Method and system for diagnosing defects of transformer core based on no-load loss of different frequencies

Abstract

The invention discloses a method and system for diagnosing transformer core defects based on different frequency no-load losses, and the method comprises the steps: carrying out the demagnetization operation of a transformer core, carrying out the low-voltage no-load loss test of a transformer at different frequencies after each demagnetization, and carrying out the fault diagnosis of the transformer core defects; after each low-voltage no-load loss test, judging whether the demagnetization of the transformer core is thorough or not according to the variance of the no-load loss data; carrying out low-voltage no-load loss tests under different frequencies on the transformer of which the iron core is thoroughly demagnetized to obtain multiple groups of transformer no-load loss test data; counting multiple groups of transformer no-load loss test data from a transverse or longitudinal angle so as to determine a no-load loss distribution range, and determining a threshold value according to the no-load loss distribution range; and comparing the multiple groups of transformer no-load loss test data with a threshold value, and judging whether the transformer core has defects or not. According to the invention, the sensitivity of transformer core defect diagnosis can be improved.

Description

Technical Field

[0001] The invention relates to a transformer fault defect detection technology, and in particular to a method and a system for diagnosing transformer core defects based on no-load losses at different frequencies. Background Art

[0002] The transformer is one of the core equipment of the substation and plays a vital role in the process of power transmission. During the operation of the transformer, defects such as local short circuits in the core and windings often occur due to poor manufacturing process control, improper transportation and installation, etc. The internal defects of the transformer may continue to deteriorate and cause failures, causing power outages for the equipment. In severe cases, it will cause large-scale power outages and endanger personal safety. The transformer core column is equipped with windings, and the core is hidden. If the core has defects, it is extremely difficult to find them during on-site internal inspection.

[0003] There are two main methods for diagnosing transformer core defects on site: (1) Oil chromatography detection. Based on the changes in the content of dissolved gases such as methane and ethylene in the oil, combined with the data from the transformer winding DC resistance test, it is inferred whether the core has defects. Relying on oil chromatography detection has problems such as insensitive detection and inability to distinguish from winding defects. (2) Low-voltage power frequency no-load loss test. This method applies an excitation voltage of 400V and 50Hz when the transformer is no-loaded, and analyzes and diagnoses the core defects by comparing the differences in power frequency no-load losses horizontally and vertically. This method applies low voltage, and the no-load loss caused by core defects changes little, so the detection is insensitive. Therefore, it is very important to achieve sensitive on-site detection of transformer core defects. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a method and system for diagnosing transformer core defects based on no-load losses at different frequencies, which can improve the sensitivity of transformer core defect diagnosis.

[0005] Technical solution: A method for diagnosing transformer core defects based on no-load losses at different frequencies of the present invention comprises:

[0006] Carry out transformer core demagnetization operation. After each demagnetization, perform low voltage no-load loss test on the transformer at different frequencies. Determine whether the transformer core is thoroughly demagnetized based on the variance of no-load loss data after multiple demagnetizations.

[0007] The transformer with the core completely demagnetized is tested for low voltage no-load loss at different frequencies to obtain multiple sets of transformer no-load loss test data;

[0008] Multiple groups of transformer no-load loss test data are counted from a horizontal or vertical perspective to determine the distribution range of the no-load loss data, and the upper and lower limits of the threshold value are determined based on the distribution range of the no-load loss; multiple groups of transformer no-load loss test data are compared with the threshold value through horizontal and vertical comparison to determine whether the transformer core has defects.

[0009] Furthermore, during the demagnetization operation of the transformer core, the residual magnetism elimination operation is achieved by applying a direct current with opposite direction and decreasing amplitude.

[0010] Furthermore, before the transformer core is completely demagnetized, the frequency of the low voltage no-load loss test after each demagnetization operation includes 50 Hz and an integer multiple of the power frequency. The frequency of the low voltage no-load loss after each demagnetization operation is the same. The voltage amplitude of each low voltage no-load loss test is consistent;

[0011] The frequency applied in the low voltage no-load loss test is between 50-300 Hz and the voltage is not less than 380V.

[0012] Furthermore, after the transformer core is completely demagnetized, the current amplitude applied during each low-voltage no-load loss test remains consistent.

[0013] Furthermore, the transformer no-load loss is approximately equal to the core loss, and the unit core loss P c The calculation formula is as follows:

[0014] P c =K1fB m n +K2f 2 B m 2 δ 2

[0015] Where f is the frequency of the external voltage; B m is the magnetic flux density amplitude; δ is the thickness of silicon steel sheet; K1 and K2 are coefficients.

