A transformer turn-to-turn short circuit detection system and method based on multiple parameters

Abstract

The present invention relates to the field of electrical equipment detection and discloses a transformer inter-turn short circuit detection system and method based on multiple parameters. The detection system includes: a vibration measurement section, a leakage magnetic field measurement section, and a result analysis section. Based on the difference in vibration and leakage magnetic field between the transformer inter-turn short circuit and normal operation, the vibration measurement device and the leakage magnetic field measurement device are sequentially opened to determine the transformer inter-turn short circuit situation. The present invention realizes the detection of transformer inter-turn short circuit and can locate the location where the inter-turn short circuit occurs. By detecting the changes in vibration information at various positions of the transformer in real time, the inter-turn short circuit situation of the inverter can be preliminarily determined. Then, by detecting the changes in the transformer leakage magnetic field, the transformer inter-turn short circuit can be detected and located. Compared with traditional detection methods, the system has significant advantages. While ensuring the accurate location of the inter-turn short circuit, the operation time of the leakage magnetic field measurement module is greatly reduced, and the energy accumulation inside the transformer is reduced.

Description

Technical Field

[0001] The present invention relates to the field of electrical equipment detection, and in particular to a transformer turn-to-turn short circuit detection system and method based on multiple parameters. Background Art

[0002] Power transformers are both expensive equipment in power systems and indispensable equipment in power transmission systems. Unexpected power outages caused by faults may interrupt power supply to users and cause huge economic losses. Turn-to-turn short circuits are a common type of fault, so transformers must be tested for turn-to-turn short circuits. Traditional transformer turn-to-turn short circuit detection methods are to collect vibration signals at different positions of the transformer box to determine whether an inter-turn short circuit has occurred (such as the public patent CN111474496A, a method for rapid diagnosis of transformer turn-to-turn short circuits based on vibration signal identification). There are also methods based on magnetic leakage detection to determine turn-to-turn short circuits (such as the invention patent CN110221159B - a method, system and device for transformer fault detection based on core magnetic leakage), which performs fault detection based on changes in magnetic flux distribution, enabling detection when the transformer is online.

[0003] The inventors discovered that traditional vibration-based diagnostic methods transmit vibration signals throughout the transformer, leading to interference between vibration measurement points and affecting the accuracy of determining the location of inter-turn short circuits. Magnetic flux leakage diagnosis, on the other hand, is an active method that requires constant operation. This consumes more energy than vibration signal detection and causes increased heat accumulation within the transformer, which is detrimental to the transformer's long-term operation. Summary of the Invention

[0004] In view of the problems in the prior art that vibration diagnosis methods are not easy to accurately locate inter-turn short circuits and leakage magnetic online detection is prone to heat accumulation, the present invention provides a transformer inter-turn short circuit detection system and method based on multiple parameters. The transformer vibration signal under normal state is used as a reference. By detecting the changes in the transformer vibration signal in real time, the transformer inter-turn short circuit situation is preliminarily judged. Then, by detecting the transformer leakage magnetic field, the transformer inter-turn short circuit is detected and located, which not only ensures the accurate positioning of the inter-turn short circuit, but also reduces the heat accumulation of the transformer.

[0005] To achieve the above objectives, a first aspect of the present invention provides a transformer turn-to-turn short circuit detection system based on multiple parameters, comprising:

[0006] The vibration measurement module is installed on the transformer and is used to measure the vibration conditions of various parts of the transformer.

[0007] The leakage magnetic field measurement module is installed inside the transformer to measure the leakage magnetic field inside the transformer.

[0008] The result analysis module is connected to the vibration measurement module and the leakage magnetic flux measurement module respectively, processes the signals of the vibration measurement module and the leakage magnetic flux measurement module to obtain the vibration measurement results and the leakage magnetic flux measurement results; then the vibration measurement results and the leakage magnetic flux measurement results are analyzed to determine the inter-turn short circuit of the transformer and locate the position where the inter-turn short circuit occurs.

