A method and apparatus for arc detection

Abstract

The application discloses a kind of arc detection method and device. Through the method can realize: according to the current frequency variation of main circuit switch determination current sampled dc bus current analysis band, can accurately obtain the effective arc frequency band of current monitoring period, improve the effectiveness and accuracy of detection. And feature value extraction is carried out to analysis band, can eliminate other frequencies, to accurately extract out arc component. Finally, the arc characteristic value corresponding to analysis band is compared with preset condition, the arc determination of analysis band can be realized, the accuracy, effectiveness and comprehensiveness of detection are improved, to prevent missed detection. And compared with prior art, since there is no requirement to the power of line setting model or equipment, and not affected by power, coupling frequency and switch frequency variation and other factors, so it can be suitable for a variety of power line arc detection of model / equipment, its scope of application is wide, adaptability is strong.

Description

Technical Field

[0001] This invention relates to the field of circuit testing technology, and in particular to a method and apparatus for arc detection. Background Technology

[0002] In series circuits, fault arcs can occur due to factors such as damaged wires, loose contacts, or poor equipment contact. These fault arcs generate electrical sparks, which can easily ignite the wires and surrounding objects, causing a fire. Therefore, arc detection of the circuit is necessary.

[0003] The existing detection methods mainly involve manually using arc detection equipment to sequentially inspect locations in the line prone to arcing or commonly used arc detection points. The working principle of the arc detection equipment is to determine whether arcing has occurred in the line by real-time detection of high-frequency current noise.

[0004] However, existing methods have the following drawbacks: When the switching frequencies of equipment or models on different lines are inconsistent, or when the impedances of different DC paths are different, the arc frequency band during arc detection can easily shift, causing the arc detection equipment to malfunction and produce false alarms or no alarms. Furthermore, different models can introduce multiple coupled switching frequencies, increasing the difficulty of arc detection. In addition, because each potential arc-generating detection point needs to be checked sequentially, the detection efficiency is low, and missed detections are possible. Summary of the Invention

[0005] This invention provides an arcing detection method and apparatus that can adapt to arcing detection of various machine models, improve detection efficiency, and prevent missed detections.

[0006] According to one aspect of the present invention, a method for detecting arcing is provided, the method comprising:

[0007] Under the current monitoring period, obtain the current frequency of the main circuit switch and determine whether the current frequency of the main circuit switch has changed;

[0008] The analysis frequency band of the currently sampled DC bus current is determined based on whether the current frequency of the main circuit switch changes; and feature values ​​are extracted from the analysis frequency band to obtain the arcing feature value corresponding to the analysis frequency band.

[0009] Determine whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions. If it does, determine that the analysis frequency band that meets the preset conditions generates arcing, and take the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle.

[0010] Optionally, determining the analysis frequency band of the currently sampled DC bus current based on whether the current frequency of the main circuit switch has changed includes:

[0011] When the current frequency of the main circuit switch changes, the current sampled DC bus current is analyzed and grouped according to the current frequency of the main circuit switch within a preset detection frequency band to obtain the first analysis frequency band;

[0012] When the current frequency of the main circuit switch does not change, the initial analysis frequency band of the current monitoring period is obtained and used as the second analysis frequency band of the currently sampled DC bus current.

[0013] Optionally, the step of performing frequency domain analysis and grouping of the currently sampled DC bus current within a preset detection frequency band based on the current frequency of the main circuit switch to obtain a first analysis frequency band includes:

[0014] The current sampled DC bus current is analyzed in the frequency domain, and the top N frequency amplitude values ​​and corresponding frequency points are found within the preset detection frequency band, and recorded as the first frequency set; where N is a natural number.

[0015] Select the frequency amplitudes and corresponding frequency points in the first frequency set that are greater than a preset amplitude, and record them as the second frequency set;

[0016] The preset detection frequency band is segmented based on the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band.

[0017] Optionally, the step of segmenting the preset detection frequency band according to the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band includes:

[0018] The multiplier of the current frequency of the main circuit switch is determined based on the number of frequency points in the second frequency set, and each multiplier value is obtained.

[0019] The current frequency and each harmonic value of the main circuit switch are inserted sequentially between the frequency points in the second frequency set in ascending order to obtain the first analysis frequency band.

[0020] Optionally, the preset detection frequency band is determined by the sampling rate of the DC bus current.

[0021] Optionally, after selecting the analysis frequency bands that meet the preset conditions as the final analysis frequency bands for the current monitoring cycle, the method further includes:

[0022] The final analysis frequency band of the current monitoring cycle will be used as the initial analysis frequency band for the next monitoring cycle.

[0023] Optionally, the step of extracting feature values ​​from the analysis frequency band to obtain the arcing feature value corresponding to the analysis frequency band includes:

[0024] The analysis frequency band is subjected to eigenvalue analysis, filtering, and mathematical calculation to obtain the arcing characteristic value corresponding to the analysis frequency band.

[0025] Optionally, determining whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions includes:

[0026] Repeat the first preset number of times to determine whether the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value, and count the number of times the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value;

[0027] Determine whether the number of times the arcing characteristic value corresponding to the analysis frequency band exceeds a preset characteristic value is greater than a second preset number. If it is greater, then determine that the corresponding analysis frequency band has generated an arc.

[0028] Optionally, before obtaining whether the current frequency of the main circuit switch has changed, the method further includes:

[0029] Determine whether the operating current of the DC bus circuit is greater than the preset detection start current, and if it is, determine whether the current frequency of the main circuit switch has changed.

