CN114755542B - Arc fault detection method, device and equipment - Google Patents
Arc fault detection method, device and equipment Download PDFInfo
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Abstract
The invention provides an arc fault detection method, device and equipment, which are used for acquiring a preset arc characteristic value calculated based on a DC side signal of an acquired inverter, acquiring an initial characteristic threshold value, judging whether a suspected arc occurs according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value, if so, executing wave-sealing operation on the inverter, and determining an arc detection result corresponding to the suspected arc at least based on an electric signal of the inverter after the wave-sealing operation; the arc detection result comprises a real arc or a false arc, the initial threshold value is adjusted based on the arc detection result, a target threshold value is obtained, and the initial characteristic threshold value is updated to the target threshold value. In the invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the actually detected suspected arc, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, and the arc fault detection accuracy is improved.
Description
Technical Field
The present invention relates to the field of arc detection, and in particular, to an arc fault detection method, apparatus, and device.
Background
The arc is a gas discharge phenomenon, and once a fault arc occurs in a photovoltaic system, if no effective measures are taken for protection, the high temperature generated by the continuous direct current arc is extremely easy to cause fire, so that serious safety accidents are caused.
To avoid arcing faults, arc fault detection techniques are typically employed for arc detection. And during detection, extracting the characteristics, comparing the characteristics with the characteristic threshold value, and determining whether arc faults occur or not through the comparison result.
In practical application, the characteristic threshold is generally a fixed threshold, when arc fault detection is carried out by using the characteristic threshold, false alarm or missing alarm is easy to occur, and the arc fault detection accuracy is low.
Disclosure of Invention
In view of the above, the present invention provides an arc fault detection method, apparatus and device, so as to solve the problem of low arc fault detection accuracy.
In order to solve the technical problems, the invention adopts the following technical scheme:
an arc fault detection method comprising:
acquiring a preset arc characteristic value calculated based on a DC side signal of the acquired inverter;
acquiring an initial characteristic threshold value, and judging whether a suspected arc occurs or not according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value;
if yes, performing wave-sealing operation on the inverter, and determining an arc detection result corresponding to the suspected arc at least based on the electric signal of the inverter after the wave-sealing operation; the arc detection result comprises a real arc or a false arc;
and adjusting the initial threshold based on the arc detection result to obtain a target threshold, and updating the initial characteristic threshold to the target threshold.
Optionally, obtaining a preset arc characteristic value calculated based on the collected dc side signal of the inverter includes:
acquiring a direct current side signal of an inverter, and extracting an alternating current signal from the direct current side signal;
and performing fast Fourier analysis on the alternating current signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.
Optionally, performing fast fourier analysis on the ac signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic, including:
performing fast Fourier analysis on the alternating current signal to obtain an analysis result;
acquiring preset arc characteristics, wherein the preset arc characteristics comprise at least one of mean value, root mean square value, variance and kurtosis;
and calculating a preset arc characteristic value corresponding to the preset arc characteristic according to the characteristic calculation mode of the preset arc characteristic based on the analysis result.
Optionally, determining whether a suspected arc occurs according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value includes:
and under the condition that the preset arc characteristic value is larger than the initial characteristic threshold value, judging that a suspicious arc is generated.
Optionally, determining an arc detection result corresponding to the suspected arc at least based on the electric signal of the inverter after the wave-sealing operation includes:
acquiring an electric signal after the inverter executes wave-sealing operation;
if the value of the electric signal is zero, determining that the arc detection result is a real arc;
if the value of the electric signal is not zero, acquiring a direct current electric signal in the direct current side signal;
and under the condition that the value of the direct current electric signal is the same as that of the electric signal, determining that the arc detection result is false arc.
Optionally, based on the arc detection result, adjusting the initial threshold to obtain a target threshold, including:
when the arc detection result is a real arc, reducing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold;
and under the condition that the arc detection result is false arc, increasing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold.
Optionally, the method further comprises:
acquiring grid-connected time of the inverter;
calculating a threshold increment corresponding to the grid-connected time;
and taking the sum or the difference between the initial characteristic threshold and the threshold increment as a target threshold.
Optionally, calculating a threshold increment corresponding to the grid-connected time includes:
and acquiring a threshold increment calculation formula, and calculating a threshold increment corresponding to the grid-connected time based on the threshold increment calculation formula.
