CN114755542A - Arc fault detection method, device and equipment - Google Patents
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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 collected direct current side signal of an inverter, acquiring an initial characteristic threshold, judging whether a suspected arc occurs according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold, if so, performing 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; and adjusting the initial threshold value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value to the target threshold value. In other words, in the invention, the used initial characteristic threshold can be adjusted according to the actually detected arc detection result of the suspected arc, so that the initial characteristic threshold is more consistent 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 invention relates to the field of arc detection, in particular to an arc fault detection method, device and equipment.
Background
The arc is a gas discharge phenomenon, and once a fault arc occurs in a photovoltaic system, if effective measures are not taken for protection, a fire disaster is easily caused by high temperature generated by continuous direct current arc, so that a major safety accident is caused.
In order to avoid the arc causing a fault, arc fault 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 the arc fault occurs according to the comparison result.
In practical application, the characteristic threshold is generally a fixed threshold, and when the characteristic threshold is used for arc fault detection, false alarm or false alarm is easy to occur, and the accuracy of arc fault detection is low.
Disclosure of Invention
In view of this, the present invention provides an arc fault detection method, apparatus and device to solve the problem of low accuracy of arc fault detection.
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 the acquired direct current side signal of the inverter;
acquiring an initial characteristic threshold, and judging whether a suspected arc occurs according to the size relation between the preset arc characteristic value and the initial characteristic threshold;
if yes, wave sealing operation is carried out on the inverter, and an arc detection result corresponding to the suspected arc is determined 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 value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value to the target threshold value.
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 carrying out 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 alternating current signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic, including:
carrying out fast Fourier analysis on the alternating current signal to obtain an analysis result;
acquiring preset electric arc characteristics, wherein the preset electric arc characteristics comprise at least one of a mean value, a root mean square value, a variance and a kurtosis;
and calculating to obtain 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 a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold includes:
and under the condition that the preset arc characteristic value is larger than the initial characteristic threshold value, judging that the arc is suspected.
Optionally, determining an arc detection result corresponding to the suspected arc based on at least the electric signal of the inverter after the wave-sealing operation includes:
acquiring an electric signal of the inverter after wave sealing operation is performed;
if the value of the electric signal is zero, determining that the electric arc detection result is a real electric 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 a false arc.
Optionally, adjusting the initial threshold based on the arc detection result to obtain a target threshold includes:
under the condition that the arc detection result is a real arc, reducing the numerical 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 the false arc, increasing the value of the initial characteristic threshold value according to a preset threshold value increment calculation rule to obtain a target threshold value.
Optionally, the method further comprises:
acquiring grid connection time of the inverter;
calculating a threshold increment corresponding to the grid connection 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 connection time includes:
and acquiring a threshold increment calculation formula, and calculating the 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 based on at least 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 operating and outputting arc fault information.
Optionally, a numerical value of a feature threshold reference value corresponding to the initial feature threshold is configured as a preset threshold; the preset threshold is a value that causes the arc detection sensitivity to be greater than a preset sensitivity.
An arc fault detection device, 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 judgment module is used for acquiring an initial characteristic threshold value and judging whether a suspected arc occurs according to the size relationship 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 the voltage across the inverter is lower than the preset voltage, 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;
and the threshold adjusting 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 used to perform the arc fault detection method described above.
An inverter includes the above 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 comprises the steps of obtaining a preset arc characteristic value obtained by calculation based on a collected direct current side signal of an inverter, obtaining an initial characteristic threshold value, judging whether a suspected arc occurs according to the size 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; and adjusting the initial threshold value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value to the target threshold value. In other words, the initial characteristic threshold used in the invention can be adjusted according to the actually detected arc detection result of the suspected arc, so that the initial characteristic threshold is more consistent with the actual application environment, the accuracy of the initial characteristic threshold is improved, the arc fault detection accuracy is improved, and the false alarm and false alarm probability are reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a flowchart of a method for detecting an arc fault 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 method flow diagram of another arc fault detection method provided by embodiments of the present invention;
FIG. 4 is a flowchart of a method of another arc fault detection method according to an embodiment of the present invention;
FIG. 5 is a flowchart of a method for another arc fault detection method according to an embodiment of the present invention;
FIG. 6 is a flowchart illustrating a fifth method for arc fault detection according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an arc fault detection apparatus according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to avoid the arc causing the fault, arc fault detection technology, such as direct current arc detection technology, is generally adopted to perform arc detection. And during detection, extracting the characteristics, comparing the characteristics with the characteristic threshold value, and determining whether the arc fault occurs according to the comparison result.
