Variable frequency series resonant withstand voltage test system and device

Abstract

This invention relates to the field of variable frequency series resonant withstand voltage testing technology, specifically disclosing a variable frequency series resonant withstand voltage testing system and apparatus, including: a theoretical resonant frequency calculation module, an output frequency information acquisition module, a test resonant frequency evaluation module, a withstand voltage test information acquisition module, a withstand voltage performance stability analysis module, and a power cable insulation performance evaluation module. This invention deeply analyzes the accuracy of the resonant frequency of the series resonant circuit in a fully resonant state, and simultaneously analyzes the withstand voltage stability and insulation performance of the power cable based on the voltage, leakage current, temperature, and partial discharge conditions during the withstand voltage test. This improves the coverage of the withstand voltage stability evaluation of the power cable, thereby enhancing the persuasiveness of the insulation performance evaluation and providing a more targeted basis for the maintenance and repair of power cables.

Description

Technical Field

[0001] This invention relates to the field of variable frequency series resonant withstand voltage test technology, and more specifically, to a variable frequency series resonant withstand voltage test system and apparatus. Background Technology

[0002] Ensuring good insulation performance of power cables is crucial in the operation and maintenance of power systems. Traditional methods for withstand voltage testing of power cables have many drawbacks. Firstly, they require extremely large power capacities, which are often difficult to meet on-site, hindering the successful conduct of the test. Secondly, traditional testing equipment is bulky and cumbersome, making transportation and on-site setup extremely inconvenient and consuming significant manpower, resources, and time. Therefore, developing an efficient, convenient, and accurate withstand voltage testing system and device is urgently needed.

[0003] For example, Chinese Patent Publication No. CN103869113B discloses a high-voltage series resonant device and a withstand voltage test method using the device. The device includes: a frequency converter cabinet, a test transformer, a resonant reactor, and a test voltage measuring device with a current sensor. The current sensor is connected in series between the high-voltage end of the test transformer and the grounding end of the capacitive test specimen. The resonant reactor has a fixed number of sections and is installed in a fixed position to keep its inductance constant. The frequency of the output voltage signal from the frequency converter cabinet is adjusted using this device so that when the series resonant circuit is in full resonance, the voltage values ​​across the resonant reactor and the test specimen are equal. The test voltage of the specimen is determined after Fourier transform. This method eliminates the need for a dedicated high-voltage divider for measuring the test voltage, thus enabling efficient, safe, and convenient withstand voltage testing while ensuring the test voltage accuracy is within the allowable range. This significantly improves the safety and efficiency of high-voltage series resonant AC withstand voltage testing.

[0004] The existing technology still has the following problems: 1. At present, only the focus is on whether the series resonant circuit is in a fully resonant state. The accuracy of the resonant frequency of the series resonant circuit in a fully resonant state is not analyzed in depth, which reduces the accuracy of the resonant frequency confirmation and reduces the accuracy of the subsequent withstand voltage test results, which has an adverse effect on the subsequent insulation performance evaluation of power cables.

[0005] 2. The analysis of the withstand voltage stability and insulation performance of the power cable was not combined with the voltage, leakage current, temperature and partial discharge conditions during the withstand voltage test. This reduced the coverage of the withstand voltage stability assessment, thereby reducing the persuasiveness of the insulation performance assessment. At the same time, it failed to provide more targeted basis for the maintenance and repair of the power cable, thus reducing the reliability and safety of the power cable operation. Summary of the Invention

[0006] In view of this, in order to solve the problems mentioned in the background art, a variable frequency series resonant withstand voltage test system and device is proposed.

[0007] The objective of this invention can be achieved through the following technical solutions: In a first aspect, this invention provides a variable frequency series resonant withstand voltage test system, comprising: a theoretical resonant frequency calculation module, used to extract the capacitance value of the target power cable and the inductance value of the target reactor in the withstand voltage test, and to calculate the theoretical resonant frequency of the target power cable.

