Arcing detection method, controller and photovoltaic system

Abstract

The invention provides an arc discharge detection method, a controller and a photovoltaic system, and the method comprises the steps: obtaining an output electric signal of a photovoltaic pole plate in a current period, and judging whether the photovoltaic pole plate is in an abnormal working condition or not according to the output electric signal in the current period; if the photovoltaic pole plate is in the abnormal working condition, determining a first target value according to the abnormal working condition; calculating a frequency spectrum amplitude of the output electric signal, and determining an arc discharge detection value of the photovoltaic pole plate according to the frequency spectrum amplitude of the output electric signal; according to the arc discharge detection value and the first target value, judging whether the photovoltaic pole plate has an arc discharge fault or not; the first target value is used for correcting the arc discharge detection value or correcting a preset arc discharge detection threshold value. According to the method, frequency spectrum lifting caused by abnormal working conditions can be counteracted, and the arc discharge detection accuracy of the photovoltaic pole plate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of arc detection, and particularly to an arc detection method, a controller and a photovoltaic system. Background Art

[0002] With the development and wide application of photovoltaic power generation technology, the technical requirements for the power generation power of photovoltaic systems are also getting higher and higher. A photovoltaic system is composed of photovoltaic panels, photovoltaic DC cables, inverters and other structures. It uses solar photovoltaic panels exposed outdoors to collect solar energy and convert it into electricity, thereby realizing photovoltaic power generation.

[0003] Arc output of photovoltaic panels refers to the phenomenon of arc discharge between photovoltaic panels due to voltage fluctuations and other reasons in a photovoltaic power generation system, which is likely to damage circuit components and cause system failures. Therefore, it is necessary to detect arc faults in a photovoltaic power generation system.

[0004] Currently, the arc detection of photovoltaic panels usually collects the output current signal of the photovoltaic panels and determines whether an arc fault occurs in the photovoltaic panels based on the change in the signal amplitude of the arc signal. However, when faults such as occlusion, hot spots, and breakage occur in the photovoltaic panels, the above method will have problems of low detection accuracy and poor reliability. Summary of the Invention

[0005] Embodiments of the present invention provide an arc detection method, a controller and a photovoltaic system to solve the problem of poor accuracy in arc detection of photovoltaic panels.

[0006] In a first aspect, embodiments of the present invention provide an arc detection method, including:

[0007] Obtain the output electrical signal of the photovoltaic panel in the current cycle, and determine whether the photovoltaic panel is in an abnormal working condition according to the output electrical signal of the current cycle;

[0008] If the photovoltaic panel is in an abnormal working condition, determine a first target value according to the abnormal working condition;

[0009] Calculate the spectral amplitude of the output electrical signal, and determine the arc detection value of the photovoltaic panel according to the spectral amplitude of the output electrical signal;

[0010] Judge whether the photovoltaic panel has an arc fault according to the arc detection value and the first target value; the first target value is used to correct the arc detection value or correct a preset arc detection threshold.

[0011] In a second aspect, an embodiment of the present invention provides a controller, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method according to any possible implementation manner of the first aspect described above are implemented.

[0012] In a third aspect, an embodiment of the present invention provides a photovoltaic system, including the controller according to the second aspect described above.

[0013] An embodiment of the present invention provides an arc strike detection method, a controller, and a photovoltaic system. Based on the characteristic that the spectrum of the electrical signal output by a photovoltaic panel will rise when the photovoltaic panel is in abnormal working conditions such as hot spot, occlusion, and breakage, when the photovoltaic panel is in the above abnormal working conditions, a corresponding first target value is set to correct the arc strike detection value or a preset arc strike detection threshold, so as to offset the spectrum rise caused by the abnormal working conditions. Finally, it is determined whether an arc strike fault occurs on the photovoltaic panel according to the arc strike detection value, improving the accuracy of arc strike detection of the photovoltaic panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0015] Figure 1 is an application scenario diagram of the arc strike detection method provided by an embodiment of the present invention;

[0016] Figure 2 is an implementation flowchart of the arc strike detection method provided by an embodiment of the present invention;

[0017] Figure 3 is a schematic diagram of the IV characteristic curve corresponding to the shadow occlusion fault type and the hot spot effect fault type of the photovoltaic panel provided by an embodiment of the present invention;

[0018] Figure 4 is a schematic structural diagram of the arc strike detection device provided by an embodiment of the present invention;

[0019] Figure 5 is a schematic diagram of the controller provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In the following description, specific details such as specific system architectures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. However, those skilled in the art should understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from obscuring the description of the present invention.

