Cable insulation evaluation method and device, electronic equipment and storage medium

Abstract

The invention discloses a cable insulation evaluation method and device, electronic equipment and a storage medium, which are used for solving the technical problem that the existing cable insulation evaluation method is low in reliability and accuracy. The method comprises the following steps: slicing a to-be-detected cable to obtain an insulation slice with a preset thickness; obtaining the lowest alternating current breakdown field strength of the insulation slice under the corresponding voltage grade; acquiring alternating-current space charge distribution characteristic data of the lowest alternating-current breakdown field strength; calculating an insulation failure characteristic value according to the alternating current space charge distribution characteristic data; testing space charge distribution characteristics of the insulation slices; calculating an average charge density and a maximum field intensity distortion rate parameter of the space charge distribution characteristics; and comparing the average charge density and the maximum field intensity distortion rate parameter with the insulation failure characteristic value to obtain an insulation evaluation result of the to-be-tested cable.

Description

Technical Field

[0001] The present invention relates to the technical field of cable insulation, and in particular to a cable insulation evaluation method, device, electronic equipment and storage medium. Background Art

[0002] With economic development and the improvement of people's living standards, users have higher and higher requirements for power supply reliability. In the urban power grid system, power cables of various voltage levels have gradually become the most inspected transmission network. However, since the cable is a typical capacitive power equipment, the damage of its insulation at a certain point will cause the failure of the entire insulation system. Therefore, the realization of cable insulation status monitoring is related to the stable operation of the urban power system.

[0003] Currently, the methods for evaluating the insulation status of AC current mainly include:

[0004] (1) Partial discharge detection: Carry out online or offline partial discharge detection on the power cable body to obtain the partial discharge characteristics and then locate the partial discharge point, so as to determine the insulation status of the cable.

[0005] (2) Withstand voltage test: This type of test includes series resonance test, ultra-low withstand voltage test, oscillation wave test, etc. These tests all require applying an AC voltage greater than its operating voltage to the high-voltage cable, with whether the withstand voltage test is passed as the only basis for evaluating the insulation status.

[0006] (3) Resistance test: Use equipment such as an insulation megger to measure the insulation resistance of the cable, and use the resistance value as the basis for judgment.

[0007] However, partial discharge can only measure the location information of the discharge in the high-voltage cable, and cannot determine the overall state of the power cable insulation, which is more accidental. The withstand voltage test is a destructive test method. Since it is necessary to apply a test voltage higher than the operating voltage to the cable, it is easy to cause secondary damage to the insulation during the test. The resistance test can only reflect the DC resistance value of the high-voltage cable insulation, but cannot effectively reflect the many key parameters in the operation of the AC cable, and has poor reliability. Summary of the invention

[0008] The present invention provides a cable insulation evaluation method, device, electronic equipment and storage medium, which are used to solve the technical problems of low reliability and accuracy of existing cable insulation evaluation methods.

[0009] The present invention provides a cable insulation evaluation method, comprising:

[0010] Slice the cable to be tested to obtain insulation slices of preset thickness;

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

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

[0013] Calculating insulation failure characteristic values ​​according to the AC space charge distribution characteristic data;

[0014] Testing the spatial charge distribution characteristics of the insulating slice;

[0015] Calculating the average charge density and maximum field intensity distortion rate parameters of the spatial charge distribution characteristics;

[0016] The average charge density and the maximum field strength distortion rate parameters are compared with the insulation failure characteristic value to obtain an insulation evaluation result of the cable to be tested.

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

[0018] Thermally aging the insulation slices 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 is tested in turn;

[0020] A thermal aging slice having a breakdown field strength lower than a minimum AC breakdown field strength is determined as a target thermal aging slice;

[0021] Calculating 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 minimum AC breakdown field strength.

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

[0024] placing the target thermally aged slice between a ground electrode and a high voltage electrode;

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

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

[0027] Inputting the square wave synchronization signal into a preset oscilloscope and a preset pulse source simultaneously;

[0028] The preset pulse source inputs a pulse signal to the target thermal aging slice in response to the square wave synchronization signal to generate an electroacoustic pulse signal;

[0029] Acquiring the electroacoustic pulse waveform of the electroacoustic pulse signal by means of the preset oscilloscope;

[0030] According to the electroacoustic pulse waveform, a single-cycle AC space charge characteristic of the target thermally aged slice is obtained.