In practical application, the characteristic threshold is generally a fixed threshold, and when the characteristic threshold is used for arc fault detection, false alarm or false alarm is easy to occur, and the accuracy of arc fault detection 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 and false alarm prevention capability by adaptively adjusting the characteristic threshold. If the threshold value is selected to be low, the detection sensitivity is high, and false alarm is often generated under the working conditions that the inverter power is suddenly changed due to illumination and the like or the time-frequency domain characteristic is suddenly changed due to environmental noise interference and the like; if the threshold is set to be high, the detection sensitivity is low, and under the arcing condition that the time-frequency domain characteristic change is relatively weak, the missing report is often generated.
Therefore, in order to improve the arc detection rate, ensure safe and reliable operation of the power station system, and effectively prevent invalid false alarm, the numerical value of the characteristic threshold needs to be reasonably determined.
The method, the device and the electronic equipment for detecting the arc faults are characterized by comprising the steps of obtaining a preset arc characteristic value obtained by calculation based on a collected direct-current side signal of an inverter, obtaining an initial characteristic threshold value, judging whether a suspected arc occurs according to the size 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; and adjusting the initial threshold value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value to the target threshold value. In other words, the initial characteristic threshold used in the invention can be adjusted according to the actually detected arc detection result of the suspected arc, so that the initial characteristic threshold is more consistent with the actual application environment, the accuracy of the initial characteristic threshold is improved, the accuracy of arc fault detection is improved, and the probability of false alarm and false alarm is reduced.
On the basis of the above, an embodiment of the present invention provides an arc fault detection method, and with reference to fig. 1, the method may include:
and 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 including a string of photovoltaic modules (connected by at least one photovoltaic module) and an inverter (e.g., a photovoltaic inverter). The number of the photovoltaic string and the number of the inverters are at least one.
The inverter is connected to the grid and the load through an L/N connection line, and an arc detection device is provided inside the inverter, and performs the arc fault detection method in the present embodiment.
When the inverter is connected to the grid for the first time, a 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 that causes the arc detection sensitivity to be greater than a preset sensitivity.
In practical applications, the predetermined 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 set according to an actual situation, and may be generally 3 milliseconds or 5 milliseconds. And in each detection period, acquiring a preset arc characteristic value calculated based on the acquired direct current 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:
and 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 detecting the direct current arc, 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 signal and an alternating current signal. The dc signal may include data such as a dc current value.
In this embodiment, it is necessary to extract an ac signal from a dc-side signal.
And S22, carrying out fast Fourier analysis on the alternating current signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.
Specifically, the signal intensity of each frequency point can be obtained by performing fast fourier analysis on the alternating current signal, and the signal intensity of each frequency point forms a frequency domain diagram. And the frequency domain graph is an analysis result obtained by performing fast Fourier analysis on the alternating current signal.
Then, a preset arc characteristic is acquired. The acquired preset arc characteristics may include at least one of a mean, a root mean square value, a variance, and a kurtosis. In addition, other arc characteristics can be added according to actual requirements.
Each preset arc characteristic has a corresponding characteristic calculation mode, for example, the average value is the average value of the signal intensity of each frequency point. Other predetermined arc characteristics are similar.
Then, according to the feature calculation mode of the preset arc feature, a preset arc feature value corresponding to the preset arc feature may be calculated based on the analysis result, that is, the frequency domain map.
For example, the average value of the signal intensities at the respective frequency points is defined as an average value, and the root mean square of the signal intensities at the respective frequency points is defined as a root mean square value.