Optionally, after determining an arc detection result corresponding to the suspected arc at least based on the electric signal of the inverter after the wave-sealing operation, the method further includes:
and under the condition that the arc detection result is a real arc, controlling the inverter to stop operation and outputting arc fault information.
Optionally, the value of the feature threshold reference value corresponding to the initial feature threshold is configured as a preset threshold; the preset threshold is a value such that the arc detection sensitivity is greater than the preset sensitivity.
An arc fault detection apparatus comprising:
the characteristic value acquisition module is used for acquiring a preset arc characteristic value calculated based on the acquired direct-current side signal of the inverter;
the arc judging module is used for acquiring an initial characteristic threshold value and judging whether a suspected arc occurs or not according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value;
the arc detection module is used for executing wave-sealing operation on the inverter if yes, and determining an arc detection result corresponding to the suspected arc at least based on the electric signal of the inverter after the wave-sealing operation; the arc detection result comprises a real arc or a false arc;
and the threshold adjustment module is used for adjusting the initial threshold based on the arc detection result to obtain a target threshold and updating the initial characteristic threshold to the target threshold.
An electronic device, comprising: a memory and a processor;
wherein the memory is used for storing programs;
the processor invokes a program and is configured to perform the arc fault detection method described above.
An inverter includes the electronic device.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides an arc fault detection method, device and equipment, which are used for acquiring a preset arc characteristic value calculated based on a DC side signal of an acquired inverter, acquiring an initial characteristic threshold value, judging whether a suspected arc occurs according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value, if so, executing wave-sealing operation on the inverter, and determining an arc detection result corresponding to the suspected arc at least based on an electric signal of the inverter after the wave-sealing operation; the arc detection result comprises real arc or false arc, the initial threshold value is adjusted based on the arc detection result to obtain a target threshold value, and the initial characteristic threshold value is updated to the target threshold value. In the invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the actually detected suspected arc, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, the arc fault detection accuracy is improved, and the probability of false alarm and missing alarm is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for detecting arc faults according to an embodiment of the present invention;
fig. 2 is a schematic view of a scenario of an inverter according to an embodiment of the present invention;
FIG. 3 is a flow chart of another arc fault detection method according to an embodiment of the present invention;
FIG. 4 is a flow chart of another arc fault detection method according to an embodiment of the present invention;
FIG. 5 is a flow chart of another arc fault detection method according to an embodiment of the present invention;
FIG. 6 is a flow chart of a fifth arc fault detection method according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an arc fault detection device according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
To avoid arc faults, arc fault detection techniques, such as dc arc detection techniques, are commonly employed for arc detection. And during detection, extracting the characteristics, comparing the characteristics with the characteristic threshold value, and determining whether arc faults occur or not through the comparison result.
In practical application, the characteristic threshold is generally a fixed threshold, when arc fault detection is carried out by using the characteristic threshold, false alarm or missing alarm is easy to occur, and the arc fault detection accuracy is low.
In order to solve the problem of low arc fault detection accuracy caused by a fixed threshold, the characteristic threshold can be adaptively adjusted based on historical time-frequency domain characteristics. However, due to the complexity of the actual power station environment and the diversity of weather, temperature, etc., it is difficult to balance the high-precision arc detection rate with the false alarm prevention capability by adaptively adjusting the characteristic threshold. If the threshold value is selected to be lower, the detection sensitivity is higher, and false alarm is often generated under the working conditions of power mutation of an inverter caused by illumination and the like or time-frequency domain characteristic mutation caused by environmental noise interference and the like; if the threshold value is set higher, the detection sensitivity is lower, and under the arcing with relatively weak characteristic change of the time-frequency domain, a missing report is often generated.
Therefore, in order to improve the arc detection rate, ensure the safe and reliable operation of the power station system and effectively prevent invalid false alarms, the numerical value of the characteristic threshold value needs to be reasonably determined.
Therefore, the embodiment of the invention provides an arc fault detection method, an arc fault detection device and electronic equipment, which are used for acquiring a preset arc characteristic value calculated based on a DC side signal of an acquired inverter, acquiring an initial characteristic threshold value, judging whether a suspected arc occurs according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value, if so, executing wave-sealing operation on the inverter, and determining an arc detection result corresponding to the suspected arc at least based on an electric signal of the inverter after the wave-sealing operation; the arc detection result comprises real arc or false arc, the initial threshold value is adjusted based on the arc detection result to obtain a target threshold value, and the initial characteristic threshold value is updated to the target threshold value. In the invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the actually detected suspected arc, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, the arc fault detection accuracy is improved, and the probability of false alarm and missing alarm is reduced.