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

[0032] calculating an average charge density of the spatial charge distribution characteristic;

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

[0034] Acquiring the maximum field intensity in the electric field distribution data;

[0035] Obtain the externally applied average field strength;

[0036] The maximum field intensity distortion rate parameter of the spatial charge distribution characteristic is calculated according to the maximum field intensity and the externally applied average field intensity.

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

[0038] A slicing module, used to slice the cable to be tested to obtain insulating slices of preset thickness;

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

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

[0041] An insulation failure characteristic value calculation module, used to calculate the insulation failure characteristic value according to the AC space charge distribution characteristic data;

[0042] A space charge distribution characteristic testing module, used for testing the space charge distribution characteristic of the insulating slice;

[0043] An 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 spatial charge distribution characteristics;

[0044] A 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 an insulation evaluation result of the cable to be tested.

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

[0046] A thermal aging submodule, used to perform thermal aging on the insulation slices according to a preset thermal aging cycle duration to obtain thermal aging slices of 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 turn;

[0048] A target thermal aging slice determination submodule, used for determining a thermal aging slice having a breakdown field strength lower than a minimum AC breakdown field strength as a target thermal aging slice;

[0049] A single-cycle AC space charge characteristic calculation submodule, used to calculate the single-cycle AC space charge characteristic of the target thermal aging slice;

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

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

[0052] A placement unit, used for placing the target thermally aged slice between a ground electrode and a high voltage electrode;

[0053] A voltage dividing unit, used for dividing the AC high voltage signal applied to the high voltage electrode through a voltage divider to obtain a low voltage power frequency synchronous signal;

[0054] A waveform conversion unit, used for inputting the low-voltage power frequency synchronization signal into a waveform conversion circuit to obtain a square wave synchronization signal;

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

[0056] An electroacoustic pulse signal generating unit, configured for the preset pulse source to input a pulse signal to the target thermal aging slice in response to the square wave synchronization signal, so as to generate an electroacoustic pulse signal;

[0057] An electroacoustic pulse waveform acquisition unit, used for acquiring the electroacoustic pulse waveform of the electroacoustic pulse signal through the preset oscilloscope;

[0058] The single-cycle AC space charge characteristic acquisition unit is used to acquire the single-cycle AC space charge characteristic of the target thermal aging slice according to the electroacoustic pulse waveform.

[0059] Optionally, the average charge density and maximum field strength distortion rate parameter calculation module includes:

[0060] An average charge density calculation submodule, used to calculate the average charge density of the spatial charge distribution characteristics;

[0061] The electric field distribution data calculation submodule is used to calculate the electric field distribution data according to the spatial charge distribution characteristics;

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

[0063] The externally applied average field strength acquisition submodule is used to obtain the externally applied 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 spatial charge distribution characteristic according to the maximum field strength and the externally 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 used to execute the cable insulation evaluation method as described above according to the instructions in the program code.

[0068] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program codes, and the program codes are used to execute the cable insulation evaluation method as described in any one of the above items.

[0069] It can be seen from the above technical scheme that the present invention has the following advantages: the present invention obtains an insulation slice of a preset thickness by slicing the cable to be tested; obtains the minimum AC breakdown field strength under the voltage level corresponding to the insulation slice; obtains the AC space charge distribution characteristic data of the minimum AC breakdown field strength; calculates the insulation failure characteristic value according to 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; compares the average charge density and maximum field strength distortion rate parameters with the insulation failure characteristic value to obtain the insulation evaluation result of the cable to be tested. The reliability and accuracy of the cable insulation evaluation are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative labor.

[0071] Figure 1 A flowchart of a method for evaluating cable insulation provided by an embodiment of the present invention;

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

[0073] Figure 3 This is the circuit diagram for measuring AC peak space charge;

[0074] Figure 4 This is a comparison chart of the conversion between sinusoidal AC signal and synchronous signal;

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

[0076] Figure 6 A structural block diagram of a cable insulation evaluation device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0077] The embodiments of the present invention provide a cable insulation evaluation method, device, electronic device and storage medium, which are used to solve the technical problems of low reliability and accuracy of existing cable insulation evaluation 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 creative work are within the scope of protection of the present invention.