Namely, acquiring a preset arc characteristic, and calculating to obtain a preset arc characteristic value corresponding to the preset arc characteristic based on the frequency domain diagram, 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 a kurtosis.
And calculating to obtain a preset arc characteristic value corresponding to the preset arc characteristic based on the frequency domain graph according to the characteristic calculation mode of the preset arc characteristic.
And S12, acquiring an initial characteristic threshold.
In this embodiment, if the arc detection device has not yet detected an over-arc fault immediately after the inverter is connected to the grid, the initial characteristic threshold is the above-mentioned characteristic threshold reference value, for example, 10.
If yes, the arc detection device performs arc fault detection, and the initial characteristic threshold is the characteristic threshold at the end of the last detection period. At this time, the value of the initial characteristic threshold reference value is still configured as the preset threshold, that is, the characteristic threshold is traced back, and the first characteristic threshold is the characteristic threshold reference value. That is, the value of the reference value of the feature threshold corresponding to the initial feature threshold is configured as a preset threshold; the preset threshold is a value that causes the arc detection sensitivity to be greater than a preset sensitivity.
S13, judging whether a suspected arc occurs; if yes, go to step S14; if not, the process returns to step S11 to continue monitoring the current-side signal.
Specifically, whether a suspected arc occurs is judged according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value.
Specifically, when the preset arc characteristic value is greater than the initial characteristic threshold value, it is determined that an arc is suspected. And under the condition that the preset arc characteristic value is not larger than the initial characteristic threshold value, judging that no suspected arc occurs, and continuing to execute the step S11, namely continuing to monitor the current side signal.
S14, wave-sealing operation is carried out on the inverter, and an arc detection result corresponding to the suspected arc is determined 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 a suspected arc is a real arc or a false arc.
In detail, a wave blocking command is sent to the inverter to make the inverter perform the wave blocking operation.
And after the wave sealing operation is carried out, secondary arc judgment is carried out. At this time, a direct current side signal of the inverter is acquired, and a direct current is extracted therefrom as an electric signal, and then, it is determined whether the suspected arc is a real arc or a false arc based on the electric signal.
In detail, referring to fig. 4, "determining an arc detection result corresponding to the suspected arc based on at least the electric signal of the inverter after the wave-sealing operation" may include:
and S31, acquiring the electric signal after the wave sealing operation of the inverter is performed.
The electrical signal may include a dc input value, and the specific acquisition process is described with reference to the above corresponding description.
S32, judging whether the value of the electric signal is zero or not; if yes, go to step S33; if not, go to step S34.
Specifically, the inverter performs a wave-blocking operation, which closes the energy transmission channels on the dc side and the ac side. (the envelope time is of the order of milliseconds, e.g. 200ms envelope duration)
If a real electric arc occurs, the electric arc is extinguished due to the fact that an energy transmission channel is closed during wave sealing, a gap is generated at the place where the electric arc occurs ((the electric arc is formed by electrolytic air, energy transmission is cut off, the electric arc is extinguished, and a gap is generated at the place where the electric arc is started)), so that the channel cannot be connected to the grid again, and therefore the channel current of the electric arc is 0 after wave sealing.
If false arcs occur, corresponding channels can be connected to the grid again after the arc is sealed, and the current can be rapidly recovered to the value of the arc before the arc is sealed. (false arc is caused by high-frequency harmonic interference, etc., and the wave-sealing operation can not influence the inverter to be connected to the grid again).
And S33, determining the arc detection result as a real arc.
That is, the suspected arc is a real arc.
And S34, acquiring the direct current signal in the direct current side signal.
Specifically, the dc-side signal in step S11 can be extracted, and generally, the dc current value in the dc electrical signal is extracted.
And S35, determining the arc detection result as 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 is the same as the current input value, namely the corresponding channel after the sealing can be connected to the grid again for operation, and the current is quickly recovered to the value before the sealing, so that the suspected arc is the false arc.
It should be noted that, in this embodiment, the determination of the false arc and the real arc is performed based on the current value, and in addition, the determination of the false arc and the real arc may also be performed according to the power value.
