A method, apparatus, electronic device, and storage medium for evaluating cable insulation.

Abstract

This invention discloses a cable insulation assessment method, apparatus, electronic device, and storage medium to address the technical problem of low reliability and accuracy in existing cable insulation assessment methods. The invention includes: slicing the cable under test to obtain insulation slices of a predetermined thickness; obtaining the lowest AC breakdown field strength at the corresponding voltage level of the insulation slice; obtaining AC space charge distribution characteristic data of the lowest AC breakdown field strength; calculating insulation failure characteristic values ​​based on the AC space charge distribution characteristic data; testing the space charge distribution characteristics of the insulation slice; calculating the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics; and comparing the average charge density and the maximum field strength distortion rate parameters with the insulation failure characteristic values ​​to obtain the insulation assessment result of the cable under test.

Description

Technical Field

[0001] This invention relates to the field of cable insulation technology, and in particular to a cable insulation assessment method, apparatus, electronic device, and storage medium. Background Technology

[0002] With economic development and the improvement of people's living standards, users have increasingly higher requirements for power supply reliability. In urban power grid systems, power cables of various voltage levels are gradually becoming the most reliable transmission network. However, since cables are typical capacitive electrical equipment, damage to the insulation in one part can trigger the failure of the entire insulation system. Therefore, achieving condition monitoring of cable insulation is crucial for the stable operation of urban power systems.

[0003] Currently, the main methods for assessing the insulation status of alternating current include:

[0004] (1) Partial discharge detection: Online or offline partial discharge detection is carried out on the power cable body to obtain partial discharge characteristics and then locate the partial discharge point, thereby determining the insulation status of the cable.

[0005] (2) Withstand voltage test: This type of test includes series resonance detection, ultra-low withstand voltage test, oscillation wave test, etc. All of these tests require applying an AC voltage value greater than its operating voltage to the high voltage cable, and whether or not the withstand voltage test is passed is the sole basis for evaluating the insulation status.

[0006] (3) Resistance test: The insulation resistance value of the cable is measured using equipment such as an insulation megohmmeter, and the resistance value is used as the basis for judgment.

[0007] However, partial discharge testing can only measure the location of discharge in high-voltage cables and cannot determine the overall state of the power cable insulation, making it highly unpredictable; withstand voltage testing is a destructive testing method, as it requires applying a test voltage higher than the operating voltage to the cable, which can easily cause secondary damage to the insulation during the test; resistance testing can only reflect the DC resistance value of the high-voltage cable insulation and cannot effectively reflect many key parameters during the operation of AC cables, resulting in poor reliability. Summary of the Invention

[0008] This invention provides a cable insulation assessment method, apparatus, electronic device, and storage medium to address the technical problems of low reliability and accuracy in existing cable insulation assessment methods.

[0009] This invention provides a method for evaluating cable insulation, comprising:

[0010] The cable under test is sliced ​​to obtain insulation slices of a preset thickness;

[0011] Obtain the lowest AC breakdown field strength of the insulation slice at the corresponding voltage level;

[0012] Obtain the AC space charge distribution characteristic data of the minimum AC breakdown field strength;

[0013] Calculate the insulation failure characteristic value based on the AC space charge distribution characteristic data;

[0014] Test the space charge distribution characteristics of the insulating slice;

[0015] Calculate the average charge density and maximum field distortion rate parameters of the space charge distribution characteristics;

[0016] The insulation evaluation results of the cable under test are obtained by comparing the average charge density and the maximum field strength distortion rate parameters with the insulation failure characteristic value.

[0017] Optionally, the step of obtaining the AC space charge distribution characteristic data of the lowest AC breakdown field strength includes:

[0018] The insulating slices are thermally aged according to a preset thermal aging cycle duration to obtain thermally aged slices with different thermal aging cycles.

[0019] The breakdown field strength of each thermally aged slice was tested sequentially.

[0020] The thermally aged sections with a breakdown field strength lower than the minimum AC breakdown field strength are identified as target thermally aged sections.

[0021] Calculate the single-cycle AC space charge characteristics of the target thermally aged slice;

[0022] The single-cycle AC space charge characteristics are used as the AC space charge distribution characteristic data of the lowest AC breakdown field strength.

