A method and system for monitoring the state of a current transformer

Abstract

The present invention relates to the technical field of current transformer protection, and discloses a method and system for monitoring the state of a current transformer. The method includes: collecting an instantaneous voltage signal at the output end of the current transformer and calculating the instantaneous current, and extracting the effective value and phase angle of the output current through fast Fourier transform; judging whether the difference between the input and output currents exceeds the limit through a dynamic threshold, and uploading the state data to the background for monitoring. Compared with the prior art, in which it is impossible to accurately detect the state of the secondary circuit of the current transformer in real time in a complex environment, especially under conditions such as large current fluctuations and strong environmental interference, and it is impossible to achieve high-reliability fault identification and protection. Since the present application realizes rapid fault judgment on the state of the current transformer through dynamic threshold and main frequency component phase extraction, the problem of damage to the transformer or system instability caused by secondary circuit faults is avoided, and the reliability and operation and maintenance efficiency of the power system operation are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of current transformer protection, and particularly relates to a method and system for monitoring the state of a current transformer. Background Art

[0002] At present, the wide application of current transformers in the power system is crucial for realizing current measurement, protection, and control. However, there are many deficiencies in the existing technology for monitoring the state of current transformers. For example, the existing technology usually relies on fixed threshold judgment methods. When the operating environment of the power system is complex, such as large current fluctuations and strong environmental interference, it is impossible to accurately detect open circuits or abnormal conditions in the secondary circuit. At the same time, the existing monitoring systems lack real-time protection mechanisms for faults and cannot effectively avoid the damage of open circuit faults to the current transformer and related equipment. The existing technology cannot fully meet the requirements of high-precision, high-reliability, and real-time monitoring in complex environments. Therefore, there is an urgent need for a method and system that can still achieve real-time monitoring of the state of current transformers, dynamic fault judgment, and reliable protection under complex conditions such as large current fluctuations and strong environmental interference, so as to improve the stability and operation and maintenance efficiency of the power system. Summary of the Invention

[0003] Aiming at the above-mentioned technical deficiencies, the purpose of the present invention is to propose a method for monitoring the state of a current transformer, aiming to solve the technical problem that the existing technology cannot accurately detect the state of the secondary circuit of the current transformer in real time in a complex environment, especially under conditions such as large current fluctuations and strong environmental interference, and cannot achieve high-reliability fault identification and protection.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions: The present invention provides a method for monitoring the state of a current transformer,

[0005] The method for monitoring the state of the current transformer includes:

[0006] Step S10: Set a sampling resistor at the output end of the current transformer, collect the instantaneous voltage signal U on the sampling resistor out , and calculate the instantaneous output current i according to the sampling resistor and the instantaneous voltage signal U out ; out ;

[0007] Step S20: Extract the effective value I of the instantaneous output current from the instantaneous output current i out , repeatedly extract the effective value I of the instantaneous output current according to a preset time period out,eff and combine them to obtain a set of sequences I of the effective values of the instantaneous output current out,eff , and use the fast Fourier transform to extract the phase angle φ of the main frequency component from the effective value I of the instantaneous output current out ; out,eff ; out, the formula is:

[0008]

[0009] where arctan is the arctangent function, and Imag(FFT(I out,eff )) is the imaginary part of the complex number part in the fast Fourier transform result, and Real(FFT(I out,eff ) is the real part of the complex number part in the fast Fourier transform result;

[0010] Step S30: Obtain the current transformer ratio K from the nameplate of the current transformer;

[0011] According to the instantaneous output current effective value sequence I out Calculate the average value of the instantaneous output current effective value

[0012] According to the current transformer ratio K and the average value of the current effective value Calculate the effective value I of the input current in,eff and the phase angle φ in :

[0013]

[0014] φ in = φ out + Δφ

[0015] where Δφ is the inherent phase shift of the current transformer, which is obtained from the nameplate of the current transformer;

[0016] Step S40: Set the dynamic threshold T threshold , compare the effective value I of the input current in,eff and the average value of the output current effective value difference ΔI, if the difference ΔI is greater than the dynamic threshold T threshold , it is determined that there is a risk of failure in the secondary circuit;

[0017] Step S50: After determining that there is a risk of failure in the secondary circuit, immediately trigger the open circuit prevention circuit switch, close the mechanical switch in parallel with the current transformer to short-circuit the secondary circuit of the current transformer, and at the same time send the status data of the current transformer to the background in JSON format.