[0021] In the description of the specification of this application and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0022] The reference to "one embodiment" or "some embodiments" etc. described in the specification of this application means that a specific feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of this application. Thus, the statements "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in another way. The terms "comprising", "including", "having", and their variants all mean "including but not limited to", unless otherwise specifically emphasized in another way.

[0023] In addition, the "plurality" mentioned in the embodiments of this application should be construed as two or more.

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will be illustrated through specific embodiments in conjunction with the accompanying drawings.

[0025] Figure 1 It is a scenario diagram of the arc-striking detection method provided for the embodiments of the present invention. As Figure 1As shown, the arc striking detection method can be applied to a photovoltaic system, which includes photovoltaic plates, a photovoltaic processing device, a signal sampling module, and a controller. Among them, the photovoltaic processing device may include a photovoltaic inverter and at least one MPPT (Maximum Power Point Tracking) module; the output ends of the photovoltaic plates (PV1, PV2 to PVn) are connected to the input ends of one or more MPPT modules, the output ends of each MPPT are connected to the DC end of the photovoltaic inverter, and the AC end of the photovoltaic inverter is used to connect to the AC bus AC-BUS of the photovoltaic system. The sampling ends of the signal sampling modules (C1, C2 to Cn) are connected to the output ends of the photovoltaic plates, and are used to collect the output electrical signals of the photovoltaic plates (PV1, PV2 to PVn), and send the output electrical signals corresponding to the photovoltaic plates (PV1, PV2 to PVn) to the controller. The controller performs arc striking detection on the photovoltaic plates based on the output electrical signals of the photovoltaic plates (PV1, PV2 to PVn).

[0026] The execution subject of this embodiment can be the above-mentioned controller, or other independent controllers. Hereinafter, taking the controller of the photovoltaic inverter as an example, the arc striking detection method provided in this embodiment will be explained and illustrated.

[0027] See Figure 2 , which shows the implementation flowchart of the arc striking detection method provided by the embodiment of the present invention, and is described in detail as follows:

[0028] S101: Obtain the output electrical signal of the photovoltaic plate in the current cycle, and judge whether the photovoltaic plate is in an abnormal working condition according to the output electrical signal of the current cycle.

[0029] In this embodiment, the output electrical signal may include a current signal, a voltage signal, and a power signal. After the controller obtains the output electrical signals of each photovoltaic plate in the current cycle, it judges whether the photovoltaic plate is in an abnormal working condition according to the output electrical signal, where the abnormal working condition includes fault phenomena such as hot spot effect, breakage, and shadow occlusion that can cause changes in the output electrical signal.

[0030] S102: If the photovoltaic plate is in an abnormal working condition, determine a first target value according to the abnormal working condition.

[0031] In this embodiment, when fault phenomena such as hot spot effect, breakage, and shadow occlusion occur in the photovoltaic panel, its output current and output power will suddenly drop, and the output voltage will increase. When the output electrical signal of the photovoltaic panel mutates, ripples will be generated in the output current signal, thereby increasing the spectral amplitude. When an arc fault occurs in the photovoltaic panel, the performance of its output electrical signal in the frequency spectrum is also an increase in amplitude. This may lead to false alarms during arc detection due to faults such as hot spots and breakage in the photovoltaic panel, resulting in a decrease in the accuracy of arc detection.

[0032] To solve the above problems, the applicant analyzed the frequency spectra of faults such as hot spot effect, breakage, and shadow occlusion and found that when faults such as hot spots, breakage, and occlusion occur in the photovoltaic panel, its spectral performance is generally an increase in amplitude at the resonant frequency, and the amplitudes in other frequency bands are normal. When an arc fault occurs in the photovoltaic panel, its spectral performance is that the amplitude will increase in a relatively long frequency band. That is, for the frequency spectrum of the entire cycle, by detecting and analyzing the change law of the spectral amplitude, it is possible to determine whether an arc fault has occurred, and there is a certain correlation between the severity of the arc fault and the size of the spectral amplitude. The more severe the arc, the stronger the electromagnetic interference generated, and the corresponding spectral amplitude is also larger. Therefore, the accuracy of arc detection can be improved by increasing the background noise of the arc detection value in the signal processing process or raising the threshold threshold for detecting arc faults, that is, the first target value.

[0033] Specifically, the spectral lift corresponding to each abnormal working condition is different, so the corresponding first target value is also different.

[0034] S103: Calculate the spectral amplitude of the output electrical signal, and determine the arc detection value of the photovoltaic panel according to the spectral amplitude of the output electrical signal.