[0009] Optionally, the result analysis module includes:

[0010] A vibration signal acquisition card, which is used to collect the signal carrying vibration information from the vibration measurement module to obtain vibration measurement results;

[0011] A magnetic flux leakage signal acquisition card, which is used to collect signals carrying magnetic flux leakage information from the magnetic flux leakage measurement module, obtain magnetic flux leakage measurement results, and transmit control information to the magnetic flux leakage measurement module;

[0012] a signal processing module, configured to receive the vibration information transmitted by the vibration signal acquisition card and the magnetic flux leakage information transmitted by the magnetic flux leakage signal acquisition card, and send a control signal to the magnetic flux leakage measurement module via the magnetic flux leakage signal acquisition card;

[0013] The signal processing module is further configured to compare the vibration information with vibration information of the normal operation of the transformer to preliminarily determine whether an inter-turn short circuit occurs inside the transformer. If a deviation between the vibration information and the vibration information during normal operation is greater than a first set ratio value, it is preliminarily determined that an inter-turn short circuit occurs inside the transformer, and an open measurement signal is sent to the leakage magnetic flux measurement module to further analyze the leakage magnetic flux information and determine the location of the inter-turn short circuit inside the transformer.

[0014] For further optimization, the result analysis module is also used to compare and analyze the leakage flux size at each position. When the symmetry is not satisfied and the deviation of the leakage flux size at each position from the normal state is greater than a second set ratio value, it is determined that an inter-turn short circuit has occurred inside the transformer, and the position where the inter-turn short circuit occurs is located at the part where the difference between the leakage flux measurement result and the normal leakage flux size is the largest.

[0015] A second aspect of the present invention provides a method for detecting turn-to-turn short circuits using the above-mentioned transformer turn-to-turn short circuit detection system based on vibration and magnetic leakage, comprising the following steps:

[0016] Step 1: Install vibration measurement modules at different locations inside the oil-immersed transformer and on the surface of the oil tank; install leakage magnetic flux measurement modules at different locations inside the oil-immersed transformer; connect the vibration measurement module and leakage magnetic flux measurement module to the result analysis module respectively to obtain vibration measurement information and leakage magnetic flux measurement information respectively, and enable efficient signal transmission between them;

[0017] Step 2: When the deviation of the vibration information measured by the vibration measurement module is greater than the first set ratio value during normal operation, the vibration information is sent to the result analysis module, the result analysis module records the vibration measurement information and preliminarily determines that an inter-turn short circuit has occurred inside the transformer; the result analysis module sends an instruction to the leakage magnetic flux measurement module to allow the leakage magnetic flux measurement signal to be opened;

[0018] If the generated deviation does not exceed the first set ratio value, it is determined that no inter-turn short circuit occurs inside the transformer, and the result analysis module does not send a command to the leakage magnetic field measurement module to allow the measurement signal to be opened;

[0019] Step 3: After preliminarily determining that a turn-to-turn short circuit has occurred in the transformer, the magnetic flux leakage measurement module receives an enable signal, opens the magnetic flux leakage measurement device to measure the magnetic flux leakage at various locations inside the transformer, obtains the magnetic flux leakage measurement results at each location, and sends the magnetic flux leakage measurement information to the result analysis module;

[0020] Step 4: The result analysis module analyzes the magnetic flux leakage measurement information, compares the normal magnetic flux leakage size at each position with the magnetic flux leakage measurement information, and determines the location of the inter-turn short circuit.

[0021] Further improvement, in step 4:

[0022] When the deviation between the measured magnetic flux leakage information and the normal magnetic flux leakage size exceeds the second set ratio value, it is determined that an inter-turn short circuit has occurred inside the transformer, and the inter-turn short circuit position is located at the part where the difference between the measured magnetic flux leakage information and the normal magnetic flux leakage size is the largest;

[0023] When the deviation between the measured magnetic flux leakage information and the normal magnetic flux leakage size does not exceed the second set ratio value, it is determined that the location where the inter-turn short circuit occurs is far away from the position or that no inter-turn short circuit occurs at the position.

[0024] As a further improvement, in step one, the vibration measurement module remains in a normally open state to measure vibration information; the magnetic flux leakage measurement module remains in a normally closed state and only measures magnetic flux leakage information when it receives a signal allowing it to open.