[0018] Preferably, in step S10, the formula for calculating the instantaneous output current i out is: where R s is the resistance value of the sampling resistor.

[0019] Preferably, in step S10, the instantaneous voltage signal U outDigitized by a 12-bit digital-to-analog converter at a sampling rate of 10 kHz.

[0020] Preferably, in step S10, the effective value I of the output current out,eff The extraction formula is:

[0021]

[0022] Where N is the number of sampling points.

[0023] Preferably, in step S40, the dynamic threshold T threshold The calculation formula is:

[0024] T threshold = T base ·(1 + α·e -βt )

[0025] Where T base Is the basic threshold, determined according to the type of current transformer; α and β are environmental correction factors, and t is the time elapsed since the last dynamic threshold calibration.

[0026] Preferably, in step S50, a short-circuit resistance R is set in the open-circuit prevention circuit short , and the size of the short-circuit resistance is determined according to the output voltage U out And the preset safety current value I safe Determine

[0027] Preferably, in step S50, the status data includes the effective value difference and phase difference between the input and output currents, environmental parameters, the switch state of the open-circuit prevention circuit, and the device identification information of the current transformer.

[0028] The present invention also provides a current transformer status monitoring system, including:

[0029] A current acquisition module, used to set a sampling resistor at the output end of the current transformer, acquire the instantaneous voltage signal U out On the sampling resistor, and calculate the instantaneous output current i out According to the sampling resistor and the instantaneous voltage signal U out ;

[0030] A signal processing module, used to extract the effective value I of the instantaneous output current from the instantaneous output current i out , repeatedly extract the effective value I of the instantaneous output current according to a preset time period out,eff And combine to obtain a set of effective value sequences I of the instantaneous output current out,eff , and use the fast Fourier transform to extract the phase angle φ of the main frequency component from the effective value I of the instantaneous output current out In out,eff Extractout , the formula is:

[0031]

[0032] where arctan is the arctangent function, and Imag(FFT(I out,eff )) is the imaginary part of the complex number part in the fast Fourier transform result, and Real(FFT(I out,eff ) is the real part of the complex number part in the fast Fourier transform result;

[0033] An input calculation module, configured to obtain the current transformer ratio K from the nameplate of the current transformer;

[0034] According to the instantaneous output current effective value sequence I out Calculate the average value of the instantaneous output current effective value

[0035] According to the current transformer ratio K and the average value of the current effective value Calculate the effective value I of the input current in,eff and the phase angle φ in :

[0036]

[0037] φ in = φ out +Δφ

[0038] where Δφ is the inherent phase shift of the current transformer, which is obtained from the nameplate of the current transformer;

[0039] A risk judgment module, configured to set a dynamic threshold T threshold , compare the effective value I of the input current in,eff and the average value of the output current effective value The difference ΔI. If the difference ΔI is greater than the dynamic threshold T threshold , it is determined that there is a fault risk in the secondary circuit;

[0040] A protection trigger module, configured to immediately trigger the open circuit prevention circuit switch and close the mechanical switch connected in parallel with the current transformer to short-circuit the secondary circuit of the current transformer after determining that there is a fault risk in the secondary circuit, and at the same time send the status data of the current transformer to the background in JSON format.

[0041] The present invention also provides a current transformer status monitoring device, including a memory, a processor, and a current transformer status monitoring program stored on the memory and executable on the processor. When the current transformer status monitoring program is executed by the processor, the current transformer status monitoring method described above is implemented.

[0042] The present invention also provides a computer program product, including a current transformer status monitoring program, which implements the current transformer status monitoring method when executed by a processor.

[0043] The beneficial effects of the present invention are as follows: Compared with the prior art where it is impossible to accurately detect the status of the secondary circuit of a current transformer in real time in a complex environment, especially under conditions such as large current fluctuations and strong environmental interference, and it is impossible to achieve highly reliable fault identification and protection. Since the present application realizes rapid fault judgment of the current transformer status through dynamic thresholds and extraction of the phase of the main frequency component, it avoids problems such as damage to the transformer or system instability caused by secondary circuit faults, and improves the reliability and operation and maintenance efficiency of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0045] Figure 1 It is a schematic flowchart of the first embodiment of a current transformer status monitoring method of the present invention.