[0023] Optionally, the step of calculating the single-cycle AC space charge characteristics of the target thermally aged slice includes:

[0024] The target thermally aged slice is placed between the ground electrode and the high-voltage electrode;

[0025] The AC high-voltage signal applied to the high-voltage electrode is divided by a voltage divider to obtain a low-voltage power frequency synchronization signal;

[0026] The low-voltage power frequency synchronization signal is input into a waveform conversion circuit to obtain a square wave synchronization signal;

[0027] The square wave synchronization signal is simultaneously input into a preset oscilloscope and a preset pulse source;

[0028] The preset pulse source responds to the square wave synchronization signal and inputs a pulse signal to the target thermal aging slice to generate an electroacoustic pulse signal.

[0029] The electroacoustic pulse waveform of the electroacoustic pulse signal is acquired using the preset oscilloscope;

[0030] Based on the electroacoustic pulse waveform, the single-cycle AC space charge characteristics of the target thermally aged slice are obtained.

[0031] Optionally, the step of calculating the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics includes:

[0032] Calculate the average charge density of the space charge distribution characteristics;

[0033] Calculate electric field distribution data based on space charge distribution characteristics;

[0034] Obtain the maximum field strength from the electric field distribution data;

[0035] Obtain the average field strength of the applied field;

[0036] The maximum field strength distortion rate parameter of the space charge distribution characteristic is calculated based on the maximum field strength and the applied average field strength.

[0037] The present invention also provides a cable insulation evaluation device, comprising:

[0038] The slicing module is used to slice the cable under test to obtain insulation slices of a preset thickness.

[0039] The minimum AC breakdown field strength acquisition module is used to obtain the minimum AC breakdown field strength of the insulation slice at the corresponding voltage level.

[0040] An AC space charge distribution characteristic data acquisition module is used to acquire AC space charge distribution characteristic data of the minimum AC breakdown field strength.

[0041] An insulation failure characteristic value calculation module is used to calculate insulation failure characteristic values ​​based on the AC space charge distribution characteristic data.

[0042] A space charge distribution characteristic testing module is used to test the space charge distribution characteristics of the insulating slice;

[0043] The average charge density and maximum field strength distortion rate parameter calculation module is used to calculate the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics.

[0044] The comparison module is used to compare the average charge density and the maximum field strength distortion rate parameters with the insulation failure characteristic value to obtain the insulation evaluation result of the cable under test.

[0045] Optionally, the AC space charge distribution characteristic data acquisition module includes:

[0046] The thermal aging submodule is used to thermally age the insulating slice according to a preset thermal aging cycle duration to obtain thermally aged slices with different thermal aging cycles.

[0047] The breakdown field strength test submodule is used to test the breakdown field strength of each thermally aged slice in sequence.

[0048] The target thermal aging section determination submodule is used to determine thermal aging sections with a breakdown field strength lower than the minimum AC breakdown field strength as target thermal aging sections.

[0049] A single-cycle AC space charge characteristic calculation submodule is used to calculate the single-cycle AC space charge characteristics of the target thermally aged slice.

[0050] The AC space charge distribution characteristic data determination submodule is used to use the single-cycle AC space charge characteristics as the AC space charge distribution characteristic data of the lowest AC breakdown field strength.

[0051] Optionally, the single-cycle AC space charge characteristic calculation submodule includes:

[0052] A placement unit is used to place the target thermally aged slice between the ground electrode and the high-voltage electrode;

[0053] The voltage divider unit is used to divide the AC high voltage signal applied to the high voltage electrode by a voltage divider to obtain a low voltage power frequency synchronization signal;

[0054] The waveform conversion unit is used to input the low-voltage power frequency synchronization signal into the waveform conversion circuit to obtain a square wave synchronization signal.

[0055] The input unit is used to simultaneously input the square wave synchronization signal into a preset oscilloscope and a preset pulse source;

[0056] An electroacoustic pulse signal generation unit is used to generate an electroacoustic pulse signal by having the preset pulse source respond to the square wave synchronization signal and input a pulse signal to the target thermal aging slice.

[0057] An electroacoustic pulse waveform acquisition unit is used to acquire the electroacoustic pulse waveform of the electroacoustic pulse signal through the preset oscilloscope;

[0058] A single-cycle AC space charge feature acquisition unit is used to acquire the single-cycle AC space charge feature of the target thermally aged slice based on the electroacoustic pulse waveform.

[0059] Optionally, the module for calculating the average charge density and maximum electric field distortion rate parameters includes:

[0060] The average charge density calculation submodule is used to calculate the average charge density of the space charge distribution characteristics.

[0061] The electric field distribution data calculation submodule is used to calculate electric field distribution data based on the characteristics of space charge distribution.

[0062] The maximum field strength acquisition submodule is used to acquire the maximum field strength in the electric field distribution data;

[0063] The external average field strength acquisition submodule is used to acquire the external average field strength.