[0016] Furthermore, the horizontal comparison is to compare transformers of the same type and with the same technical parameters, and the vertical comparison is to compare historical data of the same transformer at different times.

[0017] Furthermore, when performing statistics at a horizontal angle, the threshold value is determined by statistically analyzing data from multiple transformers; when performing statistics at a vertical angle, the threshold value is determined by statistically analyzing data from multiple tests conducted at different times on the transformer.

[0018] Based on the same inventive concept, a system for diagnosing transformer core defects based on no-load losses at different frequencies of the present invention comprises:

[0019] The core demagnetization control module is used to carry out the transformer core demagnetization operation. After each demagnetization, the transformer is tested for low voltage no-load loss at different frequencies. The variance of the no-load loss data after multiple demagnetizations is used to determine whether the transformer core is completely demagnetized.

[0020] A data acquisition module is used to perform low voltage no-load loss tests at different frequencies on the transformer after the core is completely demagnetized, and obtain multiple sets of transformer no-load loss test data;

[0021] The defect diagnosis module is used to count multiple groups of transformer no-load loss test data from a horizontal or vertical perspective, so as to determine the distribution range of the no-load loss data, and determine the upper and lower limits of the threshold value according to the distribution range of the no-load loss; compare multiple groups of transformer no-load loss test data with the threshold value by horizontal and vertical comparison to determine whether the transformer core has defects.

[0022] Based on the same inventive concept, a device for diagnosing transformer core defects based on no-load losses at different frequencies of the present invention includes a processor and a memory, wherein the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the electronic device implements the steps of the above-mentioned method for diagnosing transformer core defects based on no-load losses at different frequencies.

[0023] Based on the same inventive concept, a computer-readable storage medium of the present invention stores a computer program thereon, and when the program is executed by a processor, the steps of the method for diagnosing transformer core defects based on no-load losses at different frequencies are implemented.

[0024] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are:

[0025] The present invention determines whether the core has defects based on low-voltage no-load loss test data at different frequencies, which greatly improves the judgment accuracy compared to the traditional judgment based only on 50Hz low-voltage no-load loss data.

[0026] In the present invention, whether the residual magnetism of the transformer is completely eliminated is judged based on the low-voltage no-load loss data, thereby improving the accuracy and reliability of the low-voltage no-load data test data;

[0027] The present invention proposes a method for determining a threshold value of no-load loss data for determining whether demagnetization is thorough and whether the core has defects, which has the advantages of high anti-interference accuracy and plays an important role in the effectiveness of diagnosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of a method for diagnosing transformer core defects based on no-load losses at different frequencies disclosed in an embodiment of the present invention;

[0029] Figure 2 It is a structural schematic diagram of a system for diagnosing transformer core defects based on no-load losses at different frequencies disclosed in an embodiment of the present invention;

[0030] Figure 3 The present invention is a schematic diagram of the structure of a device for diagnosing transformer core defects based on no-load losses at different frequencies disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It will be understood by those skilled in the art that the purposes and advantages that can be achieved with the present invention are not limited to the specific description of the above beneficial effects, and the above and other purposes that can be achieved by the present invention will be more clearly understood based on the following detailed description.

[0032] It should be understood by those skilled in the art that the exemplary components, systems and methods described in conjunction with the embodiments disclosed in the present invention can be implemented in hardware, software or a combination of the two. Whether it is implemented in hardware or software depends on the specific application and design of the technical solution. Professional and technical personnel can use different methods to implement the functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0033] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0034] Example 1

[0035] See also Figure 1 , Figure 1 is a flow chart of a method for diagnosing transformer core defects based on no-load losses at different frequencies disclosed in an embodiment of the present invention, wherein: Figure 1 The method for diagnosing transformer core defects based on no-load losses at different frequencies is applied to power systems, such as transformer core defect detection, etc., which is not limited in the embodiments of the present invention. Figure 1 As shown, the method for diagnosing transformer core defects based on no-load losses at different frequencies may include the following operations:

[0036] S1. Carry out transformer core demagnetization operation. After each demagnetization, perform low voltage no-load loss test on the transformer at two frequencies. Determine whether the transformer core is thoroughly demagnetized based on the variance of the no-load loss data after multiple demagnetizations.

[0037] During the demagnetization operation of the transformer core, the residual magnetism elimination operation is achieved by applying direct current with opposite direction and decreasing amplitude.

[0038] Before the transformer core is completely demagnetized, the voltage of each low-voltage no-load loss test is the same.