[0046] Figure 2 It is a schematic diagram of the device for a current transformer status monitoring method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0048] Embodiment 1: As Figure 1 shown, it is a schematic flowchart of the first embodiment of the current transformer status monitoring method of the present invention, and the first embodiment of the current transformer status monitoring method of the present invention is proposed.

[0049] In the first embodiment, the current transformer status monitoring method includes:

[0050] Step S10: Set a sampling resistor at the output end of the current transformer, and collect the instantaneous voltage signal U on the sampling resistor out , and according to the sampling resistor and the instantaneous voltage signal U outCalculate the instantaneous output current i out ;

[0051] It should be noted that the resistance value of the sampling resistor should be small enough to avoid imposing a significant burden on the secondary circuit, and at the same time meet the accuracy requirements of the measurement range. Usually, the value is between 0.1Ω and 1Ω. The temperature coefficient of the sampling resistor needs to be low to ensure that the error of the output current value under different working environments is controlled within 0.1%.

[0052] It can be understood that the instantaneous voltage signal is the real-time voltage value obtained across the sampling resistor. It is digitized using a high-resolution analog-to-digital converter, and its sampling frequency is generally set to 10kHz or higher to ensure that the fine characteristics of the 50Hz power frequency signal can be restored. By combining the measured instantaneous voltage signal with the resistance value of the sampling resistor, the instantaneous output current can be accurately calculated.

[0053] It should be understood that by collecting the current signal in real time through the sampling resistor, the digital processing of the current signal can be achieved efficiently and at low cost. At the same time, by combining high-frequency sampling and accurate calculation, the dynamic change characteristics of the current can be quickly restored, providing accurate data for subsequent effective value calculation and frequency analysis.

[0054] Step S20: Extract the effective value I of the instantaneous output current from the instantaneous output current i out , repeat the extraction of the effective value I of the instantaneous output current according to a preset time period out,eff and combine them to obtain a set of effective value sequences I of the instantaneous output current out,eff , use the fast Fourier transform to extract the phase angle φ of the main frequency component from the effective value I of the instantaneous output current out , the formula is: out,eff out

[0055]

[0056]

[0057] where arctan is the arctangent function, Imag(FFT(I out,eff )) is the imaginary part of the complex number part in the fast Fourier transform result, and Real(FFT(I out,eff ) is the real part of the complex number part in the fast Fourier transform result;

[0057] It should be noted that the extraction formula for the effective value I of the output current out,eff is:

[0058]

[0059] Among them, N is the number of sampling points, and the sampling frequency is generally 10 kHz. Using the fast Fourier transform (FFT) can efficiently extract the main frequency component of the signal, thereby obtaining the phase angle. This process has significant advantages for high-frequency accuracy and fast response.

[0060] It can be understood that extracting the phase angle of the main frequency component is to further judge the phase characteristics of the output signal of the current transformer. By calculating the phase of the main frequency component, the phase relationship between the current signal and the reference signal can be effectively reflected, which helps to accurately monitor the dynamic characteristics of the current.

[0061] It should be understood that the fast Fourier transform result provides the complete component information of the current signal in the frequency domain. Among them, the main frequency component is the core feature of the signal. By extracting the phase angle of the main frequency, harmonic and noise interference can be excluded, and the monitoring accuracy can be improved. At the same time, the arctangent function converts the ratio of the imaginary part to the real part into an angle in the complex plane, ensuring the scientificity and accuracy of the phase calculation.

[0062] For example, assume that the instantaneous output current i out (t) is a power frequency sine signal, and the formula is:

[0063] i out (t) = 5sin(2π·50t + π / 6). Through the root mean square calculation, the effective value I of the instantaneous output current is obtained out,eff = 5 A. Performing a fast Fourier transform on this signal, the fast Fourier transform result of the main frequency component is: FFT(i out (t)) = 5e jπ / 6 , where the imaginary part Imag(FFT(I out )) = 2.5, and the real part Real(FFT(I out )) = 4.33. Calculate the phase angle through the formula:

[0064]

[0065] Thus, the phase angle of the main frequency component is obtained as 30°. This phase information can be further used for the comparative analysis and fault judgment of the input and output signals of the current transformer, reflecting the technical effect of high-precision phase detection.