[0025] As a further improvement, in step one and step four, if the deviation between the vibration measurement result and the normal operation is greater than the first set ratio value, but the deviation between the leakage magnetic field measurement result and the normal leakage magnetic field size is less than the second set ratio value, it is determined that the transformer has other faults other than inter-turn short circuit.

[0026] As a further improvement, in the step 2, the first set ratio value is set based on: a ratio value exceeding the deviation of the vibration caused by the load current change during normal operation of the transformer;

[0027] In the step 2, the second set ratio value is set based on: a ratio value exceeding the deviation of the leakage flux change caused by the winding current fluctuation during normal operation of the transformer;

[0028] Optionally, the first set ratio value is 10%, and the second set ratio value is 10%.

[0029] The present invention detects a transformer inter-turn short circuit by simultaneously utilizing vibration and magnetic leakage to quickly grasp the inter-turn short circuit situation, and can accurately locate the inter-turn short circuit position by analyzing the vibration information and magnetic leakage information, thereby realizing transformer inter-turn short circuit detection. The present invention collects and analyzes vibration information during no-load and operation. When the vibration deviation exceeds 10% of normal operation, the result analysis part preliminarily determines that an inter-turn short circuit has occurred in the transformer, and sends an open measurement signal to the magnetic leakage measurement part. By analyzing the measured magnetic leakage information, the inter-turn short circuit situation is grasped, and the position where the inter-turn short circuit has occurred is located.

[0030] The beneficial effects of the present invention are:

[0031] (1) The present invention utilizes a transformer inter-turn short-circuit detection system and method based on vibration and magnetic leakage. By detecting the changes in vibration information at various positions of the transformer in real time, the inter-turn short-circuit condition of the inverter can be preliminarily determined. Then, by detecting the changes in transformer magnetic leakage, the inter-turn short-circuit of the transformer can be detected and located. Compared with traditional detection methods, the present invention has significant advantages.

[0032] (2) Compared with the existing method of simply detecting vibration or online leakage magnetic field to detect transformer inter-turn short-circuit faults, the present invention has a vibration measurement module that is normally open, and the leakage magnetic field measurement module starts detection only when the vibration measurement module detects abnormal vibration. While ensuring accurate positioning of the inter-turn short-circuit position, the operation time of the leakage magnetic field measurement module is greatly reduced, energy accumulation is reduced, and it is beneficial to the long-term operation of the transformer equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 It is a transformer inter-turn short circuit detection system based on vibration and magnetic leakage.

[0035] In the figure, 1- vibration measurement module, 2- leakage magnetic flux measurement module, 3- result analysis module, 31- vibration signal acquisition card, 32- leakage magnetic flux signal acquisition card, 33- signal processing module. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] The first embodiment of the present invention provides a transformer turn-to-turn short circuit detection system based on vibration and magnetic leakage, such as Figure 1 As shown, a transformer inter-turn short circuit detection system based on vibration and magnetic leakage includes: a vibration measurement module 1, a magnetic leakage measurement module 2, and a result analysis module 3.

[0039] Among them, the vibration measurement module 1 is connected to the result analysis module 3, and the vibration measurement module 1 is used to measure the vibration conditions of various parts of the transformer; when the deviation between the vibration information detected by the vibration measurement module 1 and the vibration information during normal operation is greater than 10%, the vibration signal is transmitted to the result analysis module 3, and it is preliminarily judged that a turn-to-turn short circuit has occurred in the transformer.

[0040] The magnetic flux leakage measurement module 2 is connected to the result analysis module 3. The magnetic flux leakage measurement module 2 is used to measure the magnetic flux leakage inside the transformer. When the result analysis module preliminarily determines that a turn-to-turn short circuit occurs in the transformer, the magnetic flux leakage measurement module 2 starts to perform magnetic flux leakage detection and transmits the detected magnetic flux leakage signal to the result analysis module 3, thereby obtaining the magnetic flux leakage measurement result of the transformer.

[0041] Among them, the result analysis module 3 processes the signals of the vibration measurement module 1 and the leakage magnetic flux measurement module 2 to obtain the vibration measurement results and the leakage magnetic flux measurement results; then analyzes the vibration measurement results and the leakage magnetic flux measurement results to determine the inter-turn short circuit of the transformer and locate the position where the inter-turn short circuit occurs.