[0064] The maximum field strength distortion rate parameter calculation submodule is used to calculate the maximum field strength distortion rate parameter of the space charge distribution characteristics based on the maximum field strength and the applied average field strength.

[0065] The present invention also provides an electronic device, the device comprising a processor and a memory:

[0066] The memory is used to store program code and transmit the program code to the processor;

[0067] The processor is configured to execute the cable insulation assessment method as described above, according to the instructions in the program code.

[0068] The present invention also provides a computer-readable storage medium for storing program code for performing the cable insulation assessment method as described in any of the preceding claims.

[0069] As can be seen from the above technical solution, the present invention has the following advantages: The present invention obtains insulation slices of a predetermined thickness by slicing the cable under test; obtains the lowest AC breakdown field strength at the corresponding voltage level of the insulation slice; obtains AC space charge distribution characteristic data of the lowest AC breakdown field strength; calculates insulation failure characteristic values ​​based on the AC space charge distribution characteristic data; tests the space charge distribution characteristics of the insulation slice; calculates the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics; and compares the average charge density and maximum field strength distortion rate parameters with the insulation failure characteristic values ​​to obtain the insulation evaluation results of the cable under test. This improves the reliability and accuracy of cable insulation evaluation. Attached Figure Description

[0070] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0071] Figure 1 A flowchart illustrating the steps of a cable insulation evaluation method provided in this embodiment of the invention;

[0072] Figure 2 A side view showing the relationship between thermal aging and space charge provided in an embodiment of the present invention;

[0073] Figure 3 This is a circuit diagram for measuring AC peak space charge.

[0074] Figure 4 A comparison diagram of the conversion between sinusoidal AC signals and synchronization signals;

[0075] Figure 5 A schematic diagram of a continuous electroacoustic pulse signal;

[0076] Figure 6 This is a structural block diagram of a cable insulation evaluation device provided in an embodiment of the present invention. Detailed Implementation

[0077] This invention provides a cable insulation assessment method, apparatus, electronic device, and storage medium to address the technical problem of low reliability and accuracy in existing cable insulation assessment methods.

[0078] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0079] Please see Figure 1 , Figure 1 A flowchart illustrating the steps of a cable insulation evaluation method provided in an embodiment of the present invention.

[0080] The present invention provides a cable insulation evaluation method, which may specifically include the following steps:

[0081] Step 101: The cable to be tested is sliced ​​to obtain an insulation slice of a preset thickness;

[0082] In this embodiment of the invention, an insulation slice with a thickness of 0.2mm-1mm can be cut from the main insulation location of the cable under test using a sampling slicer. The slice size is not less than 50mm*50mm. The area of ​​the insulation slice can be larger than this area, but if it is smaller than this area, insufficient surface insulation distance may cause flashover during breakdown voltage measurement or discharge during space charge measurement, leading to measurement failure.

[0083] Step 102: Obtain the lowest AC breakdown field strength at the corresponding voltage level of the insulation slice;

[0084] In this embodiment of the invention, the minimum AC breakdown field strength that the insulation material of the cable under test should possess at the voltage level it transmits can be found.

[0085] Step 103: Obtain AC space charge distribution characteristic data for the lowest AC breakdown field strength;

[0086] In one example, step 103 may include the following sub-steps:

[0087] S31, thermally age the insulating slices according to the preset thermal aging cycle duration to obtain thermally aged slices with different thermal aging cycles.

[0088] S32, the breakdown field strength of each thermally aged slice was tested sequentially;

[0089] In specific implementations, such as Figure 2 As shown, Figure 2 A side view showing the relationship between thermal aging and space charge in an embodiment of the present invention.

[0090] In the process of calculating the AC space charge distribution characteristics of the minimum AC field strength, the cable insulation can first be aged using a temperature-controlled aging chamber. During the aging process, the insulation will deform due to heat. To prevent the insulation from curling and making subsequent tests impossible, glass plates are used to press the insulation slices together. Every 7 days, a set of aged samples is taken out to measure the AC breakdown field strength and space charge characteristics.

[0091] The AC breakdown field strength test process is as follows:

[0092] AC breakdown field strength was measured using a spherical electrode structure. During the measurement, the sample was immersed in insulating oil, and the AC voltage was gradually increased and recorded at the moment of breakdown. The breakdown field strength was then calculated based on the insulation thickness. The relevant formula is:

[0093] E b =U b / d

[0094] Among them, E b The breakdown field strength is expressed in kV / mm, U. b d represents the instantaneous value of AC voltage in kV, and d represents the thickness of the insulating slice in mm.

