A method and system for detecting damage to main transformers caused by short-circuit current surges.

Abstract

The application provides a method for detecting damage of a main transformer caused by short-circuit current impact, comprising the following steps: obtaining actual short-circuit currents of high, medium and low voltage sides of the transformer when the transformer is impacted by short-circuit current, and extracting the maximum as the final actual short-circuit current; obtaining allowed short-circuit currents of the high, medium and low voltage sides of the transformer based on rated capacity of the transformer, high-to-low impedance voltage of the transformer, rated current of the low voltage side of the transformer, rated capacity of the high voltage side of the transformer and rated capacity of the low voltage side of the transformer, and combining system short-circuit apparent capacity of the high, medium and low voltage sides of the transformer, and extracting the maximum as the final allowed short-circuit current; determining a current short-circuit situation, and combining the final actual short-circuit current, the final allowed short-circuit current or rated current of the main transformer to formulate test items to detect damage condition of the transformer. By implementing the application, the problem of low efficiency and error-prone of manual analysis can be overcome, and the health condition of the transformer can be evaluated by formulating a series of test items.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a method and system for detecting damage to main transformers caused by short-circuit current surges. Background Technology

[0002] Currently, traditional short-circuit current analysis mainly relies on manual operation, which is not only inefficient but also prone to errors, often failing to reflect the actual situation of the main transformer under short-circuit current impact in real time and accurately. Furthermore, traditional short-circuit current analysis does not conduct a series of detailed tests to assess its health status.

[0003] Therefore, under the development trend of power system automation and intelligence, there is an urgent need for a more efficient, accurate and real-time method for analyzing short-circuit current impact. This method can not only overcome the problems of low efficiency and error-proneness of manual analysis, but also assess the health status of transformers by developing a series of test projects. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a method and system for detecting the damage of short-circuit current impact to the main transformer. This method not only overcomes the problems of low efficiency and error-proneness of manual analysis, but also assesses the health status of the transformer by developing a series of test items.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a method for detecting damage to a main transformer caused by a short-circuit current surge, the method comprising the following steps:

[0006] S1. When the main transformer is subjected to short-circuit current impact, obtain the actual short-circuit current of the high-voltage side, medium-voltage side and low-voltage side of the transformer, and extract the largest of the actual short-circuit currents of the high-voltage side, medium-voltage side and low-voltage side of the transformer, and output it as the final actual short-circuit current.

[0007] S2. Based on the transformer's rated capacity, high-to-low impedance voltage, low-voltage side rated current, high-voltage side rated capacity, and low-voltage side rated capacity, and combined with the system short-circuit apparent capacity of the high-voltage side, medium-voltage side, and low-voltage side of the transformer, the allowable short-circuit current of the high-voltage side, medium-voltage side, and low-voltage side of the transformer is obtained. Furthermore, the largest allowable short-circuit current among the high-voltage side, medium-voltage side, and low-voltage side of the transformer is extracted, and the output is the final allowable short-circuit current.

[0008] S3. Determine the current near-circuit short-circuit situation, and based on the current near-circuit short-circuit situation, as well as the final actual short-circuit current, the final allowable short-circuit current, or the rated current of the main transformer, formulate corresponding test items to detect transformer damage; wherein, the current near-circuit short-circuit situation is a near-circuit short-circuit that occurs when the low-voltage side of the transformer trips while the high-voltage side and medium-voltage side maintain normal operation, or a near-circuit short-circuit that occurs when the low-voltage side of the transformer short-circuits and the high-voltage side and medium-voltage side trip.

[0009] The short-circuit current impact on the main transformer is determined based on the main transformer fault tripping or through the through current.

[0010] The actual short-circuit currents on the high-voltage side, medium-voltage side, and low-voltage side of the transformer are obtained by extracting them from the fault recording files and startup recording files on the high-voltage side, medium-voltage side, and low-voltage side of the transformer.

[0011] Among them, through the formula Calculate the allowable short-circuit currents on the high-voltage side, medium-voltage side, and low-voltage side of the transformer, respectively; where,

[0012] I2 represents the allowable short-circuit current for any one of the high-voltage, medium-voltage, and low-voltage sides of the corresponding transformer; S N This is the rated capacity of the transformer, which is a fixed value; S 短 The apparent capacity for a system short circuit corresponding to any one of the high-voltage, medium-voltage, and low-voltage sides of the transformer is a fixed value; U K % represents the high-to-low impedance voltage of the transformer, which is a fixed value; I 低压额 This is the rated current on the low-voltage side of the transformer, which is a fixed value; S 高压侧 This is the rated capacity of the high-voltage side of the transformer, which is a fixed value; S 低压侧 This is the rated capacity of the low-voltage side of the transformer, which is a fixed value.

