METHOD AND DEVICE FOR STRANGE ARR DETECTION AND BUILDING ELEMENT

Abstract

Method and apparatus for arc fault detection and component. The method comprises: obtaining a preset arc fault characteristic value calculated on the basis of a collected DC-side signal from an inverter (S11); obtaining an initial characteristic threshold value (S12); determining whether a presumed arc is present, according to the magnitude relationship between the preset arc fault characteristic value and the initial characteristic threshold value (S13); if so, performing a shaft sealing operation on the inverter and determining, at least on the basis of an electrical signal from the inverter after the shaft sealing operation has been performed on it, an arc fault detection result corresponding to the presumed arc (S14), wherein the arc fault detection result includes a true arc or a false arc;and, based on the arc detection result, setting an initial threshold to obtain a target threshold and updating the initial feature threshold to the target threshold (S15). That is, in this procedure, the initial feature threshold used can be adjusted according to the arc detection result of the actually detected suspected arc, so that the initial feature threshold better matches an actual application environment and the accuracy of the initial feature threshold is improved, thereby improving the accuracy of the arc fault detection.

Description

Arc fault detection method, device and equipment

[0001] This application claims priority to a domestic application filed with the Patent Office of China on April 21, 2022, with application number CN202210421305.4 and invention name “A method, device and equipment for arc fault detection”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the field of arc detection, and more particularly to an arc fault detection method, device and equipment. Background Art

[0003] Arcing is a gas discharge phenomenon. In photovoltaic systems, once a fault arc occurs, if effective protective measures are not taken, the high temperature generated by the continuous DC arc can easily cause a fire and lead to major safety accidents.

[0004] To prevent arc faults, arc fault detection technology is often used. During detection, features are extracted and compared with feature thresholds to determine whether an arc fault has occurred.

[0005] In practical applications, the characteristic threshold is generally a fixed threshold. When the characteristic threshold is used for arc fault detection, false alarms or missed alarms are likely to occur, and the arc fault detection accuracy is low.

[0006] Summary of the Invention

[0007] In view of this, the present invention provides an arc fault detection method, apparatus and device to solve the problem of low arc fault detection accuracy.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] An arc fault detection method, comprising:

[0010] Obtaining a preset arc characteristic value calculated based on the acquired DC side signal of the inverter;

[0011] Obtaining an initial characteristic threshold, and determining whether a suspected arc occurs based on a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold;

[0012] If so, performing a wave-sealing operation on the inverter, and determining an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave-sealing operation; the arc detection result includes a real arc or a false arc;

[0013] Based on the arc detection result, the initial threshold is adjusted to obtain a target threshold, and the initial feature threshold is updated to the target threshold.

[0014] Optionally, obtaining a preset arc characteristic value calculated based on the acquired DC side signal of the inverter includes:

[0015] Acquire a DC side signal of the inverter, and extract an AC signal from the DC side signal;

[0016] Performing fast Fourier analysis on the AC signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.

[0017] Optionally, performing fast Fourier analysis on the AC signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic includes:

[0018] Performing fast Fourier analysis on the AC signal to obtain an analysis result;

[0019] Acquire a preset arc feature, wherein the preset arc feature includes at least one of a mean value, a root mean square value, a variance, and a kurtosis;

[0020] Based on the analysis result, a preset arc characteristic value corresponding to the preset arc characteristic is calculated according to the characteristic calculation method of the preset arc characteristic.

[0021] Optionally, judging whether a suspected arc occurs according to a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold value includes:

[0022] When the preset arc characteristic value is greater than the initial characteristic threshold, it is determined that a suspected arc occurs.

[0023] Optionally, determining an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave blocking operation includes:

[0024] Acquiring an electrical signal after the inverter performs a wave-sealing operation;

[0025] If the value of the electrical signal is zero, determining that the arc detection result is a real arc;

[0026] If the value of the electrical signal is not zero, obtaining a DC signal in the DC side signal;

[0027] In a case where the value of the DC signal is the same as the value of the electrical signal, it is determined that the arc detection result is a false arc.

[0028] Optionally, adjusting the initial threshold based on the arc detection result to obtain a target threshold includes:

[0029] When the arc detection result is a real arc, reducing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold;

[0030] In the case that the arc detection result is a false arc, the value of the initial characteristic threshold is increased according to a preset threshold increment calculation rule to obtain a target threshold.

[0031] Optionally, it also includes:

[0032] Obtaining the grid-connected time of the inverter;

[0033] Calculating a threshold increment corresponding to the grid connection time;

[0034] The sum or difference between the initial feature threshold and the threshold increment is used as the target threshold.

