to the historical DC conductivity at each electric field and each temperature includes:

[0014] Generate historical DC conductivity coordinates according to the historical DC conductivity at each electric field and each temperature;

[0015] Fit the conductivity regression line according to the historical DC conductivity coordinates to determine the historical intersection electric field;

[0016] Divide the historical DC conductivity into ohmic region historical DC conductivity and non-ohmic region historical DC conductivity according to the historical intersection electric field;

[0017] Determine the ohmic region conductivity slope according to the ohmic region historical DC conductivity, and determine the non-ohmic region conductivity slope according to the non-ohmic region historical DC conductivity.

[0018] In one of the embodiments, the conductivity activation energy includes ohmic region conductivity activation energy and non-ohmic region conductivity activation energy;

[0019] Determining the conductivity constant according to the historical DC conductivity, conductivity slope, conductivity activation energy, electric field and temperature corresponding to the historical DC conductivity includes:

[0020] Determine the conductivity constant in the ohmic region based on the historical DC conductivity in the ohmic region, the conductivity slope in the ohmic region, the activation energy of the conductivity in the ohmic region, the electric field and temperature in the ohmic region corresponding to the historical DC conductivity in the ohmic region;

[0021] Determine the conductivity constant in the non-ohmic region based on the historical DC conductivity in the non-ohmic region, the conductivity slope in the non-ohmic region, the activation energy of the conductivity in the non-ohmic region, the electric field and temperature in the non-ohmic region corresponding to the historical DC conductivity in the non-ohmic region.

[0022] In one embodiment, determining the current DC conductivity based on the conductivity constant, the current electric field, the current temperature, the conductivity slope, and the activation energy of the conductivity includes:

[0023] Create an ohmic region conductivity model based on the ohmic region conductivity constant, the ohmic region conductivity slope, and the activation energy of the conductivity in the ohmic region, and create a non-ohmic region conductivity model based on the non-ohmic region conductivity constant, the non-ohmic region conductivity slope, and the activation energy of the conductivity in the non-ohmic region;

[0024] Determine the current intersection electric field based on the ohmic region conductivity model and the non-ohmic region conductivity model;

[0025] Select the current conductivity model from the ohmic region conductivity model and the non-ohmic region conductivity model according to the comparison result between the current intersection electric field and the current electric field;

[0026] Input the current electric field and the current temperature into the current conductivity model to obtain the current DC conductivity.

[0027] An embodiment of the present invention further provides a device for determining the DC conductivity based on an insulating material, including:

[0028] A conductivity slope determination module for determining the conductivity slope according to the historical DC conductivity at each electric field and each temperature;

[0029] A conductivity activation energy determination module for determining the activation energy of the conductivity according to the historical DC conductivity at each temperature;

[0030] A conductivity constant determination module for determining the conductivity constant according to the historical DC conductivity, the conductivity slope, the activation energy of the conductivity, the electric field and temperature corresponding to the historical DC conductivity;

[0031] A current DC conductivity determination module for determining the current DC conductivity according to the conductivity constant, the current electric field, the current temperature, the conductivity slope, and the activation energy of the conductivity.

[0032] In one embodiment, the conductivity slope determination module includes:

[0033] A historical DC conductivity coordinate unit for generating historical DC conductivity coordinates according to the historical DC conductivity at each electric field and each temperature;

[0034] A historical intersection electric field unit, which is used to fit a conductivity regression line based on historical direct current conductivity coordinates to determine the historical intersection electric field;

[0035] A division unit, which is used to divide the historical direct current conductivity into an ohmic region historical direct current conductivity and a non-ohmic region historical direct current conductivity according to the historical intersection electric field;

[0036] A conductivity slope determination unit, which is used to determine an ohmic region conductivity slope and a non-ohmic region conductivity slope according to the conductivity regression line and the historical intersection electric field.

[0037] In one embodiment, the conductivity activation energy includes an ohmic region conductivity activation energy and a non-ohmic region conductivity activation energy;

[0038] The conductivity constant determination module includes:

[0039] An ohmic region conductivity constant unit, which is used to determine an ohmic region conductivity constant according to the ohmic region historical direct current conductivity, the ohmic region conductivity slope, the ohmic region conductivity activation energy, the ohmic region electric field corresponding to the ohmic region historical direct current conductivity, and the temperature;

[0040] A non-ohmic region conductivity constant unit, which is used to determine a non-ohmic region conductivity constant according to the non-ohmic region historical direct current conductivity, the non-ohmic region conductivity slope, the non-ohmic region conductivity activation energy, the non-ohmic region electric field corresponding to the non-ohmic region historical direct current conductivity, and the temperature.

[0041] In one embodiment, the current direct current conductivity determination module includes:

[0042] A conductivity model creation unit, which is used to create an ohmic region conductivity model according to the ohmic region conductivity constant, the ohmic region conductivity slope, and the ohmic region conductivity activation energy, and create a non-ohmic region conductivity model according to the non-ohmic region conductivity constant, the non-ohmic region conductivity slope, and the non-ohmic region conductivity activation energy;

[0043] A current intersection electric field determination unit, which is used to determine the current intersection electric field according to the ohmic region conductivity model and the non-ohmic region conductivity model;

[0044] A conductivity model selection unit, which is used to select the current conductivity model from the ohmic region conductivity model and the non-ohmic region conductivity model according to the comparison result between the current intersection electric field and the current electric field;

[0045] A current direct current conductivity unit, which is used to input the current electric field and the current temperature into the current conductivity model to obtain the current direct current conductivity.

