Method for verifying the effectiveness of direct current arc current signal measurements

Abstract

A direct current arc current signal measurement effectiveness verification method mainly includes the following steps: collecting direct current arc current signals without inverter switch noise and / or mixed with inverter switch noise, and performing analog-to-digital conversion; setting a time window, calculating the current moving average value of the direct current arc current signal in each time window by removing the initial transient effect by using the moving average method, and taking the current moving average value as the mu of the normal distribution under each window, and further calculating the standard deviation sigma of the normal distribution; setting the dynamic threshold as k sigma; using the positive and negative deviations of the current moving average value mu and the dynamic threshold k sigma, setting the upper boundary of the threshold range as the sum of the current moving average value mu in each time window and the dynamic threshold k sigma, and the lower boundary as the difference between the current moving average value mu in each time window and the dynamic threshold k sigma; for the points corresponding to the instantaneous current values exceeding the threshold boundary, mark them as potential fault points.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power transmission and transformation equipment state measurement, in particular to a DC arc current signal measurement effectiveness verification method. BACKGROUND

[0002] In a DC system, due to the influence of environment and operating conditions, DC discharge may be caused for various reasons. The DC system fault arc problem is serious, and once the DC discharge develops into an arc, it is difficult to extinguish due to the absence of natural zero point of current.

[0003] Many manufacturers have developed DC arc detection devices, but the effectiveness verification still faces a series of problems. These effectiveness verification methods do not consider the actual working conditions of the DC system, and do not fully consider the interference of switch noise amplitude and frequency on the detection device, so the test method is not accurate. Therefore, a more comprehensive, comprehensive and practical verification method must be used to ensure that the verification is more accurate and reliable.

[0004] The information disclosed in the background section is only used to enhance the understanding of the background of the present application, and therefore can contain information that does not constitute prior art known to those skilled in the art. SUMMARY

[0005] In view of the deficiencies or defects of the prior art, a DC arc current signal measurement effectiveness verification method is provided, which can simulate the inverter switch noise of the DC system by changing the signal generator output signal characteristics. The steps are simple, easy to implement, low in cost, and have the advantages of easy change of noise signal and high accuracy of verification results.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] A DC arc current signal measurement effectiveness verification method comprises the following steps:

[0008] Collecting a DC arc current signal without inverter switch noise and / or mixed with inverter switch noise, and performing analog-to-digital conversion on it;

[0009] Pretreating the DC arc current signal after analog-to-digital conversion to obtain a DC arc current signal without initial transient effect;

[0010] Based on the premise that the signal fluctuation obeys normal distribution, define mu as the average value and sigma as the standard deviation. According to the 3 sigma principle, 68.27% of the data falls within mu±sigma, 95.45% of the data falls within mu±2sigma, and 99.73% of the data falls within mu±3sigma. Therefore, the dynamic threshold range is defined as mu±k sigma, where k is the threshold factor, and k takes the value of 2 or 3.

[0011] set a time window, adopt a moving average method to calculate the current moving average value of the direct current arc current signal in each time window, which is affected by the removal of the initial transient effect, and take it as the mu of the normal distribution under each window, and further calculate the standard deviation sigma of the normal distribution; set the dynamic threshold as k sigma;

[0012] By using the positive and negative deviations of the current moving average mu and the dynamic threshold k sigma, the upper boundary of the threshold range is set as the sum of the current moving average mu in each time window and the dynamic threshold k sigma, and the lower boundary is the difference between the current moving average mu in each time window and the dynamic threshold k sigma.

[0013] For the points corresponding to the transient current values exceeding the threshold boundary, mark them as potential fault points.

[0014] Preferably,

[0015] The threshold factor k is 2.

[0016] Preferably, the method further comprises the following steps:

[0017] Based on the minimum fault duration corresponding to the inverter preset by a plurality of previous experiments, filter the transient interference region with a duration less than the minimum fault duration, and keep other regions as potential effective fault regions.

[0018] Statistically count the total number of potential fault points in the potential effective fault region, and compare it with the fault point threshold preset by a plurality of previous experiments under the minimum fault duration condition. If the total number of points exceeds the fault point threshold, it is determined that there is a fault, otherwise it is determined that there is no fault.

[0019] Preferably, the method further comprises the following steps:

[0020] The noise signal is dynamically adjusted to simulate different switching frequencies and waveform characteristics of different inverters, and the output frequency and waveform type of the signal generator are changed, and the gain multiple of the power amplifier is changed to simulate the difference in noise intensity under different load conditions, bus voltage or inverter power level.

