Method and system for detecting main transformer damage caused by short-circuit current impact

Abstract

The invention provides a method for detecting damage of short-circuit current impact to a main transformer, which comprises the following steps: when the main transformer is impacted by short-circuit current, acquiring actual short-circuit current of high, medium and low voltage sides of a transformer, and extracting the maximum current as the final actual short-circuit current; 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, in combination with the system short-circuit apparent capacities of the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, allowed short-circuit currents of the high-voltage side, the medium-voltage side and the low-voltage side of the maximum current is extracted as the final allowable short-circuit current; and determining the current short-circuit condition of the near area, and formulating a test item to detect the damage condition of the transformer in combination with the final actual short-circuit current and the final allowable short-circuit current or the rated current of the main transformer. By implementing the method, the problems that manual analysis is low in efficiency and easy to make mistakes can be solved, and the health condition of the transformer can be evaluated by formulating a series of test items.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method and system for detecting damage to a main transformer caused by a short-circuit current impact. Background Art

[0002] At present, traditional short-circuit current analysis mainly relies on manual operation, which is not only inefficient but also prone to errors. It is often difficult to accurately reflect the actual situation of the main transformer under the impact of short-circuit current in real time. In addition, traditional short-circuit current analysis does not carry out a series of detailed tests to evaluate its health status.

[0003] Therefore, under the development trend of automation and intelligence of power systems, there is an urgent need for a more efficient, accurate and real-time analysis method for short-circuit current impact conditions, which can not only overcome the problems of low efficiency and easy errors in manual analysis, but also evaluate the health status of transformers by formulating 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 damage to a main transformer caused by a short-circuit current impact, which can not only overcome the problem of low efficiency and easy errors in manual analysis, but also evaluate the health status of the transformer by formulating a series of test items.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a method for detecting damage to a main transformer caused by a short-circuit current impact, the method comprising the following steps:

[0006] S1. When the main transformer is impacted by a short-circuit current, the actual short-circuit currents on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer are obtained, and the largest actual short-circuit current among the actual short-circuit currents on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer is extracted, and the output is the final actual short-circuit current;

[0007] S2. 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, 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, and the maximum allowable short-circuit current among the allowable short-circuit currents of the high-voltage side, medium-voltage side and low-voltage side of the transformer is further extracted, and the final allowable short-circuit current is output;

[0008] S3. Determine the current near-zone short-circuit situation, and formulate corresponding test items to detect transformer damage based on the current near-zone 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; wherein 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 side and the medium-voltage side maintain normal operation, or a near-zone short-circuit that occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side trip.

[0009] The main transformer being impacted by the short-circuit current is determined based on the tripping of the main transformer fault 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 extracted 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 current on the high-voltage side, medium-voltage side and low-voltage side of the transformer respectively;

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

[0013] Wherein, the step S3 specifically includes:

[0014] If the current local short-circuit situation is a local short-circuit that occurs when the low-voltage side of the transformer trips while the high-voltage side and the medium-voltage side maintain normal operation, the short-circuit current ratio is calculated based on the final actual short-circuit current and the final allowable short-circuit current, and when the short-circuit current ratio is greater than or equal to a first threshold, a first test item is formulated to detect transformer damage; wherein the first test item includes a winding deformation test under a transformer power-off state, a transformer preventive test, an oil chromatography analysis, and a gas chromatography analysis of a gas relay.

[0015] Wherein, the method further comprises:

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

[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, the first test item is used to detect transformer damage.

[0018] Wherein, the method further comprises:

[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 oil chromatography analysis, core grounding current test and oil temperature monitoring on the transformer online.

[0020] Wherein, the step S3 further includes:

[0021] If the current local short-circuit situation is a local short-circuit that occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side are tripped, the final actual short-circuit current is compared with the rated current of the main transformer, and 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 transformer damage; wherein the third test item includes online transformer winding deformation test, oil chromatography analysis, and gas chromatography analysis of the gas relay.

