阅读说明：本技术 一种电弧检测装置失效判定方法及电弧检测装置 (Arc detection device failure determination method and arc detection device ) 是由 汪晶晶 詹亮 俞雁飞 邢军 于 2019-11-11 设计创作，主要内容包括：本发明提供的电弧检测装置失效判定方法及电弧检测装置,应用于电力电子技术领域,该方法在电弧检测装置上电且自检通过后,获取电流采样信号,然后判断所得电流采样信号是否满足预设自检条件,如果判定检测结果满足预设自检条件,再次进行自检,如果电弧检测装置未通过再次自检,则可以判定电弧检测装置失效,在根据电流采样信号进行初步判断的同时,同步对电流采样信号进行电弧检测。本发明提供的方法,只有两次判断均判定电弧检测装置失效的情况下,才最终判定电弧检测装置失效,并且,对电流采样信号进行电弧检测的操作是同步进行的,不受失效判定过程的影响,可以有效提高电弧检测装置的可靠性,确保光伏发电系统的运行安全。(The invention provides a failure judgment method of an arc detection device and the arc detection device, which are applied to the technical field of power electronics. According to the method provided by the invention, the arc detection device is finally judged to be invalid only under the condition that the arc detection device is judged to be invalid in two times, and the operation of arc detection on the current sampling signal is synchronously carried out and is not influenced by the invalid judgment process, so that the reliability of the arc detection device can be effectively improved, and the operation safety of the photovoltaic power generation system is ensured.)

1. A method for determining a failure of an arc detection device, comprising:

acquiring a current sampling signal after the electric arc detection device is powered on and passes self-detection;

judging whether the current sampling signal meets a preset self-checking condition or not, and carrying out arc detection on the current sampling signal;

if the current sampling signal meets the preset self-checking condition, carrying out self-checking again;

and if the self-inspection of the arc detection device is failed again, judging that the arc detection device fails.

2. The arc detection device failure determination method according to claim 1, wherein the determining whether the current sampling signal satisfies a preset self-test condition includes:

if the duration of the current sampling signal which is not in the preset sampling range is greater than or equal to a preset duration threshold, judging that the current sampling signal meets a preset self-checking condition;

and if the current sampling signal is in the preset sampling range, or the duration that the current sampling signal is not in the preset sampling range is less than the preset duration threshold, judging that the current sampling signal does not meet the preset self-checking condition.

3. The arc detection device failure determination method according to claim 1, wherein the determining whether the current sampling signal satisfies a preset self-test condition includes:

performing FFT analysis on the current sampling signal to obtain an analysis spectrogram; wherein, the analytic spectrogram records the corresponding relation between the frequency values of a plurality of alternating current components and the amplitude values of the alternating current components;

screening a target frequency value in the analytic spectrogram and determining a target alternating current component amplitude value corresponding to the target frequency value;

if the target alternating current component amplitude is within a first preset amplitude range, judging that the current sampling signal meets a preset self-checking condition;

and if the target alternating current component amplitude is not in the first preset amplitude range, judging that the current sampling signal does not meet a preset self-checking condition.

4. The method of claim 3, wherein the screening target frequency values and determining a target AC component amplitude corresponding to the target frequency values in the analytical spectrogram comprises:

screening frequency values in an arc characteristic frequency range in the analytic spectrogram to obtain a plurality of target frequency values;

calculating the average value of the alternating current component amplitude corresponding to each target frequency value;

determining the average value as a target alternating current component amplitude value corresponding to a plurality of target frequency values;

if the target alternating current component amplitude is within a first preset amplitude range, the current sampling signal is judged to meet a preset self-checking condition, and the method comprises the following steps:

if the target alternating current component amplitude is smaller than a first preset self-detection threshold value, judging that the current sampling signal meets a preset self-detection condition;

if the target alternating current component amplitude is not in the first preset amplitude range, judging that the current sampling signal does not meet a preset self-checking condition, wherein the judgment comprises the following steps:

and if the target alternating current component amplitude is not smaller than the first preset self-detection threshold value, judging that the current sampling signal does not meet the preset self-detection condition.