Based on the foregoing, an embodiment of the present invention provides an arc fault detection method, referring to fig. 1, may include:
s11, acquiring a preset arc characteristic value calculated based on the acquired direct-current side signal of the inverter.
Referring to fig. 2, fig. 2 shows a schematic diagram of a photovoltaic system comprising a string of photovoltaic modules (connected by at least one photovoltaic module) and an inverter (e.g. a photovoltaic inverter). The number of photovoltaic strings and inverters is at least one.
The inverter is connected to the power grid and the load through the L/N connection line, and an arc detection device is provided inside the inverter, and the arc detection device performs the arc fault detection method in the present embodiment.
When the inverter is connected with the power grid for the first time, the characteristic threshold value built in the arc detection device is a characteristic threshold value reference value, and the numerical value of the characteristic threshold value reference value is configured to be a preset threshold value. The preset threshold is a value such that the arc detection sensitivity is greater than the preset sensitivity.
In practical applications, the preset threshold is a low value (e.g., 10), i.e., the initial arc detection sensitivity is high.
During the operation of the inverter, the detection period may be generally 3 ms or 5 ms, and is specifically set according to the actual situation. And in each detection period, acquiring a preset arc characteristic value calculated based on the acquired DC side signal of the inverter. Specifically, referring to fig. 3, "obtaining the preset arc characteristic value calculated based on the collected dc side signal of the inverter" may include:
s21, acquiring a direct current side signal of the inverter, and extracting an alternating current signal from the direct current side signal.
Specifically, in the process of performing direct current arc detection, the arc detection device acquires a direct current side signal of the inverter in real time. The direct current side signal comprises a direct current electric signal and an alternating current signal. The direct current electrical signal may include data such as a direct current value.
In this embodiment, it is necessary to extract an ac signal from a dc-side signal.
S22, performing fast Fourier analysis on the alternating current signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.
Specifically, by performing fast fourier analysis on the ac signal, the signal intensity of each frequency point can be obtained, and the signal intensity of each frequency point constitutes a frequency domain map. And the frequency domain diagram is the analysis result obtained by performing fast Fourier analysis on the alternating current signal.
Then, a preset arc characteristic is obtained. The obtained preset arc characteristics may include at least one of a mean, a root mean square value, a variance, and kurtosis. In addition, other arc characteristics can be added according to actual requirements.
Each preset arc characteristic has a corresponding characteristic calculation mode, such as an average value of signal intensities of all frequency points. Other preset arc characteristics are similar.
The preset arc characteristic value corresponding to the preset arc characteristic can be calculated based on the analysis result, namely the frequency domain diagram according to the characteristic calculation mode of the preset arc characteristic.
For example, an average value of signal intensities at each frequency point is taken as a mean value, and a root mean square of signal intensities at each frequency point is taken as a root mean square value.
Namely, acquiring preset arc characteristics, and based on the frequency domain diagram, calculating to obtain preset arc characteristic values corresponding to the preset arc characteristics, wherein the method comprises the following steps:
and acquiring preset arc characteristics, wherein the preset arc characteristics comprise at least one of a mean value, a root mean square value, a variance and kurtosis.
And calculating to obtain a preset arc characteristic value corresponding to the preset arc characteristic based on the frequency domain diagram according to the characteristic calculation mode of the preset arc characteristic.
S12, acquiring an initial characteristic threshold value.
In this embodiment, if the inverter is just connected to the grid, and the arc fault detection device has not yet detected an arc fault, the initial characteristic threshold is the above-mentioned characteristic threshold reference value, for example, 10.
If the arc fault detection device has performed arc fault detection, the initial characteristic threshold is the characteristic threshold at the end of the last detection period. At this time, the value of the initial feature threshold reference value is still configured as a preset threshold, that is, the feature threshold is traced back, and the first feature threshold is the feature threshold reference value. That is, the value of the feature threshold reference value corresponding to the initial feature threshold is configured as a preset threshold; the preset threshold is a value such that the arc detection sensitivity is greater than the preset sensitivity.
S13, judging whether a suspected arc occurs or not; if yes, go to step S14; if not, the process returns to step S11 to continue monitoring the current side signal.
Specifically, according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value, judging whether a suspected arc occurs or not.