[0035] In this embodiment, the controller first performs FFT (Fast Fourier Transform) processing on the output electrical signals corresponding to the photovoltaic panel in the current cycle to obtain the corresponding frequency spectrum. After obtaining the frequency spectrum, calculate the average value of the modulus of the amplitude of each frequency point in the frequency spectrum to obtain the spectral amplitude corresponding to the output electrical signal of the current cycle.

[0036] As another implementation, after obtaining the frequency spectrum corresponding to the output electrical signal of the current cycle, it is also possible to calculate the sum of the moduli of the amplitudes of each frequency point in the frequency spectrum to obtain the spectral amplitude corresponding to the output electrical signal of the current cycle.

[0037] In a possible implementation, before S103, the method provided in this embodiment further includes:

[0038] Calculate the signal reference value of the output electrical signal for the current period; and subtract the value of each sampling point in the output electrical signal for the current period from the corresponding signal reference value to obtain the processed output electrical signal.

[0039] Among them, the specific process of calculating the signal reference value of the output electrical signal for the current period may include:

[0040] Take the average of the values of each sampling point in the output electrical signal for the current period to obtain the signal reference value corresponding to the output electrical signal for the current period, or select the median value of the sampling points in the output electrical signal for the current period as the signal reference value corresponding to the output electrical signal for the current period.

[0041] After obtaining the processed output electrical signal, perform Hanning window processing on the processed output electrical signal.

[0042] Specifically, the processed output electrical signal is processed using the formula [Y] Hanning = [Y]·Q 15 to perform Hanning window processing to obtain the processed output electrical signal. Among them, [Y] Hanning represents the matrix corresponding to the output electrical signal after Hanning window processing, and the elements in this matrix are the values of the sampling points in the output electrical signal after Hanning window processing. [Y] represents the matrix corresponding to the output electrical signal without Hanning window processing, and the elements in this matrix are the values of the sampling points in the output electrical signal without Hanning window processing. Q 15 represents a preset coefficient.

[0043] The output electrical signal provided in this embodiment can be more easily detected by the controller after Hanning window processing, improving the accuracy of arc detection.

[0044] Correspondingly, the specific implementation process of the above S103 includes:

[0045] Calculate the spectral amplitude of the processed output electrical signal after Hanning window processing, and determine the arc detection value of the photovoltaic plate according to the spectral amplitude of the output electrical signal.

[0046] S104: Determine whether the photovoltaic plate has an arc fault according to the arc detection value and the first target value; the first target value is used to correct the arc detection value or correct the preset arc detection threshold.

[0047] In this embodiment, when performing arc fault detection, usually compare the arc detection value of the output electrical signal corresponding to at least one sampling period with the preset arc detection threshold. If the arc detection values corresponding to each sampling period are all greater than the preset arc detection threshold, it is determined that the photovoltaic plate has an arc fault, otherwise it is determined that the photovoltaic plate has no arc fault.

[0048] In order to reduce the influence of hot spots, breakage, and occlusion faults of photovoltaic plates on the detection of arcing faults, in this embodiment, the arcing detection value can be corrected by subtracting the background noise from the arcing detection value, so as to avoid the influence of the background noise brought by the above-mentioned faults on the arcing fault detection. At the same time, the influence of hot spots, breakage, and occlusion faults of photovoltaic plates on the arcing fault detection can also be avoided by raising the preset arcing detection threshold. The preset arcing detection threshold is a threshold value used to determine whether an arcing fault occurs in the photovoltaic plate.

[0049] As can be seen from the above embodiments, the arcing detection method provided by the embodiments of the present invention is based on the characteristic that the spectrum of the electrical signal output by the photovoltaic plate will rise when the photovoltaic plate is in abnormal working conditions such as hot spots, occlusion, and breakage. When the photovoltaic plate is in the above abnormal working conditions, corresponding first target values are set to correct the arcing detection value or the preset arcing detection threshold, so as to offset the spectrum rise caused by the abnormal working conditions. Finally, it is determined whether an arcing fault occurs in the photovoltaic plate according to the arcing detection value, improving the accuracy of arcing detection of the photovoltaic plate.

[0050] In a possible implementation manner, the abnormal working conditions include occlusion conditions, breakage conditions, and / or hot spot conditions; an implementation process of S101 includes:

[0051] According to the output voltage signal and output current signal of the photovoltaic plate in the current cycle, the IV curve of the photovoltaic plate in the current cycle is obtained;

[0052] Obtain the preset IV curves of the photovoltaic plate under at least one abnormal working condition, and calculate the similarity between the IV curve of the photovoltaic plate in the current cycle and the preset IV curves under each abnormal working condition;

[0053] Select the maximum value of the similarity between the IV curve of the photovoltaic plate in the current cycle and the preset IV curves under each abnormal working condition, and determine whether the maximum value is greater than the first preset similarity;

[0054] If the maximum value is greater than the first preset similarity, it is determined that the photovoltaic plate is in the abnormal working condition corresponding to the maximum value in the current cycle.