[0042] In practical applications, the result analysis module 3 includes: a vibration signal acquisition card 31, a magnetic flux leakage signal acquisition card 32, and a signal processing module 33;

[0043] Specifically, the vibration signal acquisition card 31 is used to collect the signal carrying vibration information from the vibration measurement module 1 to obtain the vibration measurement result;

[0044] Specifically, the magnetic flux leakage signal acquisition card 32 is used to collect the signal carrying magnetic flux leakage information from the magnetic flux leakage measurement module 2 to obtain the magnetic flux leakage measurement result;

[0045] Specifically, when the signal processing module 33 receives abnormal vibration information from the vibration measurement module, the signal processing module 33 compares the vibration information with the vibration information of the normal operation of the transformer, and preliminarily determines whether an inter-turn short circuit occurs inside the transformer. If the deviation between the vibration information and the vibration information during normal operation is greater than 10%, it is preliminarily determined that an inter-turn short circuit occurs inside the transformer, and an open measurement signal is sent to the leakage magnetic measurement module 2; the leakage magnetic measurement module 2 transmits the leakage magnetic information measured by each optical magnetic field sensor back to the result analysis module 3, and the result analysis module 3 compares and analyzes the leakage magnetic size at each position. When the symmetry is not satisfied and the leakage magnetic size at each position is significantly different from that at normal times, it is finally determined that an inter-turn short circuit occurs inside the transformer, and the position where the inter-turn short circuit occurs is located at the part where the difference between the leakage magnetic measurement result and the normal leakage magnetic size is the largest.

[0046] In practical applications, the magnetic flux leakage measurement module 2 is an optical magnetic field sensor based on the Faraday effect principle.

[0047] In this embodiment, when detecting a transformer inter-turn short circuit, vibration and leakage flux are simultaneously used to quickly obtain the inter-turn short circuit situation, and the inter-turn short circuit position can be relatively accurately located by analyzing the vibration information and leakage flux information, thereby realizing the detection of the transformer inter-turn short circuit. The present invention collects and analyzes the vibration information during no-load and operation. When the vibration deviation exceeds 10% of the normal operation, the result analysis module preliminarily determines that an inter-turn short circuit has occurred in the transformer, and sends an open measurement signal to the leakage flux measurement module. By analyzing the measured leakage flux information, the inter-turn short circuit situation is grasped, and the position of the inter-turn short circuit is located.

[0048] Compared with the existing method of simply detecting vibration or online leakage magnetic field to detect transformer inter-turn short-circuit faults, this embodiment has a vibration measurement module that is normally open, and the leakage magnetic field measurement module only starts detection when the vibration measurement module detects abnormal vibration. While ensuring accurate positioning of the short-circuit position, it also greatly reduces the operating time of the leakage magnetic field measurement module and reduces energy accumulation, which is beneficial to the long-term operation of the transformer equipment.

[0049] Example 2

[0050] A second embodiment of the present invention provides a transformer turn-to-turn short circuit detection method of a transformer turn-to-turn short circuit detection system, which uses the transformer turn-to-turn short circuit detection system based on vibration and magnetic leakage in Example 1, and includes the following steps:

[0051] Step 1: Install vibration measurement modules 1 at different locations inside the oil-immersed transformer and on the surface of the oil tank; install magnetic flux leakage measurement modules 2 at different locations inside the oil-immersed transformer; connect vibration measurement module 1 and magnetic flux leakage measurement module 2 to result analysis module 3, respectively, to obtain vibration measurement information and magnetic flux leakage measurement information, respectively, and enable efficient signal transmission between them;

[0052] Step 2: When the deviation of the vibration information measured by the vibration measurement module 1 is greater than 10% of normal operation, the vibration information is sent to the result analysis module 3, which records the vibration measurement information and preliminarily determines that a turn-to-turn short circuit has occurred inside the transformer. The result analysis module 3 transmits a signal to the leakage flux measurement module 2 to allow the leakage flux measurement to be opened. If the deviation does not exceed 10%, it is determined that no turn-to-turn short circuit has occurred inside the transformer, and the result measurement module 3 does not transmit a signal to allow the measurement to be opened to the leakage flux measurement module 2.