[0079] See also Figure 1 , Figure 1 A flowchart of the steps of a cable insulation evaluation method provided by 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, slicing the cable to be tested to obtain insulating slices of a preset thickness;

[0082] In the embodiment of the present invention, an insulation slice with a thickness of 0.2 mm to 1 mm can be cut from the main insulation position of the cable to be tested by a sampling slicer, and the slice size is not less than 50 mm*50 mm. The area of ​​the insulation slice can be larger than this area, but if it is smaller than this area, flashover may occur when measuring the breakdown voltage or discharge may occur when measuring the space charge due to insufficient surface insulation distance, resulting in measurement failure.

[0083] Step 102, obtaining the minimum AC breakdown field strength of the insulating slice at a corresponding voltage level;

[0084] In the embodiment of the present invention, the minimum AC breakdown field strength that the insulation material of the cable to be tested should have under the voltage level transmitted by the cable to be tested can be found.

[0085] Step 103, obtaining AC space charge distribution characteristic data of the minimum AC breakdown field strength;

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

[0087] S31, thermally aging the insulation slices according to a preset thermal aging cycle duration to obtain thermally aged slices with different thermal aging cycles;

[0088] S32, testing the breakdown field strength of each thermally aged slice in turn;

[0089] In the specific implementation, Figure 2 As shown, Figure 2 A side view of the corresponding relationship between thermal aging and space charge provided by an embodiment of the present invention.

[0090] In the process of calculating the AC space charge distribution characteristic data of the lowest AC field strength, the cable insulation aging can be carried out using a temperature-controllable aging chamber. During the aging process, the insulation will deform due to heat. In order to prevent the insulation from curling and making subsequent tests impossible, glass sheets are used to press the insulation slices. A group of aging samples are taken out every 7 days to carry out AC breakdown field strength and space charge characteristic measurements.

[0091] Among them, the AC breakdown field strength test process is as follows:

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

[0093] E b =U b / d

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

[0095] S33, determining a thermal aging slice whose breakdown field strength is lower than the minimum AC breakdown field strength as a target thermal aging slice;

[0096] S34, calculating 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, placing the target thermally aged slice between the ground electrode and the high voltage electrode;

[0099] S342, dividing the AC high voltage applied to the high voltage electrode by a voltage divider to obtain a low voltage signal;

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

[0101] S344, inputting the square wave synchronization signal into a preset oscilloscope and a preset pulse source simultaneously;

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

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

[0104] S347, obtaining a single-cycle AC space charge characteristic of the target thermally aged slice according to the electroacoustic pulse waveform.

[0105] In the specific implementation, Figure 3 As shown, Figure 3 The figure is the circuit diagram of AC peak space charge measurement. In the process of single-cycle AC space charge characteristic measurement, the target thermal aging slice is first cleaned and placed on the ground electrode, and silicone oil is applied between the ground electrode and the target thermal aging slice to eliminate the air gap in the middle. After that, the high-voltage electrode is covered on the upper surface of the target thermal aging slice, and the high-voltage electrode is pressed tightly. After pressing, room temperature vulcanized silicone rubber is applied around the high-voltage electrode. Then, the ground electrode, the target thermal aging slice and the high-voltage electrode are placed in a vacuum drying oven, and the vacuum is drawn to discharge the gas components in the room temperature vulcanized silicone rubber to prevent local discharge during the space charge measurement process.

[0106] After that, the target heat-aged slice is vulcanized at room temperature. After the silicone rubber is cured, an AC booster is used to obtain an AC high-voltage signal with an effective value of not less than 10kV, and the AC high-voltage signal is directly connected to the high-voltage electrode. A voltage divider is used to obtain a low-voltage power frequency synchronization signal with a voltage divider ratio of 1000:1. The phase of the low-voltage power frequency synchronization signal is exactly the same as the AC high-voltage signal. After that, the low-voltage power frequency synchronization signal is input into a waveform conversion circuit, which can realize the conversion of sinusoidal voltage to square wave voltage, thereby obtaining a square wave synchronization signal. The waveform phase relationship before and after the conversion is shown as follows: Figure 4As shown in the figure, 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 sinusoidal signal.