[0039] S2. Perform low voltage no-load loss tests at different frequencies on the transformer after the core is completely demagnetized, and obtain multiple sets of transformer no-load loss test data.

[0040] Before and after the transformer core is completely demagnetized, ensure that the current amplitude applied during each low-voltage no-load loss test remains consistent.

[0041] The frequency applied in the low voltage no-load loss test is between 50-300Hz and the voltage is not less than 380V.

[0042] S3. Count multiple groups of transformer no-load loss test data from a horizontal or vertical perspective to determine the distribution range of the no-load loss data, and determine the upper and lower limits of the threshold value based on the distribution range of the no-load loss; compare multiple groups of transformer no-load loss test data with the threshold value through horizontal and vertical comparison to determine whether the transformer core has defects.

[0043] When performing statistics at a horizontal angle, the threshold value is determined by statistically analyzing the data of multiple transformers; when performing statistics at a vertical angle, the threshold value is determined by statistically analyzing the data of multiple tests conducted on the transformer at different times.

[0044] Core defects are identified by horizontal and vertical comparison methods. Horizontal comparison mainly compares transformers of the same type and technical parameters. Vertical comparison mainly compares historical data of the same transformer at different times. The specific comparison method is to compare whether the test data exceeds the threshold value. When the no-load loss at high frequency exceeds the threshold value, it is judged that the core has defects.

[0045] Determine whether the core has defects based on whether the no-load loss exceeds the threshold value at different frequencies.

[0046] The technical scheme of the present invention comprises three steps: demagnetizing the core before no-load loss test of the transformer, no-load loss test at different frequencies, and analysis and diagnosis of core defects; wherein, whether the core is thoroughly demagnetized is judged based on the variance of no-load loss data after multiple demagnetizations; based on the positive correlation between the core loss of the transformer and the frequency, the core defects are judged by comparing with the threshold value through horizontal and vertical comparison; and the upper and lower limits of the threshold value are determined by using data statistics.

[0047] The following is an introduction to the measurement of no-load losses at 50 Hz and 200 Hz. The method for diagnosing transformer core defects based on no-load losses at different frequencies includes the following steps:

[0048] S1. Demagnetize the transformer core. Before demagnetization, carry out no-load loss measurement test under low voltage. The voltage frequency is 50Hz and 200Hz respectively, recorded as P 050(0) , P 0200(0) ; After each demagnetization operation, carry out no-load loss measurement test under low voltage, the voltage frequency is 50Hz and 200Hz respectively. To ensure complete demagnetization, carry out n1 demagnetization operations (n1≥2). Record the no-load loss test data P after the i-th demagnetization operation 050i , P 0200i , the applied voltage is consistent with the measurement before demagnetization. Construct an array consisting of the no-load loss measurement data [P 050(0) , P 050(1) ,…,P 050(i) ,…,P 050(n1) ]、[P 0200(0) , P 0200(1) ,…,P 0200(i) ,…,P 0200(n1) ], calculate the variance of three adjacent data, when the variance is less than the set threshold value σ 2 50thr1 , σ 2 200thr1 The demagnetization operation is completed when the voltage is 0.004V. The variance of the low voltage no-load loss data at 50Hz is calculated as follows, and the variance at 200Hz is calculated similarly.

[0049]

[0050] S2. After the transformer core demagnetization operation is completed, the no-load loss test is carried out at different frequencies of 50Hz and 200Hz. During the test, the current amplitude applied at different frequencies is controlled to remain consistent. The test data is recorded as the no-load loss P' at 50Hz 050(1) 、No-load loss P' at 200Hz 0200(1) .

[0051] The no-load loss of the transformer is approximately equal to the core loss. The unit core loss P c The calculation formula is shown in formula (2). The first term in the formula is hysteresis loss, and the second term is eddy current loss. The values ​​of coefficients K1 and K2 depend on the characteristics of silicon steel sheets and can be measured by experimental methods. According to formula (2), the transformer no-load loss is positively correlated with the frequency, and the high-frequency no-load loss reflects defects more sensitively.

[0052] P c =K1fB m n +K2f2 B m 2 δ 2 (2)

[0053] Where: f is the frequency of the external voltage (Hz); B m is the magnetic flux density amplitude (T); δ is the thickness of silicon steel sheet (mm).

[0054] S3. Determine the core defects by horizontal and vertical comparison.