[0008] The output frequency information acquisition module is used to slowly increase the output frequency of the target frequency converter during the withstand voltage test, acquire the current value of the target test circuit at each output frequency during the withstand voltage test, and simultaneously acquire the voltage value at both ends of the target power cable at each output frequency.

[0009] The test resonant frequency evaluation module is used to evaluate whether the test resonant frequency of the target power cable is accurate in the withstand voltage test. If it is accurate, the withstand voltage test information acquisition module is executed. If it is inaccurate, it indicates that the withstand voltage test cannot continue and feedback is provided.

[0010] The withstand voltage test information acquisition module is used to keep the test resonant frequency constant during the withstand voltage test, set the test voltage of the target power cable during the withstand voltage test, extract the reasonable range of leakage current of the target power cable, and collect the number of discharges, the discharge amount corresponding to each discharge, the cable temperature, and the voltage and leakage current corresponding to each monitoring time point of each cable segment in the withstand voltage test.

[0011] The withstand voltage performance stability analysis module is used to analyze the withstand voltage performance stability of each cable segment in the target power cable during the withstand voltage test.

[0012] The power cable insulation performance evaluation module is used to evaluate whether the insulation performance of the target power cable is up to standard. If it is not up to standard, feedback will be provided.

[0013] A second aspect of the invention provides an apparatus comprising a processor, a memory, and a communication bus. The memory stores a computer-readable program executable by the processor. The communication bus enables communication between the processor and the memory. When the processor executes the computer-readable program, it implements the aforementioned variable frequency series resonant withstand voltage test system.

[0014] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: (1) By adopting the frequency conversion series resonance method, the present invention can achieve high voltage test of cable with a lower power supply capacity compared with the traditional withstand voltage test method (such as directly using a high voltage test transformer). Because in the resonance state, the reactive power in the circuit is mainly exchanged between the reactor and the cable capacitance, and the power supply only needs to provide the active power part in the circuit, which greatly reduces the requirements for the test power supply capacity. It can be applied to the on-site test of large capacity cables, reduces the volume and weight of the test equipment, and improves the convenience of the test.

[0015] (2) This invention improves the accuracy of resonant frequency confirmation by conducting in-depth analysis of the resonant frequency accuracy of the series resonant circuit in the fully resonant state, and at the same time improves the accuracy of subsequent withstand voltage test results, thus avoiding adverse effects on the subsequent insulation performance evaluation of power cables.

[0016] (3) This invention analyzes the voltage stability and insulation performance of power cables by combining the voltage, leakage current, temperature and partial discharge conditions in the withstand voltage test. This improves the coverage of the withstand voltage stability assessment of power cables, thereby improving the persuasiveness of the insulation performance assessment of power cables. At the same time, it provides a more targeted basis for the maintenance and repair of power cables, and improves the reliability and safety of power cable operation. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the system module structure connection of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of a device according to the present invention.

[0020] Figure 3 This is a flowchart for evaluating the accuracy of the experimental resonant frequency in this invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 As shown, the present invention provides a variable frequency series resonant withstand voltage test system, including: a theoretical resonant frequency calculation module, an output frequency information acquisition module, a test resonant frequency evaluation module, a withstand voltage test information acquisition module, a withstand voltage performance stability analysis module, and a power cable insulation performance evaluation module.

[0023] Both the theoretical resonant frequency calculation module and the output frequency information acquisition module are connected to the test resonant frequency evaluation module. The test resonant frequency evaluation module is connected to the withstand voltage test information acquisition module. The withstand voltage test information acquisition module is connected to the withstand voltage performance stability analysis module. The withstand voltage performance stability analysis module is connected to the power cable insulation performance evaluation module.

[0024] The theoretical resonant frequency calculation module is used to extract the capacitance value of the target power cable and the inductance value of the target reactor in the withstand voltage test, and to calculate the theoretical resonant frequency of the target power cable.

[0025] It should be noted that the capacitance value of the target power cable is extracted from the product manual provided by the target power cable manufacturer, and the inductance value of the target reactor in the withstand voltage test is extracted from the nameplate on the target reactor itself.