[0035] Optionally, calculating the threshold increment corresponding to the grid connection time includes:

[0036] A threshold increment calculation formula is obtained, and based on the threshold increment calculation formula, a threshold increment corresponding to the grid connection time is calculated.

[0037] Optionally, after determining an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave blocking operation, the method further includes:

[0038] When the arc detection result is a real arc, the inverter is controlled to perform a shutdown operation and arc fault information is output.

[0039] Optionally, the numerical value of the characteristic threshold reference value corresponding to the initial characteristic threshold is configured as a preset threshold; the preset threshold is a numerical value that makes the arc detection sensitivity greater than the preset sensitivity.

[0040] An arc fault detection device, comprising:

[0041] A characteristic value acquisition module is used to obtain a preset arc characteristic value calculated based on the acquired DC side signal of the inverter;

[0042] an arc judgment module, configured to obtain an initial characteristic threshold and determine whether a suspected arc occurs based on a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold;

[0043] an arc detection module, configured to, if yes, perform a wave-sealing operation on the inverter, and determine an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave-sealing operation; the arc detection result includes a real arc or a false arc;

[0044] A threshold adjustment module is used to adjust the initial threshold based on the arc detection result to obtain a target threshold, and update the initial feature threshold to the target threshold.

[0045] An electronic device comprising: a memory and a processor;

[0046] Wherein, the memory is used to store programs;

[0047] The processor calls the program and is used to execute the above arc fault detection method.

[0048] An inverter includes the above-mentioned electronic device.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The present invention provides an arc fault detection method, device and equipment, which obtains a preset arc characteristic value calculated based on the collected DC side signal of the inverter, obtains an initial characteristic threshold, and judges whether a suspected arc occurs based on the size relationship between the preset arc characteristic value and the initial characteristic threshold. If so, a wave sealing operation is performed on the inverter, and an arc detection result corresponding to the suspected arc is determined based on at least the electrical signal of the inverter after the wave sealing operation; the arc detection result includes a real arc or a false arc, and based on the arc detection result, the initial threshold is adjusted to obtain a target threshold, and the initial characteristic threshold is updated to the target threshold. That is, in the present invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the suspected arc actually detected, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, thereby improving the accuracy of arc fault detection and reducing the probability of false alarms and missed alarms. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] FIG1 is a flow chart of an arc fault detection method provided by an embodiment of the present invention;

[0053] FIG2 is a schematic diagram of an inverter scenario provided by an embodiment of the present invention;

[0054] FIG3 is a flow chart of another arc fault detection method provided by an embodiment of the present invention;

[0055] FIG4 is a flow chart of another arc fault detection method provided by an embodiment of the present invention;

[0056] FIG5 is a flow chart of another arc fault detection method provided by an embodiment of the present invention;

[0057] FIG6 is a flow chart of a fifth arc fault detection method provided by an embodiment of the present invention;

[0058] FIG7 is a schematic structural diagram of an arc fault detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. It should be understood that the described embodiments are merely a portion of the embodiments of the present invention, and not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0060] To prevent arc-induced faults, arc fault detection technologies, such as DC arc detection, are often used. During detection, features are extracted and compared with feature thresholds to determine whether an arc fault has occurred.

[0061] In practical applications, the characteristic threshold is generally a fixed threshold. When the characteristic threshold is used for arc fault detection, false alarms or missed alarms are likely to occur, and the arc fault detection accuracy is low.

[0062] To address the low arc fault detection accuracy caused by fixed thresholds, the characteristic threshold can be adaptively adjusted based on historical time-frequency domain features. However, due to the complexity of actual power plant environments and the diverse variations in weather and temperature, adaptively adjusting the characteristic threshold makes it difficult to balance high-precision arc detection with the ability to prevent false alarms. If the threshold is set low, the detection sensitivity is high, which often leads to false alarms in operating conditions such as sudden changes in inverter power due to sunlight or sudden changes in time-frequency domain features due to environmental noise interference. If the threshold is set high, the detection sensitivity is low, which often leads to missed alarms in arcing conditions with relatively subtle changes in time-frequency domain features.

[0063] Therefore, in order to improve the arc detection rate, ensure the safe and reliable operation of the power station system, and effectively prevent invalid false alarms, it is necessary to reasonably determine the value of the characteristic threshold.