[0095] S33, the thermally aged section with a breakdown field strength lower than the minimum AC breakdown field strength is identified as the target thermally aged section.

[0096] S34, Calculate the single-cycle AC space charge characteristics of the target thermally aged slice;

[0097] In one example, step S34 may include the following sub-steps:

[0098] S341, the target thermally aged slice is placed between the ground electrode and the high-voltage electrode;

[0099] S342 divides the AC high voltage applied to the high voltage electrode using a voltage divider to obtain a low voltage signal;

[0100] S343 inputs the low-voltage signal into the waveform conversion circuit to obtain a square wave synchronization signal;

[0101] S344 inputs a square wave synchronization signal to a preset oscilloscope and a preset pulse source simultaneously;

[0102] S345, the preset pulse source responds to the square wave synchronization signal and inputs a pulse signal to the target thermal aging slice to generate an electroacoustic pulse signal;

[0103] S346, acquires the electroacoustic pulse waveform of the electroacoustic pulse signal through a preset oscilloscope;

[0104] S347, based on the electroacoustic pulse waveform, obtain the single-cycle AC space charge characteristics of the target thermally aged slice.

[0105] In specific implementations, such as Figure 3 As shown, Figure 3 This is a circuit diagram for measuring AC peak space charge. During single-cycle AC space charge characteristic measurement, the target thermally aged slice is first cleaned and placed on the ground electrode. Silicone oil is applied between the ground electrode and the target thermally aged slice to eliminate air gaps. Next, a high-voltage electrode is placed on the upper surface of the target thermally aged slice and pressed firmly. After pressing, room temperature vulcanizing silicone rubber is applied around the high-voltage electrode. Then, the ground electrode, the target thermally aged slice, and the high-voltage electrode are placed in a vacuum drying oven. A vacuum is then created to remove gaseous components from the room temperature vulcanizing silicone rubber, preventing partial discharge during space charge measurement.

[0106] The target thermally aged slice was then vulcanized at room temperature. After the silicone rubber cured, an AC high-voltage signal with an effective voltage of not less than 10kV was obtained using an AC booster, and this AC high-voltage signal was directly connected to the high-voltage electrode. A low-voltage power frequency synchronization signal with a voltage divider ratio of 1000:1 was obtained, and the phase of this low-voltage power frequency synchronization signal was exactly the same as that of the AC high-voltage signal. The low-voltage power frequency synchronization signal was then input into a waveform conversion circuit, which converts a sinusoidal voltage to a square wave voltage, thus obtaining a square wave synchronization signal. The phase relationship of the waveforms before and after the conversion is as follows: Figure 4As shown, the time interval between the rising edges of the two square waves is 20ms.

[0107] After obtaining the square wave synchronization signal, it can be known that the rising edge of the square wave synchronization signal corresponds to the 0° moment of the sine signal.

[0108] The subsequent oscilloscopes and continuous pulse sources all use square wave synchronization signals as synchronization trigger signals. The working mode of the continuous pulse source is as follows: when the rising edge of a synchronization signal is input to the square wave synchronization signal terminal, the output terminal of the pulse source begins to emit a cluster of high-voltage narrow pulse signals. Within this pulse cluster, the interval between two adjacent narrow pulses is 1µs, the rising and falling edges of each narrow pulse are 10ns, and the maximum voltage amplitude of the narrow pulse is +1000V.

[0109] Simultaneously, an oscilloscope is used as the waveform acquisition device for the electroacoustic pulse signal. The oscilloscope is set to waveform recording mode, meaning it can record voltage waveforms for a certain duration after the measurement begins. The single measurement duration in this invention is 10µs, therefore the required single measurement duration should be greater than 10µs. The oscilloscope and the continuous pulse source share the same square wave synchronization signal. This square wave synchronization signal arrives at both the pulse source and the oscilloscope simultaneously. Therefore, the oscilloscope will begin continuous acquisition at the same moment the electroacoustic pulse signal is emitted, recording the voltage waveform over the subsequent 10µs. This 10µs voltage waveform contains the electroacoustic pulse signal generated by 10 sets of narrow pulses.

[0110] Therefore, in order to measure the space charge signal at the peak and trough moments, an appropriate delay is required, referring to... Figure 4 When the delay time is set to 5ms, it is known that a pulse cluster signal that is synchronous with the peak of the AC voltage wave will be input to the target thermal aging slice through the coupling capacitor, thereby generating an electroacoustic pulse signal on the target thermal aging slice. This electroacoustic pulse signal is detected by the sensor and is synchronized with the pulse voltage cluster signal.