[0021] Compared with the prior art, the present application has the beneficial effects that the economic cost is low, and the previous method needs to replace the inverter to adjust the switching noise characteristics, and the present method can simulate the noise characteristics by changing the signal generator output signal.

[0022] The description is only a summary of the technical solutions of the present application, in order to make the technical means of the present application more clear and understandable, to the extent that the person skilled in the art can implement according to the content of the description, and in order to make the and other purposes, features and advantages of the present application more obvious and easy to understand, the following is an example of the specific embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0023] Various other advantages and benefits of the present application will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments, and are not to be considered as limiting of the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those of ordinary skill in the art. Moreover, the same reference numerals are used to represent the same parts throughout the drawings.

[0024] In the drawings:

[0025] Figure 1 For one embodiment, the flowchart of the method for verifying the effectiveness of the direct current arc current signal measurement disclosed by the present application is shown;

[0026] Figure 2 For another embodiment, the overall structure of the device on which the method is dependent is shown, wherein the device mainly includes three loops, namely a switch noise simulation loop, an arc loop and a sensing loop;

[0027] Figure 3 The schematic diagram of the simulation signal of the inverter switch noise is shown, when the inverter switch noise is clean, smooth and clear, the arc current waveform can more truly reflect the current characteristics of the direct current arc itself;

[0028] Figure 4 The schematic diagram of the simulation signal of the inverter switch noise is shown, when the inverter switch noise is clean, smooth and clear, the arc current waveform can more truly reflect the current characteristics of the direct current arc itself;

[0029] Figure 5 The schematic diagram of the simulation signal of the inverter switch noise is shown, when the inverter switch noise is clean, smooth and clear, the arc current waveform can more truly reflect the current characteristics of the direct current arc itself;

[0030] Figure 6 The schematic diagram of the simulation signal of the inverter switch noise is shown, when the inverter switch noise is clean, smooth and clear, the arc current waveform can more truly reflect the current characteristics of the direct current arc itself;

[0031] Figure 7A schematic diagram of the detection of a current signal mixed with 20 kHz frequency, 500 mA peak-peak, and 32 kHz frequency, 600 mA peak-peak inverter switching noise.

[0032] The application will be further explained with reference to the accompanying drawings and examples. DETAILED DESCRIPTION

[0033] The application will be further explained with reference to the accompanying drawings and examples.

[0034] It should be noted that certain terms have been used throughout the specification and claims which have been used for descriptive purposes only and thus should not be construed as limiting. It is intended that the description and examples be considered as illustrative only of the principles of the application. The scope of the application is indicated by the appended claims.

[0035] For the purpose of promoting an understanding of the principles of the application, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will, nevertheless, be understood that no limitation of the scope of the application is intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the application as described herein are contemplated as falling within the scope of the application.

[0036] For a better understanding of the application, Figures 1 to 7 A method for verifying the validity of a direct current arc current signal measurement is disclosed, comprising the following steps:

[0037] A direct current arc current signal without inverter switching noise and / or mixed with inverter switching noise (for example, 12 kHz frequency, 200 mA peak-peak inverter switching noise) is collected and analog-to-digital converted;

[0038] The analog-to-digital converted direct current arc current signal is pre-processed to obtain a direct current arc current signal without initial transient effect; for example, the signal within the initial 5-50 ms is ignored, or a sliding window average method is applied to eliminate the start-up impact;

[0039] Based on the premise that signal fluctuation obeys normal distribution, define μ as average value and σ as standard deviation, then according to 3σ principle, 68.27% data falls in μ±σ range, 95.45% data falls in μ±2σ range, and 99.73% data falls in μ±3σ range, thus define dynamic threshold range as μ±kσ, wherein k is threshold factor, k takes value 2 or 3;

[0040] For example, according to engineering practice, threshold factor k is 2 in most cases, thus preferably 2;

[0041] Set time window, adopt moving average method to calculate current moving average value of said direct current arc current signal removed from initial transient effect in each time window and take it as μ of normal distribution under each window, and further calculate standard deviation σ of normal distribution; set dynamic threshold as kσ;

[0042] Utilize positive and negative deviation of current moving average value μ and dynamic threshold kσ, set upper boundary of threshold range as sum of current moving average value μ in each time window and dynamic threshold kσ, and lower boundary as difference of current moving average value μ in each time window and dynamic threshold kσ;

[0043] For points corresponding to transient current value exceeding threshold boundary, mark them as potential fault points.