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 to the target threshold value.
Specifically, step S15 includes:
1) and under the condition that the arc detection result is a real arc, reducing the numerical value of the initial characteristic threshold value according to a preset threshold value increment calculation rule to obtain a target threshold value.
Referring to fig. 5, reducing the value of the initial characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold may include:
and S41, acquiring the grid connection time of the inverter.
Specifically, the grid connection time of the inverter refers to the time when the inverter is connected to the power grid.
And S42, calculating a threshold increment corresponding to the grid connection time.
In practical application, when the threshold increment is calculated, a corresponding threshold increment calculation formula is set.
In this embodiment, there are three threshold increment calculation formulas, and one of the three threshold increment calculation formulas can be selected for use according to an actual scene.
1. The threshold increment calculation formula is:
wherein, Δ T and T respectively represent a threshold increment and a grid connection time, and the grid connection time is generally the total grid connection hours. In this embodiment, the threshold increment calculation formula is in the form of an inverse function. And the threshold increment is attenuated along with the total grid connection time, namely the longer the grid connection time is, the smaller the threshold increment is. In the form of an inverse function, the threshold increment is changed rapidly and slowly with grid connection time.
For example, if a false arcing occurs at a grid-connected time of 0.1h of the inverter, Δ T is 1/0.1 is 10.
2. The threshold increment calculation formula is:
where Δ T and T represent the threshold increment and the grid-connection time, respectively. In this embodiment, the threshold increment calculation formula is in an exponential function form, and in the exponential function form, the threshold increment slowly changes along with grid-connected time.
3. The threshold increment calculation formula is:
where Δ T and T represent the threshold increment and grid-connection time, respectively. In this embodiment, the threshold increment calculation formula is a gaussian function form, and in the gaussian function form, the threshold increment is changed slowly, quickly, and slowly with grid connection time.
And after a threshold increment calculation formula is obtained, calculating the threshold increment corresponding to the obtained grid-connected time based on the threshold increment calculation formula.
And S43, taking the difference between the initial characteristic threshold and the threshold increment as a target threshold.
In this embodiment, when a real arc is detected, it is described that the initial feature threshold used at this time has the capability of identifying the real arc, but an optimization space still exists between the initial feature threshold and the false arc false alarm threshold, and at this time, negative correction of the current feature threshold may be attempted, so that the real arc identification capability is further improved, the arc detection rate is improved, and the false arc is prevented from being missed.
Then the difference between the initial feature threshold and the threshold increment is taken as the target threshold.
If real electric arc occurs when the inverter is connected to the grid for 1h, the threshold value is corrected as follows:
T＝T-ΔT＝22-1＝21
where T is the target threshold.
2) And under the condition that the arc detection result is false arc, increasing the value of the initial characteristic threshold value according to a preset threshold value increment calculation rule to obtain a target threshold value.
In this embodiment, when the arc detection result is a false arc, it indicates that the false arc is detected, that is, the initial characteristic threshold used at this time is too sensitive, the anti-interference capability is poor, and the capability of identifying an interference signal and a real arc is not provided, so that the current initial characteristic threshold can be corrected in a forward direction, 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 characteristic threshold according to a preset threshold increment calculation rule to obtain a target threshold, which may include:
and S51, acquiring the grid connection time of the inverter.
And S52, calculating a threshold increment corresponding to the grid connection time.
The specific implementation of these two steps is described with reference to the above corresponding descriptions.
And S53, taking the sum of the initial characteristic threshold and the threshold increment as a target threshold.
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 threshold correction mode is adopted. And when the suspected arc is the 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, if a false arc occurs when the inverter grid connection time is 0.1h, the threshold is corrected to be T +10 + 20; when the grid is connected for 0.5h, false arc occurs again, and the threshold value is corrected to be T + delta T-20 + 2-22. Where T is the target threshold.
And after the target threshold is obtained, updating the initial characteristic threshold to the target threshold, and then in the next detection period, carrying out arc detection by using the new initial characteristic threshold.