[0013] Specifically, step S3 includes:

[0014] If the current near-circuit short circuit occurs when the low-voltage side of the transformer trips while the high-voltage and medium-voltage sides maintain normal operation, then the short-circuit current ratio is calculated based on the final actual short-circuit current and the final allowable short-circuit current. When the short-circuit current ratio is greater than or equal to a first threshold, a first test item is established to detect transformer damage. The first test item includes winding deformation test under transformer de-energized conditions, transformer preventive test, oil chromatography analysis, and gas chromatography analysis of gas relays.

[0015] The method further includes:

[0016] When the short-circuit current ratio is less than the first threshold and greater than or equal to the second threshold, a first fixed integral is assigned, and a first total integral is calculated by combining the number of times the short-circuit impact time exceeds the first predetermined time threshold; or, when the short-circuit current ratio is less than the second threshold and greater than the third threshold, a second fixed integral is assigned, and a second total integral is calculated by combining the number of times the short-circuit impact time exceeds the second predetermined time threshold; or, when the short-circuit current ratio is less than the third threshold, a third fixed integral is assigned, and a third total integral is calculated by combining the number of times the short-circuit impact time exceeds the third predetermined time threshold.

[0017] If any one of the first total integral, the second total integral, and the third total integral is greater than a preset integral threshold, then the first test item will be used to detect transformer damage.

[0018] The method further includes:

[0019] When the time interval between the completion of the first test item and the completion of the first test item is no more than one month, a second test item is formulated to detect the damage of the transformer; wherein, the second test item is only to perform online oil chromatography analysis, core grounding current test and oil temperature monitoring on the transformer.

[0020] Step S3 further includes:

[0021] If the current near-circuit short circuit occurs when the transformer experiences a short circuit on the low-voltage side and trips on the high-voltage and medium-voltage sides, the final actual short-circuit current will be compared with the rated current of the main transformer. If the final actual short-circuit current is greater than or equal to the rated current of the main transformer, a third test item will be developed to detect transformer damage. The third test item includes online winding deformation testing, oil chromatography analysis, and gas chromatography analysis using a gas relay.

[0022] The method further includes:

[0023] When the final actual short-circuit current is found to be less than the rated current of the main transformer, a fourth test item is established to detect transformer damage; the fourth test item only involves online winding deformation test, oil chromatography analysis, and gas chromatography analysis of gas relays on the transformer.

[0024] This invention also provides a system for detecting damage to a main transformer caused by a short-circuit current surge, comprising:

[0025] The final actual short-circuit current acquisition unit is used to acquire the actual short-circuit current on the high-voltage side, medium-voltage side and low-voltage side of the transformer when the main transformer is subjected to short-circuit current impact, and extract the largest of the actual short-circuit currents on the high-voltage side, medium-voltage side and low-voltage side of the transformer, and output it as the final actual short-circuit current.

[0026] The final allowable short-circuit current acquisition unit is used to obtain the allowable short-circuit current of the transformer high-voltage side, medium-voltage side, and low-voltage side based on the transformer rated capacity, transformer high-to-low impedance voltage, transformer low-voltage side rated current, transformer high-voltage side rated capacity, and transformer low-voltage side rated capacity, and in combination with the system short-circuit apparent capacity of the transformer high-voltage side, medium-voltage side, and low-voltage side. It further extracts the largest allowable short-circuit current among the transformer high-voltage side, medium-voltage side, and low-voltage side, and outputs it as the final allowable short-circuit current.

[0027] The transformer damage test formulation unit is used to determine the current near-zone short circuit situation and, based on the current near-zone short circuit situation, and in conjunction with the final actual short-circuit current, the final allowable short-circuit current, or the rated current of the main transformer, formulate corresponding test items to detect transformer damage. The current near-zone short circuit situation refers to a near-zone short circuit that occurs when the low-voltage side of the transformer trips while the high-voltage and medium-voltage sides maintain normal operation, or a near-zone short circuit that occurs when the low-voltage side of the transformer shorts and the high-voltage and medium-voltage sides trip.