[0044] In another embodiment, to further improve reliability,

[0045] Based on minimum fault duration (for example 1ms) of the inverter corresponding to preset by pre-experiment, filter transient interference area with duration less than said minimum fault duration, and keep other areas as potential effective fault area;

[0046] Statistically count total point number of all potential fault points in potential effective fault area, and compare with fault point number threshold preset by pre-experiment under said minimum fault duration, if total point number exceeds fault point number threshold, determine that fault exists, otherwise determine that no fault exists.

[0047] For example, the direct current arc current signal measurement effectiveness verification method disclosed in the present application detects two kinds of direct current arc current signals mixed with 20kHz frequency, 500mA peak-peak value inverter switching noise and mixed with 32kHz frequency, 600mA peak-peak value inverter switching noise, and the results are as follows Figure 7The two signals actually exist faults and are detected as faults. In practical applications, there are many types of inverters, and the inverter switching noise waveforms, frequencies and peak-to-peak values generated by the inverters are different, so for a wider range of inverters, the time window, minimum fault duration, threshold factor and the like need to be determined by experiments to obtain different inverter switching noise interference conditions when the present application is applied.

[0048] In another embodiment, the following steps are further included:

[0049] The noise signal is dynamically adjusted to simulate different switching frequencies and waveform characteristics of different inverters, while the output frequency and waveform type of the signal generator are changed, and the gain multiple of the power amplifier is changed to simulate the difference in noise intensity under different load conditions, bus voltage or inverter power level.

[0050] For example, the switching frequencies and peak-to-peak noise of inverter models A and B are shown in Table 1:

[0051] .

[0052] It should be noted that when using inverter type A, the output frequency of the signal generator is set to 20 kHz, the waveform type is square wave, and the gain multiple of the power amplifier is changed to 1.5-3.0 to simulate different noise intensities under 1.0-3.6 kW non-inductive resistive load power changes, 193.5 V fixed bus voltage, and 0.5 A-1.0 A peak-to-peak value of low-power strings to high-power strings. When using inverter type B, the output frequency of the signal generator is set to 32 kHz, the waveform type is square wave, and the gain multiple of the power amplifier is changed to 2.2-2.5 to simulate the resonant characteristics of capacitive load, 193.5-450 V bus voltage fluctuation, and 0.6 A-0.7 A peak-to-peak value of 3.6 kW power level.

[0053] In another embodiment,

[0054] 1) According to the characteristics of the actual inverter switching noise signal, generate the inverter switching noise signal and the direct current arc current signal when the inverter switching noise signal fails through the signal generator, wherein the inverter switching noise waveform, peak-to-peak value and frequency parameters are determined according to the characteristics of the actual inverter switching noise signal, and the step motor of the arc generator is controlled to move the electrode rod at a set moving speed of 1 mm / s to adjust the electrode rod to move to 1 mm to generate a stable and repeatable direct current arc current signal when a fault occurs;

[0055] To verify the anti-interference and accuracy of the arc measurement of the 5kW photovoltaic inverter under full load conditions, a triangular wave with a peak-to-peak value of 200mA and a frequency of 12kHz is generated by adjusting the output of the signal generator according to the typical switching frequency range of the photovoltaic inverter (10kHz-30kHz) and the peak-to-peak value of the measured noise current data (up to 1%-5% of the rated current of the system). Based on signal compatibility, actual working condition coverage, and safety boundaries, the power amplifier gain can be adjusted in the range of 0.1 times to 10 times. For example, the power amplifier gain is set to 6 times, and the stepping motor of the arc generator is controlled to move the electrode rod at a set moving speed of 1mm / s, and the electrode rod is adjusted to move to 1mm to generate a stable and repeatable DC arc current signal under fault conditions. The inverter switching noise signal is simulated by adjusting the parameters of the signal generator, as shown in Figure 5 . The actual system inverter switching noise signal is as shown in Figure 6 .

[0056] 2) Start the oscilloscope acquisition function to record the DC arc current signal waveform output by the sensor (after converting the voltage to current through a non-inductive resistance load, through a current sensor) mixed with inverter switching noise;

[0057] For example, the wires of the arc circuit and the switching noise simulation circuit are simultaneously passed through a through-type current sensor, the sampling frequency of the oscilloscope is set to 100MS / s and the appropriate vertical / horizontal scale is set, the oscilloscope acquisition function is started, and the DC arc current signal waveform output by the sensor mixed with inverter switching noise is recorded, as shown in Figure 2 .