[0066] Step S30: Obtain the current transformer ratio K from the nameplate of the current transformer;

[0067] According to the sequence I of the effective values of the instantaneous output current out Calculate the average value of the effective values of the instantaneous output current

[0068] According to the current transformer ratio K and the average value of the current effective value Calculate the effective value I of the input current in,eff and the phase angle φ in :

[0069]

[0070] φ in = φ out + Δφ

[0071] where Δφ is the inherent phase shift of the current transformer and is obtained from the nameplate of the current transformer;

[0072] It should be noted that the turns ratio K of the current transformer is a rated parameter determined by the design of the transformer and is usually marked on the nameplate of the transformer. For example, K = 100:1 means that the ratio of the primary current to the secondary current is 100:1. During the measurement process, accurately obtaining and applying this parameter can effectively ensure the calculation accuracy of the input current. At the same time, the average value of the effective value of the instantaneous output current is obtained by calculating the mean value of the sampling points, and its formula is:

[0073]

[0074] where N is the number of sampling points. In addition, the phase shift Δφ is an inherent characteristic parameter of the current transformer, which is caused by the hysteresis loss of the iron core and the inductance characteristic, and is generally a fixed value within a small range, such as 1°. The specific value is marked on the nameplate or obtained through calibration tests.

[0075] It can be understood that by introducing the turns ratio K, the secondary current can be directly converted into the primary current, and this conversion method ensures the practicability and simplicity of the system. The calculation of the phase angle takes into account the inherent phase shift of the current transformer, which is due to the certain delay of the secondary current signal compared with the primary current signal. When calculating the phase angle of the input current, this part of the offset is added, which can accurately reflect the actual phase of the primary current.

[0076] Step S40: Set the dynamic threshold T threshold , compare the effective value I of the input current in,eff with the average value of the effective value of the output current to obtain the difference ΔI. If the difference ΔI is greater than the dynamic threshold T threshold , it is determined that there is a risk of failure in the secondary circuit;

[0077] It should be noted that the setting of the dynamic threshold is to improve the sensitivity and adaptability of the state judgment of the secondary circuit of the current transformer. Different from the traditional fixed threshold method, the dynamic threshold is adjusted in real time according to the environmental changes and operating conditions, and can accurately identify abnormal situations under complex conditions. The calculation formula of the dynamic threshold T threshold is:

[0078] T threshold = T base ·(1 + α·e -βt )

[0079] wherein, T base is the basic threshold value, which is determined according to the type of current transformer; α and β are environmental correction factors, and t is the time elapsed since the last dynamic threshold calibration;

[0080] Through this formula, the dynamic threshold can be adjusted according to the changes of time and external conditions, thus avoiding misjudgment and missed judgment.

[0081] It can be understood that by comparing the difference between the effective values of the input current and the output current, abnormal conditions in the secondary circuit can be quickly identified. A significant deviation between the effective values of the input and output currents usually indicates the possible existence of open circuit, short circuit or other fault risks in the secondary circuit. The introduction of the dynamic threshold effectively improves the robustness of fault judgment, especially in an environment with large current fluctuations or electromagnetic interference, and can significantly reduce system false alarms.

[0082] Step S50: After determining that there is a fault risk in the secondary circuit, immediately trigger the open - circuit prevention circuit switch, close the mechanical switch in parallel with the current transformer to short - circuit the secondary circuit of the current transformer, and at the same time send the status data of the current transformer to the background in JSON format.

[0083] It should be noted that the core purpose of this step is to quickly protect the current transformer and its connected equipment through the linkage action of the open - circuit prevention circuit and the mechanical switch when a fault occurs in the secondary circuit, avoiding damage to the equipment caused by excessive secondary voltage. This protection mechanism significantly improves the fault handling efficiency through automated response; meanwhile, the system will record the status data of the transformer in real - time and upload it to the background, facilitating remote monitoring and subsequent analysis by maintenance personnel.