[0046] An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored on the memory and running on the processor. When the processor executes the computer program, the steps of the method for determining the direct current conductivity based on an insulating material are implemented.

[0047] An embodiment of the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for determining the direct current conductivity based on an insulating material are implemented.

[0048] In the method and device for determining the direct current conductivity based on an insulating material according to the embodiment of the present invention, first, the conductivity slope is determined based on the historical direct current conductivities at various electric fields and various temperatures to determine the conductivity activation energy. Then, the conductivity constant is determined based on the historical direct current conductivity, the conductivity slope, the conductivity activation energy, the electric field and temperature corresponding to the historical direct current conductivity. Finally, the current direct current conductivity is accurately determined based on the conductivity constant, the current electric field, the current temperature, the conductivity slope, and the conductivity activation energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0050] Figure 1 It is a schematic diagram of the variation characteristics of the current density of a polymer insulating material with the electric field strength at different temperatures;

[0051] Figure 2 It is a flowchart of the method for determining the direct current conductivity based on an insulating material in the embodiment of the present invention;

[0052] Figure 3 It is a flowchart of S101 in the embodiment of the present invention;

[0053] Figure 4 It is a flowchart of S103 in the embodiment of the present invention;

[0054] Figure 5 It is a flowchart of S104 in the embodiment of the present invention;

[0055] Figure 6 It is a schematic diagram of the direct current conductance current test system in the embodiment of the present invention;

[0056] Figure 7 It is a flowchart of the direct current test in the embodiment of the present invention;

[0057] Figure 8It is a schematic diagram of historical direct current conductivity at each temperature and each electric field strength in logarithmic coordinates in the embodiments of the present invention;

[0058] Figure 9 It is a structural block diagram of a device for determining the direct current conductivity based on an insulating material in the embodiments of the present invention;

[0059] Figure 10 It is a structural block diagram of a computer device in the embodiments of the present invention. Detailed implementation manners

[0060] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0061] Those skilled in the art know that the embodiments of the present invention can be implemented as a system, a device, equipment, a method, or a computer program product. Therefore, the present disclosure can be specifically implemented in the following forms, namely: complete hardware, complete software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0062] In view of the fact that the prior art cannot accurately calculate the direct current conductivity of polymer insulating materials at different temperatures and field strengths, the embodiments of the present invention provide a method and a device for determining the direct current conductivity based on an insulating material, providing a basis for the calculation of the direct current field distribution of polymer insulating materials and being able to accurately calculate the direct current conductivity of the insulating material. The present invention will be described in detail below in conjunction with the accompanying drawings.

[0063] Figure 2 It is a flowchart of a method for determining the direct current conductivity based on an insulating material in the embodiments of the present invention. As Figure 2 shown, the method for determining the direct current conductivity based on an insulating material includes:

[0064] S101: Determine the conductivity slope according to the historical direct current conductivity at each electric field and each temperature.

[0065] Before executing S101, it further includes: performing a direct current test on a polymer insulating material specimen by the three-electrode method (the specimen is mainly a flat specimen, and the shape is not necessarily circular), obtaining the direct current values of the specimen at i temperatures and i different electric field strengths (i≥2, and the number of electric field strengths needs to ensure that the intersection point of the Ohmic region and the non-Ohmic region can be found after plotting). The historical direct current conductivity is determined by the following formula:

[0066]

[0067] Among them, γ is the historical direct current conductivity with the unit of S / m; I is the direct current with the unit of A; U is the applied direct current voltage with the unit of V; h is the sample thickness with the unit of m; d is the diameter of the measuring electrode with the unit of m; g is the ground protection ring gap with the unit of m.

[0068] Figure 3 It is the flowchart of S101 in the embodiment of the present invention. As Figure 3 shown, S101 includes:

[0069] S201: Generate historical direct current conductivity coordinates according to the historical direct current conductivity at each electric field and each temperature.

[0070] In specific implementation, draw the historical direct current conductivity coordinates at each electric field and each temperature in logarithmic coordinates according to the historical direct current conductivity calculation result, where the abscissa is the electric field strength and the ordinate is the direct current conductivity.

[0071] S202: Fit the conductivity regression line according to the historical direct current conductivity coordinates to determine the historical intersection electric field.

[0072] In specific implementation, make the conductivity regression line of the direct current conductivity and the electric field strength at each temperature according to the historical direct current conductivity coordinates, and find the electric field strength corresponding to the intersection of the regression line in the ohmic region and the regression line in the non-ohmic region at each temperature as the historical intersection electric field E Ti .

[0073] S203: Divide the historical direct current conductivity into the historical direct current conductivity in the ohmic region and the historical direct current conductivity in the non-ohmic region according to the historical intersection electric field.