[0030] According to another aspect of the present invention, an arc detection device is provided, the arc detection device comprising: a main circuit controller and an arc controller; wherein, the main circuit controller is used to control a main circuit switch;

[0031] The main circuit controller is used to determine whether the current frequency of the main circuit switch has changed during the current monitoring period, and to send the determination result to the arc controller.

[0032] The arcing controller is used to acquire and determine the analysis frequency band of the currently sampled DC bus current based on whether the current frequency of the main circuit switch has changed; and to extract feature values ​​from the analysis frequency band to obtain the arcing feature value corresponding to the analysis frequency band.

[0033] Determine whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions. If it does, determine that the analysis frequency band that meets the preset conditions generates arcing, and take the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle.

[0034] The technical solution of this invention provides an arcing detection method and apparatus. This method achieves the following: First, it determines the analysis frequency band of the currently sampled DC bus current based on the current frequency change of the main circuit switch, accurately obtaining the effective arcing frequency band for the current monitoring period, thereby improving the effectiveness and accuracy of arcing detection analysis. Second, it extracts feature values ​​from the analysis frequency band, eliminating frequency components other than the arcing frequency from the coupling frequency band, thus accurately extracting the arcing component for subsequent arcing determination. Finally, it compares the arcing feature value corresponding to the analysis frequency band with preset conditions to determine whether arcing has occurred in the analysis frequency band, achieving arcing detection and improving the accuracy, effectiveness, and comprehensiveness of detection, preventing missed detections. Compared with existing technologies, this method has no requirements on the power of the line equipment or devices and is unaffected by changes in power, coupling frequency, and switching frequency. Therefore, it is applicable to arcing detection of lines with various power levels / equipment, exhibiting wide applicability and strong adaptability.

[0035] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of an arc detection method provided in an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of an arc detection application scenario provided in an embodiment of the present invention;

[0039] Figure 3 This is a flowchart of another arc detection method provided in this embodiment of the invention;

[0040] Figure 4 This is a flowchart of another arc detection method provided in this embodiment of the invention;

[0041] Figure 5 This is a schematic diagram of the structure of an arc detection device provided in an embodiment of the present invention. Detailed Implementation

[0042] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0044] Figure 1 This is a flowchart of an arc detection method provided in an embodiment of the present invention. This embodiment is applicable to the series arc detection of DC bus circuits, can adapt to circuits of various power types, and improves detection efficiency. The method can be executed by an arc detection device, which can be implemented in hardware and / or software.

[0045] like Figure 1 As shown, the arc detection method includes the following steps:

[0046] S110. Under the current monitoring cycle, obtain the current frequency of the main circuit switch and determine whether the current frequency of the main circuit switch has changed.

[0047] The arcing detection method is performed by an arcing detection device. The arcing detection device includes an arcing controller and a main circuit controller. The main circuit switch refers to a switching element connected to the DC bus circuit, such as a transistor. The main circuit switch is electrically connected to the main circuit controller, which can acquire and determine whether the frequency of the main circuit switch has changed. The arcing controller is communicatively connected to the main circuit controller, allowing it to acquire information from the main circuit controller. For example, the main circuit controller can acquire and determine whether the current frequency of the main circuit switch has changed, and the arcing controller can acquire the current frequency of the main circuit switch and whether its current frequency has changed from the main circuit controller via the communication connection. Therefore, within the current monitoring period, the current frequency of the main circuit switch can be acquired, and it can be determined whether the current frequency of the main circuit switch has changed.

[0048] S120. Determine the analysis frequency band of the currently sampled DC bus current based on whether the current frequency of the main circuit switch changes.

[0049] The DC bus current currently sampled refers to the current operating current of the DC bus circuit, which can be obtained by detecting a current sensor.

[0050] The analysis frequency band of the currently sampled DC bus current refers to the effective analysis frequency band for arc detection analysis of the currently sampled DC bus current. In other words, its frequency range includes the effective detection frequency band, including the arc frequency or frequency band. The number of analysis frequency bands may be one, two, or more.

[0051] The current frequency change of the main circuit switch includes both frequency changes and no frequency changes. The reasons for the current frequency change of the main circuit switch are: variations in the converter's power, input / output voltage levels, etc., can cause changes in the switching frequency, which in turn alters the arcing frequency band. Therefore, by analyzing the current frequency change of the main circuit switch, the analysis frequency band of the currently sampled DC bus current can be determined, thereby obtaining an accurate arcing frequency band and achieving accurate and effective arcing detection.

[0052] S130. Extract feature values ​​from the analysis frequency band to obtain the arcing feature values ​​corresponding to the analysis frequency band.

[0053] The analysis frequency band typically contains coupling frequencies including arcing frequencies, noise frequencies, and switching frequencies. To improve the accuracy of arcing detection and analysis, it is necessary to extract the arcing frequency from the analysis frequency band. Therefore, using the eigenvalue extraction method to extract eigenvalues ​​from the analysis frequency band can accurately obtain the corresponding arcing eigenvalues.

[0054] S140. Determine whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions. If it does, determine that the analysis frequency band that meets the preset conditions generates arcing, and take the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle.

[0055] Specifically, the arcing characteristic value corresponding to the analyzed frequency band is compared with the preset conditions. If the preset conditions are met, the analyzed frequency band that meets the preset conditions is determined to have generated arcing; otherwise, the analyzed frequency band that does not meet the preset conditions is determined not to have generated arcing.