In the present embodiment, after the pseudo arc is detected, the target threshold is determined based on the grid connection time. In addition, the implementation mode can also be that the suspected arc is not detected, the initial characteristic threshold value is directly obtained in the grid-connected operation process of the inverter, and the target threshold value is determined according to the grid-connected time.
Namely, the arc fault detection method of the present invention further includes:
and acquiring the grid-connected time of the inverter, calculating a threshold increment corresponding to the grid-connected time, and taking the sum or the difference of the initial characteristic threshold and the threshold increment as a target threshold.
The process of calculating the threshold increment corresponding to the grid connection time refers to the above corresponding description.
In another embodiment of the present invention, after determining an arc detection result corresponding to the suspected arc based on at least 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 operating and outputting arc fault information.
Specifically, if the arc detection result is a real arc, if the inverter continues to operate, the arc extinguished by the wave-sealing device is easy to strike again, and the arc hazard continues to exist, possibly burning the inverter or the photovoltaic module, and even causing a serious fire. At the moment, the inverter can be controlled to stop operating, and arc fault information is output, so that operation and maintenance personnel can repair the fault in time.
In addition, after the target threshold value is determined, the inverter can be controlled to perform shutdown operation, and arc fault information can be output. The specific operation sequence can be set according to the actual scene. However, in order to protect the inverter from being burned, the inverter may be controlled to perform a shutdown operation after it is determined to be a real 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 value is obtained, and whether a suspected arc occurs is determined according to a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold value, 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 electrical signal of the inverter after the wave sealing operation; and adjusting the initial threshold value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value to the target threshold value. In other words, the initial characteristic threshold used in the invention can be adjusted according to the actually detected arc detection result of the suspected arc, so that the initial characteristic threshold is more consistent with the actual application environment, the accuracy of the initial characteristic threshold is improved, the arc fault detection accuracy is improved, and the false alarm and false alarm probability are reduced.
In addition, the initial characteristic threshold is preset during the first grid connection, and then the threshold increment function is adopted, so that the threshold optimization is realized by combining the judgment of the arc detection device and the inverter complete machine on the true and false arcs. The obtained threshold parameter can be maximally fit with various working conditions such as power station environment, climate, temperature and the like in which each inverter operates.
In addition, after the optimal threshold value optimization is realized through the wave-blocking false alarm in the large-range threshold value optimization process during the first grid connection period, improper threshold value selection in the normal operation process of the inverter is greatly reduced, the electric arc identification capability is improved, and meanwhile frequent false alarm caused by periodic interference and the like is avoided.
Alternatively, on the basis of the above embodiment of the arc fault detection method, another embodiment of the present invention provides an arc fault detection apparatus, and referring to fig. 7, the arc fault detection apparatus 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 judgment module 12 is configured to obtain an initial characteristic threshold, and judge whether a suspected arc occurs according to a size relationship between the preset arc characteristic value and the initial characteristic threshold;
an arc detection module 13, configured to, if yes, perform a wave sealing operation on the inverter, and determine an arc detection result corresponding to the suspected arc based 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;
a threshold adjusting module 14, configured to adjust the initial threshold based on the arc detection result to obtain a target threshold, and update the initial characteristic threshold to the target threshold.
Further, the feature value obtaining module 11 includes:
the signal extraction submodule is used for acquiring a direct current side signal of the inverter and extracting an alternating current signal from the direct current side signal;
and the signal analysis submodule is used for carrying out fast Fourier analysis on the alternating current signal to obtain a preset electric arc characteristic value corresponding to the preset electric arc characteristic.
Further, the signal analysis sub-module includes:
the analysis unit is used for carrying out fast Fourier analysis on the alternating current signal to obtain an analysis result;
the device comprises a characteristic acquisition unit, a detection unit and a control unit, wherein the characteristic acquisition unit is used for acquiring preset electric arc characteristics, and the preset electric arc characteristics comprise at least one of a mean value, a root mean square value, a variance and a kurtosis;
and the calculating unit is used for calculating to obtain a preset arc characteristic value corresponding to the preset arc characteristic according to the characteristic calculating 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 the arc is suspected.