[0074] In specific implementation, when the electric field E corresponding to the historical direct current conductivity coordinate ≤ E Ti , this historical direct current conductivity is the historical direct current conductivity in the ohmic region; when the electric field E corresponding to the historical direct current conductivity coordinate > E Ti , this historical direct current conductivity is the historical direct current conductivity in the non-ohmic region.

[0075] S204: Determine the conductivity slope in the ohmic region according to the historical direct current conductivity in the ohmic region, and determine the conductivity slope in the non-ohmic region according to the historical direct current conductivity in the non-ohmic region.

[0076] In specific implementation, determine the conductivity slope in the ohmic region at each temperature according to the historical direct current conductivity in the ohmic region at each temperature, and take its average value as the conductivity slope k o in the ohmic region, determine the conductivity slope in the non-ohmic region at each temperature according to the historical direct current conductivity in the non-ohmic region at each temperature, and take its average value as the conductivity slope k f in the non-ohmic region.

[0077] S102: Determine the conductivity activation energy according to the historical direct current conductivities at various temperatures.

[0078] Among them, the conductivity activation energy includes the conductivity activation energy in the ohmic region and the conductivity activation energy in the non-ohmic region.

[0079] In specific implementation, select any electric field strength in the ohmic region (it should be ensured that there are as many test temperatures as possible at this electric field strength), and select the direct current conductivities γ at each test temperature at this electric field strength o , and make the regression line of lnγ o and 1 / T, and calculate the slope k1 of the regression line in the ohmic region; where T is the thermodynamic temperature, with the unit of K.

[0080] Determine the conductivity activation energy in the ohmic region through the following formula:

[0081]

[0082] Among them, is the conductivity activation energy in the ohmic region, k1 is the slope of the regression line in the ohmic region, K b is the Boltzmann constant. If multiple electric field strengths can be used to calculate in the ohmic region, then take the average value of the calculated at each electric field strength as the final value.

[0083] Similarly, select any electric field strength in the non-ohmic region (it should be ensured that there are as many test temperatures as possible at this electric field strength), and select the direct current conductivities γ at each test temperature at this electric field strength f , and make the regression line of lnγ f and 1 / T, and calculate the slope k2 of the regression line in the non-ohmic region.

[0084] Determine the conductivity activation energy in the non-ohmic region through the following formula:

[0085]

[0086] Among them, is the conductivity activation energy in the non-ohmic region, k2 is the slope of the regression line in the non-ohmic region, K b is the Boltzmann constant. If multiple electric field strengths can be used to calculate in the non-ohmic region, then take the average value of the calculated at each electric field strength as the final value.

[0087] S103: Determine the conductivity constant according to the historical direct current conductivity, conductivity slope, conductivity activation energy, electric field and temperature corresponding to the historical direct current conductivity.

[0088] Figure 4 This is the flowchart of S103 in the embodiments of the present invention. As Figure 4 shown, S103 includes:

[0089] S301: Determine the conductivity constant in the ohmic region according to the historical DC conductivity in the ohmic region, the conductivity slope in the ohmic region, the conductivity activation energy in the ohmic region, the electric field in the ohmic region corresponding to the historical DC conductivity in the ohmic region, and the temperature.

[0090] In specific implementation, the conductivity constant in the ohmic region can be determined by the following formula:

[0091]

[0092] where A o is the conductivity constant in the ohmic region, γ o (T, E o ) is the historical DC conductivity in the ohmic region, with the unit of S / m; k o is the conductivity slope in the ohmic region, E o is the electric field in the ohmic region corresponding to the historical DC conductivity in the ohmic region, with the unit of MV / m; T is the thermodynamic temperature, with the unit of K; is the conductivity activation energy in the ohmic region. Any conductivity at the highest test temperature in the ohmic region can be used as the historical DC conductivity γ o (T, E o ).

[0093] S302: Determine the conductivity constant in the non-ohmic region according to the historical DC conductivity in the non-ohmic region, the conductivity slope in the non-ohmic region, the conductivity activation energy in the non-ohmic region, the electric field in the non-ohmic region corresponding to the historical DC conductivity in the non-ohmic region, and the temperature.

[0094] In specific implementation, the conductivity constant in the non-ohmic region can be determined by the following formula:

[0095]

[0096] where A f is the conductivity constant in the non-ohmic region, γ f (T, E f ) is the historical DC conductivity in the non-ohmic region, with the unit of S / m; k f is the conductivity slope in the non-ohmic region, E f is the electric field in the non-ohmic region corresponding to the historical DC conductivity in the non-ohmic region, with the unit of MV / m; T is the thermodynamic temperature, with the unit of K; is the conductivity activation energy in the non-ohmic region. Any conductivity at the highest test temperature in the non-ohmic region can be used as the historical DC conductivity γ f (T, E f ).

[0097] S104: Determine the current direct current conductivity based on the conductivity constant, the current electric field, the current temperature, the conductivity slope, and the conductivity activation energy.