[0056] After analyzing the arcing characteristic values ​​corresponding to the analysis frequency bands in the current monitoring period, the process further includes: using all analysis frequency bands that meet preset conditions as the final analysis frequency bands for the current monitoring period, updating the monitoring frequency band range based on the final analysis frequency bands obtained in the current monitoring period, and entering the next monitoring period for detection. This cycle repeats, enabling periodic arcing detection of the line. Furthermore, the detection can automatically perform arcing detection on the entire line, eliminating the need for separate detection of each commonly used arcing detection point as in existing technologies. This shortens the duration of each monitoring period, improves detection efficiency, and avoids missed detections.

[0057] Figure 2 This is a schematic diagram illustrating an arc detection application scenario provided in an embodiment of the present invention. The arc detection method provided in this embodiment of the present invention is applicable to series arc detection in various application scenarios. For example, it can be used in power grid systems, photovoltaic-storage grid-connected systems, etc. Exemplarily, the following embodiments of the present invention all use a photovoltaic-storage grid-connected system as an example, with reference to... Figure 2 The power conversion section typically consists of two stages of converters: a DC / DC converter and a DC / AC converter. In photovoltaic-storage grid-connected systems, the main points where series arcs are likely to occur are at wire connections. For example, in the series circuit between the photovoltaic / cell and the DC / DC converter (e.g., Figure 2 (marked 1), and on the series circuit between the DC / DC converter and the DC / AC converter (e.g. Figure 2 Mark 2), due to conductor damage, poor contact, etc., can easily generate series arcs. Existing detection methods mainly involve using arc detection equipment to sequentially detect arcing at commonly used detection points such as Mark 1 and Mark 2. The detection principle primarily involves determining whether arcing has occurred by real-time detection of high-frequency current noise. However, when different lines use equipment / models with different power ratings, their corresponding switching frequencies, DC path impedances, etc., differ, leading to a shift in the arc frequency band during arc detection. This can cause the arc detection equipment to malfunction, resulting in false alarms or no alarms. For example, Figure 2If different power DC / DC converters or DC / AC converters are used in the medium-power conversion section, the switching frequency of the main circuit will differ, and the DC path impedance of the topology will not be fixed. This can cause arc detection equipment to fail when detecting arcing on different power models / equipment. Furthermore, using different power models / equipment in the circuit will introduce multiple coupling switching frequencies, further increasing the difficulty of arc detection. For example, Figure 2 The different power ratings of the DC / DC converter and DC / AC converter in the circuit may generate coupling switching frequencies, increasing the difficulty of arcing detection. Furthermore, sequentially detecting commonly used arcing points results in long detection cycles, low efficiency, and a high risk of missed detections.

[0058] Therefore, embodiments of the present invention provide an arc detection method that allows for simple connection of the arc detection device to the circuit under test via a wire, for example, with... Figure 2 The diagram shows the positive and negative terminals of a photovoltaic / cell connected electrically. An automatic arc detection method is then implemented to enable periodic monitoring of the entire circuit. The specific working principle is as follows: First, in the current monitoring cycle, the current frequency of the main circuit switch is acquired, and it is determined whether the current frequency of the main circuit switch has changed. Based on whether the current frequency of the main circuit switch has changed, the analysis frequency band of the currently sampled DC bus current is determined. Feature values ​​are extracted from the analysis frequency band to obtain the corresponding arc characteristic value. It is then determined whether the arc characteristic value corresponding to the analysis frequency band meets preset conditions. If it does, the analysis frequency band meeting the preset conditions is determined to have generated an arc, and this analysis frequency band is taken as the final analysis frequency band for the current monitoring cycle. Therefore, this method can accurately obtain the effective arc frequency band for the current monitoring cycle by determining the analysis frequency band of the currently sampled DC bus current based on the current frequency change of the main circuit switch, thereby improving the effectiveness and accuracy of arc detection analysis. Furthermore, feature value extraction of the analysis frequency band can eliminate frequency components other than the arcing frequency in the coupling frequency band, thereby accurately extracting the arcing component for subsequent arcing determination. Finally, the arcing feature value corresponding to the analysis frequency band is compared with preset conditions to determine whether arcing has occurred in the analysis frequency band, realizing arcing detection, improving the accuracy, effectiveness, and comprehensiveness of detection, and preventing missed detections. Compared with existing technologies, since it has no requirements on the power of the line equipment or devices and is not affected by factors such as power, coupling frequency, and switching frequency changes, it can be applied to arcing detection of lines with various power models / equipment, making it widely applicable and highly adaptable.

[0059] The technical solution of this embodiment provides an arcing detection method, which includes: acquiring the current frequency of the main circuit switch in the current monitoring period and determining whether the current frequency of the main circuit switch has changed; determining the analysis frequency band of the currently sampled DC bus current based on whether the current frequency of the main circuit switch has changed; extracting feature values ​​from the analysis frequency band to obtain the arcing feature value corresponding to the analysis frequency band; determining whether the arcing feature value corresponding to the analysis frequency band meets a preset condition; if it does, determining that the analysis frequency band meeting the preset condition generates an arc, and using the analysis frequency band meeting the preset condition as the final analysis frequency band for the current monitoring period. Therefore, it can be achieved that: determining the analysis frequency band of the currently sampled DC bus current based on the current frequency change of the main circuit switch can accurately obtain the effective arcing frequency band for the current monitoring period, thereby improving the effectiveness and accuracy of arcing detection analysis. Furthermore, extracting feature values ​​from the analysis frequency band can remove other frequency components in the coupling frequency band besides the arcing frequency, thereby accurately extracting the arcing component for subsequent arcing determination. Finally, by comparing the arcing characteristic value corresponding to the analyzed frequency band with preset conditions, it is possible to determine whether arcing has occurred in the analyzed frequency band, thereby achieving arcing detection and improving the accuracy, effectiveness, and comprehensiveness of the detection, preventing missed detections. Furthermore, compared with existing technologies, this method is applicable to arcing detection of lines with various power ratings for different types of equipment because it has no requirements on the power of the line equipment or the power of the equipment itself, and is unaffected by changes in power, coupling frequency, and switching frequency. Its wide applicability and strong adaptability make it suitable for arcing detection of lines with various power ratings for different types of equipment.