[0022] Wherein, the method further comprises:

[0023] When it is found that the final actual short-circuit current is less than the rated current of the main transformer, a fourth test item is formulated to detect the damage of the transformer; wherein, the fourth test item is only to perform online winding deformation test, oil chromatography analysis and gas chromatography analysis of the gas relay on the transformer.

[0024] The embodiment of the present invention further provides a system for detecting damage to a main transformer caused by a short-circuit current impact, comprising:

[0025] The final actual short-circuit current acquisition unit is used to obtain the actual short-circuit currents on 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 largest actual short-circuit current among the actual short-circuit currents on the high-voltage side, the medium-voltage side and the 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 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 largest allowable short-circuit current among the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, and output 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 formulate corresponding test items to detect the transformer damage according to the current near-zone 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; wherein 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 side and the medium-voltage side maintain normal operation, or a near-zone short-circuit that occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side are tripped.

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

[0029] The present invention obtains the final actual short-circuit current through the actual short-circuit current on the high, medium and low voltage sides of the transformer when the main transformer is impacted by the short-circuit current, and selects the final allowable short-circuit current or the rated current of the main transformer according to the current short-circuit situation in the nearby area and the allowable short-circuit current on the high, medium and low voltage sides of the transformer, and formulates corresponding test items to detect the damage of the transformer. It can not only reflect the short-circuit current impact situation more efficiently, accurately and in real time, thereby overcoming the problems of low efficiency and easy error of manual analysis, but also can evaluate the health status of the transformer by formulating a series of test items. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

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

[0032] Figure 2 A schematic structural diagram of a system for detecting damage to a main transformer caused by a short-circuit current impact provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clear, 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, a method for detecting damage to a main transformer caused by a short-circuit current impact is provided in an embodiment of the present invention, and the method comprises the following steps:

[0035] Step S1, when the main transformer is impacted by a short-circuit current, the actual short-circuit currents on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer are obtained, and the largest of the actual short-circuit currents on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer is extracted, and the final actual short-circuit current is output;

[0036] The specific process is as follows: first, the main transformer is judged to be impacted by short-circuit current based on the main transformer fault tripping or through the through current. Secondly, when the main transformer is impacted by short-circuit current, the actual short-circuit current of the high-voltage side, medium-voltage side and low-voltage side of the transformer is extracted from the fault recording files and startup recording files on the high-voltage side, medium-voltage side and low-voltage side of the transformer. Finally, the RPA robot is used to automatically read the above waveform files of the specified path, and the waveform data is imported into the Excel table for automatic calculation. By analyzing the waveform, the maximum value of the actual short-circuit current of the high-voltage side, medium-voltage side and low-voltage side of the transformer is extracted and output as the final actual short-circuit current.

[0037] Step S2, 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 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, and the maximum allowable short-circuit current among the allowable short-circuit currents of the high-voltage side, medium-voltage side and low-voltage side of the transformer is further extracted, and the final allowable short-circuit current is output;

[0038] The specific process is as follows: first, determine the system short-circuit apparent capacity S corresponding to any one of the high-voltage side, medium-voltage side and low-voltage side of the transformer 短 , are 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 current of the high-voltage side, medium-voltage side and low-voltage side of the transformer respectively; where I2 is the allowable short-circuit current of any one of the high-voltage side, medium-voltage side and low-voltage side of the transformer; S N is the rated capacity of the transformer, which is a fixed value; U K % is the transformer high to low impedance voltage, which is a fixed value; I 低压额 is the rated current of the transformer low voltage side, which is a fixed value; S 高压侧is the rated capacity of the high-voltage side of the transformer, which is a fixed value; S 低压侧 is the rated capacity of the low-voltage side of the transformer, which is a fixed value. Finally, among the allowable short-circuit currents of the high-voltage side, medium-voltage side and low-voltage side of the transformer calculated by the above formula, the maximum value is extracted and output as the final allowable short-circuit current.

[0039] Step S3, determine the current near-zone short-circuit situation, and formulate corresponding test items to detect transformer damage based on the current near-zone 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; wherein 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 side and the medium-voltage side maintain normal operation, or a near-zone short-circuit that occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side trip.