[0055] Horizontal comparison, by comparing with the test data of transformers with the same structure and the same technical parameters, the transformer core defects are diagnosed and recorded as array [P' 050(1) , P' 050(2) , …, P' 050(k) , …, P' 050(n2) ]、[P' 0200(1) , P' 0200(2) , …, P' 0200(k) , …, P' 0200(n2) ], n2 is the number of transformers. If n2 = 2, when P' 050(1) >P' 050(2) , combined with the oil chromatography data to determine the transformer core defects. If n2>2, when P' 050(1) Exceeding the threshold value P' 050thr , P' 0200(1) Exceeding the threshold value P' 0200thr When P' 050(1) Does not exceed the threshold value P' 050thr , and P' 0200(1) Exceeding the threshold value P' 0200thr When the oil chromatography data is combined, it is determined whether the equipment has core defects.

[0056] By analyzing the test data of the same transformer at different times, the transformer core defects can be diagnosed and recorded as array [P" 050(1) ,P" 050(2) ,…,P” 050(l) ,…,P” 050(n3) ], [P” 0200(1) ,P" 0200(2) ,…,P” 0200(l) ,…,P” 0200(n3) ], n3 is the number of times the transformer is tested. If n3=2, when P” 050(1) >P" 050(2) , combined with the oil chromatography data to determine the transformer core defects. If n3>2, when P” 050(1) Exceeding the threshold value P" 050thr ,P” 0200(1)Exceeding the threshold value P'' 0200thr When P” 050(1) Does not exceed the threshold value P" 050thr , and P'' 0200(1) Exceeding the threshold value P" 0200thr When the oil chromatography data is combined, it is determined whether the equipment has core defects.

[0057] The above threshold values ​​are determined by statistical methods. 050(1) ,P" 050(2) ,…,P” 050(l) ,…,P” 050(n3) ] is used as an example to introduce the specific method: According to formula (1), calculate the average value of the array and standard deviation σ″ 050 , set the upper and lower threshold values ​​to

[0058] In the above demagnetization operation, σ 2 50thr1 , σ 2 200thr1 Refers to the lower limit. In horizontal and vertical comparisons, P' 050thr , P' 0200thr ,P” 050thr ,P” 0200thr Refers to the upper limit value.

[0059] Example 2

[0060] See also Figure 2 , Figure 2 1 is a schematic diagram of a system for diagnosing transformer core defects based on no-load losses at different frequencies disclosed in an embodiment of the present invention. The system can detect transformer core defects and specifically includes:

[0061] The core demagnetization control module is used to carry out the transformer core demagnetization operation. After each demagnetization, the transformer is tested for low voltage no-load loss at two frequencies. The variance of the no-load loss data after multiple demagnetizations is used to determine whether the transformer core is completely demagnetized.

[0062] A data acquisition module is used to perform low voltage no-load loss tests at different frequencies on the transformer after the core is completely demagnetized, and obtain multiple sets of transformer no-load loss test data;

[0063] The defect diagnosis module is used to count multiple groups of transformer no-load loss test data from a horizontal or vertical perspective, so as to determine the distribution range of the no-load loss data, and determine the upper and lower limits of the threshold value according to the distribution range of the no-load loss; compare multiple groups of transformer no-load loss test data with the threshold value by horizontal and vertical comparison to determine whether the transformer core has defects.

[0064] In an optional embodiment, a method for diagnosing transformer core defects based on no-load losses at different frequencies includes: a) performing a transformer core demagnetization operation, and after each demagnetization, performing a low-voltage no-load loss test on the transformer at two frequencies, and judging whether the transformer core is completely demagnetized based on the variance of multiple no-load loss data; b) performing low-voltage no-load loss tests at different frequencies on the transformer after the core is completely demagnetized to obtain multiple groups of transformer no-load loss test data; b) judging whether the core has defects based on the multiple groups of transformer no-load loss test data.

[0065] Example 3

[0066] See also Figure 3 , Figure 3 1 is a schematic diagram of a device for diagnosing transformer core defects based on no-load losses at different frequencies disclosed in an embodiment of the present invention. Figure 3 The described device can be applied to power systems, such as transformer core defect detection, etc., which is not limited in the embodiments of the present invention.

[0067] like Figure 3 As shown, the device may include a processor and a memory, wherein the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the electronic device implements the steps of the method described in the above embodiment and can achieve the technical effect consistent with the above method.

[0068] The memory may include computer system readable media in the form of volatile memory, such as random access memory (RAM) and / or cache memory. The device may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, the memory may be used to read and write non-removable, non-volatile magnetic media (commonly referred to as a "hard drive"). A program / utility having a set (at least one) of program modules may be stored in, for example, the memory, such program modules including but not limited to an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include the implementation of a network environment. The program modules typically perform the functions and / or methods in the embodiments described herein.

