A mutual inductor detection system based on test signal injection

Abstract

The present invention relates to the field of power detection technology, and discloses a transformer detection system based on test signal injection, comprising a data acquisition module and an intelligent evaluation module. The transformer detection system based on test signal injection obtains material specification data, signal test data, and historical maintenance records of all current transformers through the data acquisition module, and classifies and forms a data set. The intelligent evaluation module analyzes the amplitude error and angle error of each current transformer, deeply analyzes the measurement error, and clearly grasps the excitation characteristics of each current transformer. The intelligent evaluation module analyzes the fault frequency and quality score of each current transformer, and determines whether the use environment and load conditions of the current transformer are unbalanced. When the total number of times the current transformer measurement error exceeds the abnormal threshold, it indicates that the use environment and load conditions of the current transformer are unbalanced. The current transformer with the lowest quality score in each batch is marked, and hidden faults are accurately checked.

Description

Technical Field

[0001] The present invention relates to the technical field of power detection, and in particular to a mutual inductor detection system based on test signal injection. Background Art

[0002] Current transformers are widely used in power systems, primarily for measuring and protecting high-current circuits. Their operating principle is based on the law of electromagnetic induction. When a high current flows through a coil on the primary side, it induces a current on the secondary side. The magnitude of this induced current is directly proportional to the primary current and inversely proportional to the number of turns in the secondary coil. Current transformer technical specifications include accuracy class, rated current, transformation ratio, and rated capacity; these parameters determine the transformer's performance and applicability. Current transformers are widely used in power systems in substations, power plants, industrial and mining enterprises, and other locations to measure, protect, and control current. They convert the current value in high-current circuits into a low-current signal that can be received and processed by instruments, protection devices, and recorders. However, in actual use, factors such as the core material, core cross-section, and number of turns of the current transformer can affect measurement errors. Excitation current is one of the main causes of current transformer error. Excitation current is the operating current required to establish the magnetic field. The excitation current is out of phase with the primary current, resulting in amplitude and angle errors. During normal operation, the excitation impedance is large and the excitation current is low, making the error negligible. However, in saturation, the excitation impedance decreases and the excitation current increases, causing the error to increase. The correct selection, configuration, and use of current transformers are crucial to the safe and stable operation of power systems. Proper configuration ensures accurate measurement and reliable protection of power systems.

[0003] Currently, traditional transformer detection systems based on test signal injection often ignore the angular errors caused by changes in excitation current. This oversight may cause the protection device to malfunction or refuse to operate, thereby threatening the safe and stable operation of the power system. In addition, there is a lack of unified standards to evaluate the comprehensive quality score of current transformers, and fault detection is delayed, making it difficult to detect potential fault hazards in a timely manner. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In response to the shortcomings of the existing technology, the present invention provides a current transformer detection system based on test signal injection, which has the advantages of in-depth analysis of measurement errors and accurate troubleshooting of potential faults. It solves the problem that the traditional current transformer detection system based on test signal injection ignores the impact of excitation current changes on angle errors and lacks a unified standard for evaluating the comprehensive quality of current transformers.

[0006] (2) Technical solution

[0007] To achieve the above-mentioned object, the present invention provides the following technical solutions: a mutual inductor detection system based on test signal injection, comprising a data acquisition module and an intelligent evaluation module;

[0008] The data acquisition module is composed of a material data unit, a test data unit, and a history data unit. The material data unit is connected to a database via a network to collect a material data set, and the material data set includes material specification data of all current transformers. The test data unit is connected to the current transformer via a network to collect a test data set, and the test data set includes signal test data of all current transformers. The history data set is connected to the database via a network to collect a history data set, and the history data set includes historical maintenance records of all current transformers. The data acquisition module transmits the material data set, the test data set, and the history data set to the intelligent evaluation module via the network.

[0009] The intelligent evaluation module consists of an inspection and analysis unit, a fault analysis unit, and a scheduling management unit. The inspection and analysis unit analyzes the amplitude error Fzwc and angle error Jdwc of each current transformer based on the material data set and the inspection data set, and transmits the results to the scheduling management unit via the network. The fault analysis unit analyzes the fault frequency Gpl of each current transformer based on the material data set and the historical data set, and transmits the results to the scheduling management unit via the network. The scheduling management unit is provided with an evaluation period PZ of a fixed duration, and calculates the quality score Zlpc of each current transformer based on the material data set, the amplitude error Fzwc, the angle error Jdwc, and the fault frequency Gpl. The scheduling management unit is provided with an abnormality threshold YY within a fixed range, and then, based on the quality score Zlpc, determines whether the operating environment and load conditions of the current transformer are unbalanced, and outputs the corresponding judgment result.