[0064] To this end, an embodiment of the present invention provides an arc fault detection method, device, and electronic device, which obtains a preset arc characteristic value calculated based on the collected DC side signal of the inverter, obtains an initial characteristic threshold, and determines whether a suspected arc occurs based on the size relationship between the preset arc characteristic value and the initial characteristic threshold. If so, a wave sealing operation is performed on the inverter, and an arc detection result corresponding to the suspected arc is determined based on at least the electrical signal of the inverter after the wave sealing operation; the arc detection result includes a real arc or a false arc, and based on the arc detection result, the initial threshold is adjusted to obtain a target threshold, and the initial characteristic threshold is updated to the target threshold. That is, in the present invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the suspected arc actually detected, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, thereby improving the accuracy of arc fault detection and reducing the probability of false alarms and missed alarms.

[0065] Based on the above, an embodiment of the present invention provides an arc fault detection method, referring to FIG1 , which may include:

[0066] S11. Obtaining a preset arc characteristic value calculated based on the acquired DC side signal of the inverter.

[0067] 2 shows a schematic diagram of a photovoltaic system, which includes a photovoltaic string (connected by at least one photovoltaic module) and an inverter (such as a photovoltaic inverter). There is at least one photovoltaic string and inverter.

[0068] The inverter is connected to the power grid and the load via an L / N connection line. An arc detection device is provided inside the inverter, and the arc detection device executes the arc fault detection method in this embodiment.

[0069] When the inverter is first connected to the grid, the characteristic threshold built into the arc detection device is the characteristic threshold reference value, and the value of the characteristic threshold reference value is configured as a preset threshold value. The preset threshold value is a value that makes the arc detection sensitivity greater than the preset sensitivity.

[0070] In practical applications, the preset threshold is a relatively low value (eg, 10), that is, the initial arc detection sensitivity is relatively high.

[0071] During the operation of the inverter, a detection cycle can be set, which can generally be 3 milliseconds or 5 milliseconds, depending on the actual scenario. In each detection cycle, a preset arc characteristic value calculated based on the collected DC side signal of the inverter is obtained. Specifically, referring to Figure 3, "obtaining a preset arc characteristic value calculated based on the collected DC side signal of the inverter" may include:

[0072] S21 . Acquire a DC side signal of the inverter, and extract an AC signal from the DC side signal.

[0073] Specifically, during the DC arc detection process, the arc detection device collects the DC side signal of the inverter in real time. The DC side signal includes a DC signal and an AC signal. The DC signal may include data such as the DC current value.

[0074] In this embodiment, it is necessary to extract the AC signal from the DC side signal.

[0075] S22. Perform fast Fourier analysis on the AC signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.

[0076] Specifically, by performing fast Fourier analysis on the AC signal, the signal strength at each frequency point can be obtained, and the signal strength at each frequency point forms a frequency domain graph. The frequency domain graph is the analysis result obtained by performing fast Fourier analysis on the AC signal.

[0077] Then, a preset arc feature is obtained. The obtained preset arc feature may include at least one of a mean value, a root mean square value, a variance, and a kurtosis. In addition, other arc features may be added according to actual needs.

[0078] Each preset arc feature has a corresponding feature calculation method, such as the mean value is the average value of the signal strength at each frequency point. Other preset arc features are similar.

[0079] Then, the preset arc characteristic value corresponding to the preset arc characteristic can be calculated based on the above analysis result, that is, the frequency domain diagram, in accordance with the characteristic calculation method of the preset arc characteristic.

[0080] For example, the average value of the signal strength at each frequency point is taken as the mean value, and the root mean square value of the signal strength at each frequency point is taken as the root mean square value.

[0081] That is, obtaining a preset arc feature, and calculating a preset arc feature value corresponding to the preset arc feature based on the frequency domain diagram, including:

[0082] A preset arc feature is obtained, where the preset arc feature includes at least one of a mean value, a root mean square value, a variance, and a kurtosis.

[0083] According to the characteristic calculation method of the preset arc characteristic, based on the frequency domain diagram, a preset arc characteristic value corresponding to the preset arc characteristic is calculated.

[0084] S12. Obtain an initial feature threshold.

[0085] In this embodiment, if the inverter has just been connected to the grid and the arc detection device has not yet performed arc fault detection, the initial characteristic threshold is the above-mentioned characteristic threshold reference value, such as 10.