[0053] Step 3: After preliminarily determining that a turn-to-turn short circuit has occurred in the transformer, the magnetic flux leakage measurement module 2 receives the permission signal, opens the magnetic flux leakage measurement device, measures the magnetic flux leakage at various locations inside the transformer, obtains the magnetic flux leakage measurement results at each location, and sends the magnetic flux leakage measurement information to the result analysis module 3;

[0054] Step 4: The result analysis module 3 analyzes the leakage magnetic flux measurement information and compares the normal leakage magnetic flux size and the leakage magnetic flux measurement information at each position. When there is a large difference between the measured leakage magnetic flux information and the normal leakage magnetic flux size, it can be determined that an inter-turn short circuit has occurred inside the transformer, and the inter-turn short circuit position is located at the part where the difference between the leakage magnetic flux measurement information and the normal leakage magnetic flux size is the largest; if the difference between the leakage magnetic flux measurement information and the normal leakage magnetic flux size is not large, it is determined that the location where the inter-turn short circuit occurred is far away from the position or that no inter-turn short circuit has occurred at the position.

[0055] In step 1, the vibration measurement module 1 is kept in a normally open state to measure vibration information; the magnetic flux leakage measurement module 2 is kept in a normally closed state and only performs magnetic flux leakage information measurement when it receives a signal allowing opening.

[0056] In step 4, if the deviation of the vibration measurement result is greater than 10% of normal operation, but the leakage flux measurement result is not much different from the normal leakage flux, it is possible that the transformer has other faults besides the inter-turn short circuit.

[0057] In step 2, the 10% vibration deviation ratio is set based on the percentage of the vibration variation caused by load current fluctuations during normal transformer operation. In step 2, the leakage flux deviation is set based on the percentage of the leakage flux variation caused by winding current fluctuations during normal transformer operation. These two ratios are set to prevent false fault alarms during normal operation.

[0058] The transformer inter-turn short circuit detection method of the transformer inter-turn short circuit detection system provided in this embodiment, compared with the existing method of detecting transformer inter-turn short circuit faults by simply detecting vibration or online leakage magnetic field, ensures accurate positioning of the inter-turn short circuit position while also significantly reducing the operating time of the leakage magnetic field measurement module and reducing energy accumulation, which is beneficial to the long-term operation of the transformer equipment.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for the module technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A transformer turn-to-turn short circuit detection system based on multiple parameters, characterized in that: include: The vibration measurement module is installed on the transformer to measure the vibration conditions of various parts of the transformer; A magnetic flux leakage measurement module is installed inside the transformer and is used to measure the magnetic flux leakage inside the transformer; a result analysis module, which is connected to the vibration measurement module and the magnetic flux leakage measurement module respectively, processes the signals of the vibration measurement module and the magnetic flux leakage measurement module to obtain vibration measurement results and magnetic flux leakage measurement results; then analyzes the vibration measurement results and the magnetic flux leakage measurement results to determine the inter-turn short circuit of the transformer and locate the location where the inter-turn short circuit occurs; The result analysis module is used to compare and analyze the leakage flux size at each position. When the symmetry is not satisfied and the deviation of the leakage flux size at each position from the normal state is greater than a second set ratio value, it is determined that a turn-to-turn short circuit has occurred inside the transformer, and the position where the turn-to-turn short circuit occurs is located at the position where the difference between the leakage flux measurement result and the normal leakage flux size is the largest; The result analysis module includes: A vibration signal acquisition card, which is used to collect the signal carrying vibration information from the vibration measurement module to obtain vibration measurement results; A magnetic flux leakage signal acquisition card, which is used to collect signals carrying magnetic flux leakage information from the magnetic flux leakage measurement module, obtain magnetic flux leakage measurement results, and transmit control information to the magnetic flux leakage measurement module; a signal processing module, configured to receive the vibration information transmitted by the vibration signal acquisition card and the magnetic flux leakage information transmitted by the magnetic flux leakage signal acquisition card, and send a control signal to the magnetic flux leakage measurement module via the magnetic flux leakage signal acquisition card; The signal processing module is further configured to compare the vibration information with vibration information of the normal operation of the transformer to preliminarily determine whether an inter-turn short circuit occurs inside the transformer. If a deviation between the vibration information and the vibration information during normal operation is greater than a first set ratio value, it is preliminarily determined that an inter-turn short circuit occurs inside the transformer, and an open measurement signal is sent to the leakage magnetic flux measurement module to further analyze the leakage magnetic flux information and determine the location of the inter-turn short circuit inside the transformer.