[0055] In this embodiment, Figure 3 shows a schematic diagram of the IV characteristic curves corresponding to the shadow occlusion fault type and the hot spot effect fault type of the photovoltaic module. Among them, the dotted line is the IV characteristic curve corresponding to the shadow occlusion fault type, and the solid line is the IV characteristic curve corresponding to the hot spot effect fault type. Refer to Figure 3 , the shapes of the IV curves corresponding to different abnormal working conditions are different. Therefore, in this embodiment, the working condition of the photovoltaic plate can be determined by calculating the similarity between the real-time obtained IV curve and the preset IV curve.

[0056] Specifically, the controller can scan the IV curve of the photovoltaic panel every few sampling periods, and the scanning process is as follows:

[0057] Starting from the open-circuit voltage of the photovoltaic panel, adjust the output voltage of the photovoltaic panel along the first direction with a fixed voltage adjustment step until the output voltage of the photovoltaic panel is adjusted to the short-circuit voltage, and record the output current corresponding to each output voltage of the photovoltaic panel during the adjustment process, so as to obtain the complete IV characteristic data of the photovoltaic panel, and use the complete IV characteristic data of the photovoltaic panel to draw the IV curve.

[0058] After the IV curve is drawn, compare the current IV curve of the photovoltaic panel with the standard preset IV curves under various abnormal conditions, calculate the similarity between the two, and select the maximum value of the similarity between the IV curve of the photovoltaic panel in the current period and the preset IV curves under various abnormal conditions. If the maximum value is greater than the first preset similarity, it is determined that the photovoltaic panel is in the abnormal condition corresponding to the maximum value in the current period. If the maximum value is not greater than the first preset similarity threshold, it is determined that the photovoltaic panel is not in the above abnormal condition. Among them, the value range of the first preset similarity is 80% - 90%.

[0059] When the photovoltaic panel is not in the above abnormal condition currently, the first target value is zero, that is, the arc detection threshold is not subtracted by the first target value, or the preset arc detection threshold remains unchanged.

[0060] When it is determined that the working condition of the photovoltaic panel in the current period is an abnormal condition, the first target value is determined based on the type of the abnormal condition.

[0061] In a possible implementation manner, the abnormal conditions include occlusion conditions, breakage conditions, hot spot conditions, and / or increased ground capacitance conditions; Another implementation process of S101 includes:

[0062] S201: Perform FFT processing on the output electrical signal of the current period to obtain the spectrum of the current period;

[0063] S202: For each abnormal condition, obtain the specific frequency band corresponding to the abnormal condition; and extract the spectrum of the specific frequency band corresponding to the abnormal condition from the spectrum of the current period as the first spectrum;

[0064] S203: Calculate the first amplitude based on the first spectrum corresponding to the abnormal condition; calculate the second amplitude based on the spectrum of the non-specific frequency band in the spectrum of the current period, where the non-specific frequency band is any frequency band in the spectrum other than the specific frequency band corresponding to the abnormal condition;

[0065] S204: Determine whether the photovoltaic panel is in the abnormal condition according to the first amplitude and the second amplitude corresponding to the abnormal condition.

[0066] In this embodiment, as another condition for determining whether the photovoltaic panel is currently in an abnormal condition, this embodiment can determine the condition of the photovoltaic panel based on the spectral characteristics.

[0067] Specifically, in addition to the cases of hot spot, breakage, and shadow causing misreporting of arcing, when the ground capacitance between the output terminal of the photovoltaic panel and the ground increases, its output current will also increase, resulting in misreporting of arcing signals. The frequency bands where the spectrum of the output electrical signal of the photovoltaic panel rises under the above various abnormal conditions may be different. Therefore, the photovoltaic panel can be adjusted to the above various abnormal conditions, and the frequency band where its spectrum rises can be determined through experiments as a specific frequency band. Through experimental analysis, it can be known that the specific frequency bands of hot spot, breakage, and shadow are usually resonance frequency bands.