5. The method of claim 3, wherein the screening target frequency values and determining a target AC component amplitude corresponding to the target frequency values in the analytical spectrogram comprises:

determining an inverter switch frequency value as a target frequency value in the analytic spectrogram, and determining an alternating current component amplitude corresponding to the target frequency value as a target alternating current component amplitude;

if the target alternating current component amplitude is within a first preset amplitude range, the current sampling signal is judged to meet a preset self-checking condition, and the method comprises the following steps:

if the target alternating current component amplitude is larger than a second preset self-checking threshold value, judging that the alternating current sampling signal meets a preset self-checking condition;

if the target alternating current component amplitude is not in the first preset amplitude range, judging that the current sampling signal does not meet a preset self-checking condition, wherein the judgment comprises the following steps:

and if the target alternating current component amplitude is not greater than the second preset self-checking threshold value, judging that the alternating current sampling signal does not meet a preset self-checking condition.

6. The method of claim 3, wherein the screening target frequency values and determining a target AC component amplitude corresponding to the target frequency values in the analytical spectrogram comprises:

screening frequency values in an arc characteristic frequency range and inverter switch frequency values in the analytic spectrogram to obtain a plurality of target frequency values;

calculating the average value of alternating current component amplitude values corresponding to all frequency values in the arc characteristic frequency section to obtain a first target alternating current component amplitude value;

determining an alternating current component amplitude corresponding to the inverter switching frequency value as a second target alternating current component amplitude;

if the target alternating current component amplitude is within a first preset amplitude range, the current sampling signal is judged to meet a preset self-checking condition, and the method comprises the following steps:

if the first target alternating current component amplitude is smaller than a first preset self-checking threshold value, or the second target alternating current component amplitude is larger than a second preset self-checking threshold value, judging that the alternating current sampling signal meets a preset self-checking condition;

if the target alternating current component amplitude is not in the first preset amplitude range, judging that the current sampling signal does not meet a preset self-checking condition, wherein the judgment comprises the following steps:

and if the first target alternating current component amplitude is not smaller than the first preset self-checking threshold value and the second target alternating current component amplitude is not larger than the second preset self-checking threshold value, judging that the alternating current sampling signal does not meet a preset self-checking condition.

7. The arc detection device failure determination method according to any one of claims 4, 5, and 6, wherein before performing FFT analysis on the current sampling signal to obtain an analysis spectrogram, the method further comprises:

judging whether the duration of the current sampling signal which is not in the preset sampling range is smaller than a preset duration threshold value or not;

if the current sampling signal is in the preset sampling range, or the duration of the current sampling signal which is not in the preset sampling range is smaller than the preset duration threshold, performing FFT analysis on the current sampling signal to obtain an analysis spectrogram;

and if the duration of the current sampling signal which is not in the preset sampling range is greater than or equal to the preset duration threshold, judging that the current sampling signal meets the preset self-checking condition.

8. The arc detection device failure determination method according to any one of claims 1 to 6, wherein the arc detection of the current sampling signal includes:

determining the average value of alternating current component amplitudes corresponding to the characteristic frequencies of the electric arcs in the current sampling signals;

and if the average value is within a second preset amplitude range, judging that no arc fault occurs.

9. The arc detection device failure determination method according to claim 8, wherein if the average value is larger than the upper limit value of the second preset amplitude range, alarm information indicating that an arc fault has occurred is sent.

10. An arc detection device is characterized by comprising a self-checking circuit, a group current sampling circuit, an amplifying and filtering circuit and a controller, wherein,

the self-checking circuit is used for outputting a self-checking signal with arc frequency spectrum characteristics after receiving a self-checking instruction; wherein the self-test instruction is at least from the controller;

the group of serial current sampling circuits are used for outputting current sampling signals;

the amplifying and filtering circuit is used for amplifying and filtering the received current sampling signal, or the self-checking signal and the current sampling signal, and sending the processed signal to the controller;

the controller is configured to execute the arc detection device failure determination method according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of power electronics, in particular to an arc detection device failure judgment method and an arc detection device.

Background

The arc detection device can greatly reduce the risk of fire caused by arc discharge on the direct current side of the photovoltaic power generation system, and is widely applied to the photovoltaic power generation system. In order to prevent the risk caused by the failure of the arc detection device, the related standard provides that the arc detection device needs to be provided with a self-checking circuit, and whether the device itself fails or not can be identified through the self-checking circuit.