[0111] Currently, traditional electroacoustic pulse detection methods require numerous waveform averaging operations to eliminate noise components in the electroacoustic pulse signal. To achieve space charge measurement within a single cycle and obtain a stable space charge signal as quickly as possible, this invention sets the signal averaging frequency to 10 times, using 10 repeated electroacoustic pulse signals for noise reduction. To this end, this invention incorporates a high-pass filter. During measurement, the electroacoustic pulse originates from a rapidly rising pulse voltage signal, whose frequency components are all high-frequency components. Noise signals inherent in the system during measurement often originate from the power supply, external electromagnetic interference, etc. Therefore, designing a high-pass filter helps to filter out noise interference from the measurement signal. In this invention, the lower cutoff frequency of the filter is set to 1MHz to filter out interference noise in the system as much as possible. After filtering, the result can be measured on an oscilloscope as shown below. Figure 5The 10 continuous electroacoustic pulse signals u1, u2, u3, ..., u shown are 10 .

[0112] Because of the added filtering module, this embodiment of the invention uses averaging of 10 sets of electroacoustic pulse signals to obtain an electroacoustic pulse signal that meets the signal-to-noise ratio requirement. Using this method, a space charge characteristic measurement can be completed within approximately 10µs. The period of the power frequency AC signal is 20ms, therefore the time proportion of a single measurement is approximately 0.5%. Within such a short time, the power frequency AC voltage value can be approximated as unchanged; therefore, the space charge distribution characteristics can be calculated using the DC space charge inversion algorithm. The reference signal can be a DC electroacoustic pulse signal at a lower voltage, and the method is the same as for DC space charge measurement.

[0113] The process of calculating the characteristics of single-cycle AC space charge using the DC space charge inversion algorithm is as follows:

[0114] 1. The formula z=v is used to analyze electroacoustic pulse signals. s t transforms the horizontal time axis into a position axis, where z is the position and v is the position. s t represents the speed of sound, which can be measured experimentally, and t represents time.

[0115] 2. Deconvolution processing is performed on the transformed electroacoustic pulse signal to eliminate system overshoot. The specific steps of deconvolution processing are as follows: First, the system transfer function of the test equipment is calculated based on the reference signal with no space charge accumulation in the insulating slice. That is, assuming the system input signal is δ(t), and the oscilloscope acquires the signal h(t) when measuring the sample with no space charge accumulation, the system transfer function is calculated as follows:

[0116]

[0117] in, It is a time variable.

[0118] Next, the signal for eliminating system errors is calculated based on the electroacoustic pulse signals under pressurized and short-circuit conditions. Assuming the test signal is f0(t), the formula for calculating the recovery signal for eliminating system errors is:

[0119]

[0120] The recovery signal that eliminates system errors can then be obtained. , Electroacoustic pulse signals acquired by an oscilloscope.

[0121] 3. Based on the principles of acoustic wave dispersion and attenuation, data recovery is performed on the deconvolutioned signal. The signal attenuation calculation formula is:

[0122]

[0123] Where fr(t) is the recovered signal after signal supplementation, and j is the imaginary unit. ω represents the angular velocity of the sound wave signal.

[0124] 4. The recovered signal will be integrated at position to obtain the electric field distribution within the sample. The formula for calculating the electric field distribution is:

[0125]

[0126] in, The waveform of the position axis after step 3 is restored. This represents the electric field distribution within the sample.

[0127] 5. By performing differential calculations on the electric field distribution and based on the dielectric constant ε of the sample, the single-cycle AC space charge characteristics of the target thermally aged slice can be finally obtained. The calculation formula is as follows:

[0128]

[0129] in, The vacuum permittivity, is the relative permittivity of the insulating slice.

[0130] In this embodiment of the invention, when the delay module is set to 5ms, the space charge distribution characteristics of the peak point can be measured within one cycle; when the delay module is set to 15ms, the space charge distribution characteristics of the trough point can be measured within one cycle, thereby mastering the single-cycle AC space charge characteristics of the point with the maximum AC voltage value.

[0131] S35 uses the single-cycle AC space charge characteristics as the AC space charge distribution characteristic data for the lowest AC breakdown field strength.

[0132] Step 104: Calculate the insulation failure characteristic value based on the AC space charge distribution characteristic data;

[0133] In this embodiment of the invention, the insulation failure characteristic value may include the average charge density characteristic value and the maximum field strength distortion rate parameter characteristic value.