[0098] Figure 5 This is the flowchart of S104 in the embodiments of the present invention. As Figure 5 shown, S104 includes:

[0099] S401: Create an ohmic region conductivity model based on the ohmic region conductivity constant, the ohmic region conductivity slope, and the ohmic region conductivity activation energy, and create a non-ohmic region conductivity model based on the non-ohmic region conductivity constant, the non-ohmic region conductivity slope, and the non-ohmic region conductivity activation energy.

[0100] Specifically, the ohmic region conductivity model is as follows:

[0101]

[0102] Wherein, is the current direct current conductivity in the ohmic region, with the unit of S / m; A o is the ohmic region conductivity constant, is the ohmic region conductivity activation energy, k o is the ohmic region conductivity slope, E is the current electric field, and T is the current thermodynamic temperature.

[0103] The non-ohmic region conductivity model is as follows:

[0104]

[0105] Wherein, is the current direct current conductivity in the non-ohmic region, with the unit of S / m; A f is the non-ohmic region conductivity constant, is the non-ohmic region conductivity activation energy, k f is the non-ohmic region conductivity slope, E is the current electric field, and T is the current thermodynamic temperature.

[0106] S402: Determine the current intersection electric field based on the ohmic region conductivity model and the non-ohmic region conductivity model.

[0107] Specifically, the electric field corresponding to the intersection of the ohmic region conductivity model and the non-ohmic region conductivity model is used as the current intersection electric field.

[0108] S403: Select the current conductivity model from the ohmic region conductivity model and the non-ohmic region conductivity model according to the comparison result between the current intersection electric field and the current electric field.

[0109] In specific implementation, when the current electric field is less than or equal to the current intersection electric field, an Ohmic region conductivity model is adopted; when the current electric field is greater than the current intersection electric field, a non-Ohmic region conductivity model is adopted.

[0110] S404: Input the current electric field and the current temperature into the current conductivity model to obtain the current direct current conductivity.

[0111] Figure 1 The execution subject of the direct current conductivity determination method based on the insulating material shown can be a computer. Figure 1 As can be seen from the shown process, in the direct current conductivity determination method based on the insulating material in the embodiment of the present invention, first, the conductivity slope is determined according to the historical direct current conductivity at each electric field and each temperature to determine the conductivity activation energy, then the conductivity constant is determined according to the historical direct current conductivity, the conductivity slope, the conductivity activation energy, the electric field and the temperature corresponding to the historical direct current conductivity, and finally the current direct current conductivity is accurately determined according to the conductivity constant, the current electric field, the current temperature, the conductivity slope and the conductivity activation energy.

[0112] The specific process of the embodiment of the present invention is as follows:

[0113] 1. Measure the direct current of the insulating specimen through a direct current conductance current test system.

[0114] Figure 6 is a schematic diagram of the direct current conductance current test system in the embodiment of the present invention. As Figure 6 shown, the direct current conductance current test system includes a high-voltage direct current power supply, a thermal oven, a three-electrode device (a high-voltage electrode, a measurement electrode and a ground electrode), an electrometer, a data acquisition device DAQ and a computer. The high-voltage direct current power supply is used to generate a direct current test voltage, and the thermal oven is used to control the test temperature. At the same time, the metal shell of the thermal oven is grounded, thereby forming a shielding box to reduce electromagnetic interference. The three-electrode device is placed inside the thermal oven and includes three parts: a high-voltage electrode, a measurement electrode and a ground electrode. The high-voltage electrode is a stainless steel cylinder with a diameter of 45 mm, and the measurement electrode has a diameter of 30 mm; the measurement electrode is connected to the electrometer through a coaxial cable; the annular ground electrode with inner and outer diameters of 32 mm and 45 mm respectively can eliminate the leakage current on the surface of the specimen. The electrometer is used to measure the conductance current and is connected to the computer through a data acquisition device. The computer software is used to automatically collect and save the test data, and under different temperature and field strength conditions, the conductance current data collected by the electrometer during the pressurization process is recorded.

[0115] Figure 7 is a flowchart of the direct current test in the embodiment of the present invention. As Figure 7As shown, the DC current of the specimen was tested under an electric field of 2 MV / m to 20 MV / m and a temperature of 30 °C to 70 °C. First, the specimen to be tested was placed in a three-electrode device inside an oven. The specimen was pressed against the measuring electrode and the grounding electrode through the high-voltage electrode to ensure good contact between the specimen, the measuring electrode, and the grounding electrode. Then, the oven temperature was set and maintained for 2 hours to achieve thermal equilibrium inside the oven. After setting the voltage value of the high-voltage DC power supply, a 30-minute pressurized polarization test was conducted on the specimen. After the pressurization time ended, the voltage was removed and the specimen was depolarized for 30 minutes. According to the data automatically collected and recorded by the software, the average value of the current data in the last 10 seconds of the polarization process was taken as the test value of the specimen's conductance current. At this time, if the tests at all field strengths have not been completed, the voltage value of the high-voltage DC power supply was increased, and the specimen was polarized and depolarized again. If the tests at all field strengths have been completed, the oven was opened to replace the specimen. The oven temperature was increased and maintained for 2 hours, and then the specimen was polarized and depolarized at different field strengths. When the tests at all temperatures were completed, this current test was ended. For each specimen, the test process shown in Figure 7 was repeated five times. Finally, the average value of the five test results was taken as the final current test value at each temperature and electric field.