[0060] Figure 3 This is a flowchart of another arc detection method provided in an embodiment of the present invention. Optionally, as one implementation, refer to... Figure 3 The arc detection method includes the following steps:

[0061] S210. Under the current monitoring cycle, obtain the current frequency of the main circuit switch and determine whether the current frequency of the main circuit switch has changed. If it has changed, proceed to step 220; otherwise, proceed to step 230.

[0062] S220. When the current frequency of the main circuit switch changes, the current sampled DC bus current is analyzed and grouped according to the current frequency of the main circuit switch within the preset detection frequency band to obtain the first analysis frequency band.

[0063] The reason for the change in the current frequency of the main circuit switch is that changes in the converter's power, input / output voltage levels, etc., can lead to changes in the switching frequency, which in turn alters the arcing frequency band. The range of this change in the arcing frequency band may narrow or expand; that is, the frequency range after the arcing frequency band changes is not fixed. If the initial analysis frequency band of the current monitoring cycle is still used as the detection analysis frequency band for the current cycle, arcing detection may be missed or even invalid. Therefore, when the current frequency of the main circuit switch changes, a new analysis frequency band needs to be determined to ensure the effectiveness and accuracy of the detection.

[0064] The preset detection frequency band is usually a frequency band with a relatively large frequency range. The current DC bus current can be sampled within the preset detection frequency band, and the DC bus current can be dynamically analyzed and grouped in the frequency domain to obtain the effective analysis frequency band, namely the first analysis frequency band.

[0065] Optionally, the preset detection frequency band is determined by the sampling rate of the DC bus current.

[0066] The sampling rate of the DC bus current can be used to determine the sampling frequency, which in turn determines the preset detection frequency band. For example, if the sampling frequency of the DC bus current is 100kHz, then the preset detection frequency band can be set to 0-50kHz. It should be noted that the sampling rate and frequency of the DC bus current remain constant during the detection process.

[0067] S230. When the current frequency of the main circuit switch does not change, obtain the initial analysis frequency band of the current monitoring cycle and use it as the second analysis frequency band of the DC bus current currently sampled.

[0068] The initial analysis frequency band for the current monitoring cycle is the final analysis frequency band of the previous monitoring cycle. Since the final analysis frequency band of the previous monitoring cycle was the analysis frequency band that was determined to generate arcing in the previous monitoring cycle, when the current frequency of the main circuit switch in the current monitoring cycle has not changed, the final analysis frequency band of the previous monitoring cycle can be directly used as the initial analysis frequency band for arcing detection and determination in the current cycle. This can narrow the detection frequency range, reduce the amount of calculation, improve the data processing rate, and thus improve detection efficiency.

[0069] The second analysis frequency band is the final analysis frequency band of the previous monitoring period. Therefore, the specific frequency range and number of the second analysis frequency band depend on the final analysis frequency band of the previous monitoring period.

[0070] It should be noted that if no arcing occurs in any analysis frequency band during the previous monitoring period, meaning the final number of analysis frequency bands for the previous monitoring period is zero, then the initial analysis frequency band for the next monitoring period will be the preset detection frequency band. Therefore, the second analysis frequency band may also be the preset detection frequency band.

[0071] S240. Extract feature values ​​from the analysis frequency band to obtain the arcing feature values ​​corresponding to the analysis frequency band.

[0072] Optionally, the analysis frequency band is subjected to eigenvalue analysis, filtering, and mathematical calculation to obtain the arcing characteristic value corresponding to the analysis frequency band.

[0073] Eigenvalue analysis is performed using the eigenvalue analysis method. Filtering employs methods such as filtering analysis and wavelet analysis. Mathematical operations can include methods such as linear regression.

[0074] Specifically, eigenvalue analysis is performed on the analysis frequency band. Then, a filtering method is used to remove coupled noise frequencies, main circuit switching frequencies, and other frequency components from the analysis frequency band. Finally, mathematical calculations are used to obtain the arcing characteristic value of the analysis frequency band. The arcing characteristic value when the current frequency of the main circuit switch remains unchanged is denoted as... The arcing characteristic value when the current frequency of the main circuit switch changes is denoted as... .

[0075] S250. Determine whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions. If it does, determine that the analysis frequency band that meets the preset conditions generates arcing, and take the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle.

[0076] Optionally, the analysis method for determining whether an arcing occurs in the analysis frequency band can be as follows: repeat the first preset number of times to determine whether the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value, and count the number of times the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value; determine whether the number of times the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value is greater than the second preset number of times, and if it is greater, determine that the corresponding analysis frequency band has generated an arcing.