[0069] The processor executes various functional applications and data processing by running the program stored in the memory, such as implementing the method provided in the first embodiment of the present invention.

[0070] Example 4

[0071] Embodiment 4 of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the method described in the above embodiment are implemented and the technical effect consistent with the above method can be achieved.

[0072] The computer storage medium of the embodiment of the present invention can adopt any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, a device or a device or used in combination with it.

[0073] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, which carry computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0074] The program code embodied on the computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0075] Computer program code for performing the operation of the present invention may be written in one or more programming languages ​​or combinations thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer through any type of network including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0076] Of course, the storage medium containing computer executable instructions provided by an embodiment of the present invention, whose computer executable instructions are not limited to the above method operations, can also execute related operations in the method provided by any embodiment of the present invention.

[0077] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for diagnosing transformer core defects based on no-load losses at different frequencies, characterized in that: include: Carry out transformer core demagnetization operation. After each demagnetization, perform low voltage no-load loss test on the transformer at different frequencies. Determine whether the transformer core is thoroughly demagnetized based on the variance of no-load loss data after multiple demagnetizations. The transformer with the core completely demagnetized is tested for low voltage no-load loss at different frequencies to obtain multiple sets of transformer no-load loss test data; Multiple groups of transformer no-load loss test data are counted from a horizontal or vertical perspective to determine the distribution range of the no-load loss data, and the upper and lower limits of the threshold value are determined based on the distribution range of the no-load loss; multiple groups of transformer no-load loss test data are compared with the threshold value through horizontal and vertical comparison to determine whether the transformer core has defects.

2. The method for diagnosing transformer core defects based on no-load losses at different frequencies according to claim 1 is characterized in that: During the demagnetization operation of the transformer core, the residual magnetism elimination operation is achieved by applying direct current with opposite direction and decreasing amplitude.

3. The method for diagnosing transformer core defects based on no-load losses at different frequencies according to claim 1, characterized in that: Before the transformer core is completely demagnetized, the voltage of each low-voltage no-load loss test is the same; The frequency applied in the low voltage no-load loss test is between 50-300 Hz and the voltage is not less than 380V.

4. The method for diagnosing transformer core defects based on no-load losses at different frequencies according to claim 1, characterized in that: After the transformer core is completely demagnetized, the current amplitude applied during each low-voltage no-load loss test remains consistent.

5. The method for diagnosing transformer core defects based on no-load losses at different frequencies according to claim 1, characterized in that: The transformer no-load loss is approximately equal to the core loss, unit core loss P c The calculation formula is as follows: P c =K1fB m n +K2f 2 B m 2 δ 2 Where f is the frequency of the external voltage; B m is the magnetic flux density amplitude; δ is the thickness of silicon steel sheet; K1 and K2 are coefficients.

6. The method for diagnosing transformer core defects based on no-load losses at different frequencies according to claim 1, characterized in that: The horizontal comparison is to compare transformers of the same type and technical parameters, and the vertical comparison is to compare historical data of the same transformer at different times.

7. The method for diagnosing transformer core defects based on no-load losses at different frequencies according to claim 1, characterized in that: When performing statistics at a horizontal angle, the threshold value is determined by statistically analyzing the data of multiple transformers; when performing statistics at a vertical angle, the threshold value is determined by statistically analyzing the data of multiple tests conducted on the transformer at different times.

8. A system for diagnosing transformer core defects based on no-load losses at different frequencies, characterized in that: include: The core demagnetization control module is used to carry out the transformer core demagnetization operation. After each demagnetization, the transformer is tested for low voltage no-load loss at two frequencies. The variance of the no-load loss data after multiple demagnetizations is used to determine whether the transformer core is completely demagnetized. A data acquisition module is used to perform low voltage no-load loss tests at different frequencies on the transformer after the core is completely demagnetized, and obtain multiple sets of transformer no-load loss test data; The defect diagnosis module is used to count multiple groups of transformer no-load loss test data from a horizontal or vertical perspective, so as to determine the distribution range of the no-load loss data, and determine the upper and lower limits of the threshold value according to the distribution range of the no-load loss; compare multiple groups of transformer no-load loss test data with the threshold value by horizontal and vertical comparison to determine whether the transformer core has defects.

9. A device for diagnosing transformer core defects based on no-load losses at different frequencies, characterized in that: The electronic device comprises a processor and a memory, wherein the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the electronic device implements the steps of the method for diagnosing transformer core defects based on no-load losses at different frequencies as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for diagnosing transformer core defects based on no-load losses at different frequencies as described in any one of claims 1 to 7.

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