Intelligent high-voltage test platform and test method for transformer
By analyzing the electrical parameters and electromagnetic interference coefficients of the primary and secondary sides of the transformer and correcting the insulation resistance, the problem of electromagnetic interference in traditional high-voltage test platforms is solved, and high-precision evaluation of transformer insulation performance is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 国网黑龙江省电力有限公司鹤岗供电公司
- Filing Date
- 2026-03-25
- Publication Date
- 2026-05-08
AI Technical Summary
Traditional intelligent high-voltage testing platforms are subject to strong electromagnetic interference from lightning overvoltage and AC surges during the operation of high-voltage transformers, which affects the accuracy and stability of insulation performance measurement.
By measuring the electrical parameters of the primary and secondary sides of the transformer, analyzing the voltage and current signals, and combining the voltage waveform similarity and electromagnetic interference coefficient, the insulation resistance is corrected to evaluate the insulation performance of the transformer.
This improves the accuracy of transformer insulation performance measurement, reduces the impact of environmental interference on the measurement, and ensures the accuracy and reliability of the measurement results.
Smart Images
Figure CN121995180A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of transformer insulation performance diagnosis and evaluation technology, specifically to an intelligent high-voltage test platform and test method for transformers. Background Technology
[0002] During power transmission, the voltage needs to be increased to reduce line losses, involving high-voltage or ultra-high-voltage transmission. The insulation performance of the transformer directly affects its safety, reliability, and service life. Therefore, it is necessary to design intelligent high-voltage testing methods for high-voltage transformers to perform insulation testing.
[0003] In traditional intelligent high-voltage testing platforms, the insulation performance of a transformer is evaluated by applying an impulse voltage signal generated by a voltage generator and then analyzing the voltage and current signals at the insulation terminals. However, during the operation of a high-voltage transformer, it is inevitably affected by lightning overvoltages and AC impulses. At this time, transient voltage and current changes can easily generate strong electromagnetic interference, leading to significant deviations in the measurement of the high-voltage transformer's insulation performance and weak stability of the insulation performance. Summary of the Invention
[0004] To address the aforementioned technical problems, the purpose of this application is to provide an intelligent high-voltage test platform and test method for transformers. The specific technical solution adopted is as follows:
[0005] This application provides an intelligent high-voltage testing method for transformers, comprising the following steps:
[0006] The impact signal is used as the primary input of the high-voltage transformer to measure the electrical parameters of the secondary side and insulation end of the transformer during each test impact, including voltage and current.
[0007] By analyzing the similarity of the primary and secondary voltages and the differences in waveform distribution during each test group, the insulation retention of the transformer under each test group is obtained. Combined with the overlap of the voltage waveform curves on both sides, the insulation performance evaluation coefficient of the transformer under each test group is obtained.
[0008] The AC interference component before each AC cycle is obtained based on the fluctuation of the insulation resistance before each AC cycle of each test impact. Then, the electromagnetic interference coefficient in each AC cycle after each test impact is obtained by combining the degree of deviation between the insulation resistance after each AC cycle and the average resistance of the AC cycle before the impact.
[0009] The insulation resistance of the transformer in each AC cycle before the impact is corrected by using the resistance distribution and AC interference components before the impact of each test group. In combination with the insulation performance evaluation coefficient of the transformer under each test group, the insulation resistance of each AC cycle after the impact of each test group is corrected to evaluate the insulation performance of the transformer.
[0010] Preferably, the process for obtaining the insulation retention of the transformer under each group of tests is as follows: In the formula, A represents the insulation retention of the transformer under the current test group. This indicates the similarity between the primary and secondary voltage signals of the transformer under the current test group. This represents the average ratio of each peak value in the primary voltage signal of the current group of test transformers to the corresponding peak value in the secondary voltage signal. This represents the step-up ratio of the transformer under ideal preset conditions. The step-up ratio is a fixed quantity related to the number of turns of the coils on both sides of the transformer, the winding distribution, and the core saturation degree. It belongs to the fixed parameters of the transformer.