[0108] 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: when the square wave synchronization signal end inputs the rising edge of a synchronization signal, the output end of the pulse source begins to emit a cluster of high-voltage narrow pulse signals. In this pulse cluster, the interval time 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] At the same time, an oscilloscope is used as an electroacoustic pulse signal waveform acquisition device, and the oscilloscope is set to a recording mode, that is, the voltage waveform of a certain length can be recorded after the measurement starts. The single measurement duration of the present invention is 10µs, so the single measurement duration that needs to be set should be greater than 10µs. The oscilloscope and the continuous pulse source share the same square wave synchronization signal, and the square wave synchronization signal will reach the pulse source and the oscilloscope at the same time. Therefore, the oscilloscope will start continuous acquisition at the same time when the electroacoustic pulse signal is emitted, and record the voltage waveform within the next 10µs. In this 10µs voltage waveform, the electroacoustic pulse signal generated by 10 groups of narrow pulses is included.

[0110] Therefore, in order to measure the space charge signal at the peak and trough moments, it is necessary to delay it appropriately. Figure 4 When the delay time is set to 5ms, it can be seen that a pulse cluster signal at the same time as the AC voltage peak 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. The electroacoustic pulse signal is detected by the sensor and synchronized with the pulse voltage cluster signal.

[0111] At present, traditional electroacoustic pulse detection methods require a large number of waveform averaging to eliminate the noise components in the electroacoustic pulse signal. In order to achieve space charge measurement within a single cycle and obtain a stable space charge signal in the shortest possible time, the present invention sets the signal averaging times to 10 times, that is, 10 repeated electroacoustic pulse signals are used to complete the noise elimination. To this end, the present invention sets a filter, which is a high-pass filter, because in the measurement process, the electroacoustic pulse comes from a rapidly rising pulse voltage signal, and the frequency components of the signal are all high-frequency components. The noise signals in the system itself during the measurement process often come from the power supply, external electromagnetic interference, etc. Therefore, the design of a high-pass filter helps to filter out noise interference from the measurement signal. In the present invention, the lower limit cutoff frequency of the filter is set to 1MHz to filter out the interference noise in the system as much as possible. After filtering, it can be measured on an oscilloscope to obtain the following Figure 5The 10 continuous electroacoustic pulse signals u1, u2, u3, ..., u 10 .

[0112] Since the filtering module is added, the embodiment of the present invention uses 10 groups of electroacoustic pulse signals for averaging to obtain an electroacoustic pulse signal that meets the signal-to-noise ratio. Through the above method, it can be guaranteed that the measurement of the space charge characteristics is completed within about 10µs. The cycle duration of the industrial frequency AC signal is 20ms, so the proportion of time occupied by a single measurement duration is about 0.5%. In such a short time, it can be approximately considered that the value of the industrial frequency AC voltage has not changed, so the DC space charge inversion algorithm can be used to calculate the space charge distribution characteristics. Its reference signal can use a DC electroacoustic pulse signal at a lower voltage, which is also the same as the DC space charge measurement method.

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

[0114] 1. Use the formula z=v for the electroacoustic pulse signal s t transforms the horizontal time axis into a position axis, where z is the position and v is the position. s is the speed of sound, which can be measured experimentally, and t is the time.

[0115] 2. Perform deconvolution processing on the electroacoustic pulse signal obtained after transformation to eliminate system overshoot. The specific steps of deconvolution processing are as follows: First, calculate the system transfer function of the test equipment based on the reference signal without spatial charge accumulation in the insulating slice, that is, assuming that the system input signal is δ(t), when measuring the sample without spatial charge accumulation, the oscilloscope acquisition signal is h(t), then the system transfer function calculation formula is:

[0116]

[0117] in, is the time variable.