Further, the arc detection module 13 includes:
the first signal acquisition submodule is used for acquiring an electric signal of the inverter after wave sealing operation is executed;
the first arc judgment submodule is used for determining that an arc detection result is a real arc if the value of the electric signal is zero;
the second signal acquisition submodule is used for acquiring a direct current signal in the direct current side signal if the value of the electric signal is not zero;
and the second arc judgment submodule is used for determining that the arc detection result is the false arc under the condition that the value of the direct current electric signal is the same as that of the electric signal.
Further, the threshold adjusting module 14 is specifically configured to:
and under the condition that the arc detection result is a real arc, reducing the numerical 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 a false arc, increasing the numerical value of the initial characteristic threshold according to the preset threshold increment calculation rule to obtain the target threshold.
Further, still include:
the time acquisition module is used for acquiring the grid connection time of the inverter;
the increment calculation module is used for calculating a threshold increment corresponding to the grid connection time;
and the threshold value determining module is used for taking the sum or the difference of the initial characteristic threshold value and the threshold value increment as a target threshold value.
Further, the increment calculation module is specifically configured to:
and acquiring a threshold increment calculation formula, and calculating the threshold increment corresponding to the grid-connected time based on the threshold increment calculation formula.
Further, still include:
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 numerical value of the characteristic threshold reference value corresponding to the initial characteristic threshold is configured as a preset threshold; the preset threshold is a value that causes the arc detection sensitivity to be greater than a preset sensitivity.
In the embodiment, a preset arc characteristic value obtained by calculation based on a collected direct-current side signal of an inverter is obtained, an initial characteristic threshold value is obtained, whether a suspected arc occurs or not is judged according to the magnitude relation between the preset arc characteristic value and the initial characteristic threshold value, if yes, a wave sealing operation is carried out 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; and adjusting the initial threshold value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value to the target threshold value. In other words, the initial characteristic threshold used in the invention can be adjusted according to the actually detected arc detection result of the suspected arc, so that the initial characteristic threshold is more consistent with the actual application environment, the accuracy of the initial characteristic threshold is improved, the arc fault detection accuracy is improved, and the false alarm and false alarm probability are reduced.
In addition, the initial characteristic threshold is preset during the first grid connection, and then threshold increment function is combined with the electric arc detection device and the inverter complete machine to judge whether the electric arc is true or false, so that threshold optimization is realized. The obtained threshold parameters can be adapted to various working conditions such as power station environment, climate, temperature and the like operated by each inverter to the maximum extent.
In addition, after the optimal threshold value optimization is realized through the wave-blocking false alarm in the large-range threshold value optimization process during the first grid connection period, improper threshold value selection in the normal operation process of the inverter is greatly reduced, the electric arc identification capability is improved, and meanwhile frequent false alarm caused by periodic interference and the like is avoided.
It should be noted that, please refer to the corresponding description in the above embodiments for the working processes of each module, sub-module, and unit in this embodiment, which is not described herein again.
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 used to perform the arc fault detection method described above.
The electronic device in the present 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 value is obtained, and whether a suspected arc occurs is determined according to a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold value, 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 electrical signal of the inverter after the wave sealing operation; and adjusting the initial threshold value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value to the target threshold value. In other words, the initial characteristic threshold used in the invention can be adjusted according to the actually detected arc detection result of the suspected arc, so that the initial characteristic threshold is more consistent with the actual application environment, the accuracy of the initial characteristic threshold is improved, the accuracy of arc fault detection is improved, and the probability of false alarm and false alarm is reduced.
In addition, the initial characteristic threshold is preset during the first grid connection, and then threshold increment function is combined with the electric arc detection device and the inverter complete machine to judge whether the electric arc is true or false, so that threshold optimization is realized. The obtained threshold parameters can be adapted to various working conditions such as power station environment, climate, temperature and the like operated by each inverter to the maximum extent.
In addition, after the optimal threshold value optimization is realized through the wave-blocking false alarm in the large-range threshold value optimization process during the first grid connection period, improper threshold value selection in the normal operation process of the inverter is greatly reduced, the electric arc identification capability is improved, and meanwhile frequent false alarm caused by periodic interference and the like is avoided.