[0134] In practical implementation, the average charge density characteristic value and the maximum field strength distortion rate parameter characteristic value can be calculated based on the curve of the single-cycle AC space charge characteristic of the target thermally aged slice.

[0135] Step 105: Test the space charge distribution characteristics of the insulating slice;

[0136] In this embodiment of the invention, the space charge distribution characteristics of the insulating slice can be calculated by referring to the calculation process of AC space charge distribution characteristic data, which will not be repeated here.

[0137] Step 106: Calculate the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics;

[0138] In one example, step 106 may include the following sub-steps:

[0139] S61, calculate the average charge density of the space charge distribution characteristics;

[0140] S62, calculate electric field distribution data based on space charge distribution characteristics;

[0141] S63, obtain the maximum field strength in the electric field distribution data;

[0142] S64, obtain the average field strength of external application;

[0143] S65, calculates the maximum field strength distortion rate parameter of the space charge distribution characteristics based on the maximum field strength and the applied average field strength.

[0144] The average charge density of the space charge distribution characteristics refers to the charge distribution density inside the insulating slice along the direction from the high-voltage electrode to the low-voltage electrode.

[0145] The applied average electric field strength is generated by the alternating voltage applied to the high-voltage electrode.

[0146] In practical implementation, referring to the process of calculating the characteristics of single-cycle AC space charge using the inversion algorithm of DC space charge, the electric field distribution data of the space charge distribution characteristics can be calculated. The maximum field strength is obtained from the electric field distribution data, and divided by the applied average field strength to obtain the maximum field strength distortion parameter of the space charge distribution characteristics. Assuming the applied average field strength during measurement is E0, and the maximum field strength in the measured electric field distribution data is E... m Then the maximum field strength distortion rate parameter is k=E m / E0.

[0147] Step 107: Compare the average charge density and maximum field strength distortion rate parameters with the insulation failure characteristic values ​​to obtain the insulation evaluation results of the cable under test.

[0148] After obtaining the average charge density and maximum electric field distortion rate parameters, they can be compared with the insulation failure characteristic values ​​to obtain the insulation assessment results of the cable under test. As the insulation deteriorates, the average charge density and maximum electric field distortion rate parameters will gradually increase, but when the average charge density and maximum electric field distortion rate parameters reach the insulation failure characteristic values, it indicates insulation failure.

[0149] This invention involves slicing the cable under test to obtain insulation slices of a predetermined thickness; obtaining the lowest AC breakdown field strength at the corresponding voltage level of the insulation slices; acquiring AC space charge distribution characteristic data of the lowest AC breakdown field strength; calculating insulation failure characteristic values ​​based on the AC space charge distribution characteristic data; testing the space charge distribution characteristics of the insulation slices; calculating the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics; and comparing the average charge density and maximum field strength distortion rate parameters with the insulation failure characteristic values ​​to obtain the insulation assessment results of the cable under test. This improves the reliability and accuracy of cable insulation assessment.

[0150] Please see Figure 6 , Figure 6 This is a structural block diagram of a cable insulation evaluation device provided in an embodiment of the present invention.

[0151] This invention provides a cable insulation evaluation device, comprising:

[0152] The slicing module 601 is used to slice the cable under test to obtain insulation slices of a preset thickness.

[0153] The minimum AC breakdown field strength acquisition module 602 is used to acquire the minimum AC breakdown field strength of the insulation slice at the corresponding voltage level.

[0154] The AC space charge distribution characteristic data acquisition module 603 is used to acquire AC space charge distribution characteristic data with the lowest AC breakdown field strength.

[0155] The insulation failure characteristic value calculation module 604 is used to calculate the insulation failure characteristic value based on AC space charge distribution characteristic data.

[0156] Space charge distribution characteristic test module 605 is used to test the space charge distribution characteristics of insulating slices;

[0157] The average charge density and maximum field strength distortion rate parameter calculation module 606 is used to calculate the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics.

[0158] The comparison module 607 is used to compare the average charge density and maximum field strength distortion rate parameters with the insulation failure characteristic values ​​to obtain the insulation evaluation results of the cable under test.

[0159] In this embodiment of the invention, the AC space charge distribution characteristic data acquisition module 603 includes:

[0160] The thermal aging submodule is used to thermally age the insulating slices according to the preset thermal aging cycle duration to obtain thermally aged slices with different thermal aging cycles.

[0161] The breakdown field strength test submodule is used to test the breakdown field strength of each thermally aged slice in sequence.

[0162] The target thermal aging section determination submodule is used to determine thermal aging sections with a breakdown field strength lower than the minimum AC breakdown field strength as target thermal aging sections.