[0028] Implementing the embodiments of the present invention has the following beneficial effects:

[0029] This invention obtains the final actual short-circuit current by measuring the actual short-circuit current on the high, medium, and low voltage sides of the transformer when the main transformer is subjected to a short-circuit current impact. Based on the current near-zone short-circuit situation and the allowable short-circuit current on the high, medium, and low voltage sides of the transformer, the final allowable short-circuit current or the rated current of the main transformer is selected. Corresponding test items are formulated to detect transformer damage. This not only reflects the short-circuit current impact situation more efficiently, accurately, and in real time, thus overcoming the problems of low efficiency and error-proneness of manual analysis, but also assesses the health status of the transformer by formulating a series of test items. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0031] Figure 1 A flowchart of a method for detecting damage to a main transformer caused by a short-circuit current impulse, provided by an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of a system for detecting damage to a main transformer caused by a short-circuit current surge, provided as an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] like Figure 1 As shown in the figure, this invention provides a method for detecting damage to a main transformer caused by a short-circuit current surge. The method includes the following steps:

[0035] Step S1: When the main transformer is subjected to short-circuit current impact, obtain the actual short-circuit current of the high-voltage side, medium-voltage side and low-voltage side of the transformer, and extract the largest of the actual short-circuit currents of the high-voltage side, medium-voltage side and low-voltage side of the transformer, and output it as the final actual short-circuit current.

[0036] The specific process is as follows: First, the main transformer is assessed for short-circuit current impact based on fault tripping or through-current. Second, when the main transformer is impacted by a short-circuit current, the actual short-circuit currents on the high-voltage, medium-voltage, and low-voltage sides of the transformer are extracted from the fault recording files and startup recording files on the high-voltage, medium-voltage, and low-voltage sides, respectively. Finally, an RPA robot automatically reads the aforementioned waveform files along a specified path and imports the waveform data into an Excel spreadsheet for automatic calculation. Through waveform analysis, the maximum value among the actual short-circuit currents on the high-voltage, medium-voltage, and low-voltage sides of the transformer is extracted and output as the final actual short-circuit current.

[0037] Step S2: Based on the transformer's rated capacity, high-to-low impedance voltage, low-voltage side rated current, high-voltage side rated capacity, and low-voltage side rated capacity, and combined with the system short-circuit apparent capacity of the high-voltage side, medium-voltage side, and low-voltage side of the transformer, the allowable short-circuit current of the high-voltage side, medium-voltage side, and low-voltage side of the transformer is obtained. Furthermore, the largest allowable short-circuit current among the high-voltage side, medium-voltage side, and low-voltage side of the transformer is extracted, and the output is the final allowable short-circuit current.

[0038] The specific process is as follows: First, determine the apparent short-circuit capacity S of the system on any one of the high-voltage side, medium-voltage side, and low-voltage side of the corresponding transformer. 短 These are all fixed values. For example, the low-voltage side (110kV) is 9000MVA, the medium-voltage side (220kV) is 18000MVA, and the high-voltage side (500kV) is 60000MVA. Secondly, through the formula... Calculate the allowable short-circuit currents on the high-voltage side, medium-voltage side, and low-voltage side of the transformer respectively; where I2 is the allowable short-circuit current on any one of the high-voltage side, medium-voltage side, and low-voltage side of the transformer; S N U is the rated capacity of the transformer, which is a fixed value; K % represents the high-to-low impedance voltage of the transformer, which is a fixed value; I 低压额 This is the rated current on the low-voltage side of the transformer, which is a fixed value; S 高压侧This is the rated capacity of the high-voltage side of the transformer, which is a fixed value; S 低压侧 This is the rated capacity of the low-voltage side of the transformer, which is a fixed value. Finally, the maximum value is extracted from the allowable short-circuit currents calculated by the above formulas for the high-voltage, medium-voltage, and low-voltage sides of the transformer, and output as the final allowable short-circuit current.

[0039] Step S3: Determine the current near-circuit short-circuit situation, and based on the current near-circuit short-circuit situation, as well as the final actual short-circuit current, the final allowable short-circuit current, or the rated current of the main transformer, formulate corresponding test items to detect transformer damage; wherein, the current near-circuit short-circuit situation is a near-circuit short-circuit that occurs when the low-voltage side of the transformer trips while the high-voltage side and medium-voltage side maintain normal operation, or a near-circuit short-circuit that occurs when the low-voltage side of the transformer shorts and the high-voltage side and medium-voltage side trip.

[0040] The specific process is as follows: First, the near-zone short circuit situation includes the following two situations: (i) a near-zone short circuit occurs when the low-voltage side of the transformer trips while the high-voltage side and the medium-voltage side maintain normal operation; (ii) a near-zone short circuit occurs when the low-voltage side of the transformer shorts and the high-voltage side and the medium-voltage side trip.