[0010] Preferably, the expression of the material data set is {Q1 d 、Q2 d 、Q3 d ,...,Qm d}, Q1 d to Qm d They are the material specification data of the first to mth batches of current transformers, which include the number of primary and secondary turns and the accuracy grade. d represents the specific time when a single batch of current transformers begins to be put into use. In a single batch, the material specification data and the specific time when all current transformers begin to be put into use are the same.

[0011] Preferably, the expression of the detection data set is to They are the signal inspection data of the first to nth current transformers respectively, b represents the current value input to the primary side of the current transformer, and c represents the current value output from the secondary side of the current transformer.

[0012] Preferably, the expression of the historical data set is {L1 s 、L2 s 、L3 s 、...、Ln s}, L1 s To Ln s They are the historical maintenance records of the first to nth current transformers, including the cause of the failure and the historical replacement parts. s represents the total number of historical maintenance times of a single current transformer.

[0013] Preferably, the calculation process of the amplitude error Fzwc is as follows:

[0014] Extract the material specification data of the i-th batch of current transformers in the material data set, and mark the primary side turns of the i-th batch of current transformers as YC i , mark the secondary turns of the i-th batch of current transformers as EC i , mark the accuracy level of the i-th batch of current transformers as ZQ i ;

[0015] According to the test data set, the signal test data of the kth current transformer in the i-th batch is extracted, where Jk b Indicates the standard current value of the primary side of the kth current transformer, Jk c Indicates the actual current value output by the secondary side of the kth current transformer;

[0016]

[0017] In the formula, Fzwc represents the amplitude error, It represents the ratio of the primary side turns to the secondary side turns of the i-th batch of current transformers, which is the transformation ratio CT of the k-th current transformer. k , The primary side standard current value is divided by the transformation ratio to obtain the estimated value IY of the secondary side output current of the kth current transformer. k , IY k -Jk c Indicates the difference between the estimated value and the actual current value of the secondary side output current, It represents the ratio of the kth current transformer current difference to the estimated secondary output current. The amplitude error is expressed as a percentage.

[0018] Preferably, the angle error Jdwc calculation process is as follows:

[0019] According to the signal inspection data of the kth current transformer, use the phase meter to measure the phase angle of the primary side current waveform and the secondary side current waveform, and mark the phase angle of the primary side current waveform as X y , mark the phase angle of the secondary side current waveform as X y ;

[0020] Jdwc=sin(X y +X e )-sin(X y -X e )

[0021] In the formula, Jdwc represents the angle error, sin(X y +X e )-sin(X y -X e ) indicates that the angle difference calculated according to the sum-differentiation-product formula is the angle error of the kth current transformer.

[0022] Preferably, the fault frequency Gpl calculation process is as follows:

[0023] According to the historical data set, the historical maintenance record of the kth current transformer in the i-th batch is extracted, and the total number of historical maintenance times of the kth current transformer is marked as k s ;

[0024]

[0025] In the formula, Gpl represents the fault frequency, DQ represents the current time point, and k d Indicates the specific time when the kth current transformer starts to be put into use, DQ-k d represents the total time that the kth current transformer is put into use, The total number of historical maintenance times divided by the total time in use is the failure frequency of the kth current transformer.

[0026] Preferably, the quality score Zlpc calculation process is as follows:

[0027] According to the accuracy grade ZQ of the current transformer of the i-th batch i , set the corresponding amplitude threshold FY and angle difference threshold JY, and compare the amplitude error Fzwc of the k-th current transformer in the i-th batch with the amplitude threshold FY, and compare the angle error Jdwc of the k-th current transformer in the i-th batch with the angle difference threshold JY;

[0028] During the evaluation period PZ, the number of times the amplitude error Fzwc of the kth current transformer exceeds the amplitude threshold FY is counted and marked as FS;

[0029] During the evaluation period PZ, the number of times the angle error Jdwc of the kth current transformer exceeds the angle difference threshold JY is counted and marked as JS;

[0030]

[0031] In the formula, Zlpc represents the quality score, represents the average quality score of the current transformers in the i-th batch, FS+JS represents the total number of times the measurement error of the k-th current transformer exceeds the standard, α represents the weight for the number of times the error exceeds the standard, β represents the weight for the fault frequency, α and β are both constants, and α+β=1, α(FS+JS)+βGpl represents the conversion of the total number of times the measurement error of the k-th current transformer exceeds the standard and the fault frequency into a defect score according to the weights α and β. It means that the defect score of the k-th current transformer is subtracted from the average quality score of the same batch to obtain the quality score of the k-th current transformer.