In detail, if the preset arc characteristic value is greater than the initial characteristic threshold value, the occurrence of a suspected arc is judged. And under the condition that the preset arc characteristic value is not greater than the initial characteristic threshold value, judging that the suspected arc does not occur, and continuously executing the step S11, namely continuously monitoring the current side signal.
S14, performing wave-sealing operation on the inverter, and determining an arc detection result corresponding to the suspected arc at least based on the electric signal of the inverter after the wave-sealing operation.
Wherein the arc detection result comprises a real arc or a false arc. That is, it is determined whether the suspected arc is a real arc or a false arc.
Specifically, a wave-blocking command is sent to the inverter, so that the inverter performs a wave-blocking operation.
And after the wave-sealing operation is executed, performing secondary arc judgment. At this time, a direct-current side signal of the inverter is collected and a direct current is extracted therefrom as an electrical signal, and then, whether the suspected arc is a real arc or a false arc is determined based on the electrical signal.
Specifically, referring to fig. 4, "determining an arc detection result corresponding to the suspected arc based at least on the electric signal of the inverter after the wave-sealing operation" may include:
s31, acquiring an electric signal of the inverter after the wave-sealing operation is executed.
The electrical signal may include a dc input value, and the specific acquisition process is described with reference to the foregoing description.
S32, judging whether the value of the electric signal is zero; if zero, executing step S33; if not, step S34 is performed.
Specifically, the inverter performs a wave-blocking operation, and closes the energy transmission channels of the dc side and the ac side. (the seal time is in the order of milliseconds, for example 200ms seal duration)
If a real arc occurs, the arc will be extinguished due to the closing of the energy transmission channel during the wave sealing, a gap will be generated at the place where the arc occurs (the arc is formed for electrolysis air, energy transmission is cut off, the arc is extinguished, and a gap is generated at the place where the arc is started)), so that the channel cannot be operated in a grid-connected mode again, and therefore the channel current for generating the arc after the wave sealing is 0.
If false arc occurs, the corresponding channel can be in grid-connected operation again after the sealing, and the current can be quickly restored to the value of the sealing front. (the false arc is caused by high-frequency harmonic interference and the like, and the wave-sealing operation does not influence the grid connection of the inverter again).
S33, determining an arc detection result as a real arc.
I.e. the suspected arc is a real arc.
S34, acquiring a direct current electric signal in the direct current side signal.
Specifically, the dc signal may be extracted from the dc signal in step S11, and the dc value in the dc signal is generally extracted.
And S35, determining that the arc detection result is a false arc under the condition that the value of the direct current electric signal is the same as that of the electric signal.
The direct current value and the current input value are the same, namely, the corresponding channels can be operated in a grid-connected mode again after the sealing, the current is quickly recovered to the value before the sealing, and the suspected arc is a false arc.
In this embodiment, the judgment of the false arc and the real arc is performed based on the current value, and in addition, the judgment of the false arc and the real arc may be performed according to the power value.
And S15, adjusting the initial threshold value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value into the target threshold value.
Specifically, step S15 includes:
1) And under the condition that the arc detection result is a real arc, reducing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold.
Referring to fig. 5, according to a preset threshold increment calculation rule, reducing the value of the initial feature threshold to obtain a target threshold may include:
s41, acquiring grid-connected time of the inverter.
Specifically, the grid-connected time of the inverter refers to the time when the inverter is connected to the grid.
S42, calculating a threshold increment corresponding to the grid-connected time.
In practical application, when calculating the threshold increment, a corresponding threshold increment calculation formula is set.
In this embodiment, there are three threshold increment calculation formulas, and one may be selected for use according to the actual scene.
1. The threshold increment calculation formula is:
wherein, delta T and T respectively represent the threshold increment and the grid-connected time, and the grid-connected time is generally the total grid-connected hours. In this embodiment, the threshold increment calculation formula is an inverse function. The threshold increment decays with the total grid-connected time, i.e. the longer the grid-connected time, the smaller the threshold increment. In the inverse function form, the threshold increment is changed rapidly and slowly with the grid-connected time.
For example, if false arcing occurs at 0.1h of inverter grid-tie time, Δt=1/0.1=10.
2. The threshold increment calculation formula is:
wherein Δt and T represent the threshold increment and the grid-tie time, respectively. In this embodiment, the threshold increment calculation formula is an exponential function form, in which the threshold increment is slowly changed along with the grid-connected time.