[0086] If the arc detection device has already performed arc fault detection, the initial characteristic threshold is the characteristic threshold at the end of the previous detection cycle. At this point, the initial characteristic threshold reference value is still configured as the preset threshold, meaning that the characteristic threshold is retroactively reset, with the first characteristic threshold being the characteristic threshold reference value. In other words, the characteristic threshold reference value corresponding to the initial characteristic threshold is configured as the preset threshold; the preset threshold is the value that makes the arc detection sensitivity greater than the preset sensitivity.

[0087] S13, determine whether a suspected arc occurs; if so, execute step S14; if not, return to step S11 and continue monitoring the current side signal.

[0088] Specifically, whether a suspected arc occurs is determined based on the magnitude relationship between the preset arc characteristic value and the initial characteristic threshold.

[0089] Specifically, if the preset arc characteristic value is greater than the initial characteristic threshold, it is determined that a suspected arc has occurred. If the preset arc characteristic value is not greater than the initial characteristic threshold, it is determined that no suspected arc has occurred, and step S11 is continued, i.e., the current side signal is continuously monitored.

[0090] S14. Perform a wave-sealing operation on the inverter, and determine an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave-sealing operation.

[0091] The arc detection result includes a real arc or a false arc, that is, determining whether the suspected arc is a real arc or a false arc.

[0092] Specifically, a blocking instruction is sent to the inverter to enable the inverter to perform a blocking operation.

[0093] After the wave blocking operation is performed, the secondary arc judgment is performed. At this time, the DC side signal of the inverter is collected and the DC current is extracted from it as an electrical signal. Then, based on the electrical signal, it is determined whether the suspected arc is a real arc or a false arc.

[0094] In detail, referring to FIG. 4 , “determining an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave blocking operation” may include:

[0095] S31. Acquire an electrical signal after the inverter performs a wave-sealing operation.

[0096] The electrical signal may include a DC input value, and the specific acquisition process can refer to the corresponding description above.

[0097] S32. Determine whether the value of the electrical signal is zero; if it is zero, execute step S33; if it is not zero, execute step S34.

[0098] Specifically, the inverter performs a blocking operation, which closes the energy transmission channel between the DC side and the AC side. (The blocking time is in milliseconds, for example, 200ms.)

[0099] If a real arc occurs, the arc will be extinguished due to the closure of the energy transmission channel during the wave closure period, and a gap will be generated where the arc occurs (the arc is formed by the electrolysis of air, and the energy transmission is cut off, the arc is extinguished, and a gap is generated where the arc starts)), resulting in a circuit break. The channel cannot be connected to the grid again, so the current in the channel where the arc occurs after the wave closure is 0.

[0100] If a false arc occurs, the corresponding channel can be reconnected to the grid after the wave is blocked, and the current will quickly return to the value before the wave is blocked. (False arcs are caused by high-frequency harmonic interference, etc., and the wave blocking operation will not affect the inverter's ability to reconnect to the grid.)

[0101] S33. Determine that the arc detection result is a real arc.

[0102] That is, the suspected arc is a real arc.

[0103] S34. Acquire a DC signal from the DC side signal.

[0104] Specifically, it can be extracted from the DC side signal in step S11. Generally, the DC current value in the DC signal is extracted.

[0105] S35 . When the value of the DC signal is the same as the value of the electrical signal, determine that the arc detection result is a false arc.

[0106] The above DC current value is the same as the current input value, that is, the corresponding channel can be connected to the grid again after the wave is blocked, and the current will quickly recover to the value before the wave is blocked, which means that the suspected arc is a false arc.

[0107] It should be noted that, in this embodiment, the judgment between a false arc and a real arc is performed based on the current value. In addition, the judgment between a false arc and a real arc can also be performed based on the power value.

[0108] S15. Based on the arc detection result, adjust the initial threshold to obtain a target threshold, and update the initial feature threshold to the target threshold.

[0109] Specifically, step S15 includes:

[0110] 1) When the arc detection result is a real arc, the value of the initial characteristic threshold is reduced according to a preset threshold increment calculation rule to obtain a target threshold.

[0111] 5 , according to the preset threshold increment calculation rule, reducing the value of the initial feature threshold to obtain the target threshold may include:

[0112] S41: Obtain the grid-connected time of the inverter.

[0113] Specifically, the grid-connected time of the inverter refers to the time the inverter is connected to the grid.

[0114] S42: Calculate a threshold increment corresponding to the grid connection time.

[0115] In practical applications, when calculating the threshold increment, a corresponding threshold increment calculation formula is set.

[0116] In this embodiment, there are three threshold increment calculation formulas, and one can be selected for use according to the actual scenario.