[0026] In a specific embodiment of the present invention, the method for calculating the theoretical resonant frequency of the target power cable is as follows: the capacitance value of the target power cable and the inductance value of the target reactor in the withstand voltage test are respectively denoted as C and L.

[0027] Calculate the theoretical resonant frequency f of the target power cable. 理 ,

[0028] The output frequency information acquisition module is used to slowly increase the output frequency of the target frequency converter in the withstand voltage test, acquire the current value of the target test circuit at each output frequency in the withstand voltage test, and acquire the voltage value at both ends of the target power cable at each output frequency.

[0029] It should be noted that the current values ​​of the target circuit at each output frequency in the withstand voltage test are obtained by current transformers, and the voltage values ​​at both ends of the target power cable at each output frequency are measured by capacitive voltage dividers.

[0030] The test resonant frequency evaluation module is used to evaluate whether the test resonant frequency of the target power cable is accurate in the withstand voltage test. If it is accurate, the withstand voltage test information acquisition module is executed. If it is inaccurate, it indicates that the withstand voltage test cannot continue and feedback is provided.

[0031] In a specific embodiment of the present invention, the specific process of evaluating whether the test resonant frequency of the target power cable in the withstand voltage test is accurate is as follows: construct a current-frequency curve in the withstand voltage test with the output frequency as the abscissa and the current value as the ordinate, and locate the output frequency corresponding to the maximum current value from the curve and record it as the first output frequency.

[0032] With the output frequency as the horizontal axis and the voltage values ​​at both ends as the vertical axis, a voltage-frequency curve is constructed for the withstand voltage test. The output frequency corresponding to the voltage peak value is located from the curve and recorded as the second output frequency.

[0033] Calculate the accuracy β of the test resonant frequency of the target power cable during the withstand voltage test.

[0034] In a specific embodiment of the present invention, the specific process of calculating the accuracy of the test resonant frequency of the target power cable in the withstand voltage test is as follows: the theoretical resonant frequency of the target power cable is subtracted from the first output frequency to obtain the output frequency deviation between the theoretical resonant frequency and the first output frequency, and is denoted as Δf1.

[0035] The difference between the theoretical resonant frequency and the second output frequency of the target power cable is calculated to obtain the output frequency deviation between the theoretical resonant frequency and the second output frequency, which is denoted as Δf2.

[0036] The difference between the first output frequency and the second output frequency is calculated to obtain the output frequency deviation between the first output frequency and the second output frequency, which is denoted as Δf3.

[0037] Calculate the accuracy β of the test resonant frequency of the target power cable during the withstand voltage test. Where Δf represents the set permissible output frequency deviation, and e represents the natural constant.

[0038] Please see Figure 3 As shown, the accuracy of the test resonant frequency of the target power cable in the withstand voltage test is compared with the accuracy of the set reference resonant frequency. If the accuracy of the test resonant frequency of the target power cable in the withstand voltage test is greater than or equal to the accuracy of the set reference resonant frequency, it indicates that the test resonant frequency of the target power cable in the withstand voltage test is accurate; otherwise, it indicates that the test resonant frequency of the target power cable in the withstand voltage test is inaccurate.

[0039] This invention improves the accuracy of resonant frequency confirmation by conducting in-depth analysis of the resonant frequency accuracy of a series resonant circuit in a fully resonant state. It also improves the accuracy of subsequent withstand voltage test results and avoids adverse effects on the subsequent insulation performance evaluation of power cables.

[0040] The withstand voltage test information acquisition module is used to keep the test resonant frequency constant during the withstand voltage test, set the test voltage of the target power cable during the withstand voltage test, extract the reasonable range of leakage current of the target power cable, and collect the number of discharges, the discharge amount corresponding to each discharge, the cable temperature, and the voltage and leakage current corresponding to each monitoring time point of each cable segment in the withstand voltage test.

[0041] It should be noted that the test voltage for the target power cable in the withstand voltage test is set as follows: the test voltage value is determined according to the rated voltage of the target power cable and relevant standards. For example, for a 110kV cable, the test voltage may be 1.7 times the rated voltage (i.e., 187kV).