3. The threshold increment calculation formula is:
wherein Δt and T represent the threshold increment and the grid-tie time, respectively. In this embodiment, the threshold increment calculation formula is in a gaussian function form, and in the gaussian function form, the threshold increment is changed slowly firstly, then quickly and then slowly along with the grid-connected time.
After the threshold increment calculation formula is obtained, calculating the threshold increment corresponding to the obtained grid-connected time based on the threshold increment calculation formula.
S43, taking the difference between the initial characteristic threshold and the threshold increment as a target threshold.
In this embodiment, when the actual arc is detected, it is indicated that the initial feature threshold used at this time has the capability of identifying the actual arc, but there is still an optimization space between the initial feature threshold and the threshold of false arc, at this time, it is possible to try to negatively correct the current feature threshold, further improve the capability of identifying the actual arc, improve the arc detection rate, and prevent the false arc from missing.
And taking the difference value between the initial characteristic threshold value and the threshold increment as a target threshold value.
If a real arc occurs when the inverter is connected for 1h, the threshold value is corrected as follows:
T＝T-ΔT＝22-1＝21
wherein T is a target threshold.
2) And under the condition that the arc detection result is false arc, increasing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold.
In this embodiment, when the arc detection result is a false arc, it is indicated that the false arc is detected, that is, the initial feature threshold used at this time is too sensitive, and the anti-interference capability is poor, and the capability of identifying the interference signal and the real arc is not provided, so that the current initial feature threshold can be corrected forward, the anti-interference capability is improved, and the false alarm of the arc is reduced.
Then, referring to fig. 6, increasing the value of the initial feature threshold according to a preset threshold increment calculation rule to obtain a target threshold may include:
s51, acquiring grid-connected time of the inverter.
S52, calculating a threshold increment corresponding to the grid-connected time.
For a specific implementation of these two steps, reference is made to the corresponding description above.
And S53, taking the sum of the initial characteristic threshold value and the threshold increment as a target threshold value.
The difference between the initial characteristic threshold and the threshold increment is used as a target threshold when the suspected arc is a real arc, namely, a negative correction threshold is adopted. And when the suspected arc is a false arc, taking the sum of the initial characteristic threshold and the threshold increment as a target threshold, and adopting a forward correction threshold mode.
If the initial characteristic threshold is 10 and false arc occurs when the grid-connected time of the inverter is 0.1h, the threshold is corrected to be t=t+Δt=10+10=20; the false arc occurs again at grid connection for 0.5h, and the threshold is corrected to t=t+Δt=20+2=22. Wherein T is a target threshold.
After the target threshold is obtained, the initial characteristic threshold is updated to be the target threshold, and then in the next detection period, arc detection is carried out by using the new initial characteristic threshold.
In this embodiment, the target threshold is determined based on the grid-connected time after the suspected arc is detected. In addition, the implementation method can also be that the suspected arc is not detected, an initial characteristic threshold value is directly obtained in the grid-connected operation process of the inverter, and a target threshold value is determined according to the grid-connected time.
Namely, the arc fault detection method in the invention further comprises the following steps:
and acquiring grid-connected time of the inverter, calculating a threshold increment corresponding to the grid-connected time, and taking the sum or the difference between the initial characteristic threshold and the threshold increment as a target threshold.
The process of calculating the threshold increment corresponding to the grid-connected time is described with reference to the above corresponding description.
In another embodiment of the present invention, after determining an arc detection result corresponding to the suspected arc based at least on an electrical signal of the inverter after the wave-sealing operation, the method further includes:
and under the condition that the arc detection result is a real arc, controlling the inverter to stop operation and outputting arc fault information.
Specifically, if the arc detection result is a real arc, if the inverter is continuously operated, the arc which is extinguished by the sealing wave is easy to strike again, and the arc hazard exists continuously, so that the inverter or the photovoltaic module can be burnt, and even a major fire disaster is caused. At the moment, the inverter can be controlled to stop operation, arc fault information is output, and fault repair is conducted timely by operation and maintenance personnel.
In addition, after the target threshold is determined, the inverter may be controlled to perform a shutdown operation, and arc fault information may be output. The specific order of operation may be set according to the actual scenario. However, in order to protect the inverter from being burned out, the inverter may be controlled to perform a shutdown operation after determining that it is a true arc.