In practical applications, the arc detection device generally performs a self-check at power-on, that is, a failure determination is triggered by the controller, and in addition, an unscheduled failure determination can be performed by a manual triggering manner. Referring to fig. 1, fig. 1 is a block diagram illustrating an arc detection apparatus according to the related art. As shown in the figure, the controller of the arc detection device can generate a self-check instruction when being powered on, the self-check circuit receives the self-check instruction and then outputs a self-check signal with arc frequency spectrum characteristics, the self-check signal is combined with the group string current signal collected by the group string current sampling circuit and then sent to the amplifying and filtering circuit, the amplifying and filtering circuit is used for sending the combined signal to the controller for arc detection, if the detection result shows that the received signal contains an arc, the arc detection device works normally, and if the analysis result shows that the received signal does not contain the arc, the arc detection device fails.

This means that if some key components are suddenly damaged after the arc detection device is powered on for self-detection, the arc detection function will fail, but the photovoltaic power generation system cannot timely acquire this information, and the device cannot be found to have failed until the arc detection device is powered on for self-detection next time, or when the failure determination is manually triggered next time.

Disclosure of Invention

The invention provides a failure judgment method of an arc detection device and the arc detection device, which can improve the reliability of the arc detection device and ensure the operation safety of a photovoltaic power generation system.

In order to achieve the purpose, the technical scheme provided by the application is as follows:

in a first aspect, the present invention provides a method for determining a failure of an arc detection device, including:

acquiring a current sampling signal after the electric arc detection device is powered on and passes self-detection;

judging whether the current sampling signal meets a preset self-checking condition or not, and carrying out arc detection on the current sampling signal;

if the current sampling signal meets the preset self-checking condition, carrying out self-checking again;

and if the self-inspection of the arc detection device is failed again, judging that the arc detection device fails.

Optionally, the determining whether the current sampling signal meets a preset self-checking condition includes:

if the duration of the current sampling signal which is not in the preset sampling range is greater than or equal to a preset duration threshold, judging that the current sampling signal meets a preset self-checking condition;

and if the current sampling signal is in the preset sampling range, or the duration that the current sampling signal is not in the preset sampling range is less than the preset duration threshold, judging that the current sampling signal does not meet the preset self-checking condition.

Optionally, the determining whether the current sampling signal meets a preset self-checking condition includes:

performing FFT analysis on the current sampling signal to obtain an analysis spectrogram; wherein, the analytic spectrogram records the corresponding relation between the frequency values of a plurality of alternating current components and the amplitude values of the alternating current components;

screening a target frequency value in the analytic spectrogram and determining a target alternating current component amplitude value corresponding to the target frequency value;

if the target alternating current component amplitude is within a first preset amplitude range, judging that the current sampling signal meets a preset self-checking condition;

and if the target alternating current component amplitude is not in the first preset amplitude range, judging that the current sampling signal does not meet a preset self-checking condition.

Optionally, the screening a target frequency value and determining a target alternating current component amplitude corresponding to the target frequency value in the analysis spectrogram includes:

screening frequency values in an arc characteristic frequency range in the analytic spectrogram to obtain a plurality of target frequency values;

calculating the average value of the alternating current component amplitude corresponding to each target frequency value;

determining the average value as a target alternating current component amplitude value corresponding to a plurality of target frequency values;

if the target alternating current component amplitude is within a first preset amplitude range, the current sampling signal is judged to meet a preset self-checking condition, and the method comprises the following steps:

if the target alternating current component amplitude is smaller than a first preset self-detection threshold value, judging that the current sampling signal meets a preset self-detection condition;

if the target alternating current component amplitude is not in the first preset amplitude range, judging that the current sampling signal does not meet a preset self-checking condition, wherein the judgment comprises the following steps:

and if the target alternating current component amplitude is not smaller than the first preset self-detection threshold value, judging that the current sampling signal does not meet the preset self-detection condition.