[0077] Specifically, when the arcing characteristic value of a certain analysis frequency band exceeds a preset characteristic value, it indicates that an arc has occurred within that analysis frequency band. To accurately determine whether the analysis frequency band is truly the one that generates arcing, or to determine whether the frequency of arcing reaches the preset arcing level, it is necessary to repeatedly check the number of times the arcing characteristic value exceeds the preset characteristic value for each analysis frequency. The preset arcing level refers to the level at which the generated arcing is likely to cause harm or adverse effects; it can be set according to actual conditions and is not specifically limited here.

[0078] Here, the first preset number of times is the number of times the judgment is repeated. The preset feature value is the feature value threshold that generates the arc, denoted as . The specific values ​​for the first preset number of times and the preset feature value can be set according to the specific situation, and no specific limitation is made here.

[0079] Among them, the number of times the arcing characteristic value corresponding to the analysis frequency band exceeds the preset characteristic value is recorded as follows: .

[0080] For example, assuming the first preset number of times is 6 and the second preset number of times is 4, if the arcing characteristic value corresponding to a certain analysis frequency band appears to be greater than the preset characteristic value 5 times, then it is determined that the analysis frequency band has generated arcing.

[0081] The second preset number of times refers to the threshold at which the arc-drawing characteristic value exceeds the preset characteristic value. Its specific value can be set according to the actual situation and is not specifically limited here.

[0082] In this embodiment, the arc detection method works as follows: First, during the current monitoring period, the current frequency of the main circuit switch is acquired, and it is determined whether the current frequency of the main circuit switch has changed. If the current frequency of the main circuit switch changes, the current sampled DC bus current is analyzed and grouped according to the current frequency of the main circuit switch within a preset detection frequency band to obtain a first analysis frequency band. If the current frequency of the main circuit switch does not change, the initial analysis frequency band of the current monitoring period is acquired and used as the second analysis frequency band of the current sampled DC bus current. Then, feature value extraction is performed on the analysis frequency band (first analysis frequency band or second analysis frequency band) to obtain the arc feature value corresponding to the analysis frequency band. Finally, it is determined whether the arc feature value corresponding to the analysis frequency band meets a preset condition. If it does, it is determined that the analysis frequency band that meets the preset condition generates an arc, and the analysis frequency band that meets the preset condition is used as the final analysis frequency band of the current monitoring period. Therefore, this method enables the determination of the analysis frequency band of the currently sampled DC bus current based on the current frequency change of the main circuit switch, accurately obtaining the effective arcing frequency band of the current monitoring period, thereby improving the effectiveness and accuracy of arcing detection analysis. Furthermore, by performing eigenvalue analysis, filtering, and mathematical operations on the analysis frequency band, other frequency components besides the arcing frequency can be eliminated from the coupling frequency band, thus accurately extracting and calculating the arcing characteristic value for subsequent arcing determination. Finally, the arcing characteristic value corresponding to the analysis frequency band is repeatedly analyzed to accurately determine whether arcing has occurred in the analysis frequency band, thereby achieving arcing detection, improving the accuracy, effectiveness, and comprehensiveness of detection, and preventing missed detections. Compared with existing technologies, this method is applicable to arcing detection of lines with various power ratings / equipment because it has no requirements on the power of the line installation model or equipment and is not affected by factors such as power, coupling frequency, and switching frequency changes. It has a wide range of applications and strong adaptability.

[0083] Figure 4 This is a flowchart of another arc detection method provided in an embodiment of the present invention. Optionally, as one implementation, refer to... Figure 4 The arc detection method includes the following steps:

[0084] S310. Under the current monitoring cycle, determine whether the operating current of the DC bus circuit is greater than the preset detection start current.

[0085] Among them, the preset detection start current is used to determine the converter (e.g. Figure 2The current threshold used to determine whether a DC / DC converter or DC / AC converter is operating at high or low power is defined. The operating current of the DC bus circuit typically increases and decreases throughout the day. When the operating current of the DC bus circuit is less than or equal to the preset detection starting current, the converter is operating at low power. In low-power operation, even if a series arc occurs, it will have a negligible impact. Therefore, when the operating current of the DC bus circuit is less than or equal to the preset detection starting current, series arc detection is not required. However, when the operating current of the DC bus circuit exceeds the preset detection starting current, the converter is operating at high power. In high-power operation, if a series arc occurs, it will have a significant impact. Therefore, when the operating current of the DC bus circuit exceeds the preset detection starting current, it is necessary to further determine whether the current frequency of the main circuit switch has changed, and then perform arc detection on the line.

[0086] The specific value of the preset detection start current can be set according to the actual situation, and no specific limit is made here.

[0087] It should be noted that the judgment condition of whether the operating current of the DC bus circuit is greater than the preset detection starting current and the judgment condition of whether the current frequency of the main circuit switch has changed can be judged in parallel. That is, under normal circumstances, it is first judged whether the operating current of the DC bus circuit is greater than the preset detection starting current. If the operating current of the DC bus circuit is greater than the preset detection starting current, then it is further judged whether the current frequency of the main circuit switch has changed. However, if a change in the current frequency of the main circuit switch is directly detected, then the subsequent operation can directly detect whether arcing occurs.

[0088] S320: When the operating current of the DC bus circuit is greater than the preset detection start current, determine whether the current frequency of the main circuit switch has changed. If it has changed, execute S330; otherwise, execute S340.

[0089] Specifically, when the operating current of the DC bus circuit exceeds the preset detection start current, it is necessary to further determine whether the current frequency of the main circuit switch has changed. Then, based on the change in the current frequency of the main circuit switch, the analysis frequency band of the currently sampled DC bus current can be determined, thereby obtaining an accurate arcing frequency band and achieving accurate and effective arcing detection. When the current frequency of the main circuit switch changes, step S330 is executed to obtain the first analysis frequency band; when the current frequency of the main circuit switch does not change, step S340 is executed to obtain the second analysis frequency band.