[0084] It can be understood that when the secondary circuit is open - circuited, the output voltage of the current transformer will rise rapidly, which may cause insulation breakdown or equipment damage. The open - circuit prevention circuit is triggered immediately after the fault is determined, and the secondary circuit of the transformer is short - circuited by short - circuiting the mechanical switch, thereby limiting the further rise of the voltage and ensuring system safety. At the same time, by sending the status data to the background in JSON format, accurate recording of the fault location, time and status can be achieved, improving the efficiency of fault troubleshooting.

[0085] It should be understood that the design of the open - circuit prevention circuit combines the high reliability of the mechanical switch and the high sensitivity of the control unit, and can complete the short - circuit protection action at the millisecond level, minimizing the impact on the equipment. In addition, the JSON - format structured storage of the status data is convenient for system integration and remote operation, improving the maintenance efficiency.

[0086] In addition, a current transformer status monitoring system provided by the present invention adopts a current transformer status monitoring method in the above-mentioned embodiment, and can solve the technical problem of current transformer status monitoring. Compared with the prior art, the beneficial effects of the current transformer status monitoring system provided by the present invention are the same as those of the current transformer status monitoring method provided by the above-mentioned embodiment, and other technical features in the current transformer status monitoring system are the same as the features disclosed in the method of the above-mentioned embodiment, and will not be elaborated here.

[0087] The present invention provides a current transformer status monitoring device. Please refer to Figure 2, A current transformer status monitoring device includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute a current transformer status monitoring method in Embodiment 1 above. A current transformer status monitoring device in an embodiment of the present invention may include, but is not limited to, mobile terminals such as mobile phones, laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistant), PADs (Portable Application Description: tablet computers), PMPs (Portable Media Player: portable multimedia players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. A current transformer status monitoring device is merely an example and should not impose any limitations on the functions and usage scope of the embodiments of the present invention. A current transformer status monitoring device may include a processing device 1001 (such as a central processing unit, a graphics processing unit, etc.), which may perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM: Random Access Memory) 1004. In the RAM 1004, various programs and data required for the operation of a current transformer status monitoring device are also stored. The processing device 1001, the ROM 1002, and the RAM 1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems may be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 may allow a current transformer status monitoring device to communicate with other devices wirelessly or wiredly to exchange data. Although a current transformer status monitoring device with various systems is shown in the figure, it should be understood that it is not required to implement or have all the shown systems. More or fewer systems may be implemented or had alternatively.

[0088] The present invention also provides a computer program product, including a computer program which, when executed by a processor, implements the steps of a current transformer status monitoring method as described above. The computer program product provided by the present invention can solve the technical problem of current transformer status monitoring. Compared with the prior art, the beneficial effects of the computer program product provided by the present invention are the same as those of the current transformer status monitoring method provided by the above embodiment, and will not be elaborated herein.

[0089] In particular, according to the embodiments disclosed by the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, an embodiment disclosed by the present invention includes a computer program product which includes a computer program carried on a computer-readable medium, and the computer program includes program codes for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by a processing device 1001, it executes the above functions defined in the method of the embodiment disclosed by the present invention.

[0090] It should be understood that each part disclosed by the present invention can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0091] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A current transformer state monitoring method, characterized in that: Methods include: Step S10: Set a sampling resistor at the output end of the current transformer to collect the instantaneous voltage signal on the sampling resistor , according to the sampling resistance and instantaneous voltage signal Calculate the instantaneous output current ; Step S20: Output current from the instantaneous Extract the instantaneous output current effective value from , repeatedly extract the instantaneous output current effective value according to the preset time period And combine to get a set of instantaneous output current effective value sequence , use fast Fourier transform to extract the instantaneous output current effective value Extract the phase angle of the main frequency component from , the formula is: in, is the inverse tangent function, is the imaginary part of the complex number in the fast Fourier transform result, is the real part of the complex number in the fast Fourier transform result; Step S30: Obtain the current transformer transformation ratio K from the current transformer nameplate; According to the instantaneous output current effective value sequence Calculate the average value of the instantaneous output current effective value ; According to the current transformer ratio K and the average value of the current effective value Calculate the effective value of the input current and phase angle : in, is the inherent phase shift of the current transformer, obtained from the current transformer nameplate; Step S40: Setting a dynamic threshold , compare the effective value of the input current and the average value of the output current effective value Difference , if the difference Greater than dynamic threshold , it is determined that there is a risk of failure in the secondary circuit; among them, the dynamic threshold The calculation formula is: ,in, is the basic threshold value, which is determined according to the current transformer model; and is the environmental correction factor, is the time that has passed since the last dynamic threshold calibration; Step S50: After determining that there is a risk of failure in the secondary circuit, immediately trigger the open circuit prevention circuit switch, and close the mechanical switch in parallel with the current transformer to short-circuit the secondary circuit of the current transformer, and at the same time send the status data of the current transformer to the background in JSON format.