Optionally, the screening a target frequency value and determining a target alternating current component amplitude corresponding to the target frequency value in the analysis spectrogram includes:

determining an inverter switch frequency value as a target frequency value in the analytic spectrogram, and determining an alternating current component amplitude corresponding to the target frequency value as a target alternating current component amplitude;

if the target alternating current component amplitude is within a first preset amplitude range, the current sampling signal is judged to meet a preset self-checking condition, and the method comprises the following steps:

if the target alternating current component amplitude is larger than a second preset self-checking threshold value, judging that the alternating current sampling signal meets a preset self-checking condition;

if the target alternating current component amplitude is not in the first preset amplitude range, judging that the current sampling signal does not meet a preset self-checking condition, wherein the judgment comprises the following steps:

and if the target alternating current component amplitude is not greater than the second preset self-checking threshold value, judging that the alternating current sampling signal does not meet a preset self-checking condition.

Optionally, the screening a target frequency value and determining a target alternating current component amplitude corresponding to the target frequency value in the analysis spectrogram includes:

screening frequency values in an arc characteristic frequency range and inverter switch frequency values in the analytic spectrogram to obtain a plurality of target frequency values;

calculating the average value of alternating current component amplitude values corresponding to all frequency values in the arc characteristic frequency section to obtain a first target alternating current component amplitude value;

determining an alternating current component amplitude corresponding to the inverter switching frequency value as a second target alternating current component amplitude;

if the target alternating current component amplitude is within a first preset amplitude range, the current sampling signal is judged to meet a preset self-checking condition, and the method comprises the following steps:

if the first target alternating current component amplitude is smaller than a first preset self-checking threshold value, or the second target alternating current component amplitude is larger than a second preset self-checking threshold value, judging that the alternating current sampling signal meets a preset self-checking condition;

if the target alternating current component amplitude is not in the first preset amplitude range, judging that the current sampling signal does not meet a preset self-checking condition, wherein the judgment comprises the following steps:

and if the first target alternating current component amplitude is not smaller than the first preset self-checking threshold value and the second target alternating current component amplitude is not larger than the second preset self-checking threshold value, judging that the alternating current sampling signal does not meet a preset self-checking condition.

Optionally, before performing FFT analysis on the current sampling signal to obtain an analysis spectrogram, the method further includes:

judging whether the duration of the current sampling signal which is not in the preset sampling range is smaller than a preset duration threshold value or not;

if the current sampling signal is in the preset sampling range, or the duration of the current sampling signal which is not in the preset sampling range is smaller than the preset duration threshold, performing FFT analysis on the current sampling signal to obtain an analysis spectrogram;

and if the duration of the current sampling signal which is not in the preset sampling range is greater than or equal to the preset duration threshold, judging that the current sampling signal meets the preset self-checking condition.

Optionally, the arc detection on the current sampling signal includes:

determining the average value of alternating current component amplitudes corresponding to the characteristic frequencies of the electric arcs in the current sampling signals;

and if the average value is within a second preset amplitude range, judging that no arc fault occurs.

Optionally, if the average value is greater than the upper limit value of the second preset amplitude range, sending alarm information representing that an arc fault occurs.

In a second aspect, the present invention provides an arc detection device, comprising a self-test circuit, a string current sampling circuit, an amplifying and filtering circuit, and a controller,

the self-checking circuit is used for outputting a self-checking signal with arc frequency spectrum characteristics after receiving a self-checking instruction; wherein the self-test instruction is at least from the controller;

the group of serial current sampling circuits are used for outputting current sampling signals;

the amplifying and filtering circuit is used for amplifying and filtering the received current sampling signal, or the self-checking signal and the current sampling signal, and sending the processed signal to the controller;

the controller is configured to execute the arc detection device failure determination method according to any one of the first aspect of the invention.

The invention provides a failure judgment method of an arc detection device, which is characterized in that after the arc detection device is powered on and passes self-checking, a current sampling signal is obtained, whether the obtained current sampling signal meets a preset self-checking condition is judged, namely whether the arc detection device fails is preliminarily judged, if the detection result meets the preset self-checking condition, the failure of the arc detection device is judged after preliminary judgment, then further confirmation is carried out, namely, the self-checking is carried out again, if the arc detection device does not pass the self-checking again, the failure of the arc detection device can be judged, and the arc detection is synchronously carried out on the current sampling signal while the preliminary judgment is carried out according to the current sampling signal.