[0058] 3) Verify the measurement effectiveness: input the DC arc current signal mixed with inverter switching noise and the DC arc current signal without inverter switching noise into the arc fault detection algorithm respectively, obtain two kinds of judgment results corresponding to the two kinds of DC arc current signals, and compare the two kinds of judgment results with

[0059] In another embodiment, referring to Figure 2 , the present application discloses a device for performing a DC arc current signal measurement effectiveness verification method, comprising:

[0060] an arc circuit for generating a DC arc current signal, wherein the arc circuit comprises a DC power supply, a non-inductive resistance load R1 and an arc generator forming a first series circuit; the arc generator comprises an adjustable gap, a stepping motor and two electrode rods, wherein the two electrode rods comprise a fixed electrode rod and a movable electrode rod; the stepping motor is controlled to move the movable electrode rod to generate an arc signal between the two electrode rods; wherein each time the movable electrode rod is moved, the adjustable gap between the movable electrode rod and the fixed electrode rod changes accordingly;

[0061] a switch noise simulation circuit for simulating the high-frequency switch noise generated by the inverter, the switch noise simulation circuit comprising a power amplifier and a non-inductive resistance load R2 forming a second series circuit, and a signal generator connected to the power amplifier, wherein the signal generator outputs an inverter switch noise signal with a set waveform, frequency and peak-to-peak value, which is amplified by the power amplifier and then loaded into the non-inductive resistance load; wherein the second series circuit does not form a conductive loop with the first series circuit and is independent of each other;

[0062] a sensing circuit for collecting the DC arc current signal mixed with the inverter switch noise and recorded by an oscilloscope. For example, the sensing circuit comprises a current sensor and an oscilloscope connected to each other. The current sensor senses the current mixed with the inverter switch noise in a non-contact manner, i.e. the DC arc current signal mixed with the inverter switch noise, from both the first series circuit of the arc circuit and the second series circuit of the switch noise simulation circuit.

[0063] It should be noted that,

[0064] According to the UL1699B standard for DC arc generators, it includes an adjustable gap, a stepper motor and an electrode rod. In this example, the electrode rod is made of red copper, the gap distance is 1 mm, and the moving speed of the stepper motor is 1 mm / s. In the arc generator, the movement of the electrode can be controlled by the stepper motor, thereby generating a DC arc to provide an arc signal for verifying the effectiveness of the detection algorithm;

[0065] The non-inductive resistance load is used to avoid introducing additional inductive impedance at high frequency and to ensure that a pure resistance load is loaded, thereby truly simulating the performance of high-frequency noise on the non-inductive path.

[0066] The signal generator and the power amplifier can jointly simulate the high-frequency switch noise signals generated by different types of inverters.

[0067] In another embodiment,

[0068] The switch noise simulation circuit further comprises a through-type current sensor and an oscilloscope, the through-type current sensor simultaneously passing through the conductors of the arc circuit and the switch noise simulation circuit, so as to facilitate the sensing circuit to collect the DC arc current signal mixed with the inverter switch noise signal.

[0069] For this embodiment, the arc loop and the switch noise loop are two independent circuits in electricity, and there is no direct series or parallel element connection between them, the sensing loop realizes the magnetic coupling of the arc loop and the switch noise simulation loop through the physical structure of the through-type current sensor, and places the two key current paths of the arc loop and the switch noise simulation loop in the measurement range of the through-type current sensor at the same time, which is the key of the through-type current sensor output reflecting the superposition of the current signals of the two loops.

[0070] In another embodiment,

[0071] The through-type current sensor comprises a Hall coil or a Rogowski coil.

[0072] In another embodiment,

[0073] The set waveform comprises one or more combinations of a sine wave, a square wave or a triangular wave.

[0074] In another embodiment,

[0075] The power amplifier gain is adjustable to change the amplitude of the noise signal.

[0076] In another embodiment,

[0077] The electrode rod material is red copper.

[0078] In another embodiment,

[0079] The gap between the two electrode rods is 0.5-2mm, and the stepping motor moving speed is 0.1-2mm / s.

[0080] In another embodiment,

[0081] The frequency range of the switch noise signal is 1kHz-100kHz, and the peak-to-peak value range is 100mA-1A.