[0042] It should also be noted that the reasonable range of leakage current of the target power cable is extracted from the product manual provided by the target power cable manufacturer. The number of discharges and the discharge amount corresponding to each discharge of each cable segment in the withstand voltage test are obtained by a partial discharge detector. The cable temperature of each cable segment in the target power cable during the withstand voltage test is measured by an infrared thermal imager. The voltage and leakage current corresponding to each monitoring time point of each cable segment in the target power cable during the withstand voltage test are measured by a voltmeter and a microammeter connected in series in the test circuit, respectively.

[0043] The withstand voltage performance stability analysis module is used to analyze the withstand voltage performance stability of each cable segment in the target power cable during the withstand voltage test.

[0044] In a specific embodiment of the present invention, the specific process for analyzing the withstand voltage performance stability of each cable segment in the target power cable during the withstand voltage test is as follows: based on the number of discharges, the discharge amount corresponding to each discharge, the cable temperature, and the voltage and leakage current corresponding to each monitoring time point in each cable segment of the target power cable during the withstand voltage test, the voltage stability χ of each cable segment in the target power cable during the withstand voltage test is calculated respectively. i Leakage current reasonableness δ i Partial discharge abnormality index and temperature anomaly index θ i , where i represents the cable segment number, i = 1, 2, ..., n.

[0045] In a specific embodiment of the present invention, the specific process of calculating the voltage stability of each cable segment in the target power cable during the withstand voltage test is as follows: The voltage corresponding to each monitoring time point of each cable segment in the target power cable during the withstand voltage test is subtracted from the test voltage of the target power cable during the withstand voltage test to obtain the voltage deviation corresponding to each monitoring time point of each cable segment in the target power cable during the withstand voltage test. This deviation is then compared with the voltage deviation set as a reference for the corresponding cable segment. If the voltage deviation corresponding to a certain monitoring time point of a certain cable segment during the withstand voltage test is greater than or equal to the voltage deviation set as a reference for that cable segment, then that monitoring time point is recorded as an abnormal time point. The number of abnormal time points of each cable segment in the target power cable during the withstand voltage test is counted and recorded as ε. i .

[0046] Calculate the voltage stability χ of each cable segment in the target power cable during the withstand voltage test. i , Where ε′ represents the number of abnormal time points set as a reference.

[0047] In a specific embodiment of the present invention, the specific process of calculating the reasonableness of leakage current of each cable segment in the target power cable during the withstand voltage test is as follows: the leakage current corresponding to each monitoring time point of each cable segment in the target power cable during the withstand voltage test is compared with the reasonable range of leakage current of the target power cable. If the leakage current corresponding to each monitoring time point of a certain cable segment in the target power cable is within the reasonable range of leakage current, then the reasonableness of leakage current of that cable segment in the withstand voltage test is recorded as τ1.

[0048] If a section of the target power cable has a leakage current at a monitoring time point that is not within the reasonable range during the withstand voltage test, then the reasonableness of the leakage current of that section of the cable during the withstand voltage test is recorded as τ2.

[0049] If the leakage current of a certain cable segment in the target power cable is not within the reasonable range of leakage current at each monitoring time point in the withstand voltage test, then the reasonableness of the leakage current of the cable segment in the withstand voltage test is recorded as τ3.

[0050] In summary, the reasonableness δ of the leakage current of each cable segment in the withstand voltage test of the target power cable is obtained. i δ i The value of is τ1, τ2, or τ3, where τ1 > τ2 > τ3.

[0051] In one specific embodiment of the present invention, the value of τ1 is set to 1, and the value of τ2 is set to... The value of τ3 is set to 0.

[0052] In a specific embodiment of the present invention, the specific process for calculating the partial discharge anomaly index of each cable segment in the target power cable during the withstand voltage test is as follows: the number of discharges of each cable segment in the target power cable during the withstand voltage test is denoted as μ. i .