[0011] Preferably, the process for obtaining the insulation performance evaluation coefficient of the transformer under each group of tests is as follows: In the formula, B represents the insulation performance evaluation coefficient of the transformer under the current group of tests, norm() represents the normalization function, and A represents the insulation retention degree of the transformer under the current group of tests. This represents the difference in the closed area of the voltage curves on both sides of the transformer under the current test group.
[0012] Preferably, the process for obtaining the difference in the closed area of the voltage curves on both sides of the transformer under the current group of tests is as follows: , and This indicates the occurrence and end time of the impulse voltage under the current test group. These are the primary and secondary voltages of the transformer, respectively.
[0013] Preferably, the process of obtaining the AC interference component before each test impact is as follows: calculate the insulation resistance corresponding to each AC cycle before each test impact using Ampere's rule, and statistically analyze the average absolute deviation of the insulation resistance of all AC cycles before each test impact, which is taken as the AC interference component before each test impact.
[0014] Preferably, the process for obtaining the electromagnetic interference coefficient within each AC cycle after each test impact is as follows: In the formula, Indicates the number of tests conducted after the current group's impact. Electromagnetic interference coefficient within one AC cycle Indicates the number of tests conducted after the current group's impact. Insulation resistance per AC cycle, This represents the average insulation resistance of all AC cycles before the current test impact. This represents the AC interference component before the current group's test impact, max{ R} represents the insulation resistance of each AC cycle before the current group of test impacts. The difference between them is taken as the maximum absolute value.
[0015] Preferably, the transformer insulation resistance correction process for each AC cycle before each test impact is as follows: In the formula, and These represent the insulation resistance after correction and before correction in the m-th AC cycle before the current group's test impact, respectively. `sign()` represents the sign function. This indicates the AC interference component before the current group's test impact. This indicates the skewness value of the insulation resistance distribution before the current group of tests.
[0016] Preferably, if the distribution of insulation resistance of all AC cycles before the current test impact shows a left skewness, then the skewness value is... The value is -1. If the distribution is right-skewed, the skewness value is... The value is 1.
[0017] Preferably, the correction process for the insulation resistance after each AC cycle following the test impact is as follows: In the formula, The first test after the current group's impact Insulation resistance per AC cycle, The first test after the current group's impact Insulation resistance after AC cycle correction Indicates the number of tests conducted after the current group's impact. The insulation resistance after AC cycle correction, of which hour, , represents the insulation resistance after correction during the last AC cycle before the current group's test impact;
[0018] Indicates the correction factor. Where B represents the insulation performance evaluation coefficient of the transformer under the current group of tests. Indicates the number of tests conducted after the current group's impact. Electromagnetic interference coefficient within one AC cycle.
[0019] This application also provides an intelligent high-voltage test platform for a transformer, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any of the above-described intelligent high-voltage test methods for a transformer.
[0020] As can be seen from the above, the intelligent high-voltage test platform and test method for transformers provided in this application have at least the following beneficial effects:
[0021] This application addresses the issue that traditional transformer insulation performance assessments under overvoltage surges neglect the impact of electromagnetic interference generated by simulated lightning overvoltages on measured electrical parameters, thus reducing the accuracy of the test platform's measurement of transformer insulation performance. Therefore, this application utilizes an intelligent test platform to generate AC and surge signals. By analyzing voltage changes on the transformer's input and output sides, the insulation condition of the transformer during the surge is estimated. Simultaneously, the distribution of insulation resistance values at the measurement terminals is used to obtain information on electromagnetic interference, thereby correcting the transformer's insulation resistance during the measurement process, improving the accuracy of transformer insulation measurement, and reducing the impact of environmental interference on measurement accuracy. Attached Figure Description
[0022] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 A flowchart illustrating the steps of an intelligent high-voltage testing method for a transformer provided in this application;
[0024] Figure 2 This is a block diagram of an intelligent high-voltage test platform for a transformer, provided as an embodiment of this application. Detailed Implementation
[0025] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an intelligent high-voltage test platform and test method for a transformer proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.
[0026] Unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0027] The following description, in conjunction with the accompanying drawings, details the specific scheme of the intelligent high-voltage test platform and test method for transformers provided in this application.