[0082] In another embodiment,

[0083] The sampling frequency of the sensing loop is 100MS / s.

[0084] In another embodiment,

[0085] The method or the device is applied to a photovoltaic system, an electric vehicle charging system and an energy storage system.

[0086] In another embodiment,

[0087] The output terminal of the signal generator is connected to the input terminal of the power amplifier through a coaxial cable, and the output terminal and the ground terminal of the power amplifier are connected to both ends of the non-inductive resistance load through wires, forming a closed loop of the noise signal.

[0088] In another embodiment,

[0089] In the arc circuit, the positive terminal of the DC power supply is connected to one end of the non-inductive resistance load through a wire, the other end of the non-inductive resistance load is connected to the end of the movable electrode rod of the arc generator through a wire, the end of the fixed electrode rod of the arc generator is connected to the negative terminal of the DC power supply through a wire, and a complete DC current path (i.e., the first series circuit described above) can be formed, wherein the DC arc is generated in the process of moving the movable electrode rod by controlling the adjustable gap between the front ends of the movable electrode rod and the fixed electrode rod.

[0090] In another embodiment,

[0091] The through-hole current sensor is connected in series with the oscilloscope as a current sensor.

[0092] Therefore, the current sensor can collect the DC arc current signal mixed with the inverter switching noise and display it on the oscilloscope.

[0093] In another embodiment,

[0094] The inverter switching noise signal and the DC arc current signal are generated, wherein the inverter switching noise waveform, the peak-to-peak value, and the frequency parameters are determined, and in this example, the peak-to-peak value of the noise waveform is determined to be 200 mA and the frequency is determined to be 12 kHz. According to the parameters, the output of the signal generator is adjusted to output an analog inverter switching noise signal, as shown in FIG. 4. The actual system inverter switching noise signal is shown in FIG. 5. The electrode is controlled to generate a DC arc current signal. For further reference, FIG. 6 shows that for the DC arc current signal mixed with 20 kHz noise and the DC arc current signal mixed with 32 kHz noise, the method disclosed by the present application can effectively identify faults. Figure 5 Figure 6 The inverter switching noise signal and the DC arc current signal are generated, wherein the inverter switching noise waveform, the peak-to-peak value, and the frequency parameters are determined, and in this example, the peak-to-peak value of the noise waveform is determined to be 200 mA and the frequency is determined to be 12 kHz. According to the parameters, the output of the signal generator is adjusted to output an analog inverter switching noise signal, as shown in FIG. 4. The actual system inverter switching noise signal is shown in FIG. 5. The electrode is controlled to generate a DC arc current signal. For further reference, FIG. 6 shows that for the DC arc current signal mixed with 20 kHz noise and the DC arc current signal mixed with 32 kHz noise, the method disclosed by the present application can effectively identify faults. Figure 7

[0095] ​​Further, the application simulates real arc fault scenarios by precisely controlling the electrode separation process, generating stable and repeatable DC arc current signals to provide real test inputs for detection algorithms. According to the design of UL1699B arc generator, it ensures that the experimental results have industry recognition and standardized basis. Easy to adjust and control, the stepper motor drive mode makes the parameters such as the timing, intensity and duration of arc generation controllable, which is conducive to the construction of structured test data set. The signal generator outputs noise signals with set waveform, frequency and amplitude; the power amplifier amplifies the noise signal and loads it to the non-inductive resistance load; the signal generator frequency (such as 1kHz~100kHz), peak-peak value (such as 100mA~1A) and power amplifier gain can be adjusted. Low-cost alternative inverter switching noise source: traditional method needs to replace different types of inverters to obtain different noise characteristics, which is high in cost and complex in operation; this method can flexibly simulate various inverter switching noise characteristics through signal generator + power amplifier.