[0053] The total discharge amount of each cable segment in the target power cable during the withstand voltage test is obtained by summing the discharge amounts of each discharge during the withstand voltage test, and is denoted as Q. i .

[0054] Calculate the partial discharge anomaly index of each cable segment in the target power cable during the withstand voltage test. Where μ′ and Q′ represent the number of discharges and the amount of discharge set as a reference, respectively.

[0055] It should be noted that the specific process for calculating the temperature anomaly index of each cable segment in the target power cable during the withstand voltage test is as follows: the cable temperature of each cable segment in the target power cable during the withstand voltage test is compared with the set reference normal cable temperature range. If the cable temperature of a certain cable segment in the target power cable during the withstand voltage test is within the set reference normal cable temperature range, then the temperature anomaly index of that cable segment during the withstand voltage test is recorded as σ1.

[0056] If the cable temperature of a certain cable segment in the target power cable is not within the normal cable temperature range set for reference during the withstand voltage test, the temperature anomaly index of that cable segment during the withstand voltage test shall be recorded as σ2.

[0057] In summary, the temperature anomaly index θ of each cable segment in the target power cable during the withstand voltage test is obtained. i θ i The value of is σ1 or σ2, where σ1 < σ2.

[0058] In one specific embodiment of the present invention, σ1 is set to 0 and σ2 is set to 1.

[0059] Calculate the withstand voltage performance stability of each cable segment in the target power cable during the withstand voltage test. Where a1, a2, a3 and a4 represent the weights of the voltage stability, leakage current rationality, partial discharge anomaly index and temperature anomaly index respectively in the evaluation of withstand voltage performance stability, and a1+a2+a3+a4=1.

[0060] In a specific embodiment of the present invention, the values ​​of a1, a2, a3, and a4 are all set to 0.25. When calculating the withstand voltage performance stability of each cable segment of the target power cable in the withstand voltage test, the voltage stability, leakage current rationality, partial discharge abnormality index, and temperature abnormality index are all very important factors, as they reflect the withstand voltage performance of the cable from different aspects.

[0061] The power cable insulation performance evaluation module is used to evaluate whether the insulation performance of the target power cable is qualified. If it is not qualified, feedback is provided.

[0062] In a specific embodiment of the present invention, the specific process for evaluating whether the insulation performance of the target power cable is qualified is as follows: calculate the insulation performance qualification degree ξ of the target power cable. in, This indicates the set reference withstand voltage stability, and n represents the number of cable segments.

[0063] The insulation performance qualification of the target power cable is compared with the set reference insulation performance qualification. If the insulation performance qualification of the target power cable is less than the set reference insulation performance qualification, it indicates that the insulation performance of the target power cable is unqualified. Conversely, it indicates that the insulation performance of the target power cable is qualified.

[0064] This invention analyzes the withstand voltage stability and insulation performance of power cables by combining the voltage, leakage current, temperature, and partial discharge conditions during withstand voltage tests. This improves the coverage of withstand voltage stability assessment and enhances the persuasiveness of insulation performance assessment. It also provides more targeted basis for the maintenance and repair of power cables, thereby improving the reliability and safety of power cable operation.

[0065] Please see Figure 2 As shown, this invention proposes an apparatus comprising a processor, a memory, and a communication bus. The memory stores a computer-readable program executable by the processor. The communication bus enables communication between the processor and the memory. When the processor executes the computer-readable program, it implements the aforementioned variable frequency series resonant withstand voltage test system.

[0066] This invention, by employing a variable frequency series resonance method, can achieve high-voltage testing of cables with a lower power supply capacity compared to traditional withstand voltage testing methods (such as directly using a high-voltage test transformer). This is because, in the resonant state, the reactive power in the circuit is mainly exchanged between the reactor and the cable capacitance, and the power supply only needs to provide the active power portion of the circuit, greatly reducing the requirements for the test power supply capacity. This method is suitable for on-site testing of large-capacity cables, reduces the size and weight of the test equipment, and improves the convenience of the test.