[0116] Table 1 is the DC current table of the insulating material. The DC current values of the specimen at different temperatures and different electric field strengths are shown in Table 1.

[0117] Table 1

[0118]

[0119] 2. Figure 8 is the schematic diagram of the historical DC conductivity at each temperature and each electric field strength in the logarithmic coordinate system in the embodiment of the present invention. As shown in Figure 8 , according to , the historical DC conductivity was calculated, and the regression lines of the historical DC conductivity and the electric field strength were plotted at each temperature.

[0120] 3. At each temperature, the electric field strengths E 303.15 , E 313.15 , E 323.15 , E 333.15 , and E 343.15 corresponding to the intersection points of the regression lines in the ohmic region and the non-ohmic region are 3.2 MV·m -1 , 3.6 MV·m -1 , 4.4 MV·m -1 , 6.5 MV·m -1 , and 9.7 MV·m -1 respectively. At the same time, the slopes of the regression lines were calculated, and the average value k ois 0, and the average value k of the slope at each temperature in the non - Ohmic region f is 3.0.

[0121] 4. Select the direct - current conductivity γ at each test temperature under the electric - field strength of 2.96 MV·m−1 in the Ohmic region o , and plot the regression line of lnγ o versus 1 / T, and calculate the slope k1 of the regression line. According to , find the activation energy of the direct - current conductivity in the Ohmic region is 0.65. Similarly, in the non - Ohmic region, select the direct - current conductivity γ at each test temperature under the electric - field strengths of 10.14 MV·m -1 and 15.21 MV·m -1 , find the activation energy of the direct - current conductivity, and take its average value 1.16 as f the final value.

[0122] 5. For the direct - current conductivity in the Ohmic region, substitute the obtained k o and the conductivity γ at 343.15 K and 2.53 MV·m -1 in the Ohmic region o (T, E o ) into to obtain the value of A o as 2.05×10 -5 , and thus obtain the conductivity model in the Ohmic region:

[0123]

[0124] For the direct - current conductivity in the non - Ohmic region, substitute the obtained k f and the conductivity γ at 343.15 K and 15.21 MV·m -1 in the non - Ohmic region f (T, E f ) into to obtain the value of A f as 2.65×10 -17 , and thus obtain the conductivity model in the non - Ohmic region:

[0125]

[0126] 6. Determine the current intersection - point electric field according to the above two conductivity models and the non - Ohmic - region conductivity model When the current electric field is less than or equal to the current intersection - point electric field , input the current electric field and the current temperature into the conductivity model in the Ohmic region to obtain the conductivity in the Ohmic region; when the current electric field is greater than the current intersection - point electric field ​When, input the current electric field and the current temperature into the non - ohmic region conductivity model to obtain the non - ohmic region conductivity.

[0127] In summary, the present invention can fit the direct current conductivity of polymer insulating materials at different temperatures and different electric field strengths, obtain the relationship between the direct current conductivity and temperature and electric field, so as to calculate and analyze the electric field distribution of polymer insulating materials under different direct current conditions. For the fitting of the direct current conductivity of polymer insulating materials, most of the existing fitting formulas do not consider piece - wise fitting, and the electric field strength coefficient therein has no clear physical meaning, and the values of each undetermined constant are not easy to determine. Based on the space - charge - limited current theory, the present invention improves the fitting effect by piece - wise fitting of the measured direct current conductivity. At the same time, each undetermined constant can be determined without complex operations, and the operability is stronger, and then an accurate direct current conductivity can be obtained.

[0128] Based on the same inventive concept, the embodiment of the present invention also provides a device for determining the direct current conductivity based on an insulating material. Since the principle of solving problems by this device is similar to that of the method for determining the direct current conductivity based on an insulating material, the implementation of this device can refer to the implementation of the method, and the repeated parts will not be described again.

[0129] Figure 9 is the structural block diagram of the device for determining the direct current conductivity based on an insulating material in the embodiment of the present invention. As Figure 9 shown, the device for determining the direct current conductivity based on an insulating material includes:

[0130] A conductivity slope determination module, configured to determine the conductivity slope according to the historical direct current conductivities at each electric field and each temperature;

[0131] A conductivity activation energy determination module, configured to determine the conductivity activation energy according to the historical direct current conductivities at each temperature;

[0132] A conductivity constant determination module, configured to determine the conductivity constant according to the historical direct current conductivity, conductivity slope, conductivity activation energy, electric field and temperature corresponding to the historical direct current conductivity;

[0133] A current direct current conductivity determination module, configured to determine the current direct current conductivity according to the conductivity constant, current electric field, current temperature, conductivity slope and conductivity activation energy.

[0134] In one of the embodiments, the conductivity slope determination module includes:

[0135] A historical direct current conductivity coordinate unit, configured to generate historical direct current conductivity coordinates according to the historical direct current conductivities at each electric field and each temperature;

[0136] A historical intersection electric field unit, configured to fit a conductivity regression line according to the historical direct current conductivity coordinates to determine the historical intersection electric field;

[0137] A dividing unit, configured to divide the historical direct current conductivity into an ohmic region historical direct current conductivity and a non-ohmic region historical direct current conductivity according to the historical intersection electric field;

[0138] A conductivity slope determination unit, configured to determine an ohmic region conductivity slope and a non-ohmic region conductivity slope according to a conductivity regression line and the historical intersection electric field.