[0032] Preferably, when the total number of times the current transformer measurement error exceeds the abnormal threshold YY, it indicates that the use environment and load conditions of the current transformer are unbalanced, the historical maintenance records of the current transformer in the historical data set are extracted, and an abnormal alarm is generated to remind the management personnel to perform calibration.

[0033] Preferably, the scheduling management unit arranges the current transformers of the same batch according to the quality score Zlpc from high to low, marks the last current transformer in each batch, and compiles a replacement list to remind management personnel to replace the current transformers in time.

[0034] Compared with the prior art, the present invention provides a mutual inductor detection system based on test signal injection, which has the following beneficial effects:

[0035] 1. The present invention connects the database and current transformers through a data acquisition module network to obtain material specification data, signal inspection data, and historical maintenance records of all current transformers, and classifies them into material data sets, inspection data sets, and historical data sets. The intelligent evaluation module analyzes the amplitude error Fzwc and angle error Jdwc of each current transformer based on the material data sets and inspection data sets, accurately calculates the error of each current transformer during the current conversion process, deeply analyzes the measurement error, and clearly grasps the excitation characteristics of each current transformer. This can better match and adjust the current transformers, ensure their stable operation under various load conditions, and optimize the overall performance of the power system.

[0036] 2. The present invention uses an intelligent evaluation module to analyze the fault frequency Gpl and quality score Zlpc of each current transformer based on the material data set and the historical data set, and determines whether the operating environment and load conditions of the current transformer are unbalanced. When the total number of times the current transformer measurement error exceeds the abnormal threshold YY, it indicates that the operating environment and load conditions of the current transformer are unbalanced. The historical maintenance records of the current transformer in the historical data set are extracted, and an abnormality alarm is generated to remind management personnel to perform calibration. The scheduling management unit arranges the current transformers in the same batch from high to low according to the quality score Zlpc, marks the last current transformer in each batch, and compiles a replacement list to remind management personnel to replace the current transformers in a timely manner and accurately detect potential fault hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the system flow of the present invention. DETAILED DESCRIPTION

[0038] 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 the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Traditional current transformer detection systems based on test signal injection often ignore the angle error caused by changes in the excitation current. This oversight can cause protection devices to malfunction or refuse to operate, threatening the safe and stable operation of the power system. Furthermore, the lack of a unified standard for evaluating the comprehensive quality of current transformers leads to delayed fault detection, making it difficult to detect potential fault hazards in a timely manner. Therefore, a current transformer detection system based on test signal injection is proposed. Please refer to the following. Figure 1 ,The system includes a data acquisition module and an intelligent evaluation module;

[0040] The data acquisition module consists of a material data unit, a test data unit, and a historical data unit. The material data unit connects to the database through a network to collect material data sets. The material data sets include material specification data of all current transformers. The expression of the material data set is {Q1 d 、Q2 d 、Q3 d ,...,Qm d}, Q1 d to Qm dThe material specification data of the current transformers from the first to the mth batch respectively include the number of primary and secondary turns and the accuracy level. The accuracy levels include 0.2, 0.5, 1, 3, and 5. Among them, level 0.2 is the highest accuracy, and the current value error range is usually +0.2%. d represents the specific time when the current transformers of a single batch began to be put into use. In a single batch, the material specification data and the specific time when they were put into use are the same for all current transformers. The current transformer tables are classified by batch to facilitate the subsequent rapid identification and detection of equipment with potential fault hazards in the same batch.

[0041] The test data unit is connected to the current transformer through the network to collect the test data set. The test data set includes the signal test data of all current transformers. The expression of the test data set is: to These are the signal test data of the first to nth current transformers, respectively. b represents the current value input to the primary side of the current transformer, and c represents the current value output from the secondary side of the current transformer. Real-time monitoring of the output feedback generated by the current transformer in response to the input test signal is the key basis for subsequent judgment of whether the error exceeds the standard.