[0067] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A variable frequency series resonant withstand voltage test system, characterized by, include: The theoretical resonant frequency calculation module is used to extract the capacitance value of the target power cable and the inductance value of the target reactor in the withstand voltage test, and calculate the theoretical resonant frequency of the target power cable. The output frequency information acquisition module is used to slowly increase the output frequency of the target frequency converter in the withstand voltage test, acquire the current value of the target test circuit at each output frequency in the withstand voltage test, and acquire the voltage value of the two ends of the target power cable at each output frequency. The test resonant frequency evaluation module is used to evaluate whether the test resonant frequency of the target power cable is accurate in the withstand voltage test. If it is accurate, the withstand voltage test information acquisition module is executed. If it is inaccurate, it indicates that the withstand voltage test cannot continue and feedback is given. The withstand voltage test information acquisition module is used to keep the test resonant frequency constant during the withstand voltage test, set the test voltage of the target power cable during the withstand voltage test, extract the reasonable range of leakage current of the target power cable, and collect the number of discharges, the discharge amount corresponding to each discharge, the cable temperature, and the voltage and leakage current corresponding to each monitoring time point of each cable segment in the withstand voltage test. The withstand voltage performance stability analysis module is used to analyze the withstand voltage performance stability of each cable segment in the target power cable during the withstand voltage test. The power cable insulation performance evaluation module is used to evaluate whether the insulation performance of the target power cable is up to standard. If it is not up to standard, feedback will be provided. The specific process for evaluating the accuracy of the test resonant frequency of the target power cable in the withstand voltage test is as follows: With the output frequency as the horizontal axis and the current value as the vertical axis, a current-frequency curve is constructed in the withstand voltage test, and the output frequency corresponding to the maximum current value is located from the curve and recorded as the first output frequency. With the output frequency as the horizontal axis and the voltage values ​​at both ends as the vertical axis, a voltage-frequency curve is constructed in the withstand voltage test, and the output frequency corresponding to the voltage peak value is located from the curve and recorded as the second output frequency. Accuracy of the test resonant frequency of a power cable under test in a withstand voltage test ; The accuracy of the test resonant frequency of the target power cable in the withstand voltage test is compared with the accuracy of the set reference resonant frequency. If the accuracy of the test resonant frequency of the target power cable in the withstand voltage test is greater than or equal to the accuracy of the set reference resonant frequency, it indicates that the test resonant frequency of the target power cable in the withstand voltage test is accurate. Otherwise, it indicates that the test resonant frequency of the target power cable in the withstand voltage test is inaccurate. The specific process for calculating the accuracy of the test resonant frequency of the target power cable in the withstand voltage test is as follows: differencing the theoretical resonance frequency of the target power cable from the first output frequency, to obtain an output frequency deviation between the theoretical resonance frequency and the first output frequency, and denoted as ; differencing the theoretical resonance frequency of the target power cable from the second output frequency, to obtain an output frequency deviation between the theoretical resonance frequency and the second output frequency, and denoted as ; differencing the first output frequency from the second output frequency to obtain an output frequency deviation between the first output frequency and the second output frequency, and denoted as ; Accuracy of the test resonant frequency of a power cable under test in a withstand voltage test , , wherein represents a set permitted output frequency deviation, represents a natural constant.

2. The variable frequency series resonant withstand voltage test system according to claim 1, characterized in that: The method for calculating the theoretical resonant frequency of the target power cable is as follows: The capacitance value of the target power cable and the inductance value of the target reactor in the withstand voltage test are respectively denoted as and ; Calculating the theoretical resonance frequency of a power cable , .

3. The variable frequency series resonant withstand voltage test system according to claim 1, characterized in that: The specific process for analyzing the stability of the withstand voltage performance of each cable segment in the target power cable during the withstand voltage test is as follows: Based on the number of discharges, the discharge amount corresponding to each discharge, the cable temperature, and the voltage and leakage current at each monitoring time point in the withstand voltage test of each cable segment of the target power cable, the voltage stability of each cable segment in the withstand voltage test is calculated. Reasonableness of leakage current Partial discharge abnormality index and temperature anomaly index ,in, Indicates the cable segment number, ; Calculate the withstand voltage performance stability of each cable segment in the target power cable during the withstand voltage test. , ,in, , , and These represent the weightings of the voltage stability, leakage current rationality, partial discharge anomaly index, and temperature anomaly index in the withstand voltage performance stability assessment. .