[0117] 1. The calculation formula for the threshold increment is:

[0118]

[0119] Where ΔT and t represent the threshold increment and grid connection time, respectively. The grid connection time is generally the total number of grid connection hours. In this embodiment, the threshold increment calculation formula is an inverse function. The threshold increment decays with the total grid connection time; that is, the longer the grid connection time, the smaller the threshold increment. In the inverse function form, the threshold increment first changes rapidly and then slowly with the grid connection time.

[0120] For example, if a false arc occurs when the inverter is connected to the grid for 0.1 h, then ΔT = 1 / 0.1 = 10.

[0121] 2. The calculation formula for the threshold increment is:

[0122]

[0123] Wherein, ΔT and t represent the threshold increment and the grid connection time, respectively. In this embodiment, the threshold increment calculation formula is in the form of an exponential function, in which the threshold increment changes slowly with the grid connection time.

[0124] 3. The calculation formula for the threshold increment is:

[0125]

[0126] Wherein, ΔT and t represent the threshold increment and grid connection time, respectively. In this embodiment, the threshold increment calculation formula is in the form of a Gaussian function, in which the threshold increment changes first slowly, then quickly, and then slowly again with the grid connection time.

[0127] After obtaining the threshold value increment calculation formula, the threshold value increment corresponding to the obtained grid connection time is calculated based on the threshold value increment calculation formula.

[0128] S43. Taking the difference between the initial feature threshold and the threshold increment as the target threshold.

[0129] In this embodiment, when a real arc is detected, it means that the initial feature threshold used at this time has the ability to identify the real arc, but there is still room for optimization between the initial feature threshold and the threshold for false alarms of false arcs. At this time, you can try to negatively correct the current feature threshold to further improve the ability to identify real arcs, improve the arc detection rate, and prevent the omission of weak arcs.

[0130] Then, the difference between the initial feature threshold and the threshold increment is used as the target threshold.

[0131] For example, if a real arc occurs when the inverter is connected to the grid for 1 hour, the threshold value is corrected to:

[0132] T=T-ΔT=22-1=21

[0133] Where T is the target threshold.

[0134] 2) When the arc detection result is a false arc, the value of the initial characteristic threshold is increased according to a preset threshold increment calculation rule to obtain a target threshold.

[0135] In this embodiment, when the arc detection result is a false arc, it means that a false arc is detected, which means that the initial characteristic threshold used at this time is too sensitive and has poor anti-interference ability, and does not have the ability to identify interference signals and real arcs. Therefore, the current initial characteristic threshold can be positively corrected to improve the anti-interference ability and reduce the false alarm of the arc.

[0136] 6 , according to the preset threshold increment calculation rule, increasing the value of the initial feature threshold to obtain the target threshold may include:

[0137] S51: Obtain the grid-connected time of the inverter.

[0138] S52: Calculate a threshold increment corresponding to the grid connection time.

[0139] For the specific implementation process of these two steps, please refer to the corresponding instructions above.

[0140] S53: Taking the sum of the initial feature threshold and the threshold increment as the target threshold.

[0141] This step differs from the previous step in that, when the suspected arc is a real arc, the difference between the initial characteristic threshold and the threshold increment is used as the target threshold, i.e., a negative threshold correction method is used. When the suspected arc is a false arc, the sum of the initial characteristic threshold and the threshold increment is used as the target threshold, and a positive threshold correction method is used.

[0142] For example, if the initial characteristic threshold is 10 and a false arc occurs 0.1 hours after the inverter is connected to the grid, the threshold is adjusted to T = T + ΔT = 10 + 10 = 20. If a false arc occurs again 0.5 hours after the inverter is connected to the grid, the threshold is adjusted to T = T + ΔT = 20 + 2 = 22. Here, T is the target threshold.

[0143] After the target threshold is obtained, the initial characteristic threshold is updated to the target threshold, and then in the next detection cycle, the new initial characteristic threshold is used to perform arc detection.

[0144] It should be noted that in this embodiment, the target threshold is determined based on the grid connection time after a suspected arc is detected. Alternatively, an implementation method may be to obtain the initial characteristic threshold directly during the inverter grid connection operation without detecting a suspected arc, and then determine the target threshold based on the grid connection time.

[0145] That is, the arc fault detection method in the present invention further includes:

[0146] The grid-connected time of the inverter is obtained, a threshold increment corresponding to the grid-connected time is calculated, and the sum or difference between the initial characteristic threshold and the threshold increment is used as a target threshold.

[0147] The process of calculating the threshold increment corresponding to the grid connection time is described with reference to the above corresponding description.