In this embodiment, a preset arc characteristic value calculated based on a collected dc side signal of an inverter is obtained, an initial characteristic threshold is obtained, whether a suspected arc occurs is judged according to a magnitude relation between the preset arc characteristic value and the initial characteristic threshold, if yes, a wave-sealing operation is performed on the inverter, and an arc detection result corresponding to the suspected arc is determined at least based on an electric signal of the inverter after the wave-sealing operation; the arc detection result comprises real arc or false arc, the initial threshold value is adjusted based on the arc detection result to obtain a target threshold value, and the initial characteristic threshold value is updated to the target threshold value. In the invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the actually detected suspected arc, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, the arc fault detection accuracy is improved, and the probability of false alarm and missing alarm is reduced.
In addition, the invention presets the initial characteristic threshold value when grid connection is performed for the first time, and then combines the judgment of the arc detection device and the inverter complete machine on the true and false arcs through the threshold increment function to realize threshold value optimization. The obtained threshold parameters can be matched with the various working conditions such as the power station environment, the climate, the temperature and the like of the operation of each inverter to the greatest extent.
In addition, the invention greatly reduces improper threshold selection in the normal operation process of the inverter by sealing wave false alarm in the threshold value large-range optimizing process during the first grid connection period and after realizing the optimal threshold value optimizing, improves the arc identification capability and simultaneously avoids frequent false alarm caused by periodic interference and the like.
Alternatively, on the basis of the embodiment of the arc fault detection method, another embodiment of the present invention provides an arc fault detection apparatus, referring to fig. 7, which may include:
the characteristic value acquisition module 11 is used for acquiring a preset arc characteristic value calculated based on the acquired direct-current side signal of the inverter;
the arc judging module 12 is configured to obtain an initial characteristic threshold, and judge whether a suspected arc occurs according to a magnitude relation between the preset arc characteristic value and the initial characteristic threshold;
the arc detection module 13 is configured to perform a wave-sealing operation on the inverter if yes, and determine an arc detection result corresponding to the suspected arc based on at least an electrical signal of the inverter after the wave-sealing operation; the arc detection result comprises a real arc or a false arc;
and the threshold adjustment module 14 is configured to adjust the initial threshold based on the arc detection result, obtain a target threshold, and update the initial feature threshold to the target threshold.
Further, the feature value acquisition module 11 includes:
the signal extraction sub-module is used for obtaining a direct current side signal of the inverter and extracting an alternating current signal from the direct current side signal;
and the signal analysis sub-module is used for carrying out fast Fourier analysis on the alternating current signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.
Further, the signal analysis submodule includes:
the analysis unit is used for carrying out fast Fourier analysis on the alternating current signal to obtain an analysis result;
a feature acquisition unit configured to acquire a preset arc feature including at least one of a mean value, a root mean square value, a variance, and kurtosis;
and the calculating unit is used for calculating and obtaining a preset arc characteristic value corresponding to the preset arc characteristic according to the characteristic calculation mode of the preset arc characteristic based on the analysis result.
Further, the arc determination module 12 is specifically configured to:
and under the condition that the preset arc characteristic value is larger than the initial characteristic threshold value, judging that a suspicious arc is generated.
Further, the arc detection module 13 includes:
the first signal acquisition sub-module is used for acquiring an electric signal after the inverter executes wave-sealing operation;
the first electric arc judging sub-module is used for determining that an electric arc detection result is a real electric arc if the value of the electric signal is zero;
the second signal acquisition sub-module is used for acquiring the direct current electric signal in the direct current side signal if the value of the electric signal is not zero;
and the second arc judging sub-module is used for determining that an arc detection result is a false arc under the condition that the value of the direct current electric signal is the same as the value of the electric signal.
Further, the threshold adjustment module 14 is specifically configured to:
and when the arc detection result is a false arc, increasing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold.
Further, the method further comprises the following steps:
the time acquisition module is used for acquiring grid-connected time of the inverter;
the increment calculation module is used for calculating a threshold increment corresponding to the grid-connected time;
and the threshold determining module is used for taking the sum or the difference between the initial characteristic threshold and the threshold increment as a target threshold.
Further, the increment calculating module is specifically configured to:
and acquiring a threshold increment calculation formula, and calculating a threshold increment corresponding to the grid-connected time based on the threshold increment calculation formula.
Further, the method further comprises the following steps:
and the shutdown control module is used for controlling the inverter to perform shutdown operation and outputting arc fault information under the condition that the arc detection result is a real arc.
Further, the value of the feature threshold reference value corresponding to the initial feature threshold is configured as a preset threshold; the preset threshold is a value such that the arc detection sensitivity is greater than the preset sensitivity.