[0139] In one embodiment, the conductivity activation energy includes an ohmic region conductivity activation energy and a non-ohmic region conductivity activation energy;

[0140] The conductivity constant determination module includes:

[0141] An ohmic region conductivity constant unit, configured to determine an ohmic region conductivity constant according to the ohmic region historical direct current conductivity, the ohmic region conductivity slope, the ohmic region conductivity activation energy, the ohmic region electric field corresponding to the ohmic region historical direct current conductivity, and the temperature;

[0142] A non-ohmic region conductivity constant unit, configured to determine a non-ohmic region conductivity constant according to the non-ohmic region historical direct current conductivity, the non-ohmic region conductivity slope, the non-ohmic region conductivity activation energy, the non-ohmic region electric field corresponding to the non-ohmic region historical direct current conductivity, and the temperature.

[0143] In one embodiment, the current direct current conductivity determination module includes:

[0144] A conductivity model creation unit, configured to create an ohmic region conductivity model according to the ohmic region conductivity constant, the ohmic region conductivity slope, and the ohmic region conductivity activation energy, and create a non-ohmic region conductivity model according to the non-ohmic region conductivity constant, the non-ohmic region conductivity slope, and the non-ohmic region conductivity activation energy;

[0145] A current intersection electric field determination unit, configured to determine a current intersection electric field according to the ohmic region conductivity model and the non-ohmic region conductivity model;

[0146] A conductivity model selection unit, configured to select a current conductivity model from the ohmic region conductivity model and the non-ohmic region conductivity model according to a comparison result between the current intersection electric field and the current electric field;

[0147] A current direct current conductivity unit, configured to input the current electric field and the current temperature into the current conductivity model to obtain the current direct current conductivity.

[0148] In summary, the DC conductivity determination device based on an insulating material according to an embodiment of the present invention first determines the conductivity slope based on the historical DC conductivities at various electric fields and temperatures to determine the conductivity activation energy, then determines the conductivity constant based on the historical DC conductivity, conductivity slope, conductivity activation energy, electric field, and temperature corresponding to the historical DC conductivity, and finally accurately determines the current DC conductivity based on the conductivity constant, current electric field, current temperature, conductivity slope, and conductivity activation energy.

[0149] An embodiment of the present invention also provides a specific implementation manner of a computer device that can implement all steps in the DC conductivity determination method based on an insulating material in the above embodiment. Figure 10 It is a structural block diagram of the computer device in an embodiment of the present invention. Refer to Figure 10 The computer device specifically includes the following:

[0150] A processor 1001 and a memory 1002.

[0151] The processor 1001 is used to call a computer program in the memory 1002. When the processor executes the computer program, all steps in the DC conductivity determination method based on an insulating material in the above embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0152] Determine the conductivity slope based on the historical DC conductivities at various electric fields and temperatures;

[0153] Determine the conductivity activation energy based on the historical DC conductivities at various temperatures;

[0154] Determine the conductivity constant based on the historical DC conductivity, conductivity slope, conductivity activation energy, electric field, and temperature corresponding to the historical DC conductivity;

[0155] Determine the current DC conductivity based on the conductivity constant, current electric field, current temperature, conductivity slope, and conductivity activation energy.

[0156] In summary, the computer device according to an embodiment of the present invention first determines the conductivity slope based on the historical DC conductivities at various electric fields and temperatures to determine the conductivity activation energy, then determines the conductivity constant based on the historical DC conductivity, conductivity slope, conductivity activation energy, electric field, and temperature corresponding to the historical DC conductivity, and finally accurately determines the current DC conductivity based on the conductivity constant, current electric field, current temperature, conductivity slope, and conductivity activation energy.

[0157] An embodiment of the present invention also provides a computer-readable storage medium capable of implementing all steps in the method for determining the direct current conductivity based on an insulating material in the above embodiment. A computer program is stored on the computer-readable storage medium. When the computer program is executed by a processor, all steps in the method for determining the direct current conductivity based on an insulating material in the above embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0158] Determine the conductivity slope according to the historical direct current conductivities at various electric fields and various temperatures;

[0159] Determine the conductivity activation energy according to the historical direct current conductivities at various temperatures;

[0160] Determine the conductivity constant according to the historical direct current conductivity, conductivity slope, conductivity activation energy, electric field and temperature corresponding to the historical direct current conductivity;

[0161] Determine the current direct current conductivity according to the conductivity constant, current electric field, current temperature, conductivity slope and conductivity activation energy.

[0162] In summary, the computer-readable storage medium of the embodiment of the present invention first determines the conductivity slope based on the historical direct current conductivities at various electric fields and various temperatures to determine the conductivity activation energy, then determines the conductivity constant according to the historical direct current conductivity, conductivity slope, conductivity activation energy, electric field and temperature corresponding to the historical direct current conductivity, and finally accurately determines the current direct current conductivity according to the conductivity constant, current electric field, current temperature, conductivity slope and conductivity activation energy.