[0096] Further, in the present application, the noise parameters are precisely controlled, supporting independent adjustment of noise waveform, frequency and amplitude, meeting the verification needs of detection algorithm robustness under different working conditions. The test efficiency and flexibility are improved, the noise type can be quickly switched without physical replacement of the equipment, the test cycle is shortened, and the verification efficiency is improved. The current signal is collected using a through-type current sensor (such as a Rogowski coil or a Hall coil); the arc loop and the noise simulation loop wires pass through the center of the sensor at the same time; and the mixed signal waveform is recorded using an oscilloscope. Signal mixing and acquisition: the arc signal and the switching noise signal are collected synchronously to simulate the coexistence of the two in the actual system current environment, improving the authenticity of the test. Non-invasive measurement: the through-type sensor does not change the circuit structure, avoids introducing additional interference, and ensures measurement accuracy. Strong compatibility: suitable for various types of arc detection algorithm input interfaces, facilitating algorithm integration and verification. Change the output frequency and waveform of the signal generator, adjust the gain of the power amplifier to change the noise amplitude; collect mixed signals under different noise conditions multiple times to comprehensively evaluate algorithm performance, simulate different actual operating environments through multiple noise parameter combinations, and test the stability and accuracy of the algorithm under complex electromagnetic interference. Enhance the credibility of the verification results, avoid accidental errors caused by single noise condition verification, and improve the scientificity and reliability of algorithm evaluation. Support algorithm optimization iteration to provide rich test data support for subsequent improvement of the detection algorithm, guide parameter adjustment and model optimization. The collected mixed signals are input into the arc detection algorithm to be verified; the arc fault detection algorithm output arc judgment result is recorded; the actual arc state and the algorithm judgment are compared, and the accuracy rate and other indicators are calculated. Quantitative evaluation of detection effect: by comparing the actual arc state and the algorithm recognition result, the detection accuracy, false positive rate, and false negative rate of the algorithm are objectively evaluated. Closed-loop verification mechanism: form a closed-loop process of "signal input-algorithm processing-result comparison" for automated testing and batch verification. Support algorithm selection and deployment decision: provide data basis for selecting the optimal detection algorithm in engineering applications, and promote the landing and transformation of the algorithm to the actual system.

[0097] The above describes the basic principles of the present application in conjunction with specific embodiments, but it should be noted that the advantages, advantages, effects, etc. mentioned in the present application are only examples and not limitations, and these advantages, advantages, effects, etc. cannot be considered as the must-have of each embodiment of the present application. In addition, the above specific details are only for the purpose of example and for the purpose of understanding, and are not limited to the above specific details to realize the present application.

[0098] The above description has been given for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although the above has discussed a plurality of example aspects and embodiments, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for verifying the validity of DC arc current signal measurement, characterized in that, The method comprises the following steps: Collecting a direct current arc current signal without inverter switch noise and / or with inverter switch noise mixed in, and performing analog-to-digital conversion thereon; Performing preprocessing on the direct current arc current signal after analog-to-digital conversion to obtain a direct current arc current signal with the influence of initial transient effect removed; Based on the premise that signal fluctuation obeys normal distribution, μ is the mean value, and σ is the standard deviation, according to the 3σ principle, 68.27% of the data falls within μ±σ, 95.45% of the data falls within μ±2σ, and 99.73% of the data falls within μ±3σ, and thus, the dynamic threshold range is defined as μ±kσ, wherein k is a threshold factor, and k takes the value of 2 or 3; Setting a time window, calculating the current moving average of the direct current arc current signal in each time window by using the moving average method, and taking the current moving average as the μ of the normal distribution under each window, and further calculating the standard deviation σ of the normal distribution; and setting the dynamic threshold as kσ; Using the positive and negative deviations of the current moving average μ and the dynamic threshold kσ, setting the upper boundary of the threshold range as the sum of the current moving average μ in each time window and the dynamic threshold kσ, and the lower boundary as the difference between the current moving average μ in each time window and the dynamic threshold kσ; For the points corresponding to the transient current values exceeding the threshold boundary, mark them as potential fault points.

2. The method according to claim 1, characterized in that, The threshold factor k is 2.

3. The method of claim 1, wherein, Further comprising the following steps: Based on the minimum fault duration corresponding to the inverter preset by a plurality of previous experiments, filtering transient interference regions with a duration less than the minimum fault duration, and retaining other regions as potential effective fault regions; Counting the total number of potential fault points in the potential effective fault regions, and comparing the total number of points with the fault point threshold preset by a plurality of previous experiments under the minimum fault duration condition, if the total number of points exceeds the fault point threshold, it is determined that there is a fault, otherwise, it is determined that there is no fault.

4. The method of claim 1, wherein, Further comprising the following steps: Dynamically adjusting the noise signal to simulate different switching frequencies and waveform characteristics of different inverters, simultaneously changing the output frequency and waveform type of the signal generator, and changing the gain multiple of the power amplifier to simulate the difference in noise intensity under different load conditions, bus voltage or inverter power level.

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