[0028] Please see Figure 1 The document illustrates a flowchart of an intelligent high-voltage testing method for a transformer according to an embodiment of this application, including the following steps:
[0029] S1: Use the impact signal as the primary input of the high-voltage transformer to measure the electrical parameters of the transformer's secondary side and insulation terminals during each test impact, including voltage and current.
[0030] In this embodiment, the transformer under test needs to be prepared before the test. The transformer is de-energized in advance so that the transformer discharge time is not less than 5 minutes. Under normal circumstances, there is insulating oil inside the high-voltage transformer for heat dissipation and insulation. Therefore, it is necessary to ensure that the transformer has sufficient insulating oil and that the resting time exceeds 24 hours. In this embodiment, the transformer discharge time is set to 15 minutes and the resting time is 30 hours.
[0031] After the transformer pre-test preparations are completed, the transformer is connected to the intelligent high-voltage test platform, and intelligent sensors are connected to the insulation terminals of the high-voltage transformer. In this embodiment, an impulse voltage is generated by an impulse voltage generator, and the electrical signal information at the insulation terminals is monitored and analyzed. Since the impulse signal serves as the input to the primary side of the high-voltage transformer, intelligent sensors, including voltage and current sensors, are used on the secondary side and insulation terminals of the transformer to measure the electrical parameters of the high-voltage transformer, including voltage and current data. To obtain more accurate operating information of the transformer during the impulse process, the sampling frequency of the sensors should be no less than 20 kHz. In this embodiment, preferably, the sampling frequency is 20 kHz.
[0032] For each impact signal applied to a different phase of an AC signal, at least 100 sets of data are tested, and the data in a single test is at least 1000ms. Preferably, in this embodiment, the number of test sets is 100 sets and the data in a single test is 1000ms.
[0033] S2: By measuring the similarity of the primary and secondary voltages of the transformer during each test group and the differences in waveform distribution, the insulation retention of the transformer under each test group is obtained. Combined with the overlap of the voltage waveform curves on both sides, the insulation performance evaluation coefficient of the transformer under each test group is obtained.
[0034] In this embodiment, the following analysis uses electrical parameter information from any test. During operation, a high-voltage transformer primarily transforms voltage to reduce line losses during transmission. Ideally, the waveforms on the primary and secondary sides of a high-voltage transformer are essentially identical; the voltage ratio between them is called the turns ratio, indicating the degree of voltage transformation.
[0035] When subjected to an overvoltage surge during normal AC conversion, if the transformer has good overall insulation, the voltage waveforms on the primary and secondary sides will be consistent, and the overall turns ratio will remain essentially unchanged. However, for transformers with poor insulation, overvoltage surges can easily cause internal breakdown or partial discharge, leading to distortion of the secondary voltage waveform and a significant difference from the primary waveform.
[0036] Based on the electrical parameter information from a single set of measurements, the insulation retention A of the transformer under this set of tests is obtained: In the formula, A represents the insulation retention of the transformer under the current test group. This represents the similarity between the primary and secondary voltage signals of the transformer under the current test group. It can be measured using either the Pearson correlation coefficient or cosine similarity; this embodiment uses cosine similarity. This represents the average ratio of each peak value in the primary voltage signal of the current test transformer to the corresponding peak value in the secondary voltage signal. It should be noted that under normal circumstances, the transformer converts the primary voltage to the secondary voltage based on the turns ratio; therefore, the voltage change curves on both sides are consistent. That is, a peak value on the primary side must have a corresponding peak value on the secondary side. However, during impact testing, if the number of peak values on both sides is inconsistent, the calculation based on the number of peak values is used. The peak value's index refers to the number of the peak value appearing in the voltage signal; the first peak value is indexed as 1, and so on. This represents the step-up ratio of a transformer under ideal preset conditions. It is a fixed quantity related to the number of turns of the coils on both sides of the transformer, the winding distribution, and the saturation degree of the iron core. It belongs to the fixed parameters of the transformer.