[0090] Step 330: When the current frequency of the main circuit switch changes, perform frequency domain analysis and grouping on the currently sampled DC bus current within the preset detection frequency band according to the current frequency of the main circuit switch to obtain the first analysis frequency band.

[0091] Optionally, the first analysis frequency band can be obtained as follows: First, perform frequency domain analysis on the currently sampled DC bus current, and find the top N frequency amplitude values ​​and corresponding frequency points within the preset detection frequency band, which are denoted as the first frequency set; where N is a natural number. Then, filter out the frequency amplitude values ​​and corresponding frequency points in the first frequency set that are greater than the preset amplitude value, and denoted as the second frequency set; finally, segment the preset detection frequency band according to the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band.

[0092] Specifically, when the current frequency of the main circuit switch changes, frequency domain analysis is performed on the currently sampled DC bus current. This analysis allows the identification of the top N frequency amplitude values ​​and the corresponding frequency points within a preset detection frequency band. The first frequency set is denoted as... .

[0093] The preset amplitude can be set according to the actual situation, and no specific limit is set here.

[0094] The preset amplitude is denoted as The second frequency set is denoted as .

[0095] The number of frequency points in the second frequency set refers to the number of frequency amplitudes selected from the first frequency set whose amplitudes are greater than a preset amplitude.

[0096] Optionally, the preset detection frequency band is segmented according to the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band, including:

[0097] The multiplication factor of the current frequency of the main circuit switch is determined based on the number of frequency points in the second frequency set, and the multiplication factor values ​​are obtained.

[0098] The current frequency of the main circuit switch and each harmonic value are inserted sequentially into the frequency points of the second frequency set in ascending order to obtain the first analysis frequency band.

[0099] For example, suppose the frequency points in the second frequency set are 10K, 20K, 30K, and 40K respectively, and the number of frequency points in the second frequency set is 4. The current frequency of the main circuit switch is 8K. Then, based on the number of frequency points in the second frequency set, the multiplier of the current frequency of the main circuit switch can be determined to be 4 times, and the multiplier values ​​are 16K, 24K, and 32K respectively. Then, 8K, 16K, 24K, and 32K are inserted into the second frequency set 0K, 10K, 20K, 30K, and 40K in ascending order, and the frequency bands 0K, 8K, 10K, 16K, 20K, 24K, 30K, 32K, and 40K are obtained, which are the first analysis frequency bands.

[0100] S340. When the current frequency of the main circuit switch does not change, obtain the initial analysis frequency band of the current monitoring cycle and use it as the second analysis frequency band of the DC bus current currently sampled.

[0101] S350. Extract feature values ​​from the analysis frequency band to obtain the arcing feature values ​​corresponding to the analysis frequency band.

[0102] S360. Determine whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions. If it does, determine that the analysis frequency band that meets the preset conditions generates arcing, and take the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle.

[0103] S370. The analysis frequency band that generates arcing is taken as the final analysis frequency band of the current monitoring cycle, and the final analysis frequency band of the current monitoring cycle is taken as the initial analysis frequency band of the next monitoring cycle.

[0104] The final analysis frequency band for the current monitoring cycle is the analysis frequency band that generates arcing. Updating the final analysis frequency band for the current monitoring cycle to the initial analysis frequency band for the next monitoring cycle can further narrow the detection range and improve detection efficiency. Especially when the main circuit switching frequency does not change in the next monitoring cycle, directly using the final analysis frequency band that generated arcing in the previous monitoring cycle as the initial analysis frequency band for arcing detection and judgment can narrow the detection frequency band and improve detection efficiency.

[0105] In this embodiment, the arc detection method works as follows: First, during the current monitoring period, it is determined whether the operating current of the DC bus circuit is greater than the preset detection start current. If it is greater, it is determined whether the current frequency of the main circuit switch has changed. If the current frequency of the main circuit switch has changed, the current sampled DC bus current is analyzed and grouped according to the current frequency of the main circuit switch within the preset detection frequency band to obtain the first analysis frequency band. If the current frequency of the main circuit switch has not changed, the initial analysis frequency band of the current monitoring period is obtained and used as the second analysis frequency band of the current sampled DC bus current. Feature value extraction is performed on the analysis frequency band to obtain the arc feature value corresponding to the analysis frequency band. Finally, it is determined whether the arc feature value corresponding to the analysis frequency band meets the preset conditions. If it does, it is determined that the analysis frequency band that meets the preset conditions generates an arc, and the analysis frequency band that meets the preset conditions is used as the final analysis frequency band of the current monitoring period. The analysis frequency band that generates an arc is used as the final analysis frequency band of the current monitoring period, and the final analysis frequency band of the current monitoring period is used as the initial analysis frequency band of the next monitoring period. Therefore, this method enables the determination of the analysis frequency band of the currently sampled DC bus current based on the current frequency change of the main circuit switch, accurately obtaining the effective arcing frequency band of the current monitoring period, thereby improving the effectiveness and accuracy of arcing detection analysis. Furthermore, by performing eigenvalue analysis, filtering, and mathematical operations on the analysis frequency band, other frequency components besides the arcing frequency can be eliminated from the coupling frequency band, thus accurately extracting and calculating the arcing characteristic value for subsequent arcing determination. Finally, the arcing characteristic value corresponding to the analysis frequency band is repeatedly analyzed to accurately determine whether arcing has occurred in the analysis frequency band, thereby achieving arcing detection, improving the accuracy, effectiveness, and comprehensiveness of detection, and preventing missed detections. Compared with existing technologies, this method is applicable to arcing detection of lines with various power ratings / equipment because it has no requirements on the power of the line installation model or equipment and is not affected by factors such as power, coupling frequency, and switching frequency changes. It has a wide range of applications and strong adaptability.