According to the failure judgment method of the arc detection device, provided by the invention, the failure judgment process comprises primary judgment based on the current sampling signal and secondary confirmation based on secondary self-checking, the failure of the arc detection device is finally judged only under the condition that the failure of the arc detection device is judged by both the primary judgment and the secondary judgment, and the operation of carrying out arc detection on the current sampling signal is synchronously carried out without being influenced by the failure judgment process, so that detection blind areas can be effectively reduced.

Furthermore, only when the detection result of the current sampling signal meets the preset self-detection condition, the self-detection is carried out again, so that frequent triggering of the self-detection operation can be avoided, the influence of the self-detection operation on the normal detection work of the arc detection device is effectively reduced, and the reliability of the arc detection device is further improved.

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 some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a block diagram of an arc detection device according to the prior art;

fig. 2 is a flowchart of a first arc detection device failure determination method according to an embodiment of the present invention;

fig. 3 is a flowchart of a second method for determining the failure of the arc detection device according to the embodiment of the present invention;

FIG. 4 is a flow chart of a third method for determining the failure of an arc detection device according to an embodiment of the present invention;

fig. 5 is a flowchart of a fourth method for determining the failure of the arc detection device according to the embodiment of the present invention;

fig. 6 is a flowchart of a fifth method for determining failure of an arc detection device according to an embodiment of the present invention;

fig. 7 is a flowchart of a sixth method for determining failure of an arc detection device according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.

Optionally, referring to fig. 2, fig. 2 is a flowchart of a first method for determining failure of an arc detection apparatus according to an embodiment of the present invention, where the method is applicable to an arc detection apparatus, and specifically, to a controller in the arc detection apparatus, and obviously, the controller may also be implemented by a server on a network side in some cases. As shown in fig. 2, a flow of a failure determination method for an arc detection apparatus according to an embodiment of the present invention may include:

and S100, acquiring a current sampling signal after the arc detection device is powered on and passes self-detection.

After the arc detection device is powered on and started successfully, the controller firstly sends a self-checking instruction to carry out power-on self-checking operation on the arc detection device, and if the power-on self-checking of the arc detection device is not abnormal, a current sampling signal is further obtained. Optionally, if the arc detection device finds abnormality in the power-on self-detection process, which indicates that the arc detection device has a fault, the alarm information representing the failure of the arc detection device may be directly sent.

Optionally, as mentioned above, the self-checking process of the arc detection apparatus is substantially as follows: the controller sends a self-checking instruction to a self-checking circuit of the arc detection device shown in fig. 1, the self-checking circuit outputs a self-checking signal with arc frequency spectrum characteristics after receiving the self-checking instruction, the self-checking signal is combined with a group string current signal collected by a group string current sampling circuit and then sent to an amplifying and filtering circuit, the amplifying and filtering circuit is used for sending the combined signal to the controller for arc detection, if a detection result shows that the received signal contains an arc, the arc detection device works normally, otherwise, if an analysis result shows that the received signal does not contain the arc, the arc detection device fails, and corresponding alarm information and the like can be sent.

Optionally, in the method for determining the failure of the arc detection device provided in the embodiment of the present invention, the current sampling signal may be provided by a string current sampling circuit, and specifically, the direct current obtained by the string current sampling circuit may be derived from an output end of any one photovoltaic string in the photovoltaic power generation system, or may be derived from an input end of an inverter connected to a plurality of photovoltaic strings. Of course, other dc current sampling points capable of carrying arc characteristic information are optional, and are within the protection scope of the present invention without departing from the scope of the core idea of the present invention.

S110a, judging whether the current sampling signal meets the preset self-checking condition, if so, executing S120.

After the current sampling signal is obtained, judging whether the current sampling signal meets a preset self-checking condition, if so, executing S120 to perform self-checking on the arc detection device again; correspondingly, if the preset self-test condition is determined not to be met according to the current sampling signal, the process may return to S100, and the current sampling signal continues to be acquired.

In the embodiment of the invention, the self-detection condition is preset, the primary judgment of the arc detection device is realized by judging whether the current sampling signal meets the preset self-detection condition, and if the arc detection device is judged to be invalid through the primary judgment, further secondary confirmation is carried out.

And S120, performing self-checking again.