[0037] When a transformer has good insulation, although it experiences overvoltage surges, the impact is only felt during the period of surge signal regeneration. During testing, the smaller the waveform difference between the two voltage sides, the higher the similarity between the voltage sides, and the more stable the turns ratio. However, if the transformer's insulation is poor, the surge voltage may cause internal breakdown or discharge, leading to a greater waveform difference and negatively affecting the stability of the turns ratio.
[0038] Furthermore, in the analysis of insulation retention, the focus is on the voltage changes on both sides during the test, which may cause the insulation information to be reduced during the brief moment of overvoltage charging. Therefore, the analysis is performed on the signal during the period when the impact signal occurs.
[0039] Ideally, the voltages on the primary and secondary sides of a transformer have only a linear relationship based on the turns ratio. Therefore, by comparing the waveforms of the voltage signals on both sides when an impulse voltage occurs, if the waveforms of the two sides basically overlap or the enclosed area is smaller, it indicates that the insulation performance of the transformer is good even when an impulse voltage occurs; conversely, it indicates that the insulation performance of the transformer will be affected during the period when the impulse signal is generated.
[0040] Based on the overlap of the voltage waveform curves on both sides of the transformer during the impact period, the insulation performance evaluation coefficient of the transformer under this set of tests is obtained: In the formula, B represents the insulation performance evaluation coefficient of the transformer under the current group of tests, norm() represents the normalization function, and A represents the insulation retention degree of the transformer under the current group of tests. This represents the difference in the closed area of the voltage curves on both sides of the transformer under the current test group. Preferably, in this embodiment, the calculation process of the closed area difference is as follows: , and This indicates the occurrence and end time of the impulse voltage under the current group test. It is mainly generated by the impulse voltage generator and obtained through statistical time, so this time is a known quantity. These are the primary and secondary voltages of the transformer, respectively. This indicates that a linear correction is applied to the voltage on the secondary side, so that the voltages on both sides are of the same order of magnitude. This represents the difference between the primary and secondary voltage curves, and the integral of this difference is used to measure the size of the enclosed area formed by the voltages on both sides and the endpoints during the impulse voltage period. It should be noted that since the primary and secondary voltages are actually collected, there is a certain measurement error; therefore, the area under this integral will not be zero.
[0041] This allows for the evaluation of the insulation performance of the entire transformer. The better the insulation performance of the transformer, the smaller the difference in the monitoring signals on both sides of the transformer, and the larger the final insulation performance evaluation value. Conversely, when an impulse voltage is generated and the insulation performance inside the transformer is poor, it may be affected by partial discharge or breakdown, resulting in a smaller insulation performance evaluation coefficient obtained from the electrical data characteristics on both sides of the transformer.
[0042] S3: Based on the fluctuation of insulation resistance in each AC cycle before each test impact, obtain the AC interference component before each test impact. Then, combine the deviation between the insulation resistance in each AC cycle after the impact and the average resistance level of the AC cycle before the impact to obtain the electromagnetic interference coefficient in each AC cycle after each test impact.
[0043] The above analysis mainly focuses on the voltage signals of the primary and secondary sides of the transformer during the measurement period, in order to evaluate the insulation performance of the transformer under the current set of measured electrical parameter data. To further measure the transformer's insulation performance, the electrical signals at the insulation terminals are measured and analyzed, as detailed below:
[0044] When measuring the insulation resistance of a transformer, the primary and secondary sides inside the transformer are not connected, resulting in a large resistance value between them. It is possible to quantitatively assess the insulation performance of the transformer by measuring the resistance value.
[0045] Using the time point of the transformer overvoltage impact as the dividing point, the electrical parameter information collected at the insulation end before and after the impact can be compared. For the electrical parameter information measured at the insulation end, for each AC cycle, in this embodiment the AC frequency is 50HZ and each AC cycle is 20ms. In this embodiment, the resistance value corresponding to each AC cycle will be obtained by using Ampere's law. In this embodiment, it is recorded as the insulation resistance of each AC cycle.