[0163] In the specific embodiments described above, the purpose, technical solution and beneficial effects of the present invention are further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0164] Those skilled in the art can also understand that the various illustrative logical blocks, units, and steps listed in the embodiments of the present invention can be implemented by electronic hardware, computer software, or a combination of both. To clearly show the interchangeability of hardware and software, the above-mentioned various illustrative components, units, and steps have been generally described in terms of their functions. Whether such functions are implemented by hardware or software depends on the specific application and the design requirements of the entire system. Those skilled in the art can use various methods to implement the described functions for each specific application, but such implementation should not be construed as exceeding the scope of protection of the embodiments of the present invention.

[0165] In the embodiments of the present invention, the various illustrative logical blocks, or units, or devices can all be implemented or operate the described functions through a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above designs. The general-purpose processor can be a microprocessor. Optionally, the general-purpose processor can also be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented by a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration.

[0166] The steps of the methods or algorithms described in the embodiments of the present invention can be directly embedded in hardware, software modules executed by a processor, or a combination of both. The software modules can be stored in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium in the art. Exemplarily, the storage medium can be connected to the processor so that the processor can read information from the storage medium and write information to the storage medium. Optionally, the storage medium can also be integrated into the processor. The processor and the storage medium can be disposed in an ASIC, and the ASIC can be disposed in a user terminal. Optionally, the processor and the storage medium can also be disposed in different components of the user terminal.

[0167] In one or more exemplary designs, the functions described above in embodiments of the present invention may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. A computer-readable medium includes both computer storage media and communication media that facilitate transfer of a computer program from one place to another. The storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store program code in the form of instructions or data structures and that can be accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor. In addition, any connection is properly termed a computer-readable medium, such as if software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave. Disk and disc include compact disk, laser disk, optical disk, DVD, floppy disk, and Blu-ray disk, where disks usually reproduce data magnetically, while discs usually reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

Claims

1. A method for determining the direct current conductivity based on an insulating material, characterized in that, Comprising: Determining a conductivity slope based on historical direct current conductivities at various electric fields and various temperatures; Determining a conductivity activation energy based on historical direct current conductivities at various temperatures; Determining a conductivity constant based on the historical direct current conductivity, the conductivity slope, the conductivity activation energy, the electric field and the temperature corresponding to the historical direct current conductivity; Determining a current direct current conductivity based on the conductivity constant, the current electric field, the current temperature, the conductivity slope and the conductivity activation energy; Wherein, the conductivity activation energy includes an ohmic region conductivity activation energy and a non-ohmic region conductivity activation energy; Determining a conductivity constant based on the historical direct current conductivity, the conductivity slope, the conductivity activation energy, the electric field and the temperature corresponding to the historical direct current conductivity includes: Determining an ohmic region conductivity constant based on the historical direct current conductivity in the ohmic region, the ohmic region conductivity slope, the ohmic region conductivity activation energy, the ohmic region electric field and the temperature corresponding to the historical direct current conductivity in the ohmic region, and determining the ohmic region conductivity constant through the following formula: Among them, A o is the conductivity constant in the ohmic region, γ o (T, E o ) is the historical DC conductivity in the ohmic region, with the unit of S / m; k o is the conductivity slope in the ohmic region, E o is the electric field in the ohmic region corresponding to the historical DC conductivity in the ohmic region, with the unit of MV / m; T is the thermodynamic temperature, with the unit of K; is the activation energy of the conductivity in the ohmic region; Determining a non-ohmic region conductivity constant based on the historical direct current conductivity in the non-ohmic region, the non-ohmic region conductivity slope, the non-ohmic region conductivity activation energy, the non-ohmic region electric field and the temperature corresponding to the historical direct current conductivity in the non-ohmic region, and determining the non-ohmic region conductivity constant through the following formula: Among them, A f is the non-ohmic region conductivity constant, γ f (T, E f ) is the non-ohmic region historical direct current conductivity, with the unit of S / m; k f is the non-ohmic region conductivity slope, E f is the ohmic region electric field corresponding to the non-ohmic region historical direct current conductivity, with the unit of MV / m; T is the thermodynamic temperature, with the unit of K; is the non-ohmic region conductivity activation energy.

2. The method for determining the direct current conductivity based on an insulating material according to claim 1, wherein Determining a conductivity slope based on historical direct current conductivities at various electric fields and various temperatures includes: Generating historical direct current conductivity coordinates based on historical direct current conductivities at various electric fields and various temperatures; Fitting a conductivity regression line based on the historical direct current conductivity coordinates to determine a historical intersection electric field; Dividing the historical direct current conductivity into a historical direct current conductivity in the ohmic region and a historical direct current conductivity in the non-ohmic region based on the historical intersection electric field; Determining an ohmic region conductivity slope based on the historical direct current conductivity in the ohmic region, and determining a non-ohmic region conductivity slope based on the historical direct current conductivity in the non-ohmic region.