[0118] Next, the signal for eliminating the system error is calculated based on the electroacoustic pulse signal under pressure and short circuit conditions. Assuming that the test signal is f0(t), the calculation formula for the recovery signal for eliminating the system error is:

[0119]

[0120] The restored signal that eliminates the system error can be obtained , It is the electroacoustic pulse signal collected by the oscilloscope.

[0121] 3. According to the principle of acoustic wave dispersion and attenuation, the deconvolution signal is restored. The signal attenuation calculation formula is:

[0122]

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

[0124] 4. The restored signal will be integrated to obtain the electric field distribution in the sample. The calculation formula of the electric field distribution is:

[0125]

[0126] in, This is the waveform of the position axis after recovery in step 3. is the electric field distribution inside the sample.

[0127] 5. Perform differential calculation on the electric field distribution, and finally obtain the single-cycle AC space charge characteristics of the target thermal aging slice according to the dielectric constant ε of the sample. The calculation formula is:

[0128]

[0129] in, is the dielectric constant of vacuum, is the relative dielectric constant of the insulating slice.

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

[0131] S35, using the single-cycle AC space charge characteristics as AC space charge distribution characteristic data of the minimum AC breakdown field strength.

[0132] Step 104, calculating the insulation failure characteristic value according to the AC space charge distribution characteristic data;

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

[0134] In a specific implementation, the average charge density characteristic value and the maximum field intensity distortion rate parameter characteristic value can be calculated based on the curve of the single-cycle AC space charge characteristic of the target thermal aging slice.

[0135] Step 105, testing the spatial charge distribution characteristics of the insulating slice;

[0136] In the embodiment of the present invention, the spatial charge distribution characteristics of the insulating slice can refer to the calculation process of the AC spatial charge distribution characteristic data, which will not be repeated here.

[0137] Step 106, calculating the average charge density and maximum field intensity distortion rate parameters of the spatial charge distribution characteristics;

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

[0139] S61, calculating the average charge density of the spatial charge distribution characteristics;

[0140] S62, calculating electric field distribution data according to spatial charge distribution characteristics;

[0141] S63, obtaining the maximum field intensity in the electric field distribution data;

[0142] S64, obtain the externally applied average field strength;

[0143] S65, calculating a maximum field intensity distortion rate parameter of a spatial charge distribution characteristic according to the maximum field intensity and the externally applied average field intensity.

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

[0145] The applied average field strength is generated by the AC voltage applied to the high voltage electrodes.

[0146] In the specific implementation, referring to the process of calculating the single-cycle AC space charge characteristics using the inversion algorithm of DC space charge, the space charge distribution characteristics can be calculated to calculate the electric field distribution data, and the maximum field strength can be obtained from the electric field distribution data. Dividing it by the externally applied average field strength, the maximum field strength distortion parameter of the space charge distribution characteristics can be obtained. Assuming that the externally applied average field strength during measurement is E0, the maximum field strength in the electric field distribution data obtained by measurement is E m , then the maximum field strength distortion parameter is k=E m / E0.

[0147] Step 107, comparing the average charge density and the maximum field strength distortion rate parameters with the insulation failure characteristic value to obtain an insulation evaluation result of the cable to be tested.

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

[0149] The present invention obtains insulation slices of preset thickness by slicing the tested cable; obtains the minimum AC breakdown field strength under the voltage level corresponding to the insulation slice; obtains AC space charge distribution characteristic data of the minimum AC breakdown field strength; calculates insulation failure characteristic values ​​according to 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; compares the average charge density and maximum field strength distortion rate parameters with the insulation failure characteristic values, and obtains the insulation evaluation result of the tested cable. The reliability and accuracy of the cable insulation evaluation are improved.

[0150] See also Figure 6 , Figure 6 A structural block diagram of a cable insulation evaluation device provided in an embodiment of the present invention.

[0151] An embodiment of the present invention provides a cable insulation evaluation device, comprising:

[0152] Slicing module 601, used for slicing the cable to be tested to obtain insulating slices of preset thickness;

[0153] A minimum AC breakdown field strength acquisition module 602 is used to acquire the minimum AC breakdown field strength at a voltage level corresponding to the insulation slice;

[0154] The AC space charge distribution characteristic data acquisition module 603 is used to acquire the AC space charge distribution characteristic data of the minimum AC breakdown field strength;

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

[0156] A space charge distribution characteristic test module 605 is used to test the space charge distribution characteristic of the insulating slice;

[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 spatial charge distribution characteristics;

[0158] The comparison module 607 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 to be tested.