[0163] The single-cycle AC space charge characteristic calculation submodule is used to calculate the single-cycle AC space charge characteristics of the target thermally aged slice.

[0164] The AC space charge distribution characteristic data determination submodule is used to use the single-cycle AC space charge characteristics as the AC space charge distribution characteristic data with the lowest AC breakdown field strength.

[0165] In this embodiment of the invention, the single-cycle AC space charge characteristic calculation submodule includes:

[0166] A placement unit is used to place the target thermally aged slice between the ground electrode and the high-voltage electrode;

[0167] The voltage divider unit is used to divide the AC high voltage signal applied to the high voltage electrode to obtain a low voltage power frequency synchronization signal.

[0168] The waveform conversion unit is used to input the low-voltage power frequency synchronization signal into the waveform conversion circuit to obtain a square wave synchronization signal.

[0169] The input unit is used to simultaneously input a square wave synchronization signal to a preset oscilloscope and a preset pulse source;

[0170] An electroacoustic pulse signal generation unit is used to input a pulse signal to the target thermal aging slice by pre-setting a pulse source response square wave synchronization signal, thereby generating an electroacoustic pulse signal.

[0171] An electroacoustic pulse waveform acquisition unit is used to acquire the electroacoustic pulse waveform of an electroacoustic pulse signal through a preset oscilloscope;

[0172] A single-cycle AC space charge feature acquisition unit is used to acquire the single-cycle AC space charge features of the target thermally aged slice based on the electroacoustic pulse waveform.

[0173] In this embodiment of the invention, the average charge density and maximum electric field distortion rate parameter calculation module 606 includes:

[0174] The average charge density calculation submodule is used to calculate the average charge density of the space charge distribution characteristics.

[0175] The electric field distribution data calculation submodule is used to calculate electric field distribution data based on the characteristics of space charge distribution.

[0176] The maximum field strength acquisition submodule is used to acquire the maximum field strength in the electric field distribution data;

[0177] The external average field strength acquisition submodule is used to acquire the external average field strength.

[0178] The maximum field strength distortion rate parameter calculation submodule is used to calculate the maximum field strength distortion rate parameter based on the maximum field strength and the applied average field strength to determine the characteristics of the space charge distribution.

[0179] This invention also provides an electronic device, which includes a processor and a memory:

[0180] The memory is used to store program code and transfer the program code to the processor;

[0181] The processor is used to execute the cable insulation evaluation method of this invention according to the instructions in the program code.

[0182] This invention also provides a computer-readable storage medium for storing program code for executing the cable insulation evaluation method of this invention.

[0183] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0184] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0185] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, embodiments of the present invention can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of the present invention can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0186] Embodiments of the present invention are described with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0187] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0188] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0189] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0190] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0191] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating cable insulation, characterized in that, include: The cable under test is sliced ​​to obtain insulation slices of a preset thickness; Obtain the lowest AC breakdown field strength of the insulation slice at the corresponding voltage level; Obtain the AC space charge distribution characteristic data of the minimum AC breakdown field strength; Calculate the insulation failure characteristic value based on the AC space charge distribution characteristic data; Test the space charge distribution characteristics of the insulating slice; Calculate the average charge density and maximum field distortion rate parameters of the space charge distribution characteristics; The insulation evaluation results of the cable under test are obtained by comparing the average charge density and the maximum field strength distortion rate parameters with the insulation failure characteristic value.

2. The method according to claim 1, characterized in that, The step of obtaining the AC space charge distribution characteristic data of the lowest AC breakdown field strength includes: The insulating slices are thermally aged according to a preset thermal aging cycle duration to obtain thermally aged slices with different thermal aging cycles. The breakdown field strength of each thermally aged slice was tested sequentially. The thermally aged sections with a breakdown field strength lower than the minimum AC breakdown field strength are identified as target thermally aged sections. Calculate the single-cycle AC space charge characteristics of the target thermally aged slice; The single-cycle AC space charge characteristics are used as the AC space charge distribution characteristic data of the lowest AC breakdown field strength.

3. The method according to claim 2, characterized in that, The step of calculating the single-cycle AC space charge characteristics of the target thermally aged slice includes: The target thermally aged slice is placed between the ground electrode and the high-voltage electrode; The AC high-voltage signal applied to the high-voltage electrode is divided by a voltage divider to obtain a low-voltage power frequency synchronization signal; The low-voltage power frequency synchronization signal is input into a waveform conversion circuit to obtain a square wave synchronization signal; The square wave synchronization signal is simultaneously input into a preset oscilloscope and a preset pulse source; The preset pulse source responds to the square wave synchronization signal and inputs a pulse signal to the target thermal aging slice to generate an electroacoustic pulse signal. The electroacoustic pulse waveform of the electroacoustic pulse signal is acquired using the preset oscilloscope; Based on the electroacoustic pulse waveform, the single-cycle AC space charge characteristics of the target thermally aged slice are obtained.