In the case that it is determined that there is a possibility of one or more component faults in the arc detection device after the preliminary determination of S110, which results in failure of the arc detection device, S120 is performed to perform self-checking on the arc detection device again, that is, perform further secondary confirmation.

Specifically, the controller sends out the self-checking instruction again, the self-checking circuit outputs the self-checking signal with the arc spectrum characteristic again according to the received self-checking instruction, and then the arc detection device is subjected to failure determination again according to the self-checking process stated in S100, which is not repeated here.

And S130, judging whether the arc detection device passes the self-checking again, if not, executing S140, and if so, returning to execute S100.

If the arc electric measuring device passes the self-checking again, returning to execute S100; accordingly, if the arc detection means fails the self-test again, S140 is performed. The criterion for passing or not of self-checking can also be performed with reference to the self-checking process set forth in S100, and is not described here again.

And S140, judging that the arc detection device fails.

If it is determined that the arc detection means has a fault through the preliminary determination of S110a and the secondary confirmation of S120 and S130, it may be finally determined that the arc detection means has failed.

It should be noted that, the method for determining the failure of the arc detection device provided by the embodiment of the present invention does not affect the normal arc detection process when determining the failure of the arc detection device. As shown in the flowchart of fig. 2, S110b is synchronously performed while S110a is performed.

S110, b, arc detection is carried out on the current sampling signal.

After the current sampling signal is obtained, arc detection is synchronously carried out on the current sampling signal, and whether arc faults occur or not is judged.

Optionally, an embodiment of the present invention provides a method for detecting an arc in a current sampling signal. After the current sampling signal is obtained, performing FFT analysis on the current sampling signal, that is, performing time-frequency domain conversion on the current sampling signal to obtain an analysis spectrogram, where frequency values of a plurality of alternating current components and alternating current component amplitude information are recorded in the analysis spectrogram, and the frequency values and the alternating current component amplitudes are in one-to-one correspondence, and according to the analysis spectrogram, an alternating current component amplitude corresponding to any frequency value obtained by performing FFT analysis on the current sampling signal can be obtained.

Then, in the obtained analytical spectrogram, frequency values within the arc characteristic frequency are screened out, and generally, a plurality of frequency values are often included in the arc characteristic frequency, and each frequency value corresponds to an alternating current component amplitude. In the embodiment of the invention, the average value of the alternating current component amplitude corresponding to each frequency value in the arc characteristic frequency is calculated, and whether the arc fault occurs is judged according to the obtained average value.

It should be noted that, for the analytic spectrogram obtained through the FFT analysis, other methods may also be used to process and analyze information contained in the analytic spectrogram, so as to determine whether an arc fault occurs, but the method also falls within the protection scope of the present invention without exceeding the scope of the core idea of the present invention.

S110c, judging whether an arc fault occurs, if yes, executing S110d, if no, returning to executing S100.

If the average value found in S11b is within the second preset amplitude range, it is determined that no arc fault has occurred. Optionally, in this embodiment of the present invention, the second preset amplitude range is set based on the arc characteristic spectrum, specifically, a lower limit and an upper limit of the second preset amplitude range are set, and when the obtained average value is in the second preset amplitude range, that is, greater than or equal to the lower limit of the second preset amplitude range and less than or equal to the upper limit of the second preset amplitude range, it may be determined that no arc fault occurs.

It should be particularly noted that, in the embodiment of the present invention, when the average value of the ac component amplitudes corresponding to the obtained arc characteristic frequency values is greater than the upper limit value of the second preset amplitude range, it is determined that an arc fault occurs; however, when the average value is smaller than the lower limit value of the second preset amplitude range, it is determined that the arc fault occurs, and it is determined that the preset self-checking condition is satisfied, and the self-checking needs to be performed again.

If it is determined that the arc fault occurs, execution continues with S110 d; on the contrary, if it is determined that the arc fault has not occurred, the process returns to the execution of S100.

And S110d, sending alarm information for representing the occurrence of the arc fault.

And if the arc fault is determined to occur, sending alarm information representing the occurrence of the arc fault.

Optionally, the specific form of the alarm information, the specific method for sending the alarm information, and the receiver of the alarm information may be performed according to the manner in the prior art, which is not limited in the present invention.