[0068] When the photovoltaic panel is in an abnormal condition, the amplitude of the spectrum in the specific frequency band will increase, while the amplitude of the spectrum in the non-specific frequency band will not change. Therefore, there will be a certain difference between the amplitude of the spectrum in the specific frequency band and the amplitude of the spectrum in the non-specific frequency band. In this embodiment, when it is detected that there is a difference between the amplitudes of the spectrum in the specific frequency band and the non-specific frequency band, it is determined that the photovoltaic panel is in the above abnormal condition. When there is no difference between the amplitudes of the spectrum in the specific frequency band and the non-specific frequency band, it is considered that the photovoltaic panel is in a normal state or there is an arcing fault.

[0069] Specifically, the specific implementation process of S203 includes: summing the moduli of the amplitudes of each frequency point in the first spectrum corresponding to the abnormal condition to obtain the first amplitude; summing the moduli of the amplitudes corresponding to each frequency point in the spectrum corresponding to the non-specific frequency band to obtain the second amplitude.

[0070] As another implementation method, this embodiment can also average the moduli of the amplitudes of each frequency point in the first spectrum corresponding to the abnormal condition to obtain the first amplitude; average the moduli of the amplitudes corresponding to each frequency point in the spectrum corresponding to the non-specific frequency band to obtain the second amplitude.

[0071] In a possible implementation manner, the specific implementation process of S204 includes:

[0072] Dividing the first amplitude corresponding to the abnormal condition by the second amplitude to obtain the first ratio corresponding to the abnormal condition;

[0073] If the first ratio corresponding to the abnormal condition is greater than the preset ratio threshold, it is determined that the photovoltaic panel is in the abnormal condition.

[0074] In a possible implementation, another implementation process of S204 includes: subtracting the second amplitude from the first amplitude to obtain a first difference, and if the first difference is greater than a second preset value, it is determined that the photovoltaic panel is in an abnormal working condition.

[0075] In a possible implementation, the specific implementation process of determining the first target value according to the abnormal working condition in S102 includes:

[0076] Based on the abnormal working condition - target value association relationship, determine the first target value corresponding to the abnormal working condition in which the photovoltaic panel is located.

[0077] In this embodiment, during the preliminary experiment, the photovoltaic panel can be first adjusted to different abnormal working conditions. For any abnormal working condition, the preset arc strike detection threshold is adjusted, the critical value at which the controller can clearly distinguish between the abnormal working condition and the normal working condition is found, and the first target value is obtained by subtracting the preset arc strike detection threshold from the critical value. The first target value corresponding to each abnormal working condition is determined, and then the corresponding relationship between the first target value and the abnormal working condition is constructed and the first target value, the abnormal working condition, and their corresponding relationship are stored. During the subsequent arc strike detection, after detecting the abnormal working condition in which the photovoltaic panel is currently located, the corresponding first target value can be found based on the abnormal working condition, thereby improving the efficiency of arc strike detection.

[0078] In a possible implementation, another implementation process of determining the first target value according to the abnormal working condition in S102 includes:

[0079] Based on the abnormal working condition - target value association relationship, determine the target value corresponding to the photovoltaic panel under each abnormal working condition;

[0080] Perform weighted summation on the target values under each abnormal working condition to obtain the first target value.

[0081] In this embodiment, since hot spots, breakage, and occlusion usually result in spectral uplift caused by current instantaneous step - generated ripples, the target values usually do not differ much. To reduce the computational load and prevent the selected target value from deviating too much from the ideal target value when there is a deviation in the detection of abnormal working condition categories, which may lead to a decrease in the accuracy of arc strike detection, this embodiment performs weighted summation on the target values corresponding to each abnormal working condition to obtain a comprehensive first target value. Among them, the weight of each abnormal working condition is determined according to the occurrence probability of this condition.

[0082] In a possible implementation, the first target value includes a background noise value; a specific implementation process of S104 includes:

[0083] Subtract the background noise value from the arc strike detection value to obtain a processed arc strike detection value;

[0084] Determine whether the processed arc striking detection value is greater than the preset arc striking detection threshold. If the processed arc striking detection value is greater than the preset arc striking detection threshold, it is determined that an arc striking fault has occurred on the photovoltaic plate.

[0085] In this embodiment, the background noise value is a value greater than zero.

[0086] In a possible implementation manner, the first target value includes a preset coefficient; another implementation process of S104 includes:

[0087] Multiply the preset arc striking detection threshold by the preset coefficient to obtain a first arc striking detection threshold;

[0088] Determine whether the arc striking detection value is greater than the first arc striking detection threshold. If the arc striking detection value is greater than the first arc striking detection threshold, it is determined that an arc striking fault has occurred on the photovoltaic plate.

[0089] In this embodiment, the preset coefficient is a value greater than 1.