[0042] The historical data set is collected through the network connection database. The historical data set includes the historical maintenance records of all current transformers. The expression of the historical data set is {L1 s 、L2 s 、L3 s 、...、Ln s}, L1 s To Ln s The historical maintenance records of the first to nth current transformers include the cause of the failure and the historical replacement parts. s represents the total number of historical maintenance times for a single current transformer. Detailed records of the historical maintenance process of each current transformer help managers quickly handle potential fault hazards and ensure the safe and stable operation of the power system.

[0043] The data acquisition module transmits the material data set, the inspection data set and the historical data set to the intelligent evaluation module through the network;

[0044] The intelligent evaluation module consists of an inspection and analysis unit, a fault analysis unit, and a dispatch management unit. The inspection and analysis unit analyzes the amplitude error Fzwc and angle error Jdwc of each current transformer based on the material data set and the inspection data set, and transmits the results to the dispatch management unit via the network. The calculation process is as follows:

[0045] Extract the material specification data of the i-th batch of current transformers in the material data set, and mark the primary side turns of the i-th batch of current transformers as YCi , mark the secondary turns of the i-th batch of current transformers as EC i , mark the accuracy level of the i-th batch of current transformers as ZQi;

[0046] According to the test data set, the signal test data of the kth current transformer in the i-th batch is extracted, where Kk b Indicates the standard current value of the primary side of the kth current transformer, Jk c Indicates the actual current value output by the secondary side of the kth current transformer;

[0047]

[0048] In the formula, Fzwc represents the amplitude error, It represents the ratio of the primary side turns to the secondary side turns of the i-th batch of current transformers, that is, the transformation ratio CTk of the k-th current transformer. The primary side standard current value is divided by the transformation ratio to obtain the estimated value IY of the secondary side output current of the kth current transformer. k , IY k -Jk c Indicates the difference between the estimated value and the actual current value of the secondary side output current, It represents the ratio of the current difference of the kth current transformer to the estimated secondary output current. The amplitude error is expressed as a percentage, accurately calculating the error of each current transformer in the current conversion process.

[0049] According to the signal inspection data of the kth current transformer, use the phase meter to measure the phase angle of the primary side current waveform and the secondary side current waveform, and mark the phase angle of the primary side current waveform as X y , mark the phase angle of the secondary side current waveform as X y ;

[0050] Jdwc=sin(X y +X e )-sin(X y -X e )

[0051] In the formula, Jdwc represents the angle error, sin(X y +X e )-sin(X y -X e ) indicates that the angle difference calculated according to the product-sum-differential formula is the angle error of the kth current transformer. In-depth analysis of the measurement error and clear understanding of the excitation characteristics of each current transformer can better match and adjust the current transformers, ensuring their stable operation under various load conditions and optimizing the overall performance of the power system;

[0052] The fault analysis unit analyzes the fault frequency Gpl of each current transformer based on the material data set and the historical data set, and transmits it to the dispatch management unit through the network. The calculation process is as follows:

[0053] According to the historical data set, the historical maintenance record of the kth current transformer in the i-th batch is extracted, and the total number of historical maintenance times of the kth current transformer is marked as k s ;

[0054]

[0055] In the formula, Gpl represents the fault frequency, DQ represents the current time point, and k d Indicates the specific time when the kth current transformer starts to be put into use, DQ-k d represents the total time that the kth current transformer is put into use, The total number of historical maintenance times divided by the total time in use is the failure frequency of the kth current transformer;

[0056] The scheduling management unit sets a fixed-length evaluation period PZ and calculates the quality score Zlpc of each current transformer based on the material data set, amplitude error Fzwc, angle error Jdwc, and fault frequency Gpl. The calculation process is as follows:

[0057] According to the accuracy grade ZQ of the current transformer of the i-th batch i , set the corresponding amplitude threshold FY and angle difference threshold JY, and compare the amplitude error Fzwc of the k-th current transformer in the i-th batch with the amplitude threshold FY, and compare the angle error Jdwc of the k-th current transformer in the i-th batch with the angle difference threshold JY;

[0058] During the evaluation period PZ, the number of times the amplitude error Fzwc of the kth current transformer exceeds the amplitude threshold FY is counted and marked as FS;

[0059] During the evaluation period PZ, the number of times the angle error Jdwc of the kth current transformer exceeds the angle difference threshold JY is counted and marked as JS;

[0060]