[0148] In another embodiment of the present invention, after determining the arc detection result corresponding to the suspected arc based on at least the electrical signal of the inverter after the wave blocking operation, the method further includes:

[0149] When the arc detection result is a real arc, the inverter is controlled to perform a shutdown operation and arc fault information is output.

[0150] Specifically, if the arc detection result is a true arc, continuing to operate the inverter can easily cause the arc that was extinguished by the blocking wave to re-ignite, posing a continuing arc hazard and potentially damaging the inverter or PV panels, or even causing a major fire. In this case, the inverter can be shut down and an arc fault message can be output, allowing maintenance personnel to promptly perform fault repairs.

[0151] Alternatively, after determining the target threshold, the inverter can be shut down and arc fault information can be output. The specific operation sequence can be set based on the actual scenario. However, to protect the inverter from burning, the inverter can be shut down after determining that a true arc has occurred.

[0152] In this embodiment, a preset arc characteristic value calculated based on the collected DC side signal of the inverter is obtained, an initial characteristic threshold is obtained, and based on the size relationship between the preset arc characteristic value and the initial characteristic threshold, it is determined whether a suspected arc occurs. If so, a wave sealing operation is performed on the inverter, and the arc detection result corresponding to the suspected arc is determined based on at least the electrical signal of the inverter after the wave sealing operation; the arc detection result includes a real arc or a false arc, and based on the arc detection result, the initial threshold is adjusted to obtain a target threshold, and the initial characteristic threshold is updated to the target threshold. That is, in the present invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the suspected arc actually detected, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, thereby improving the accuracy of arc fault detection and reducing the probability of false alarms and missed alarms.

[0153] Furthermore, the present invention presets an initial characteristic threshold value during initial grid connection. This threshold value is then optimized using a threshold increment function, combined with the arc detection device and the inverter's overall determination of true and false arcs. The resulting threshold parameters are optimally adapted to the diverse operating conditions of each inverter, including the power plant environment, climate, and temperature.

[0154] In addition, the present invention greatly reduces inappropriate threshold selection during the normal operation of the inverter by eliminating false alarms during the large-scale threshold optimization process during the first grid connection and achieving optimal threshold optimization, thereby improving arc recognition capabilities and avoiding frequent false alarms caused by periodic interference.

[0155] Optionally, based on the embodiment of the arc fault detection method described above, another embodiment of the present invention provides an arc fault detection device, which, referring to FIG. 7 , may include:

[0156] A characteristic value acquisition module 11 is used to obtain a preset arc characteristic value calculated based on the collected DC side signal of the inverter;

[0157] The arc judgment module 12 is used to obtain an initial characteristic threshold and determine whether a suspected arc occurs based on the relationship between the preset arc characteristic value and the initial characteristic threshold;

[0158] an arc detection module 13 configured to, if yes, perform a wave-sealing operation on the inverter and determine an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave-sealing operation; the arc detection result may include a real arc or a false arc;

[0159] The threshold adjustment module 14 is configured to adjust the initial threshold based on the arc detection result to obtain a target threshold, and update the initial characteristic threshold to the target threshold.

[0160] Furthermore, the feature value acquisition module 11 includes:

[0161] A signal extraction submodule, configured to obtain a DC side signal of the inverter and extract an AC signal from the DC side signal;

[0162] The signal analysis submodule is used to perform fast Fourier analysis on the AC signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.

[0163] Furthermore, the signal analysis submodule includes:

[0164] an analysis unit, configured to perform fast Fourier analysis on the AC signal to obtain an analysis result;

[0165] a feature acquisition unit, configured to acquire a preset arc feature, wherein the preset arc feature includes at least one of a mean value, a root mean square value, a variance, and a kurtosis;

[0166] A calculation unit is used to calculate a preset arc characteristic value corresponding to the preset arc characteristic based on the analysis result and in accordance with a characteristic calculation method of the preset arc characteristic.

[0167] Furthermore, the arc judgment module 12 is specifically configured to:

[0168] When the preset arc characteristic value is greater than the initial characteristic threshold, it is determined that a suspected arc occurs.

[0169] Furthermore, the arc detection module 13 includes:

[0170] A first signal acquisition submodule is used to acquire the electrical signal after the inverter performs the wave sealing operation;

[0171] a first arc judgment submodule, configured to determine that the arc detection result is a real arc if the value of the electrical signal is zero;

[0172] a second signal acquisition submodule, configured to acquire a DC signal from the DC side signal if the value of the electrical signal is not zero;

[0173] The second arc judgment submodule is configured to determine that the arc detection result is a false arc when the value of the DC signal is the same as the value of the electrical signal.