[0041] Secondly, based on the two situations mentioned above, we will analyze them separately and specify corresponding test items to detect transformer damage. The specific process is as follows:

[0042] First, in the first scenario, the short-circuit current ratio is calculated based on the final actual short-circuit current and the final allowable short-circuit current (e.g., using the formula...). (To calculate), and when the short-circuit current ratio is greater than or equal to the first threshold (e.g., 65%), the first test item is established to detect transformer damage; the first test item includes, but is not limited to, winding deformation test under transformer de-energized condition, transformer preventive test, oil chromatography analysis and gas chromatography analysis of gas relay, etc.

[0043] For example, when M > 65%, the transformer is completely de-energized, and the first test item is used to detect the damage to the transformer.

[0044] In addition, considering the different short-circuit current ratios that transformers can withstand, corresponding scores are recorded according to Table 1 below. When the total score exceeds the preset score threshold (e.g., 10 points), the above-mentioned first test item will also be used to detect the transformer damage. After the test is passed, the score is cleared to zero.

[0045] Table 1

[0046]

[0047] Therefore, based on Table 1, it is considered to set the first threshold at 65%, the second threshold at 50%, and the third threshold at 20%. In the first case, the following methods are also included:

[0048] (1.1) When the short - circuit current ratio M is less than the first threshold of 65% and greater than or equal to the second threshold of 50%, a first fixed integral (such as 4 points) is assigned, and combined with the number of times (such as N1) that the short - circuit impact time exceeds the first predetermined time threshold (such as 0.5S), the first total integral is calculated. For example, when 50% ≤ M < 65%, the first total integral = the first fixed integral * the number of times = 4 * N1;

[0049] When the first total integral is greater than the preset integral threshold (such as 10 points), the above - mentioned first test item is used to detect the damage condition of the transformer. That is, if it is determined that 4 * N1 > 10, a complete power outage of the transformer is carried out, and the first test item is used to detect the damage condition of the transformer.

[0050] (1.2) When the short - circuit current ratio M is less than the second threshold of 50% and greater than the third threshold of 20%, a second fixed integral (such as 2 points) is assigned, and combined with the number of times (such as N2) that the short - circuit impact time exceeds the second predetermined time threshold (such as 0.5S), the second total integral is calculated. For example, when 20% < M < 50%, the second total integral = the second fixed integral * the number of times = 2 * N2;

[0051] When the second total integral is greater than the preset integral threshold (such as 10 points), the above - mentioned first test item is used to detect the damage condition of the transformer. That is, if it is determined that 2 * N2 > 10, a complete power outage of the transformer is carried out, and the first test item is used to detect the damage condition of the transformer.

[0052] (1.3) When the short - circuit current ratio M is less than the third threshold of 20%, a third fixed integral (such as 1 point) is assigned, and combined with the number of times (such as N3) that the short - circuit impact time exceeds the third predetermined time threshold (such as 0.5S), the third total integral is calculated. For example, when M ≤ 20%, the third total integral = the third fixed integral * the number of times = 1 * N3;

[0053] When the third total integral is greater than the preset integral threshold (such as 10 points), the above - mentioned first test item is used to detect the damage condition of the transformer. That is, if it is determined that 1 * N3 > 10, a complete power outage of the transformer is carried out, and the first test item is used to detect the damage condition of the transformer.

[0054] It can be understood that after the transformer is powered off for test inspection, even if the inspection test is qualified, online chromatographic tracking analysis (only for transformers equipped with online oil chromatographic monitoring devices), core grounding current testing, and oil temperature monitoring should be carried out within one month after being put into operation.

[0055] Therefore, the method further includes: when the time interval between the completion of the first test item is no more than one month, a second test item is formulated to detect transformer damage; wherein, the second test item is only to perform online oil chromatography analysis, core grounding current test and oil temperature monitoring on the transformer.

[0056] Secondly, in the second scenario, the final actual short-circuit current is compared with the rated current of the main transformer, and based on the comparison results, different test items are developed to detect transformer damage:

[0057] (2.1) When the final actual short-circuit current is found to be greater than or equal to the rated current of the main transformer, a third test item is formulated to detect the damage of the transformer; the third test item includes online winding deformation test, oil chromatography analysis and gas chromatography analysis of gas relay.