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

[0160] A thermal aging submodule, used to perform thermal aging on the insulation slices according to a preset thermal aging cycle duration to obtain thermal aging 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 turn;

[0162] A target thermal aging slice determination submodule, used for determining a thermal aging slice having a breakdown field strength lower than a minimum AC breakdown field strength as a target thermal aging slice;

[0163] A single-cycle AC space charge characteristic calculation submodule is used to calculate the single-cycle AC space charge characteristic of the target thermal aging 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 of the minimum AC breakdown field strength.

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

[0166] A placement unit, used for placing a target thermal aging slice between a ground electrode and a high voltage electrode;

[0167] A voltage dividing unit, used for dividing the AC high voltage signal applied to the high voltage electrode through a voltage divider to obtain a low voltage power frequency synchronous signal;

[0168] A waveform conversion unit, used for inputting a low-voltage power frequency synchronization signal into a waveform conversion circuit to obtain a square wave synchronization signal;

[0169] An input unit, used for simultaneously inputting a square wave synchronization signal into a preset oscilloscope and a preset pulse source;

[0170] An electroacoustic pulse signal generating unit, used for inputting a pulse signal to a target thermal aging slice in response to a square wave synchronization signal by a preset pulse source, so as to generate an electroacoustic pulse signal;

[0171] An electroacoustic pulse waveform acquisition unit, used for acquiring the electroacoustic pulse waveform of the electroacoustic pulse signal through a preset oscilloscope;

[0172] The single-cycle AC space charge characteristic acquisition unit is used to acquire the single-cycle AC space charge characteristic of the target thermal aging slice according to the electroacoustic pulse waveform.

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

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

[0175] The electric field distribution data calculation submodule is used to calculate the electric field distribution data according to the spatial charge distribution characteristics;

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

[0177] The externally applied average field strength acquisition submodule is used to obtain the externally applied average field strength;

[0178] The maximum field strength distortion rate parameter calculation submodule is used to calculate the maximum field strength distortion rate parameter of the spatial charge distribution characteristics according to the maximum field strength and the externally applied average field strength.

[0179] An embodiment of the present invention further provides an electronic device, the device comprising a processor and a memory:

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

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

[0182] The embodiment of the present invention further provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the cable insulation evaluation method of the embodiment of the present invention.

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

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

[0185] It will be appreciated by those skilled in the art that the embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the embodiments of the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0186] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0187] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0188] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0189] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0190] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[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 aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may 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 cable insulation evaluation method, characterized in that: include: Slice the cable to be tested to obtain insulation slices of preset thickness; Obtain the minimum AC breakdown field strength at the corresponding voltage level of the insulation slice; Acquiring AC space charge distribution characteristic data of the minimum AC breakdown field strength; Calculating insulation failure characteristic values ​​according to the AC space charge distribution characteristic data; Testing the spatial charge distribution characteristics of the insulating slice; Calculating the average charge density and maximum field intensity distortion rate parameters of the spatial charge distribution characteristics; The average charge density and the maximum field strength distortion rate parameters are compared with the insulation failure characteristic value to obtain an insulation evaluation result of the cable to be tested.

2. The method according to claim 1, characterized in that The step of obtaining the AC space charge distribution characteristic data of the minimum AC breakdown field strength comprises: Thermally aging the insulation slices 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 is tested in turn; A thermal aging slice having a breakdown field strength lower than a minimum AC breakdown field strength is determined as a target thermal aging slice; Calculating 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 minimum 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 comprises: placing the target thermally aged slice between a ground electrode and a high voltage electrode; Dividing the AC high voltage signal applied to the high voltage electrode by a voltage divider to obtain a low voltage power frequency synchronization signal; Inputting the low-voltage power frequency synchronization signal into a waveform conversion circuit to obtain a square wave synchronization signal; Inputting the square wave synchronization signal into a preset oscilloscope and a preset pulse source simultaneously; The preset pulse source inputs a pulse signal to the target thermal aging slice in response to the square wave synchronization signal to generate an electroacoustic pulse signal; Acquiring the electroacoustic pulse waveform of the electroacoustic pulse signal by means of the preset oscilloscope; According to the electroacoustic pulse waveform, a single-cycle AC space charge characteristic of the target thermally aged slice is obtained.