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 (13)
1. An arc fault detection method, comprising:
acquiring a preset arc characteristic value calculated based on the acquired direct current side signal of the inverter;
acquiring an initial characteristic threshold, and judging whether a suspected arc occurs according to the size relation between the preset arc characteristic value and the initial characteristic threshold;
if yes, wave sealing operation is carried out 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 a real arc or a false arc;
and adjusting the initial threshold value based on the arc detection result to obtain a target threshold value, and updating the initial characteristic threshold value to the target threshold value.
2. The arc fault detection method of claim 1, wherein obtaining the preset arc characteristic value calculated based on the collected dc-side signal of the inverter comprises:
acquiring a direct current side signal of an inverter, and extracting an alternating current signal from the direct current side signal;
and carrying out fast Fourier analysis on the alternating current signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic.
3. The arc fault detection method of claim 2, wherein performing fast fourier analysis on the ac signal to obtain a preset arc characteristic value corresponding to the preset arc characteristic comprises:
carrying out fast Fourier analysis on the alternating current signal to obtain an analysis result;
acquiring preset electric arc characteristics, wherein the preset electric arc characteristics comprise at least one of a mean value, a root mean square value, a variance and a kurtosis;
and calculating to obtain 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.
4. The arc fault detection method according to claim 1, wherein determining whether a suspected arc occurs according to a magnitude relationship between the preset arc characteristic value and the initial characteristic threshold includes:
and under the condition that the preset arc characteristic value is larger than the initial characteristic threshold value, judging that the arc is suspected.
5. The arc fault detection method of claim 1, wherein determining the arc detection result corresponding to the suspected arc based on at least the electrical signal of the inverter after the wave-sealing operation comprises:
acquiring an electric signal of the inverter after wave sealing operation is performed;
if the value of the electric signal is zero, determining that the electric arc detection result is a real electric 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 a false arc.
6. The arc fault detection method of claim 1, wherein adjusting the initial threshold based on the arc detection results to obtain a target threshold comprises:
under the condition that the arc detection result is a real arc, reducing the numerical 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 the false arc, increasing the value of the initial characteristic threshold value according to a preset threshold value increment calculation rule to obtain a target threshold value.
7. The arc fault detection method of claim 1, further comprising:
acquiring grid connection time of the inverter;
calculating a threshold increment corresponding to the grid connection time;
and taking the sum or the difference between the initial characteristic threshold and the threshold increment as a target threshold.
8. The arc fault detection method of claim 7, wherein calculating the threshold increment corresponding to the grid-tie time comprises:
and acquiring a threshold increment calculation formula, and calculating the threshold increment corresponding to the grid-connected time based on the threshold increment calculation formula.
9. The arc fault detection method of claim 1, further comprising, after determining an arc detection result corresponding to the suspected arc based on at least the electrical signal of the inverter after the wave-sealing operation:
and under the condition that the arc detection result is a real arc, controlling the inverter to stop operating and outputting arc fault information.
10. The arc fault detection method according to claim 1, wherein the initial characteristic threshold value corresponds to a characteristic threshold value reference value, and the value of the characteristic threshold value reference value is configured as a preset threshold value; the preset threshold is a value that causes the arc detection sensitivity to be greater than a preset sensitivity.
11. An arc fault detection device, 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 judgment module is used for acquiring an initial characteristic threshold value and judging whether a suspected arc occurs according to the size 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 the detected voltage is positive, 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 adjusting 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.
12. 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 according to any of claims 1-10.
13. An inverter, characterized by comprising the electronic device of claim 12.
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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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| WO2023202078A1 (en) * | 2022-04-21 | 2023-10-26 | 阳光电源股份有限公司 | Arc fault detection method and apparatus, and device |
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| CN114755542B (en) | 2024-02-09 |
| WO2023202078A1 (en) | 2023-10-26 |
| WO2023202078A9 (en) | 2023-12-07 |
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