[0040] The specific process is that, first, the local short-circuit situation includes the following two situations: (1) the local 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; (2) the local short-circuit occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side trip.

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

[0042] First, in the first case, the short-circuit current ratio is calculated based on the final actual short-circuit current and the final allowable short-circuit current (e.g., by the formula to calculate), and when the short-circuit current ratio is greater than or equal to a first threshold value (such as 65%), a first test item is formulated to detect transformer damage; wherein the first test item includes but is not limited to a winding deformation test under a transformer power-off state, a transformer preventive test, oil chromatography analysis, and a gas chromatography analysis of a gas relay, etc.

[0043] For example, when it is determined that M>65%, the transformer is completely powered off, and the first test item is used to detect transformer damage.

[0044] In addition, taking into account the different short-circuit current ratios that the transformer can withstand, the corresponding scores are recorded according to the provisions of Table 1 below, and when the total score exceeds the preset score threshold (such as 10 points), the above-mentioned first test item will also be used to detect the damage of the transformer, and after the test is passed, the score is reset to zero.

[0045] Table 1

[0046]

[0047] Therefore, based on Table 1, it is possible to consider setting 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 in combination 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 in combination 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 in combination 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, formulating a second test item to detect the damage of the transformer; wherein the second test item is only to perform oil chromatography analysis, core grounding current test and oil temperature monitoring on the transformer online.

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

[0057] (2.1) When the final actual short-circuit current is compared to be ≥ 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 transformer winding deformation test, oil chromatography analysis and gas chromatography analysis of the gas relay.

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

[0059] It should be noted that the rated current of the main transformer is a fixed value set when the transformer leaves the factory.

[0060] like Figure 2 As shown in the figure, a system for detecting damage to a main transformer caused by a short-circuit current impact 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 currents on 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 largest of the actual short-circuit currents on the high-voltage side, the medium-voltage side and the 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 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 allowable short-circuit current among the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, and output 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 formulate corresponding test items to detect the transformer damage according to the current near-zone 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; wherein 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 side and the medium-voltage side maintain normal operation, or a near-zone short-circuit that occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side trip.

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

[0065] The present invention obtains the final actual short-circuit current through the actual short-circuit current on the high, medium and low voltage sides of the transformer when the main transformer is impacted by the short-circuit current, and selects the final allowable short-circuit current or the rated current of the main transformer according to the current short-circuit situation in the nearby area and the allowable short-circuit current on the high, medium and low voltage sides of the transformer, and formulates corresponding test items to detect the damage of the transformer. It can not only reflect the short-circuit current impact situation more efficiently, accurately and in real time, thereby overcoming the problems of low efficiency and easy error of manual analysis, but also can evaluate the health status of the transformer by formulating a series of test items.

[0066] It is worth noting that in the above system embodiment, the various system modules included 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 the various functional modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0067] A person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, CD-ROM, etc.

[0068] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to 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 caused by a short-circuit current impact, characterized in that: The method comprises the following steps: S1. When the main transformer is impacted by a short-circuit current, the actual short-circuit currents on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer are obtained, and the largest actual short-circuit current among the actual short-circuit currents on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer is extracted, and the output is the final actual short-circuit current; S2. 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, 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, and the maximum allowable short-circuit current among the allowable short-circuit currents of the high-voltage side, medium-voltage side and low-voltage side of the transformer is further extracted, and the final allowable short-circuit current is output; S3. Determine the current near-zone short-circuit situation, and formulate corresponding test items to detect transformer damage based on the current near-zone 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; wherein 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 side and the medium-voltage side maintain normal operation, or a near-zone short-circuit that occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side trip.

2. The method for detecting damage to a main transformer caused by a short-circuit current impact as claimed in claim 1, characterized in that: The main transformer is impacted by the short-circuit current based on the tripping of the main transformer fault or the through current.

3. The method for detecting damage to a main transformer caused by a short-circuit current shock as claimed in claim 1, characterized in that: The actual short-circuit currents on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer are obtained by extracting the fault recording files and the startup recording files on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer.