[0090] As can be seen from the above embodiments, the arc striking detection method provided in this embodiment is based on the characteristic that the spectrum of the electrical signal output by the photovoltaic plate will increase when the photovoltaic plate is in abnormal working conditions such as hot spots, shading, and breakage. When the photovoltaic plate is in the above abnormal working conditions, a corresponding first target value is set to correct the arc striking detection value or the preset arc striking detection threshold, so as to offset the spectrum increase caused by the abnormal working conditions. Finally, it is determined whether an arc striking fault has occurred on the photovoltaic plate according to the arc striking detection value, improving the accuracy of arc striking detection of the photovoltaic plate. On the other hand, the arc striking detection method provided in this embodiment does not need to avoid the abnormal working condition period to ensure the accuracy of arc striking detection, thereby improving the adaptability of arc striking detection.

[0091] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The order of execution of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0092] The following is an apparatus embodiment of the present invention. For the details not described in detail, reference may be made to the corresponding method embodiments above.

[0093] Figure 4 The structural schematic diagram of the arc striking detection apparatus provided in the embodiments of the present invention is shown. For the convenience of description, only the parts related to the embodiments of the present invention are shown and are described in detail as follows:

[0094] As Figure 4 shown, the arc striking detection apparatus 100 includes:

[0095] An abnormal condition judgment module 110 is configured to obtain the output electrical signal of the photovoltaic panel in the current period, and judge whether the photovoltaic panel is in an abnormal condition according to the output electrical signal of the current period;

[0096] A first target value determination module 120 is configured to, if the photovoltaic panel is in an abnormal condition, determine a first target value according to the abnormal condition;

[0097] An arc detection value calculation module 130 is configured to calculate the spectral amplitude of the output electrical signal, and determine the arc detection value of the photovoltaic panel according to the spectral amplitude of the output electrical signal;

[0098] An arc fault detection module 140 is configured to judge whether the photovoltaic panel has an arc fault according to the arc detection value and the first target value; the first target value is used to correct the arc detection value or correct a preset arc detection threshold.

[0099] In a possible implementation manner, the abnormal conditions include an occlusion condition, a breakage condition, and / or a hot spot condition; the abnormal condition judgment module 110 is specifically configured to:

[0100] Obtain the IV curve of the photovoltaic panel in the current period according to the output voltage signal and the output current signal of the photovoltaic panel in the current period;

[0101] Obtain the preset IV curves of the photovoltaic panel under at least one abnormal condition, and calculate the similarity between the IV curve of the photovoltaic panel in the current period and the preset IV curves under each abnormal condition;

[0102] Select the maximum value of the similarity between the IV curve of the photovoltaic panel in the current period and the preset IV curves under each abnormal condition, and judge whether the maximum value is greater than a first preset similarity;

[0103] If the maximum value is greater than the first preset similarity, it is determined that the photovoltaic panel is in the abnormal condition corresponding to the maximum value in the current period.

[0104] In a possible implementation manner, the abnormal conditions include an occlusion condition, a breakage condition, a hot spot condition, and / or a condition of increased ground capacitance; the abnormal condition judgment module 110 is specifically configured to:

[0105] A spectrum acquisition unit is configured to perform FFT processing on the output electrical signal of the current period to obtain the spectrum of the current period;

[0106] A first spectrum extraction unit is configured to, for each abnormal condition, obtain the specific frequency band corresponding to the abnormal condition; and extract the spectrum of the specific frequency band corresponding to the abnormal condition from the spectrum of the current period as the first spectrum;

[0107] An amplitude calculation unit, configured to calculate a first amplitude based on a first spectrum corresponding to the abnormal condition; calculate a second amplitude based on a spectrum of a non-specific frequency band in the spectrum of the current period, where the non-specific frequency band is any frequency band in the spectrum except the specific frequency band corresponding to the abnormal condition;

[0108] An abnormal condition determination unit, configured to determine whether the photovoltaic panel is in the abnormal condition according to the first amplitude and the second amplitude corresponding to the abnormal condition.

[0109] In a possible implementation manner, the abnormal condition determination unit is specifically configured to:

[0110] Divide the first amplitude corresponding to the abnormal condition by the second amplitude to obtain a first ratio corresponding to the abnormal condition;

[0111] If the first ratio corresponding to the abnormal condition is greater than a preset ratio threshold, it is determined that the photovoltaic panel is in the abnormal condition.

[0112] In a possible implementation manner, the first target value determination module 120 is specifically configured to:

[0113] Based on the abnormal condition - target value association relationship, determine a first target value corresponding to the abnormal condition in which the photovoltaic panel is located.