4. The variable frequency series resonant withstand voltage test system according to claim 3, characterized in that: The specific process for calculating the voltage stability of each cable segment in the target power cable during the withstand voltage test is as follows: The voltage at each monitoring time point during the withstand voltage test of each cable segment in the target power cable is subtracted from the test voltage of the target power cable during the withstand voltage test to obtain the voltage deviation at each monitoring time point during the withstand voltage test of each cable segment in the target power cable. This deviation is then compared with the voltage deviation set as a reference for the corresponding cable segment. If the voltage deviation at a certain monitoring time point during the withstand voltage test of a certain cable segment is greater than or equal to the voltage deviation set as a reference for that cable segment, then that monitoring time point is recorded as an abnormal time point. The number of abnormal time points for each cable segment in the withstand voltage test of the target power cable is counted and recorded as follows: ; Calculate the voltage stability of each cable segment in the target power cable during the withstand voltage test. , ,in, This indicates the number of abnormal time points to be set as a reference.

5. The variable frequency series resonant withstand voltage test system according to claim 3, characterized in that: The specific process for calculating the reasonableness of the leakage current of each cable segment in the target power cable during the withstand voltage test is as follows: The leakage current at each monitoring time point of the withstand voltage test for each cable segment of the target power cable is compared with the reasonable range of leakage current for the target power cable. If the leakage current at each monitoring time point of the withstand voltage test for a certain cable segment of the target power cable is within the reasonable range of leakage current, then the reasonableness of the leakage current of that cable segment in the withstand voltage test is recorded as follows: ; If, during a withstand voltage test, the leakage current of a certain cable segment at a monitoring time point is outside the reasonable range, then the reasonableness of the leakage current of that cable segment during the withstand voltage test is recorded as follows: ; If the leakage current of a certain cable segment in the target power cable is not within the reasonable range at any of the monitoring time points during the withstand voltage test, then the reasonableness of the leakage current of that cable segment in the withstand voltage test is recorded as follows: ; In summary, the reasonableness of leakage current in each cable segment of the target power cable during the withstand voltage test is obtained. , The value is or or ,in, .

6. The variable frequency series resonant withstand voltage test system according to claim 3, characterized in that: The specific process for calculating the partial discharge abnormality index of each cable segment in the target power cable during the withstand voltage test is as follows: The number of discharges in each cable segment of the target power cable during the withstand voltage test is recorded as follows: ; The discharge amounts corresponding to each discharge of each cable segment in the withstand voltage test are summed to obtain the total discharge amount of each cable segment in the target power cable during the withstand voltage test, and this total discharge amount is denoted as . ; Calculate the partial discharge anomaly index of each cable segment in the target power cable during the withstand voltage test. , ,in, and These represent the number of discharges and the amount of discharge set as a reference, respectively.

7. The variable frequency series resonant withstand voltage test system according to claim 3, characterized in that: The specific process for assessing whether the insulation performance of the target power cable is qualified is as follows: Calculate the insulation performance qualification rate of the target power cable , ,in, This indicates the stability of the withstand voltage performance as a reference setting. Indicates the number of cable segments; The insulation performance qualification of the target power cable is compared with the set reference insulation performance qualification. If the insulation performance qualification of the target power cable is less than the set reference insulation performance qualification, it indicates that the insulation performance of the target power cable is unqualified. Conversely, it indicates that the insulation performance of the target power cable is qualified.

8. An apparatus, characterized in that, include: Processor, memory, and communication bus; The memory stores a computer-readable program that can be executed by the processor; The communication bus enables communication between the processor and the memory; When the processor executes the computer-readable program, it implements the variable frequency series resonant withstand voltage test system as described in any one of claims 1-7.

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