[0058] (2.2) When the final actual short-circuit current is found to be less than the rated current of the main transformer, a fourth test item is formulated to detect the damage of the transformer; among them, the fourth test item is only to conduct online winding deformation test, oil chromatography analysis and gas chromatography analysis of gas relay on the transformer.

[0059] It should be noted that the rated current of the main transformer is a fixed value set at the time of manufacture.

[0060] like Figure 2 As shown in the figure, a system for detecting damage to a main transformer caused by a short-circuit current surge is provided in an embodiment of the present invention, comprising:

[0061] The final actual short-circuit current acquisition unit 110 is used to acquire the actual short-circuit current of the high-voltage side, medium-voltage side and low-voltage side of the transformer when the main transformer is subjected to short-circuit current impact, and extract the largest of the actual short-circuit currents of the high-voltage side, medium-voltage side and low-voltage side of the transformer, and output it as the final actual short-circuit current.

[0062] The final allowable short-circuit current acquisition unit 120 is used to obtain the allowable short-circuit current of the transformer high-voltage side, medium-voltage side, and low-voltage side based on the transformer rated capacity, transformer high-to-low impedance voltage, transformer low-voltage side rated current, transformer high-voltage side rated capacity, and transformer low-voltage side rated capacity, and in combination with the system short-circuit apparent capacity of the transformer high-voltage side, medium-voltage side, and low-voltage side. Furthermore, it extracts the largest allowable short-circuit current among the transformer high-voltage side, medium-voltage side, and low-voltage side, and outputs it as the final allowable short-circuit current.

[0063] The transformer damage test formulation unit 120 is used to determine the current near-zone short circuit situation and, based on the current near-zone short circuit situation, and in conjunction with the final actual short circuit current, the final allowable short circuit current, or the rated current of the main transformer, formulate corresponding test items to detect transformer damage. The current near-zone short circuit situation is a near-zone short circuit that occurs when the low-voltage side of the transformer trips while the high-voltage and medium-voltage sides maintain normal operation, or a near-zone short circuit that occurs when the low-voltage side of the transformer shorts and the high-voltage and medium-voltage sides trip.

[0064] Implementing the embodiments of the present invention has the following beneficial effects:

[0065] This invention obtains the final actual short-circuit current by measuring the actual short-circuit current on the high, medium, and low voltage sides of the transformer when the main transformer is subjected to a short-circuit current impact. Based on the current near-zone short-circuit situation and the allowable short-circuit current on the high, medium, and low voltage sides of the transformer, the final allowable short-circuit current or the rated current of the main transformer is selected. Corresponding test items are formulated to detect transformer damage. This not only reflects the short-circuit current impact situation more efficiently, accurately, and in real time, thus overcoming the problems of low efficiency and error-proneness of manual analysis, but also assesses the health status of the transformer by formulating a series of test items.

[0066] It is worth noting that the system modules included in the above system embodiments are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional module are only for easy differentiation and are not used to limit the scope of protection of the present invention.

[0067] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, optical disk, etc.

[0068] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for detecting damage to a main transformer by a short circuit current impulse, characterized by, The method comprises the following steps: S1, obtaining actual short-circuit currents of a high-voltage side, a medium-voltage side and a low-voltage side of a transformer under a short-circuit current impact of a main transformer, and extracting the maximum of the actual short-circuit currents of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer to output a final actual short-circuit current; S2, obtaining allowable short-circuit currents of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer based on a rated capacity of the transformer, a high-to-low impedance voltage of the transformer, a rated current of the low-voltage side of the transformer, a rated capacity of the high-voltage side of the transformer and a rated capacity of the low-voltage side of the transformer, and combining system short-circuit apparent capacities of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, and further extracting the maximum of the allowable short-circuit currents of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer to output a final allowable short-circuit current; S3, determining a current near-zone short-circuit situation, and formulating corresponding test items to detect a transformer damage condition according to the current near-zone short-circuit situation and in combination with the final actual short-circuit current, the final allowable short-circuit current or a rated current of the main transformer; wherein the current near-zone short-circuit situation is a near-zone short-circuit occurring when a low-voltage side of the transformer trips and a high-voltage side and a medium-voltage side of the transformer maintain normal operation, or a near-zone short-circuit occurring when the low-voltage side of the transformer trips and the high-voltage side and the medium-voltage side of the transformer trip.

2. The method of claim 1, wherein the method comprises: The short-circuit current impact of the main transformer is obtained based on a fault trip of the main transformer or a through current.