In summary, according to the failure determination method for the arc detection device provided by the embodiment of the present invention, the failure determination process includes primary determination based on the current sampling signal and secondary confirmation based on secondary self-checking, the arc detection device is finally determined to be failed only when the arc detection device is determined to be failed by both of the two determinations, and the operation of performing arc detection on the current sampling signal is performed synchronously, which is not affected by the failure determination process, and thus, detection blind areas can be effectively reduced.

Furthermore, only when the detection result of the current sampling signal meets the preset self-detection condition, the self-detection is carried out again, so that frequent triggering of the self-detection operation can be avoided, the influence of the self-detection operation on the normal detection work of the arc detection device is effectively reduced, and the reliability of the arc detection device is further improved.

It should be noted that, the method for determining failure of an arc detection apparatus according to the embodiment of the present invention may continuously detect whether the arc detection apparatus fails during the power-on operation of the arc detection apparatus, as shown in the embodiment of fig. 2, in S130, if it is determined that the arc detection apparatus passes the self-test, immediately return to S100, continue to acquire the current sampling signal, and perform the next detection process. Of course, the arc detection device may also be determined to be invalid according to a preset detection period by adopting a periodic detection mode. In this way, after it is determined in S130 that the arc detection apparatus has passed the self-test again, it is not necessary to return to S100 immediately, and only when the next failure determination period starts, S100 is executed again, thereby realizing the periodic failure determination.

It is conceivable that, in the embodiment shown in fig. 2, after the current sampling signal is obtained, whether self-checking and arc detection need to be performed again is performed synchronously, and if the arc detection device fails, the arc detection result at this time is meaningless, so that the process of arc detection and the process of failure determination can be combined, and only after the initial determination, arc detection is performed again under the condition that the preset self-checking condition is not satisfied, so that the process of arc detection without meaningless can be avoided, that is, the overall execution process of the program can be accelerated, and the requirement on the hardware performance of the controller can be reduced to a certain extent. In the embodiments provided subsequently, the failure determination and arc detection processes are handled in this manner.

Optionally, referring to fig. 3, fig. 3 is a flowchart of a second method for determining a failure of an electrical arcing device according to an embodiment of the present invention, where the flowchart may include:

and S200, acquiring a current sampling signal after the arc detection device is powered on and passes self-detection.

Optionally, an optional implementation of S200 may be performed with reference to the content of S100 in the embodiment of fig. 2, and details are not described here.

S210a, judging whether the current sampling signal is in a preset sampling range, if so, executing S210b, and if not, executing S220.

The current of the photovoltaic string or other equipment is collected by the string current sampling circuit, and is sent to the ADC for sampling after being processed by the amplifying and filtering circuit, and for any ADC sampling circuit, a corresponding preset sampling range exists, and only when the sampling value is in the preset sampling range, the obtained sampling value is credible, and when the sampling value exceeds the upper limit value and the lower limit value of the preset sampling range and the duration time exceeds a certain duration, the ADC sampling is saturated, and invalid components and parts exist in the arc detection device, so that preset self-checking conditions can be set according to the ADC sampling value and the preset sampling range.

Specifically, if the current sampling signal is within the preset sampling range, S210b is executed; in contrast, if the current sampling signal is not within the preset sampling range, S220 is performed.

S220, judging whether the duration of the current sampling signal which is not in the preset sampling range is larger than or equal to a preset duration threshold, if so, executing S230, and if not, executing S210 b.

Considering the fluctuation of the current sampling signal, it is necessary to count the duration that the current sampling signal is not within the preset sampling range, and if the duration is greater than or equal to the preset duration threshold, it indicates that the current sampling signal is stable, and the short time does not exceed the preset sampling range, and the arc detection device does have a faulty component, in this case, S230 is performed, and the arc detection device is self-checked again, and correspondingly, if the duration that the current sampling signal is not within the preset sampling range is less than the preset duration threshold, or, as described above, the current sampling signal is within the preset sampling range, S210b is performed.

Optionally, the execution processes of S230-S250 can be implemented by referring to the execution processes of S120-S140 in the embodiment shown in fig. 2; the execution processes of S210b-S210d can also be implemented with reference to the execution processes of S110b-S110d in the embodiment shown in fig. 2, and are not described herein again.