[0046] Before the impact, the voltage signals on the primary and secondary sides of the transformer are basically stable. At this time, the overall electromagnetic interference is weak and relatively stable. Therefore, the AC interference component can be obtained by using the resistance distribution before the impact of each test. In this embodiment, the specific method of obtaining the insulation resistance is as follows: the insulation resistance corresponding to each AC cycle before each test impact is calculated using Ampere's rule; for the insulation resistance of all AC cycles before each test impact, the average absolute deviation of all insulation resistances before each test impact is calculated, which is used as the AC interference component before each test impact.
[0047] Following an impact, the instantaneous surge voltage generates strong electromagnetic interference, which in turn causes electromagnetic interference in the voltage and current signals measured at the insulated terminals, distorting the overall measurement data. Therefore, the electromagnetic interference coefficient C is derived from the resistance value within a single AC cycle after the impact. In the formula, Indicates the number of tests conducted after the current group's impact. Electromagnetic interference coefficient within one AC cycle Indicates the number of tests conducted after the current group's impact. Insulation resistance per AC cycle, This represents the average insulation resistance of all AC cycles before the current test impact. This represents the AC interference component before the current group's test impact, max{ R} represents the insulation resistance of each AC cycle before the current group of test impacts. The difference between them is taken as the maximum absolute value.
[0048] Thus, according to the above process in this embodiment, the electromagnetic interference coefficient in each AC cycle after each group of test impacts can be obtained, so as to analyze the electromagnetic interference situation of the electrical parameter signal in each AC cycle.
[0049] S4: The insulation resistance of the transformer in each AC cycle before the impact is corrected by using the resistance distribution and AC interference components before the impact of each group of tests. Combined with the insulation performance evaluation coefficient of the transformer under each group of tests, the insulation resistance of each AC cycle after the impact of each group of tests is corrected to evaluate the insulation performance of the transformer.
[0050] Therefore, based on the above insulation and electromagnetic interference analyses, the insulation resistance measured by the transformer is analyzed, and the insulation resistance correction for each AC cycle before each test impact is as follows: In the formula, and These represent the insulation resistance after correction and before correction in the m-th AC cycle before the current group's test impact, respectively. `sign()` represents the sign function. This indicates the AC interference component before the current group's test impact. This indicates the skewness value of the insulation resistance distribution before the current test impulse. The skewness value measures the distribution of insulation resistance across all AC cycles before the current test impulse. If the distribution of insulation resistance across all AC cycles before the current test impulse shows a left skewness, it indicates that an extreme large value has occurred under AC electromagnetic interference. In this case, the skewness value is less than zero. The value is -1, meaning the AC interference component needs to be subtracted to correct the insulation resistance. When the distribution shows a right skewness, it indicates that a certain extreme minimum value has occurred, at which point the skewness is greater than zero. The value is 1, which means the insulation resistance before correction is added to the AC interference component, thus achieving the correction of the insulation resistance.
[0051] After the impact reaction, the insulation resistance is corrected according to the insulation performance evaluation coefficient of the transformer under each group of tests: In the formula, and These represent the numbers after the current group's test impact. Insulation resistance before and after one AC cycle correction Indicates the number of tests conducted after the current group's impact. The insulation resistance after AC cycle correction. Indicates the correction factor. Where B represents the insulation performance evaluation coefficient of the transformer under the current group of tests. Indicates the number of tests conducted after the current group's impact. Electromagnetic interference coefficient within one AC cycle It should be noted that, hour, In this embodiment, represents the insulation resistance after correction during the last AC cycle before the current group's test impact.
[0052] When correcting insulation resistance after an impact, the focus is on analyzing the transformer's insulation performance evaluation coefficient and electromagnetic interference coefficient to calibrate the insulation resistance. Better insulation performance (i.e., a larger insulation performance evaluation coefficient) and a smaller electromagnetic interference coefficient result in higher accuracy of the measured resistance value, thus placing greater weight on the measured insulation resistance. Conversely, poorer insulation performance (i.e., a smaller insulation performance evaluation coefficient) and greater electromagnetic interference result in lower weight on the measured insulation resistance. When calibrating the insulation resistance over an AC cycle, the calibration will be more inclined towards the insulation resistance calibration value of the previous AC cycle, thereby achieving accurate calibration of the measured insulation resistance.