3. The method for determining the direct current conductivity based on an insulating material according to claim 1, characterized in that Determining a current direct current conductivity based on the conductivity constant, the current electric field, the current temperature, the conductivity slope and the conductivity activation energy includes: Creating an ohmic region conductivity model based on the ohmic region conductivity constant, the ohmic region conductivity slope and the ohmic region conductivity activation energy, and creating a non-ohmic region conductivity model based on the non-ohmic region conductivity constant, the non-ohmic region conductivity slope and the non-ohmic region conductivity activation energy; Determining a current intersection electric field based on the ohmic region conductivity model and the non-ohmic region conductivity model; Selecting a current conductivity model from the ohmic region conductivity model and the non-ohmic region conductivity model according to a comparison result between the current intersection electric field and the current electric field; Inputting the current electric field and the current temperature into the current conductivity model to obtain the current direct current conductivity.

4. A direct current conductivity determination device based on an insulating material, characterized in that, Comprising: A conductivity slope determination module for determining a conductivity slope based on historical direct current conductivities at various electric fields and various temperatures; A conductivity activation energy determination module for determining a conductivity activation energy based on historical direct current conductivities at various temperatures; A conductivity constant determination module, configured to determine a conductivity constant according to the historical direct current conductivity, the conductivity slope, the conductivity activation energy, the electric field and temperature corresponding to the historical direct current conductivity; A current direct current conductivity determination module, configured to determine the current direct current conductivity according to the conductivity constant, the current electric field, the current temperature, the conductivity slope and the conductivity activation energy; Wherein, the conductivity activation energy includes an ohmic region conductivity activation energy and a non-ohmic region conductivity activation energy; the conductivity constant determination module includes: An ohmic region conductivity constant unit, configured to determine an ohmic region conductivity constant according to the ohmic region historical direct current conductivity, the ohmic region conductivity slope, the ohmic region conductivity activation energy, the ohmic region electric field and temperature corresponding to the ohmic region historical direct current conductivity, and determine the ohmic region conductivity constant through the following formula: Among them, A o is the conductivity constant in the ohmic region, γ o (T, E o ) is the historical DC conductivity in the ohmic region, with the unit of S / m; k o is the conductivity slope in the ohmic region, E o is the electric field in the ohmic region corresponding to the historical DC conductivity in the ohmic region, with the unit of MV / m; T is the thermodynamic temperature, with the unit of K; is the activation energy of the conductivity in the ohmic region; A non-ohmic region conductivity constant unit, configured to determine a non-ohmic region conductivity constant according to the non-ohmic region historical direct current conductivity, the non-ohmic region conductivity slope, the non-ohmic region conductivity activation energy, the non-ohmic region electric field and temperature corresponding to the non-ohmic region historical direct current conductivity, and determine the non-ohmic region conductivity constant through the following formula: Among them, A f is the non-ohmic region conductivity constant, γ f (T, E f ) is the non-ohmic region historical DC conductivity, with the unit of S / m; k f is the non-ohmic region conductivity slope, E f is the ohmic region electric field corresponding to the non-ohmic region historical DC conductivity, with the unit of MV / m; T is the thermodynamic temperature, with the unit of K; is the non-ohmic region conductivity activation energy.

5. The direct current conductivity determination device based on an insulating material according to claim 4, wherein The conductivity slope determination module includes: A historical direct current conductivity coordinate unit, configured to generate historical direct current conductivity coordinates according to the historical direct current conductivity at each electric field and each temperature; A historical intersection electric field unit, configured to fit a conductivity regression line according to the historical direct current conductivity coordinates to determine the historical intersection electric field; A division unit, configured to divide the historical direct current conductivity into an ohmic region historical direct current conductivity and a non-ohmic region historical direct current conductivity according to the historical intersection electric field; A conductivity slope determination unit, configured to determine the ohmic region conductivity slope and the non-ohmic region conductivity slope according to the conductivity regression line and the historical intersection electric field.

6. The device for determining the direct current conductivity based on an insulating material according to claim 4, characterized in that, The current direct current conductivity determination module includes: A conductivity model creation unit, configured to create an ohmic region conductivity model according to the ohmic region conductivity constant, the ohmic region conductivity slope and the ohmic region conductivity activation energy, and create a non-ohmic region conductivity model according to the non-ohmic region conductivity constant, the non-ohmic region conductivity slope and the non-ohmic region conductivity activation energy; A current intersection electric field determination unit, configured to determine the current intersection electric field according to the ohmic region conductivity model and the non-ohmic region conductivity model; A conductivity model selection unit, configured to select a current conductivity model from the ohmic region conductivity model and the non-ohmic region conductivity model according to the comparison result between the current intersection electric field and the current electric field; A current direct current conductivity unit, configured to input the current electric field and the current temperature into the current conductivity model to obtain the current direct current conductivity.

7. A computer device, comprising a memory, a processor, and a computer program stored on the memory and running on the processor, characterized in that, When the processor executes the computer program, the steps of the direct current conductivity determination method based on an insulating material according to any one of claims 1 to 3 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the direct current conductivity determination method based on an insulating material according to any one of claims 1 to 3 are implemented.

Images