4. The method according to claim 1, characterized in that, The steps for calculating the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics include: Calculate the average charge density of the space charge distribution characteristics; Calculate electric field distribution data based on space charge distribution characteristics; Obtain the maximum field strength from the electric field distribution data; Obtain the average field strength of the applied field; The maximum field strength distortion rate parameter of the space charge distribution characteristic is calculated based on the maximum field strength and the applied average field strength.

5. A cable insulation evaluation device, characterized in that, include: The slicing module is used to slice the cable under test to obtain insulation slices of a preset thickness. The minimum AC breakdown field strength acquisition module is used to obtain the minimum AC breakdown field strength of the insulation slice at the corresponding voltage level. An AC space charge distribution characteristic data acquisition module is used to acquire AC space charge distribution characteristic data of the minimum AC breakdown field strength. An insulation failure characteristic value calculation module is used to calculate insulation failure characteristic values ​​based on the AC space charge distribution characteristic data. A space charge distribution characteristic testing module is used to test the space charge distribution characteristics of the insulating slice; The average charge density and maximum field strength distortion rate parameter calculation module is used to calculate the average charge density and maximum field strength distortion rate parameters of the space charge distribution characteristics. The comparison module is used to compare the average charge density and the maximum field strength distortion rate parameters with the insulation failure characteristic value to obtain the insulation evaluation result of the cable under test.

6. The apparatus according to claim 5, characterized in that, The AC space charge distribution characteristic data acquisition module includes: The thermal aging submodule is used to thermally age the insulating slice according to a preset thermal aging cycle duration to obtain thermally aged slices with different thermal aging cycles. The breakdown field strength test submodule is used to test the breakdown field strength of each thermally aged slice in sequence. The target thermal aging section determination submodule is used to determine thermal aging sections with a breakdown field strength lower than the minimum AC breakdown field strength as target thermal aging sections. A single-cycle AC space charge characteristic calculation submodule is used to calculate the single-cycle AC space charge characteristics of the target thermally aged slice. The AC space charge distribution characteristic data determination submodule is used to use the single-cycle AC space charge characteristics as the AC space charge distribution characteristic data of the lowest AC breakdown field strength.

7. The apparatus according to claim 6, characterized in that, The single-period AC space charge characteristic calculation submodule includes: A placement unit is used to place the target thermally aged slice between the ground electrode and the high-voltage electrode; The voltage divider unit is used to divide the AC high voltage signal applied to the high voltage electrode by a voltage divider to obtain a low voltage power frequency synchronization signal; The waveform conversion unit is used to input the low-voltage power frequency synchronization signal into the waveform conversion circuit to obtain a square wave synchronization signal. The input unit is used to simultaneously input the square wave synchronization signal into a preset oscilloscope and a preset pulse source; An electroacoustic pulse signal generation unit is used to generate an electroacoustic pulse signal by having the preset pulse source respond to the square wave synchronization signal and input a pulse signal to the target thermal aging slice. An electroacoustic pulse waveform acquisition unit is used to acquire the electroacoustic pulse waveform of the electroacoustic pulse signal through the preset oscilloscope; A single-cycle AC space charge feature acquisition unit is used to acquire the single-cycle AC space charge feature of the target thermally aged slice based on the electroacoustic pulse waveform.

8. The apparatus according to claim 5, characterized in that, The module for calculating the average charge density and maximum field strength distortion rate parameters includes: The average charge density calculation submodule is used to calculate the average charge density of the space charge distribution characteristics. The electric field distribution data calculation submodule is used to calculate electric field distribution data based on the characteristics of space charge distribution. The maximum field strength acquisition submodule is used to acquire the maximum field strength in the electric field distribution data; The external average field strength acquisition submodule is used to acquire the external average field strength. The maximum field strength distortion rate parameter calculation submodule is used to calculate the maximum field strength distortion rate parameter of the space charge distribution characteristics based on the maximum field strength and the applied average field strength.

9. An electronic device, characterized in that, The device includes a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the cable insulation evaluation method according to any one of claims 1-4 according to the instructions in the program code.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program code for performing the cable insulation evaluation method according to any one of claims 1-4.

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