[0053] The above process enables the measurement and correction of the transformer's insulation resistance. Furthermore, in this embodiment, the insulation performance is evaluated based on the corrected insulation resistance and transformer standards. Preferably, in this embodiment, after an impact reaction, if the corrected insulation resistance is less than the required value, it indicates that the transformer under test has a potential insulation performance defect and requires further inspection. It should be noted that the required resistance value of the transformer is related to the corresponding voltage amplitude. Specifically, the resistance values are specified as follows: at 20℃, 300MΩ for 3-10KV, 400MΩ for 20-35KV, 800MΩ for 63-220KV, and 3000MΩ for 500KV. The specific value will vary depending on the actual application scenario, and this embodiment does not impose any special restrictions.
[0054] Based on the same inventive concept as the above method, this application embodiment also provides an intelligent high-voltage test platform for transformers, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any of the above-described intelligent high-voltage test methods for transformers.
[0055] Preferably, in this embodiment, the intelligent high-voltage test platform mainly evaluates the insulation performance of the high-voltage transformer by simulating the impact signal of a lightning strike in nature and measuring voltage and current signals at the measurement end. Specifically, a block diagram of an intelligent high-voltage test platform for a transformer is shown below. Figure 2 As shown. In this embodiment, an intelligent high-voltage test platform for a transformer includes: an impulse voltage generator: used to simulate overvoltage conditions under extreme conditions such as lightning strikes, typically required to generate impulse voltage signals above 200kV; in this embodiment, model HZCJ-DY-200kV / 20kJ is selected.
[0056] AC test generator: used to generate stable AC signals to simulate AC signals during line transmission. Since it is designed for high-voltage transmission lines and high-voltage transformers, it is required to generate 800kV / 80kA AC signals.
[0057] Insulation performance evaluation module: It is used to take the impulse signal as the primary side input of the high-voltage transformer, measure the electrical parameters of the secondary side and insulation end of the transformer during each group of test impulses, including voltage and current. By the similarity of the voltage on the primary side and secondary side of the transformer and the difference in waveform distribution during each group of tests, the insulation retention of the transformer under each group of tests is obtained. Combined with the overlap of the voltage waveform curves on both sides, the insulation performance evaluation coefficient of the transformer under each group of tests is obtained.
[0058] The electromagnetic interference analysis module is used to obtain the AC interference components before each AC cycle based on the fluctuation of the insulation resistance before each AC cycle of each test impact. Then, combined with the deviation between the insulation resistance after each AC cycle and the average resistance level before the impact, the electromagnetic interference coefficient in each AC cycle after each test impact is obtained.
[0059] Resistance correction and evaluation module: It is used to correct the transformer insulation resistance of each AC cycle before the impact by using the resistance distribution and AC interference components before each group of test impacts. Combined with the insulation performance evaluation coefficient of the transformer under each group of tests, it corrects the insulation resistance of each AC cycle after each group of test impacts in order to evaluate the insulation performance of the transformer.
[0060] It is understood that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.
[0061] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.
[0062] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of this application.
Claims
1. An intelligent high-voltage testing method for transformers, characterized in that, Includes the following steps: The impact signal is used as the primary input of the high-voltage transformer to measure the electrical parameters of the secondary side and insulation end of the transformer during each test impact, including voltage and current. By analyzing the similarity of the primary and secondary voltages and the differences in waveform distribution during each test group, the insulation retention of the transformer under each test group is obtained. Combined with the overlap of the voltage waveform curves on both sides, the insulation performance evaluation coefficient of the transformer under each test group is obtained. The AC interference component before each AC cycle is obtained based on the fluctuation of the insulation resistance before each AC cycle of each test impact. Then, the electromagnetic interference coefficient in each AC cycle after each test impact is obtained by combining the degree of deviation between the insulation resistance after each AC cycle and the average resistance of the AC cycle before the impact. The insulation resistance of the transformer in each AC cycle before the impact is corrected by using the resistance distribution and AC interference components before the impact of each test group. In combination with the insulation performance evaluation coefficient of the transformer under each test group, the insulation resistance of each AC cycle after the impact of each test group is corrected to evaluate the insulation performance of the transformer.