[0114] In a possible implementation manner, the first target value determination module 120 is specifically configured to:

[0115] Based on the abnormal condition - target value association relationship, determine the target value corresponding to the photovoltaic panel under each abnormal condition;

[0116] Perform a weighted sum of the target values under each abnormal condition to obtain the first target value.

[0117] In a possible implementation manner, the first target value includes a background noise value; the arc fault detection module 140 is specifically configured to:

[0118] Subtract the background noise value from the arc detection value to obtain a processed arc detection value;

[0119] Determine whether the processed arc detection value is greater than the preset arc detection threshold. If the processed arc detection value is greater than the preset arc detection threshold, it is determined that the photovoltaic panel has an arc fault.

[0120] In a possible implementation manner, the first target value includes a preset coefficient; the arc fault detection module 140 is specifically configured to:

[0121] Multiply the preset arc detection threshold by the preset coefficient to obtain a first arc detection threshold;

[0122] Determine whether the arc striking detection value is greater than the first arc striking detection threshold. If the arc striking detection value is greater than the first arc striking detection threshold, it is determined that an arc striking fault has occurred in the photovoltaic plate.

[0123] As can be seen from the above embodiments, the arc striking detection device provided in this embodiment is based on the characteristic that the spectrum of the electrical signal output by the photovoltaic plate will rise when the photovoltaic plate is in abnormal working conditions such as hot spots, shading, and breakage. When the photovoltaic plate is in the above abnormal working conditions, corresponding first target values are set to correct the arc striking detection value or the preset arc striking detection threshold, so as to offset the spectrum rise caused by the abnormal working conditions. Finally, it is determined whether an arc striking fault has occurred in the photovoltaic plate according to the arc striking detection value, improving the accuracy of arc striking detection of the photovoltaic plate. On the other hand, the arc striking detection device provided in this embodiment does not need to avoid the abnormal working condition period in order to ensure the accuracy of arc striking detection, thereby improving the adaptability of arc striking detection.

[0124] Figure 5 It is a schematic diagram of the terminal provided by the embodiment of the present invention. As Figure 5 shown, the controller 5 of this embodiment includes: a processor 50 and a memory 51. The memory 51 is used to store a computer program 52, and the processor 50 is used to call and run the computer program 52 stored in the memory 51, and execute the steps in each of the above arc striking detection method embodiments, such as Figure 2 the steps S101 to S104 shown. Alternatively, the processor 50 is used to call and run the computer program 52 stored in the memory 51 to implement the functions of each module / unit in each of the above device embodiments, such as Figure 4 the functions of the modules 110 to 140 shown.

[0125] Exemplarily, the computer program 52 can be divided into one or more modules / units. The one or more modules / units are stored in the memory 51 and executed by the processor 50 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, and these instruction segments are used to describe the execution process of the computer program 52 in the controller 5.

[0126] The controller 5 can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The controller 5 may include, but is not limited to, a processor 50 and a memory 51. Those skilled in the art can understand that Figure 5 this is only an example of the controller 5 and does not constitute a limitation on the controller 5. It may include more or fewer components than shown in the figure, or combine some components, or different components. For example, the terminal may further include input / output devices, network access devices, a bus, etc.

[0127] The so-called processor 50 may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor, or the processor may also be any conventional processor, etc.

[0128] The memory 51 may be an internal storage unit of the controller 5, such as the hard disk or memory of the controller 5. The memory 51 may also be an external storage device of the controller 5, such as a plug-in hard disk equipped on the controller 5, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. Further, the memory 51 may also include both the internal storage unit of the controller 5 and the external storage device. The memory 51 is used to store the computer program and other programs and data required by the terminal. The memory 51 may also be used to temporarily store the data that has been output or is to be output.

[0129] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the above division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiments may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0130] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0131] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present invention.

[0132] In the embodiments provided by the present invention, it should be understood that the disclosed device / terminal and method can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in an electrical, mechanical or other forms.

[0133] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0134] In addition, the functional units in each embodiment of the present invention can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0135] When the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-mentioned embodiment methods of the present invention, it can also be completed by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned various arc detection method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0136] The above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for detecting arcing, characterized in that: include: Acquire an output electrical signal of the photovoltaic panel in a current cycle, and determine whether the photovoltaic panel is in an abnormal working condition according to the output electrical signal of the current cycle; If the photovoltaic panel is in an abnormal operating condition, determining a first target value according to the abnormal operating condition; Calculating the frequency spectrum amplitude of the output electrical signal, and determining the arc detection value of the photovoltaic panel according to the frequency spectrum amplitude of the output electrical signal; According to the arc detection value and the first target value, it is determined whether the photovoltaic panel has an arc fault; the first target value is used to correct the arc detection value or correct a preset arc detection threshold.