[0174] Furthermore, the threshold adjustment module 14 is specifically configured to:

[0175] When the arc detection result is a true arc, the value of the initial characteristic threshold is reduced according to the preset threshold increment calculation rule to obtain the target threshold. When the arc detection result is a false arc, the value of the initial characteristic threshold is increased according to the preset threshold increment calculation rule to obtain the target threshold.

[0176] Furthermore, it also includes:

[0177] A time acquisition module, used to obtain the grid-connected time of the inverter;

[0178] An increment calculation module, configured to calculate a threshold increment corresponding to the grid connection time;

[0179] The threshold determination module is used to take the sum or difference between the initial feature threshold and the threshold increment as the target threshold.

[0180] Furthermore, the incremental calculation module is specifically used to:

[0181] A threshold increment calculation formula is obtained, and based on the threshold increment calculation formula, a threshold increment corresponding to the grid connection time is calculated.

[0182] Furthermore, it also includes:

[0183] A shutdown control module is used to control the inverter to perform a shutdown operation and output arc fault information when the arc detection result is a real arc.

[0184] Furthermore, the numerical value of the characteristic threshold reference value corresponding to the initial characteristic threshold is configured as a preset threshold; the preset threshold is a numerical value that makes the arc detection sensitivity greater than the preset sensitivity.

[0185] In this embodiment, a preset arc characteristic value calculated based on the collected DC side signal of the inverter is obtained, an initial characteristic threshold is obtained, and based on the size relationship between the preset arc characteristic value and the initial characteristic threshold, it is determined whether a suspected arc occurs. If so, a wave sealing operation is performed on the inverter, and the arc detection result corresponding to the suspected arc is determined based on at least the electrical signal of the inverter after the wave sealing operation; the arc detection result includes a real arc or a false arc, and based on the arc detection result, the initial threshold is adjusted to obtain a target threshold, and the initial characteristic threshold is updated to the target threshold. That is, in the present invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the suspected arc actually detected, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, thereby improving the accuracy of arc fault detection and reducing the probability of false alarms and missed alarms.

[0186] Furthermore, the present invention presets an initial characteristic threshold value during initial grid connection. This threshold value is then optimized using a threshold increment function, combined with the arc detection device and the inverter's overall determination of true and false arcs. The resulting threshold parameters are optimally adapted to the diverse operating conditions of each inverter, including the power plant environment, climate, and temperature.

[0187] In addition, the present invention greatly reduces inappropriate threshold selection during the normal operation of the inverter by eliminating false alarms during the large-scale threshold optimization process during the first grid connection and achieving optimal threshold optimization, thereby improving arc recognition capabilities and avoiding frequent false alarms caused by periodic interference.

[0188] It should be noted that, for the working process of each module, sub-module and unit in this embodiment, please refer to the corresponding description in the above embodiment, which will not be repeated here.

[0189] Optionally, based on the above embodiments of the arc fault detection method and apparatus, another embodiment of the present invention provides an electronic device, including: a memory and a processor;

[0190] Wherein, the memory is used to store programs;

[0191] The processor calls the program and is used to execute the above arc fault detection method.

[0192] It should be noted that the electronic device in this embodiment may be the arc detection device mentioned above.

[0193] Optionally, based on the embodiment of the above electronic device, another embodiment of the present invention provides an inverter including the above electronic device.

[0194] In this embodiment, a preset arc characteristic value calculated based on the collected DC side signal of the inverter is obtained, an initial characteristic threshold is obtained, and based on the size relationship between the preset arc characteristic value and the initial characteristic threshold, it is determined whether a suspected arc occurs. If so, a wave sealing operation is performed on the inverter, and the arc detection result corresponding to the suspected arc is determined based on at least the electrical signal of the inverter after the wave sealing operation; the arc detection result includes a real arc or a false arc, and based on the arc detection result, the initial threshold is adjusted to obtain a target threshold, and the initial characteristic threshold is updated to the target threshold. That is, in the present invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the suspected arc actually detected, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, thereby improving the accuracy of arc fault detection and reducing the probability of false alarms and missed alarms.

[0195] Furthermore, the present invention presets an initial characteristic threshold value during initial grid connection. This threshold value is then optimized using a threshold increment function, combined with the arc detection device and the inverter's overall determination of true and false arcs. The resulting threshold parameters are optimally adapted to the diverse operating conditions of each inverter, including the power plant environment, climate, and temperature.