[0106] Figure 5 This is a schematic diagram of the structure of an arc detection device provided in an embodiment of the present invention. Figure 5 As shown, the device 100 includes: a main circuit controller 101 and an arc controller 102; wherein, the main circuit controller 101 is used to control the main circuit switch 10;

[0107] The main circuit controller 101 is used to determine whether the current frequency of the main circuit switch 10 has changed during the current monitoring cycle, and to send the determination result to the arc controller 102.

[0108] The arc controller 102 is used to acquire and determine the analysis frequency band of the currently sampled DC bus current based on whether the current frequency of the main circuit switch has changed; and to extract the feature value of the analysis frequency band to obtain the arc characteristic value corresponding to the analysis frequency band.

[0109] Determine whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions. If it does, determine that the analysis frequency band that meets the preset conditions has generated an arc, and take the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle.

[0110] The technical solution of this embodiment provides an arcing detection device, which includes a main circuit controller and an arcing controller. The main circuit controller controls a main circuit switch. During the current monitoring period, the main circuit controller determines whether the current frequency of the main circuit switch has changed and sends the determination result to the arcing controller. The arcing controller acquires and determines the analysis frequency band of the currently sampled DC bus current based on whether the current frequency of the main circuit switch has changed. It then extracts feature values ​​from the analysis frequency band to obtain the corresponding arcing feature value. Finally, it determines whether the arcing feature value of the analysis frequency band meets a preset condition. If it does, the analysis frequency band meeting the preset condition is determined to have generated an arc, and this analysis frequency band is used as the final analysis frequency band for the current monitoring period. Therefore, it is possible to determine the analysis frequency band of the currently sampled DC bus current based on the current frequency change of the main circuit switch, accurately obtain the effective arcing frequency band for the current monitoring period, and thus improve the effectiveness and accuracy of arcing detection and analysis. Furthermore, feature value extraction of the analysis frequency band can eliminate frequency components other than the arcing frequency in the coupling frequency band, thereby accurately extracting the arcing component for subsequent arcing determination. Finally, the arcing feature value corresponding to the analysis frequency band is compared with preset conditions to determine whether arcing has occurred in the analysis frequency band, realizing arcing detection, improving the accuracy, effectiveness, and comprehensiveness of detection, and preventing missed detections. Compared with existing technologies, since it has no requirements on the power of the line equipment or devices and is not affected by factors such as power, coupling frequency, and switching frequency changes, it can be applied to arcing detection of lines with various power models / equipment, making it widely applicable and highly adaptable.

[0111] Optionally, the arc controller 102 is used to: when the current frequency of the main circuit switch changes, perform frequency domain analysis and grouping on the currently sampled DC bus current within a preset detection frequency band according to the current frequency of the main circuit switch to obtain a first analysis frequency band; when the current frequency of the main circuit switch does not change, obtain the initial analysis frequency band of the current monitoring cycle and use it as the second analysis frequency band of the currently sampled DC bus current.

[0112] Optionally, within a preset detection frequency band, the sampled DC bus current is analyzed and grouped according to the current frequency of the main circuit switch to obtain a first analysis frequency band. This includes: performing frequency domain analysis on the sampled DC bus current, finding the top N frequency amplitude values ​​and corresponding frequency points within the preset detection frequency band, and recording them as a first frequency set; where N is a natural number; filtering out the frequency amplitude values ​​and corresponding frequency points in the first frequency set that are greater than a preset amplitude, and recording them as a second frequency set; and segmenting the preset detection frequency band according to the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band.

[0113] Optionally, the preset detection frequency band is segmented according to the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band, including: determining the multiplier of the current frequency of the main circuit switch according to the number of frequency points in the second frequency set, and obtaining each multiplier value; and inserting the current frequency of the main circuit switch and each multiplier value into the frequency points in the second frequency set in ascending order to obtain the first analysis frequency band.

[0114] Optionally, the preset detection frequency band is determined by the sampling rate of the DC bus current.

[0115] Optionally, after using the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle, the method further includes: using the final analysis frequency band of the current monitoring cycle as the initial analysis frequency band of the next monitoring cycle.

[0116] Optionally, feature value extraction is performed on the analysis frequency band to obtain the arcing feature value corresponding to the analysis frequency band, including: performing feature value analysis, filtering, and calculation using mathematical operation methods to obtain the arcing feature value corresponding to the analysis frequency band.

[0117] Optionally, determining whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions includes: repeatedly determining whether the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value a first preset number of times, and counting the number of times the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value; determining whether the number of times the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value is greater than the second preset number of times, and if it is greater, determining that the corresponding analysis frequency band has generated an arc.

[0118] Optionally, before obtaining whether the current frequency of the main circuit switch has changed, the method further includes: determining whether the operating current of the DC bus circuit is greater than the preset detection start current, and if it is greater, determining whether the current frequency of the main circuit switch has changed.