2. The arc detection method according to claim 1, characterized in that: The abnormal working condition includes a shielding working condition, a broken working condition and / or a hot spot working condition; the output electrical signal includes an output voltage signal and an output current signal, and judging whether the photovoltaic panel is in an abnormal working condition according to the output electrical signal of the current cycle includes: Obtaining an IV curve of the photovoltaic panel in the current cycle according to an output voltage signal and an output current signal of the photovoltaic panel in the current cycle; Obtaining a preset IV curve of the photovoltaic panel under at least one abnormal working condition, and calculating the similarity between the IV curve of the photovoltaic panel in a current cycle and the preset IV curve under each abnormal working condition; Selecting the maximum value of the similarity between the IV curve of the photovoltaic panel in the current cycle and the preset IV curve under each abnormal working condition, and determining whether the maximum value is greater than a first preset similarity; If the maximum value is greater than the first preset similarity, it is determined that the photovoltaic panel is in an abnormal operating condition corresponding to the maximum value in the current cycle.

3. The arc detection method according to claim 1, characterized in that: The abnormal operating conditions include shielding conditions, broken conditions, hot spot conditions and / or increased junction capacitance to ground conditions; The determining whether the photovoltaic panel is in an abnormal working condition according to the output electrical signal of the current cycle includes: Performing FFT processing on the output electrical signal of the current cycle to obtain the frequency spectrum of the current cycle; For each abnormal operating condition, a specific frequency band corresponding to the abnormal operating condition is obtained; and a frequency spectrum of the specific frequency band corresponding to the abnormal operating condition is extracted from the frequency spectrum of the current period as a first frequency spectrum; Calculating a first amplitude based on a first spectrum corresponding to the abnormal operating condition; calculating a second amplitude based on a spectrum of a non-specific frequency band in the spectrum of the current period, wherein the non-specific frequency band is any frequency band in the spectrum except the specific frequency band corresponding to the abnormal operating condition; According to the first amplitude and the second amplitude corresponding to the abnormal operating condition, it is determined whether the photovoltaic panel is in the abnormal operating condition.

4. The arc detection method according to claim 3, characterized in that: The determining whether the photovoltaic panel is in the abnormal operating condition according to the first amplitude and the second amplitude corresponding to the abnormal operating condition includes: Dividing the first amplitude corresponding to the abnormal operating condition by the second amplitude to obtain a first ratio corresponding to the abnormal operating condition; If the first ratio corresponding to the abnormal operating condition is greater than a preset ratio threshold, it is determined that the photovoltaic panel is in the abnormal operating condition.

5. The arc detection method according to claim 1, characterized in that: The determining the first target value according to the abnormal operating condition comprises: Based on the abnormal operating condition-target value association relationship, a first target value corresponding to the abnormal operating condition of the photovoltaic panel is determined.

6. The arc detection method according to claim 1, characterized in that: The determining the first target value according to the abnormal operating condition comprises: Based on the abnormal operating condition-target value association relationship, determining the target value corresponding to the photovoltaic panel under each abnormal operating condition; The target value under each abnormal operating condition is weightedly summed to obtain the first target value.

7. The arc detection method according to any one of claims 1 to 6, characterized in that: The first target value includes a noise floor value; The step of judging whether an arc fault occurs on the photovoltaic panel according to the arc detection value and the first target value includes: Subtract the background noise value from the arc detection value to obtain a processed arc detection value; It is determined whether the processed arc detection value is greater than the preset arc detection threshold value. If the processed arc detection value is greater than the preset arc detection threshold value, it is determined that an arc fault occurs in the photovoltaic panel.

8. The arc detection method according to any one of claims 1 to 6, characterized in that: The first target value includes a preset coefficient; The step of judging whether an arc fault occurs on the photovoltaic panel according to the arc detection value and the first target value includes: Multiplying the preset arc detection threshold by the preset coefficient to obtain a first arc detection threshold; It is determined whether the arc detection value is greater than the first arc detection threshold value. If the arc detection value is greater than the first arc detection threshold value, it is determined that an arc fault occurs in the photovoltaic panel.

9. A controller, characterized in that: It comprises a processor and a memory, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the arc detection method according to any one of claims 1 to 8.

10. A photovoltaic system, characterized in that: Comprising a controller as claimed in claim 9.

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