In this embodiment, a preset arc characteristic value calculated based on a collected dc side signal of an inverter is obtained, an initial characteristic threshold is obtained, whether a suspected arc occurs is judged according to a magnitude relation between the preset arc characteristic value and the initial characteristic threshold, if yes, a wave-sealing operation is performed on the inverter, and an arc detection result corresponding to the suspected arc is determined at least based on an electric signal of the inverter after the wave-sealing operation; the arc detection result comprises real arc or false arc, the initial threshold value is adjusted based on the arc detection result to obtain a target threshold value, and the initial characteristic threshold value is updated to the target threshold value. In the invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the actually detected suspected arc, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, the arc fault detection accuracy is improved, and the probability of false alarm and missing alarm is reduced.
In addition, the invention presets the initial characteristic threshold value when grid connection is performed for the first time, and then combines the judgment of the arc detection device and the inverter complete machine on the true and false arcs through the threshold increment function to realize threshold value optimization. The obtained threshold parameters can be matched with the various working conditions such as the power station environment, the climate, the temperature and the like of the operation of each inverter to the greatest extent.
In addition, the invention greatly reduces improper threshold selection in the normal operation process of the inverter by sealing wave false alarm in the threshold value large-range optimizing process during the first grid connection period and after realizing the optimal threshold value optimizing, improves the arc identification capability and simultaneously avoids frequent false alarm caused by periodic interference and the like.
It should be noted that, in the working process of each module, sub-module and unit in this embodiment, please refer to the corresponding description in the above embodiment, and the description is omitted here.
Optionally, on the basis of the embodiments of the arc fault detection method and apparatus, another embodiment of the present invention provides an electronic device, including: a memory and a processor;
wherein the memory is used for storing programs;
the processor invokes a program and is configured to perform the arc fault detection method described above.
Note that, the electronic device in this embodiment may be the arc detection device described above.
Optionally, on the basis of the embodiment of the electronic device, another embodiment of the present invention provides an inverter, including the electronic device.
In this embodiment, a preset arc characteristic value calculated based on a collected dc side signal of an inverter is obtained, an initial characteristic threshold is obtained, whether a suspected arc occurs is judged according to a magnitude relation between the preset arc characteristic value and the initial characteristic threshold, if yes, a wave-sealing operation is performed on the inverter, and an arc detection result corresponding to the suspected arc is determined at least based on an electric signal of the inverter after the wave-sealing operation; the arc detection result comprises real arc or false arc, the initial threshold value is adjusted based on the arc detection result to obtain a target threshold value, and the initial characteristic threshold value is updated to the target threshold value. In the invention, the initial characteristic threshold used can be adjusted according to the arc detection result of the actually detected suspected arc, so that the initial characteristic threshold is more in line with the actual application environment, the accuracy of the initial characteristic threshold is improved, the arc fault detection accuracy is improved, and the probability of false alarm and missing alarm is reduced.
In addition, the invention presets the initial characteristic threshold value when grid connection is performed for the first time, and then combines the judgment of the arc detection device and the inverter complete machine on the true and false arcs through the threshold increment function to realize threshold value optimization. The obtained threshold parameters can be matched with the various working conditions such as the power station environment, the climate, the temperature and the like of the operation of each inverter to the greatest extent.
In addition, the invention greatly reduces improper threshold selection in the normal operation process of the inverter by sealing wave false alarm in the threshold value large-range optimizing process during the first grid connection period and after realizing the optimal threshold value optimizing, improves the arc identification capability and simultaneously avoids frequent false alarm caused by periodic interference and the like.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. An arc fault detection method, comprising:
the method for obtaining the preset arc characteristic value calculated based on the collected direct current side signal of the inverter comprises the following steps: acquiring a direct current side signal of an inverter, and extracting an alternating current signal from the direct current side signal; performing fast Fourier analysis on the alternating current signal to obtain an analysis result; acquiring preset arc characteristics, wherein the preset arc characteristics comprise at least one of mean value, root mean square value, variance and kurtosis; based on the analysis result, calculating to obtain a preset arc characteristic value corresponding to the preset arc characteristic according to a characteristic calculation mode of the preset arc characteristic;
acquiring an initial characteristic threshold, and judging whether a suspected arc occurs according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold, wherein the initial characteristic threshold is the characteristic threshold at the last detection period;
if yes, performing wave-sealing operation on the inverter, and determining an arc detection result corresponding to the suspected arc at least based on the electric signal of the inverter after the wave-sealing operation; the arc detection result comprises a real arc or a false arc;
based on the arc detection result, adjusting the initial threshold value to obtain a target threshold value, and updating the initial characteristic threshold value into the target threshold value;
based on the arc detection result, the initial threshold is adjusted to obtain a target threshold, which comprises the following steps:
when the arc detection result is a real arc, reducing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold;
and under the condition that the arc detection result is false arc, increasing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold.