4. The method for detecting damage to a main transformer caused by a short-circuit current shock as claimed in claim 1, characterized in that: By formula Calculate the allowable short-circuit current on the high-voltage side, medium-voltage side and low-voltage side of the transformer respectively; I2 is the allowable short-circuit current of any one of the high-voltage side, medium-voltage side and low-voltage side of the corresponding transformer; S N is the rated capacity of the transformer, which is a fixed value; S 短 is the system short-circuit apparent capacity corresponding to any one of the high-voltage side, medium-voltage side and low-voltage side of the transformer, all of which are fixed values; U K % is the transformer high to low impedance voltage, which is a fixed value; S 低压额 is the rated current of the transformer low voltage side, which is a fixed value; S 高压侧 is the rated capacity of the high-voltage side of the transformer, which is a fixed value; S 低压侧 is the rated capacity of the low-voltage side of the transformer, which is a fixed value.

5. The method for detecting damage to a main transformer caused by a short-circuit current shock as claimed in claim 1, characterized in that: The step S3 specifically includes: If the current local short-circuit situation is a local short-circuit that occurs when the low-voltage side of the transformer trips while the high-voltage side and the medium-voltage side maintain normal operation, the short-circuit current ratio is calculated based on the final actual short-circuit current and the final allowable short-circuit current, and when the short-circuit current ratio is greater than or equal to a first threshold, a first test item is formulated to detect transformer damage; wherein the first test item includes a winding deformation test under a transformer power-off state, a transformer preventive test, an oil chromatography analysis, and a gas chromatography analysis of a gas relay.

6. The method for detecting damage to a main transformer caused by a short-circuit current shock as claimed in claim 5, characterized in that: The method further comprises: When the short-circuit current ratio is less than the first threshold value and greater than or equal to the second threshold value, a first fixed integral is assigned, and a first total integral is calculated in combination with the number of times the short-circuit impact time exceeds the 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 calculated in combination with the number of times the short-circuit impact time exceeds the 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 calculated in combination with the number of times the short-circuit impact time exceeds the 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, the first test item is used to detect transformer damage.

7. The method for detecting damage to a main transformer caused by a short-circuit current shock as claimed in claim 6, characterized in that: The method further comprises: 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 oil chromatography analysis, core grounding current test and oil temperature monitoring on the transformer online.

8. The method for detecting damage to a main transformer caused by a short-circuit current shock as claimed in claim 1, characterized in that: The step S3 further comprises: If the current local short-circuit situation is a local short-circuit that occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side are tripped, the final actual short-circuit current is compared with the rated current of the main transformer, and 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 transformer damage; wherein the third test item includes online transformer winding deformation test, oil chromatography analysis, and gas chromatography analysis of the gas relay.

9. The method for detecting damage to a main transformer caused by a short-circuit current impact as claimed in claim 8, characterized in that: The method further comprises: When it is found that the final actual short-circuit current is less than the rated current of the main transformer, a fourth test item is formulated to detect the damage of the transformer; wherein, the fourth test item is only to perform online winding deformation test, oil chromatography analysis and gas chromatography analysis of the gas relay on the transformer.

10. A system for detecting damage to a main transformer caused by a short-circuit current shock, characterized in that: include: The final actual short-circuit current acquisition unit is used to obtain the actual short-circuit currents on 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 largest actual short-circuit current among the actual short-circuit currents on the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, and output it as the final actual short-circuit current; The final allowable short-circuit current acquisition unit is used 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 largest allowable short-circuit current among the high-voltage side, the medium-voltage side and the low-voltage side of the transformer, and output it as the final allowable short-circuit current; The transformer damage test formulation unit is used to determine the current near-zone short-circuit situation, and formulate corresponding test items to detect the transformer damage according to the current near-zone 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; wherein 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 side and the medium-voltage side maintain normal operation, or a near-zone short-circuit that occurs when the low-voltage side of the transformer is short-circuited and the high-voltage side and the medium-voltage side are tripped.

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