4. The method according to claim 1, characterized in that: The step of calculating the average charge density and the maximum field intensity distortion rate parameter of the spatial charge distribution characteristic comprises: calculating an average charge density of the spatial charge distribution characteristic; Calculate electric field distribution data based on spatial charge distribution characteristics; Acquiring the maximum field intensity in the electric field distribution data; Obtain the externally applied average field strength; The maximum field intensity distortion rate parameter of the spatial charge distribution characteristic is calculated according to the maximum field intensity and the externally applied average field intensity.

5. A cable insulation evaluation device, characterized in that: include: A slicing module, used to slice the cable to be tested to obtain insulating slices of preset thickness; A minimum AC breakdown field strength acquisition module is used to obtain the minimum AC breakdown field strength at the corresponding voltage level of the insulation slice; An AC space charge distribution characteristic data acquisition module, used to acquire the AC space charge distribution characteristic data of the minimum AC breakdown field strength; An insulation failure characteristic value calculation module, used to calculate the insulation failure characteristic value according to the AC space charge distribution characteristic data; A space charge distribution characteristic testing module, used for testing the space charge distribution characteristic of the insulating slice; An 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 spatial charge distribution characteristics; A 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 an insulation evaluation result of the cable to be tested.

6. The device according to claim 5, characterized in that The AC space charge distribution characteristic data acquisition module comprises: A thermal aging submodule, used to perform thermal aging on the insulation slices according to a preset thermal aging cycle duration to obtain thermal aging slices of different thermal aging cycles; The breakdown field strength test submodule is used to test the breakdown field strength of each thermally aged slice in turn; A target thermal aging slice determination submodule, used for determining a thermal aging slice having a breakdown field strength lower than a minimum AC breakdown field strength as a target thermal aging slice; A single-cycle AC space charge characteristic calculation submodule, used to calculate the single-cycle AC space charge characteristic of the target thermal aging slice; The AC space charge distribution characteristic data determination submodule is used to use the single-cycle AC space charge characteristic as the AC space charge distribution characteristic data of the minimum AC breakdown field strength.

7. The device according to claim 6, characterized in that The single-cycle AC space charge characteristic calculation submodule includes: A placement unit, used for placing the target thermally aged slice between a ground electrode and a high voltage electrode; A voltage dividing unit, used for dividing the AC high voltage signal applied to the high voltage electrode through a voltage divider to obtain a low voltage power frequency synchronous signal; A waveform conversion unit, used for inputting the low-voltage power frequency synchronization signal into a waveform conversion circuit to obtain a square wave synchronization signal; An input unit, used to input the square wave synchronization signal into a preset oscilloscope and a preset pulse source simultaneously; An electroacoustic pulse signal generating unit, configured for the preset pulse source to input a pulse signal to the target thermal aging slice in response to the square wave synchronization signal, so as to generate an electroacoustic pulse signal; An electroacoustic pulse waveform acquisition unit, used for acquiring the electroacoustic pulse waveform of the electroacoustic pulse signal through the preset oscilloscope; The single-cycle AC space charge characteristic acquisition unit is used to acquire the single-cycle AC space charge characteristic of the target thermal aging slice according to the electroacoustic pulse waveform.

8. The device according to claim 5, characterized in that The average charge density and maximum field strength distortion rate parameter calculation module includes: An average charge density calculation submodule, used to calculate the average charge density of the spatial charge distribution characteristics; The electric field distribution data calculation submodule is used to calculate the electric field distribution data according to the spatial charge distribution characteristics; A maximum field strength acquisition submodule, used to acquire the maximum field strength in the electric field distribution data; The externally applied average field strength acquisition submodule is used to obtain the externally applied 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 spatial charge distribution characteristic according to the maximum field strength and the externally applied average field strength.

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

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