2. The intelligent high-voltage testing method for a transformer as described in claim 1, characterized in that, The process for obtaining the insulation retention of the transformer under each group of tests is as follows: In the formula, A represents the insulation retention of the transformer under the current test group. This indicates the similarity between the primary and secondary voltage signals of the transformer under the current test group. This represents the average ratio of each peak value in the primary voltage signal of the current group of test transformers to the corresponding peak value in the secondary voltage signal. This represents the step-up ratio of the transformer under ideal preset conditions. The step-up ratio is a fixed quantity related to the number of turns of the coils on both sides of the transformer, the winding distribution, and the core saturation degree. It belongs to the fixed parameters of the transformer.
3. The intelligent high-voltage testing method for a transformer as described in claim 1, characterized in that, The process for obtaining the insulation performance evaluation coefficients of the transformers under each group of tests is as follows: In the formula, B represents the insulation performance evaluation coefficient of the transformer under the current group of tests, norm() represents the normalization function, and A represents the insulation retention degree of the transformer under the current group of tests. This represents the difference in the closed area of the voltage curves on both sides of the transformer under the current test group.
4. The intelligent high-voltage testing method for a transformer as described in claim 3, characterized in that, The process for obtaining the difference in the closed area of the voltage curves on both sides of the transformer under the current test group is as follows: , and This indicates the occurrence and end time of the impulse voltage under the current test group. These are the primary and secondary voltages of the transformer, respectively.
5. The intelligent high-voltage testing method for a transformer as described in claim 1, characterized in that, The process of obtaining the AC interference components before each test impact is as follows: the insulation resistance corresponding to each AC cycle before each test impact is calculated using Ampere's law, and the average absolute deviation of the insulation resistance of all AC cycles before each test impact is statistically analyzed, which is taken as the AC interference component before each test impact.
6. The intelligent high-voltage testing method for a transformer as described in claim 1, characterized in that, The process for obtaining the electromagnetic interference coefficient within each AC cycle after each test impact is as follows: In the formula, Indicates the number of tests conducted after the current group's impact. Electromagnetic interference coefficient within one AC cycle Indicates the number of tests conducted after the current group's impact. Insulation resistance per AC cycle, This represents the average insulation resistance of all AC cycles before the current test impact. This represents the AC interference component before the current group's test impact, max{ R} represents the insulation resistance of each AC cycle before the current group of test impacts. The difference between them is taken as the maximum absolute value.
7. The intelligent high-voltage testing method for a transformer as described in claim 1, characterized in that, The transformer insulation resistance correction process for each AC cycle before each test impact is as follows: In the formula, and These represent the insulation resistance after correction and before correction in the m-th AC cycle before the current group's test impact, respectively. `sign()` represents the sign function. This indicates the AC interference component before the current group's test impact. This indicates the skewness value of the insulation resistance distribution before the current group of tests.
8. The intelligent high-voltage testing method for a transformer as described in claim 7, characterized in that, If the distribution of insulation resistance for all AC cycles before the current test impact shows a left-biased trend, then the skewness value is... The value is -1. If the distribution is right-skewed, the skewness value is... The value is 1.
9. The intelligent high-voltage testing method for a transformer as described in claim 1, characterized in that, The correction process for insulation resistance after each AC cycle following the test impact is as follows: In the formula, The first test after the current group's impact Insulation resistance per AC cycle, The first test after the current group's impact Insulation resistance after AC cycle correction Indicates the number of tests conducted after the current group's impact. The insulation resistance after AC cycle correction, of which hour, , represents the insulation resistance after correction during the last AC cycle before the current group's test impact; Indicates the correction factor. Where B represents the insulation performance evaluation coefficient of the transformer under the current group of tests. Indicates the number of tests conducted after the current group's impact. Electromagnetic interference coefficient within one AC cycle.
10. An intelligent high-voltage testing platform for a transformer, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the intelligent high-voltage testing method for a transformer as described in any one of claims 1-9.