2. The arc fault detection method according to claim 1, wherein determining whether a suspected arc occurs according to a magnitude relation between the preset arc characteristic value and the initial characteristic threshold value comprises:
and under the condition that the preset arc characteristic value is larger than the initial characteristic threshold value, judging that a suspicious arc is generated.
3. The arc fault detection method according to claim 1, wherein determining an arc detection result corresponding to the suspected arc based at least on an electric signal of the inverter after a wave-sealing operation, comprises:
acquiring an electric signal after the inverter executes wave-sealing operation;
if the value of the electric signal is zero, determining that the arc detection result is a real arc;
if the value of the electric signal is not zero, acquiring a direct current electric signal in the direct current side signal;
and under the condition that the value of the direct current electric signal is the same as that of the electric signal, determining that the arc detection result is false arc.
4. The arc fault detection method according to claim 1, further comprising:
acquiring grid-connected time of the inverter;
calculating a threshold increment corresponding to the grid-connected time;
and taking the sum or the difference between the initial characteristic threshold and the threshold increment as a target threshold.
5. The arc fault detection method of claim 4, wherein calculating the threshold increment for the grid-tie time comprises:
and acquiring a threshold increment calculation formula, and calculating a threshold increment corresponding to the grid-connected time based on the threshold increment calculation formula.
6. The arc fault detection method according to claim 1, further comprising, after determining an arc detection result corresponding to the suspected arc based at least on an electric signal of the inverter after the envelope operation:
and under the condition that the arc detection result is a real arc, controlling the inverter to stop operation and outputting arc fault information.
7. The arc fault detection method according to claim 1, wherein the value of the feature threshold reference value corresponding to the initial feature threshold is configured as a preset threshold; the preset threshold is a value such that the arc detection sensitivity is greater than the preset sensitivity.
8. An arc fault detection apparatus, comprising:
the characteristic value obtaining module is used for obtaining a preset arc characteristic value obtained by calculation based on the collected direct-current side signal of the inverter, and comprises the following steps: acquiring a direct current side signal of an inverter, and extracting an alternating current signal from the direct current side signal; performing fast Fourier analysis on the alternating current signal to obtain an analysis result; acquiring preset arc characteristics, wherein the preset arc characteristics comprise at least one of mean value, root mean square value, variance and kurtosis; based on the analysis result, calculating to obtain a preset arc characteristic value corresponding to the preset arc characteristic according to a characteristic calculation mode of the preset arc characteristic;
the arc judgment module is used for acquiring an initial characteristic threshold value and judging whether a suspected arc occurs or not according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value, wherein the initial characteristic threshold value is the characteristic threshold value at the last detection period;
the arc detection module is used for executing wave-sealing operation on the inverter if yes, and determining an arc detection result corresponding to the suspected arc at least based on the electric signal of the inverter after the wave-sealing operation; the arc detection result comprises a real arc or a false arc;
the threshold adjustment module is used for adjusting the initial threshold based on the arc detection result to obtain a target threshold and updating the initial characteristic threshold to the target threshold;
the threshold adjustment module is specifically configured to:
when the arc detection result is a real arc, reducing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold;
and under the condition that the arc detection result is false arc, increasing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold.
9. An electronic device, comprising: a memory and a processor;
wherein the memory is used for storing programs;
a processor invokes a program and is adapted to perform the arc fault detection method according to any one of claims 1-7.
10. An inverter comprising the electronic device of claim 9.
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| CN202210421305.4A CN114755542B (en) | 2022-04-21 | 2022-04-21 | Arc fault detection method, device and equipment |
| PCT/CN2022/134752 WO2023202078A1 (en) | 2022-04-21 | 2022-11-28 | Arc fault detection method and apparatus, and device |
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| CN114755542A (en) | 2022-07-15 |
| WO2023202078A1 (en) | 2023-10-26 |
| WO2023202078A9 (en) | 2023-12-07 |
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