2. A current transformer state monitoring method according to claim 1, characterized in that: In step S10, the instantaneous output current The calculation formula is: ,in, is the resistance of the sampling resistor.

3. A current transformer state monitoring method as claimed in claim 1, characterized in that: In step S10, the instantaneous voltage signal The data is digitized by a 12-bit digital-to-analog converter at a sampling rate of 10kHz.

4. A current transformer state monitoring method as claimed in claim 1, characterized in that: In step S20, the output current effective value The extraction formula is: Where N is the number of sampling points.

5. A current transformer state monitoring method as claimed in claim 1, characterized in that: In step S50, a short circuit resistor is set in the open circuit prevention circuit. , the short-circuit resistance is determined by the instantaneous voltage signal And preset safe current value Sure .

6. A current transformer state monitoring method according to claim 1, characterized in that: In step S50, the status data includes the effective value difference and phase difference between the input and output currents, environmental parameters, the switch status of the open circuit prevention circuit, and the device identification information of the current transformer.

7. A current transformer status monitoring system, characterized in that: The current transformer state monitoring system comprises: The current acquisition module is used to set a sampling resistor at the output end of the current transformer and collect the instantaneous voltage signal on the sampling resistor. , according to the sampling resistance and instantaneous voltage signal Calculate the instantaneous output current ; Signal processing module for outputting current from instantaneous Extract the instantaneous output current effective value from , repeatedly extract the instantaneous output current effective value according to the preset time period And combine to get a set of instantaneous output current effective value sequence , use fast Fourier transform to extract the instantaneous output current effective value Extract the phase angle of the main frequency component from , the formula is: in, is the inverse tangent function, is the imaginary part of the complex number in the fast Fourier transform result, is the real part of the complex number in the fast Fourier transform result; An input calculation module is used to obtain the current transformer ratio K from the current transformer nameplate; According to the instantaneous output current effective value sequence Calculate the average value of the instantaneous output current effective value ; According to the current transformer ratio K and the average value of the current effective value Calculate the effective value of the input current and phase angle : in, is the inherent phase shift of the current transformer, obtained from the current transformer nameplate; Risk judgment module, used to set dynamic thresholds , compare the effective value of the input current and the average value of the output current effective value Difference , if the difference Greater than dynamic threshold , it is determined that there is a risk of failure in the secondary circuit; among them, the dynamic threshold The calculation formula is: ,in, is the basic threshold value, which is determined according to the current transformer model; and is the environmental correction factor, is the time that has passed since the last dynamic threshold calibration; The protection trigger module is used to immediately trigger the open circuit prevention circuit switch after determining that there is a risk of failure in the secondary circuit, and close the mechanical switch in parallel with the current transformer to short-circuit the secondary circuit of the current transformer, and at the same time send the status data of the current transformer to the background in JSON format.

8. A current transformer status monitoring device, characterized in that: The current transformer state monitoring device comprises: a memory, a processor and a current transformer state monitoring program stored in the memory and executable on the processor. When the current transformer state monitoring program is executed by the processor, the current transformer state monitoring method described in any one of claims 1 to 6 is implemented.

9. A computer program product, characterized in that The computer program product comprises a current transformer state monitoring program, and when the current transformer state monitoring program is executed by a processor, the current transformer state monitoring method according to any one of claims 1 to 6 is implemented.

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