[0061] In the formula, Zlpc represents the quality score, represents the average quality score of the current transformers in the i-th batch, FS+JS represents the total number of times the measurement error of the k-th current transformer exceeds the standard, α represents the weight for the number of times the error exceeds the standard, β represents the weight for the fault frequency, α and β are both constants, and α+β=1, α(FS+JS)+βGpl represents the conversion of the total number of times the measurement error of the k-th current transformer exceeds the standard and the fault frequency into a defect score according to the weights α and β. The quality score of the kth current transformer is obtained by subtracting the defect score of the kth current transformer from the average quality score of the same batch. If the average quality score of the current transformers in this batch has not yet been calculated, the average quality score of another batch of current transformers with similar material specifications and service time can be selected as the basic score;

[0062] The dispatching management unit is set with a fixed range of abnormal threshold YY, and combined with the quality score Zlpc, it determines whether the operating environment and load conditions of the current transformer are unbalanced. When the total number of times the current transformer measurement error exceeds the abnormal threshold YY, it indicates that the operating environment and load conditions of the current transformer are unbalanced. The historical maintenance records of the current transformer in the historical data set are extracted, and an abnormal alarm is generated to remind management personnel to perform calibration. The dispatching management unit arranges the current transformers of the same batch from high to low according to the quality score Zlpc, marks the last current transformer in each batch, and compiles a replacement list to remind management personnel to replace the current transformers in time and accurately detect potential fault hazards.

[0063] Example 1: In this experiment, a current transformer with 200 primary turns and 5 secondary turns was selected as the experimental object. After a current of 100A was input into the primary side of the current transformer, the actual current value output on the secondary side was detected to be 2A. The amplitude error Fzwc of the current transformer was calculated as follows:

[0064]

[0065] In the formula, Fzwc represents the amplitude error, Indicates the ratio of the primary side turns to the secondary side turns of the current transformer. 40 is the transformation ratio CT of the current transformer. k , Indicates the primary side standard current value divided by the transformation ratio, which is the estimated value IY of the secondary side output current of the current transformer. k The current transformer current difference is 2.5A, and 20% represents the ratio of the current difference of the current transformer to the estimated value of the secondary side output current. The amplitude error is expressed in the form of a percentage.

[0066] Example 2: In this experiment, current transformers from the same batch with an average quality score of 90 were selected as experimental objects. According to statistics, within one hour, the amplitude error Fzwc of the current transformer exceeded the amplitude threshold FY 5 times, and the angle error Jdwc exceeded the angle difference threshold JY 2 times. The failure frequency of the current transformer after it was put into use was once per month. The quality score Zlpc of the current transformer was calculated as follows:

[0067]

[0068] In the formula, Zlpc represents the quality score, 90 represents the average quality score of the current transformers in this batch, 5+2 represents the total number of times the measurement error of the current transformer exceeds the standard, 0.4 represents the weight for the number of times the error exceeds the standard, 0.6 represents the weight for the fault frequency, α and β are both constants, and 0.4+0.6=1, 0.4(5+2)+0.6×1 represents the conversion of the total number of times the measurement error of the current transformer exceeds the standard and the fault frequency into defect scores according to the weights of α and β, and 90-[0.4(5+2)+0.6×1] represents the subtraction of the defect score of the current transformer from the average quality score of the same batch, and the quality score of the current transformer is 86.6.

[0069] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A mutual inductor detection system based on test signal injection, characterized in that: Including data acquisition module and intelligent evaluation module; The data acquisition module is composed of a material data unit, a test data unit, and a history data unit. The material data unit is connected to a database via a network to collect a material data set, and the material data set includes material specification data of all current transformers. The test data unit is connected to the current transformer via a network to collect a test data set, and the test data set includes signal test data of all current transformers. The history data unit is connected to the database via a network to collect a history data set, and the history data set includes historical maintenance records of all current transformers. The data acquisition module transmits the material data set, the test data set, and the history data set to the intelligent evaluation module via the network. The intelligent evaluation module consists of a test analysis unit, a fault analysis unit and a scheduling management unit. The test analysis unit analyzes the amplitude error of each current transformer based on the material data set and the test data set. and angular error and transmitted to the dispatch management unit through the network. The fault analysis unit analyzes the fault frequency of each current transformer based on the material data set and the historical data set. and transmitted to the scheduling management unit via the network, the scheduling management unit is set with a fixed-length evaluation cycle , and combined with the material data set, amplitude error , angular error and failure frequency , calculate the quality score of each current transformer The scheduling management unit is set with a fixed range of abnormal thresholds , combined with the quality score , judge whether the operating environment and load conditions of the current transformer are unbalanced, and output the corresponding judgment result.