2. A method for detecting turn-to-turn short circuit using the transformer turn-to-turn short circuit detection system according to claim 1, characterized in that: The following steps are involved: Step 1: Install vibration measurement modules at different locations inside the oil-immersed transformer and on the surface of the oil tank; install leakage magnetic flux measurement modules at different locations inside the oil-immersed transformer; connect the vibration measurement module and leakage magnetic flux measurement module to the result analysis module respectively to obtain vibration measurement information and leakage magnetic flux measurement information respectively, and enable efficient signal transmission between them; Step 2: When the deviation of the vibration information measured by the vibration measurement module is greater than the first set ratio value during normal operation, the vibration information is sent to the result analysis module, the result analysis module records the vibration measurement information and preliminarily determines that an inter-turn short circuit has occurred inside the transformer; the result analysis module sends an instruction to the leakage magnetic flux measurement module to allow the leakage magnetic flux measurement signal to be opened; If the generated deviation does not exceed the first set ratio value, it is determined that no inter-turn short circuit occurs inside the transformer, and the result analysis module does not send a command to the leakage magnetic field measurement module to allow the measurement signal to be opened; Step 3: After preliminarily determining that a turn-to-turn short circuit has occurred in the transformer, the magnetic flux leakage measurement module receives an enable signal, opens the magnetic flux leakage measurement device to measure the magnetic flux leakage at various locations inside the transformer, obtains the magnetic flux leakage measurement results at each location, and sends the magnetic flux leakage measurement information to the result analysis module; Step 4: The result analysis module analyzes the magnetic flux leakage measurement information, compares the normal magnetic flux leakage size at each position with the magnetic flux leakage measurement information, and determines the location of the inter-turn short circuit.

3. The turn-to-turn short circuit detection method according to claim 2, wherein: In the step 4: When the deviation between the measured magnetic flux leakage information and the normal magnetic flux leakage size exceeds the second set ratio value, it is determined that an inter-turn short circuit has occurred inside the transformer, and the inter-turn short circuit position is located at the part where the difference between the measured magnetic flux leakage information and the normal magnetic flux leakage size is the largest; When the deviation between the measured magnetic flux leakage information and the normal magnetic flux leakage size does not exceed the second set ratio value, it is determined that the location where the inter-turn short circuit occurs is far away from the position or that no inter-turn short circuit occurs at the position.

4. The turn-to-turn short circuit detection method according to claim 3, wherein: In the step 1, the vibration measurement module is kept in a normally open state to measure vibration information; the magnetic flux leakage measurement module is kept in a normally closed state and only performs magnetic flux leakage information measurement when it receives an opening permission signal.

5. The turn-to-turn short circuit detection method according to claim 2, wherein: In step one and step four, if the deviation between the vibration measurement result and the normal operation is greater than the first set ratio value, but the deviation between the leakage magnetic flux measurement result and the normal leakage magnetic flux size is less than the second set ratio value, it is determined that other faults other than the inter-turn short circuit have occurred in the transformer.

6. The turn-to-turn short circuit detection method according to claim 2, wherein: In the step 2, the first set ratio value is set based on: exceeding the ratio value of the vibration deviation caused by the load current change during normal operation of the transformer; In the step 2, the second set ratio value is set based on: a ratio value exceeding the deviation of the leakage magnetic flux change caused by the winding current fluctuation during normal operation of the transformer.

7. The turn-to-turn short circuit detection method according to claim 6, wherein: The first set ratio value is 10%, and the second set ratio value is 10%.

Images