3. The method for detecting damage to the main transformer caused by short-circuit current impulse as described in claim 1, characterized in that, The actual short-circuit currents of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer are obtained by extracting from fault recording files and start recording files of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer.

4. The method of claim 1, wherein the method comprises: The step S3 specifically comprises: If the current near-zone short-circuit situation is the near-zone short-circuit occurring when the low-voltage side of the transformer trips and the high-voltage side and the medium-voltage side of the transformer maintain normal operation, a short-circuit current ratio is calculated according to the final actual short-circuit current and the final allowable short-circuit current, and a first test item is formulated to detect the transformer damage condition when the short-circuit current ratio is greater than or equal to a first threshold value; wherein the first test item comprises a winding deformation test under a transformer power-off state, a transformer preventive test, oil chromatographic analysis and gas chromatographic analysis of a gas relay.

5. The method of claim 4, wherein the step of detecting the short circuit current impulse damage to the main transformer comprises the steps of: determining the short circuit current impulse damage to the main transformer based on the comparison of the measured current and the calculated current. 5 The method further comprises: when the short-circuit current ratio is less than the first threshold value and greater than or equal to a second threshold value, a first fixed integral is assigned, and a first total integral is counted in combination with a number of times that a short-circuit impact time exceeds a first predetermined time threshold value; or, when the short-circuit current ratio is less than the second threshold value and greater than a third threshold value, a second fixed integral is assigned, and a second total integral is counted in combination with a number of times that the short-circuit impact time exceeds a second predetermined time threshold value; or, when the short-circuit current ratio is less than the third threshold value, a third fixed integral is assigned, and a third total integral is counted in combination with a number of times that the short-circuit impact time exceeds a third predetermined time threshold value; If any one of the first total integral, the second total integral and the third total integral is greater than a preset integral threshold value, the first test item is used to detect the transformer damage condition.

6. The method of claim 5, wherein the short-circuit current impulse is detected by measuring a voltage across the main transformer. The method further comprises: When the time interval of the first test project is not more than one month, a second test project is formulated to detect the transformer damage condition; wherein the second test project is only online oil chromatographic analysis, core grounding current test and oil temperature monitoring of the transformer.

7. The method of claim 1, wherein the step of detecting the short circuit current impulse damage to the main transformer comprises: determining a ratio of the short circuit current to a rated current of the main transformer; and comparing the ratio to a threshold value. The step S3 further comprises: If the current near-zone short-circuit situation is a near-zone short-circuit when the transformer low-voltage side trips and the high-voltage side and the medium-voltage side trip, the final actual short-circuit current is compared with the main transformer rated current, and when the final actual short-circuit current is greater than or equal to the main transformer rated current, a third test project is formulated to detect the transformer damage condition; wherein the third test project comprises online winding deformation test, oil chromatographic analysis and gas chromatographic analysis of the gas relay of the transformer.

8. The method for detecting damage to the main transformer caused by short-circuit current impulse as described in claim 7, characterized in that, The method further comprises: When the final actual short-circuit current is less than the main transformer rated current, a fourth test project is formulated to detect the transformer damage condition; wherein the fourth test project is only online winding deformation test, oil chromatographic analysis and gas chromatographic analysis of the gas relay of the transformer.

9. A system for detecting damage to a main transformer caused by a short-circuit current surge, characterized in that, Comprise: A final actual short-circuit current acquisition unit is configured to acquire the actual short-circuit current of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer when the main transformer is impacted by the short-circuit current, and extract the maximum of the actual short-circuit current of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, and output as the final actual short-circuit current; A final allowable short-circuit current acquisition unit is configured to obtain the allowable short-circuit current of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer based on the rated capacity of the transformer, the high-to-low impedance voltage of the transformer, the rated current of the low-voltage side of the transformer, the rated capacity of the high-voltage side of the transformer and the rated capacity of the low-voltage side of the transformer, and in combination with the system short-circuit apparent capacity of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, and further extract the maximum of the allowable short-circuit current of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, and output as the final allowable short-circuit current; A transformer damage test formulation unit is configured to determine the current near-zone short-circuit situation, and formulate a corresponding test project to detect the transformer damage condition according to the current near-zone short-circuit situation, in combination with the final actual short-circuit current, the final allowable short-circuit current or the main transformer rated current; wherein the current near-zone short-circuit situation is a near-zone short-circuit when the low-voltage side of the transformer trips and the high-voltage side and the medium-voltage side maintain normal operation, or a near-zone short-circuit when the low-voltage side of the transformer short-circuits and the high-voltage side and the medium-voltage side trip.

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