2. A mutual inductor detection system based on test signal injection according to claim 1, characterized in that: The expression of the material data set is , to The first to the Material specification data for each batch of current transformers, including primary and secondary turns and accuracy grade, Indicates the specific time when a batch of current transformers begins to be put into use. In a single batch, all current transformers have the same material specifications and the same specific time when they are put into use.

3. The mutual inductor detection system based on test signal injection according to claim 2, characterized in that: The expression of the test data set is , to The first to the Signal test data of each current transformer, Indicates the current value of the primary side of the input current transformer, Indicates the current value output by the secondary side of the current transformer.

4. The mutual inductor detection system based on test signal injection according to claim 3, characterized in that: The expression of the historical data set is , to The first to the The historical maintenance records of each current transformer include the cause of the failure and the historical replacement parts. Indicates the total number of historical maintenance times of a single current transformer.

5. The mutual inductor detection system based on test signal injection according to claim 4, characterized in that: The amplitude error The calculation process is as follows: Extract the material data set The material specification data of the current transformer batch The primary turns of a batch of current transformers are marked as , will The secondary turns of a batch of current transformers are marked as , will The accuracy level of each batch of current transformers is marked as ; According to the test data set, the In the batch Signal verification data of current transformers, among which, Indicates input The standard current value of the primary side of a current transformer, Indicates the The actual current value output by the secondary side of a current transformer; In the formula, represents the amplitude error, Indicates the The ratio of the primary side turns to the secondary side turns of the current transformer in the first batch is The transformation ratio of a current transformer , Indicates the primary side standard current value divided by the transformation ratio, and the Estimated output current of the secondary side of a current transformer , Indicates the difference between the estimated value and the actual current value of the secondary side output current, Indicates the The ratio of the current difference of the current transformer to the estimated value of the secondary side output current. The amplitude error is expressed as a percentage.

6. The mutual inductor detection system based on test signal injection according to claim 5, characterized in that: The angular error The calculation process is as follows: According to The signal test data of the current transformer is obtained by using a phase meter to measure the phase angle of the primary side current waveform and the secondary side current waveform, and the phase angle of the primary side current waveform is marked as , the phase angle of the secondary current waveform is marked as ; In the formula, represents the angle error, According to the formula of sum-difference-product, the angle difference calculated is The angular error of each current transformer.

7. The mutual inductor detection system based on test signal injection according to claim 6, characterized in that: The fault frequency The calculation process is as follows: Based on the historical data set, extract the In the batch The historical maintenance records of the current transformers and The total number of historical maintenance times of the current transformer is marked as ; In the formula, Indicates the fault frequency, Indicates the current time point, Indicates the The specific time when each current transformer was put into use, Indicates the The total time that each current transformer has been put into use, The total number of historical maintenance times divided by the total time in use is the The fault frequency of each current transformer.

8. The mutual inductor detection system based on test signal injection according to claim 7, characterized in that: The quality score The calculation process is as follows: According to Accuracy level of current transformers in batches , set the corresponding amplitude threshold Sum angle difference threshold , and the In the batch Amplitude error of a current transformer Contrast amplitude threshold , will In the batch Angle error of a current transformer Contrast angle difference threshold ; Statistical evaluation cycle During the period, Current transformer amplitude error Exceeding the amplitude threshold , and marked as ; Statistical evaluation cycle During the period, Current transformer angle error Exceeding the angular difference threshold , and marked as ; In the formula, represents the quality score, Indicates the The average quality score of the current transformers in the batches, Indicates the The total number of times the current transformer measurement error exceeds the standard, represents the weight for the number of times the error exceeds the standard, represents the weight for the fault frequency, and are constants, and , Indicates that and Weight, the The total number of times the current transformer measurement error exceeds the standard and the fault frequency are converted into defect scores. It means the average quality score of the same batch minus the The defect fraction of the current transformer is obtained Quality rating of a current transformer.

9. The mutual inductor detection system based on test signal injection according to claim 8, characterized in that: The total number of times the current transformer measurement error exceeds the standard exceeds the abnormal threshold When the current transformer is detected, it indicates that the operating environment and load conditions of the current transformer are unbalanced. The historical maintenance records of the current transformer in the historical data set are extracted, and an abnormal alarm is generated to remind the management personnel to perform calibration.

10. The mutual inductor detection system based on test signal injection according to claim 9, characterized in that: The scheduling management unit scores the Arrange the current transformers in the same batch from high to low, mark the last current transformer in each batch, and form a replacement list to remind management personnel to replace the current transformers in time.

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