[0119] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0120] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for detecting arcing, characterized in that, include: Under the current monitoring period, obtain the current frequency of the main circuit switch and determine whether the current frequency of the main circuit switch has changed; The analysis frequency band of the currently sampled DC bus current is determined based on whether the current frequency of the main circuit switch changes; and feature values ​​are extracted from the analysis frequency band to obtain the arcing feature value corresponding to the analysis frequency band. Determine whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions. If it does, determine that the analysis frequency band that meets the preset conditions generates arcing, and take the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle. The step of determining the analysis frequency band of the currently sampled DC bus current based on whether the current frequency of the main circuit switch has changed includes: When the current frequency of the main circuit switch changes, the current sampled DC bus current is analyzed and grouped according to the current frequency of the main circuit switch within a preset detection frequency band to obtain a first analysis frequency band; the preset detection frequency band is determined by the sampling rate of the DC bus current. When the current frequency of the main circuit switch does not change, the initial analysis frequency band of the current monitoring cycle is obtained and used as the second analysis frequency band of the DC bus current currently sampled; the initial analysis frequency band of the current monitoring cycle is the final analysis frequency band of the previous monitoring cycle. The step of performing frequency domain analysis and grouping of the currently sampled DC bus current within a preset detection frequency band based on the current frequency of the main circuit switch to obtain the first analysis frequency band includes: The current sampled DC bus current is analyzed in the frequency domain, and the top N frequency amplitude values ​​and corresponding frequency points are found within the preset detection frequency band, and recorded as the first frequency set; where N is a natural number. Select the frequency amplitudes and corresponding frequency points in the first frequency set that are greater than a preset amplitude, and record them as the second frequency set; The preset detection frequency band is segmented based on the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band.

2. The arc detection method according to claim 1, characterized in that, The step of segmenting the preset detection frequency band according to the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band includes: The multiplier of the current frequency of the main circuit switch is determined based on the number of frequency points in the second frequency set, and each multiplier value is obtained. The current frequency and each harmonic value of the main circuit switch are inserted sequentially between the frequency points in the second frequency set in ascending order to obtain the first analysis frequency band.

3. The arc detection method according to claim 1, characterized in that, The preset detection frequency band is determined by the sampling rate of the DC bus current.

4. The arc detection method according to claim 1, characterized in that, After selecting the analysis frequency band that meets the preset conditions as the final analysis frequency band for the current monitoring cycle, the method further includes: The final analysis frequency band of the current monitoring cycle will be used as the initial analysis frequency band for the next monitoring cycle.

5. The arc detection method according to claim 1, characterized in that, The step of extracting feature values ​​from the analysis frequency band to obtain the arcing feature value corresponding to the analysis frequency band includes: The analysis frequency band is subjected to eigenvalue analysis, filtering, and mathematical calculation to obtain the arcing characteristic value corresponding to the analysis frequency band.

6. The arc detection method according to claim 1, characterized in that, The step of determining whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions includes: Repeat the first preset number of times to determine whether the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value, and count the number of times the arcing characteristic value corresponding to the analysis frequency band is greater than the preset characteristic value; Determine whether the number of times the arcing characteristic value corresponding to the analysis frequency band exceeds a preset characteristic value is greater than a second preset number. If it is greater, then determine that the corresponding analysis frequency band has generated an arc.

7. The arc detection method according to claim 1, characterized in that, Before determining whether the current frequency of the main circuit switch has changed, the following steps are also included: Determine whether the operating current of the DC bus circuit is greater than the preset detection start current, and if it is, determine whether the current frequency of the main circuit switch has changed.

8. An arc detection device, characterized in that, include: The main circuit controller and the arc-pulling controller; wherein the main circuit controller is used to control the main circuit switch; The main circuit controller is used to determine whether the current frequency of the main circuit switch has changed during the current monitoring period, and to send the determination result to the arc controller. The arcing controller is used to acquire and determine the analysis frequency band of the currently sampled DC bus current based on whether the current frequency of the main circuit switch has changed; and to extract feature values ​​from the analysis frequency band to obtain the arcing feature value corresponding to the analysis frequency band. Determine whether the arcing characteristic value corresponding to the analysis frequency band meets the preset conditions. If it does, determine that the analysis frequency band that meets the preset conditions generates arcing, and take the analysis frequency band that meets the preset conditions as the final analysis frequency band of the current monitoring cycle. The arc-pulling controller is specifically used to perform frequency domain analysis and grouping of the currently sampled DC bus current within a preset detection frequency band according to the current frequency of the main circuit switch when the current frequency of the main circuit switch changes, to obtain a first analysis frequency band; the preset detection frequency band is determined by the sampling rate of the DC bus current; when the current frequency of the main circuit switch does not change, the initial analysis frequency band of the current monitoring cycle is obtained and used as the second analysis frequency band of the currently sampled DC bus current; the initial analysis frequency band of the current monitoring cycle is the final analysis frequency band of the previous monitoring cycle; The arc-pulling controller is used to perform frequency domain analysis and grouping of the currently sampled DC bus current within a preset detection frequency band according to the current frequency of the main circuit switch to obtain a first analysis frequency band. This includes: performing frequency domain analysis on the currently sampled DC bus current, and finding the top N frequency amplitude maximum values ​​and corresponding frequency points within the preset detection frequency band, and recording them as a first frequency set; where N is a natural number; filtering out frequency amplitude values ​​greater than a preset amplitude and corresponding frequency points in the first frequency set, and recording them as a second frequency set; and segmenting the preset detection frequency band according to the number of frequency points in the second frequency set and the current frequency of the main circuit switch to obtain the first analysis frequency band.

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