[0196] In addition, the present invention greatly reduces inappropriate threshold selection during the normal operation of the inverter by eliminating false alarms during the large-scale threshold optimization process during the first grid connection and achieving optimal threshold optimization, thereby improving arc recognition capabilities and avoiding frequent false alarms caused by periodic interference.

[0197] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting an arc fault, characterized in that: include: Obtaining a preset arc characteristic value calculated based on the acquired DC side signal of the inverter; Obtaining an initial characteristic threshold, and determining whether a suspected arc occurs based on a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold; If so, performing a wave-sealing operation on the inverter, and determining an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave-sealing operation; the arc detection result includes a real arc or a false arc; Based on the arc detection result, the initial threshold is adjusted to obtain a target threshold, and the initial feature threshold is updated to the target threshold.

2. The arc fault detection method according to claim 1, wherein: Obtaining a preset arc characteristic value calculated based on the acquired DC side signal of the inverter, including: Acquire a DC side signal of the inverter, and extract an AC signal from the DC side signal; Performing fast Fourier analysis on the AC signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.

3. The arc fault detection method according to claim 2, wherein: Performing a fast Fourier analysis on the AC signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic includes: Performing fast Fourier analysis on the AC signal to obtain an analysis result; Acquire a preset arc feature, wherein the preset arc feature includes at least one of a mean value, a root mean square value, a variance, and a kurtosis; Based on the analysis result, a preset arc characteristic value corresponding to the preset arc characteristic is calculated according to the characteristic calculation method of the preset arc characteristic.

4. The arc fault detection method according to claim 1, wherein: Determining whether a suspected arc occurs based on a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold value includes: When the preset arc characteristic value is greater than the initial characteristic threshold, it is determined that a suspected arc occurs.

5. The arc fault detection method according to claim 1, wherein: Determining an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave blocking operation, including: Acquiring an electrical signal after the inverter performs a wave-sealing operation; If the value of the electrical signal is zero, determining that the arc detection result is a real arc; If the value of the electrical signal is not zero, obtaining a DC signal in the DC side signal; In a case where the value of the DC signal is the same as the value of the electrical signal, it is determined that the arc detection result is a false arc.

6. The arc fault detection method according to claim 1, wherein: Adjusting the initial threshold based on the arc detection result to obtain a target threshold includes: When the arc detection result is a real arc, reducing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold; In the case that the arc detection result is a false arc, the value of the initial characteristic threshold is increased according to a preset threshold increment calculation rule to obtain a target threshold.

7. The arc fault detection method according to claim 1, wherein: Also includes: Obtaining the grid-connected time of the inverter; Calculating a threshold increment corresponding to the grid connection time; The sum or difference between the initial feature threshold and the threshold increment is used as the target threshold.

8. The arc fault detection method according to claim 7, characterized in that: Calculating a threshold increment corresponding to the grid connection time includes: A threshold increment calculation formula is obtained, and based on the threshold increment calculation formula, a threshold increment corresponding to the grid connection time is calculated.

9. The arc fault detection method according to claim 1, wherein: After determining the arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave blocking operation, the method further includes: When the arc detection result is a real arc, the inverter is controlled to perform a shutdown operation and arc fault information is output.

10. The arc fault detection method according to claim 1, wherein: The numerical value of the characteristic threshold reference value corresponding to the initial characteristic threshold is configured as a preset threshold; the preset threshold is a numerical value that makes the arc detection sensitivity greater than the preset sensitivity.

11. An arc fault detection device, characterized in that: include: A characteristic value acquisition module is used to obtain a preset arc characteristic value calculated based on the acquired DC side signal of the inverter; an arc judgment module, configured to obtain an initial characteristic threshold and determine whether a suspected arc occurs based on a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold; an arc detection module, configured to, if yes, perform a wave-sealing operation on the inverter, and determine an arc detection result corresponding to the suspected arc based at least on the electrical signal of the inverter after the wave-sealing operation; the arc detection result includes a real arc or a false arc; A threshold adjustment module is used to adjust the initial threshold based on the arc detection result to obtain a target threshold, and update the initial feature threshold to the target threshold.

12. An electronic device, characterized in that: include: memory and processor; Wherein, the memory is used to store programs; The processor calls the program and is used to execute the arc fault detection method according to any one of claims 1 to 10.

13. An inverter, characterized in that: Comprising the electronic device as claimed in claim 12.

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