In summary, in the embodiments of the present invention, the preset self-check condition is set based on the current sampling signal, and when the duration of the current sampling signal that is not within the preset sampling range is greater than or equal to the preset duration threshold, the arc detection device is self-checked again, so as to determine the failure of the arc detection device.

It is conceivable that the ADC sampling is saturated, which indicates that there is a faulty component in the arc detection device, but when there is a faulty component in the arc detection device, the ADC sampling is not necessarily saturated, and therefore, the embodiment shown in fig. 3 has a certain risk of missing detection. In consideration of the fact that whether the arc fault can be effectively detected is the core of the arc detection device, and the arc fault detection is mainly realized on the basis of the frequency spectrum characteristics of the arc, therefore, the frequency spectrum characteristics representing the characteristics of the sampling current can be introduced in the analysis process, and the reliability of the failure judgment method of the arc detection device provided by the embodiment of the invention is improved.

Optionally, the FFT analysis may be performed on the current sampling signal to obtain an analysis spectrogram, and as described above, the analysis spectrogram records a correspondence between frequency values of a plurality of ac components and ac component amplitudes, so that in the analysis spectrogram, a target frequency value may be screened and a target ac component amplitude corresponding to the target frequency value may be determined, and a preset self-check condition may be set based on the ac component amplitude. Specifically, a first preset amplitude range is set, and if the target alternating current component amplitude is within the first preset amplitude range, the current sampling signal is judged to meet a preset self-checking condition; correspondingly, if the target alternating current component amplitude is not in the first preset amplitude range, the current sampling signal is judged not to meet the preset self-checking condition. The setting of the first preset amplitude range needs to be performed according to the specifically selected target frequency value and the actual determination experience.

Specifically, the frequency spectrum value that can be used for judging whether the arc detection device is failed includes at least each arc characteristic frequency value in the arc characteristic frequency section, and meanwhile, because when the inverter is running, the current signal of the photovoltaic string contains the harmonic corresponding to the inverter switching frequency, and the amplitude of the alternating current component corresponding to the inverter switching frequency is much larger than the amplitude of the alternating current component at other harmonic frequencies, a preset self-checking condition can be set according to the frequency spectrum characteristic corresponding to the inverter switching frequency. The embodiment of the invention provides various arc detection device failure determination methods based on the above contents.

Optionally, referring to fig. 4, fig. 4 is a flowchart of a third method for determining failure of an arc detection device according to an embodiment of the present invention, where the flowchart may include:

and S300, acquiring a current sampling signal after the arc detection device is powered on and passes self-detection.

Optionally, an optional implementation of S300 may be performed with reference to the content of S100 in the embodiment of fig. 2, and details are not described here.

S310, carrying out FFT analysis on the current sampling signal to obtain an analysis spectrogram.

Optionally, an optional implementation of S310 may be performed with reference to relevant content in S110b in the embodiment of fig. 2, and details are not described here.

S320, screening frequency values in the arc characteristic frequency range in the analytic spectrogram to obtain a plurality of target frequency values.

In the embodiment of the present invention, each frequency value included in the arc characteristic frequency segment is used as a determination basis, and therefore, each frequency value in the arc characteristic frequency segment is screened as a target frequency value.

S330, calculating the average value of the alternating current component amplitude corresponding to each target frequency value.

Because the arc characteristic frequency segment comprises a plurality of arc characteristic frequency values, and correspondingly, the amplitude of the alternating current component corresponding to each frequency value can be obtained.

And S340, determining the average value as the target alternating current component amplitude values corresponding to the plurality of target frequency values.

And after the average value of the alternating current component amplitude values corresponding to all the target frequency values is obtained, taking the obtained average value as the target alternating current component amplitude values corresponding to the plurality of target frequency values.

S350a, judging whether the target alternating current component amplitude is smaller than a first preset self-checking threshold value, if so, executing S360, and if not, executing S350 b.

In the embodiment of the invention, a first preset range is set based on a first preset self-checking threshold value, and when the target alternating current component amplitude is smaller than the first preset self-checking threshold value, the current sampling signal is judged to meet a preset self-checking condition; correspondingly, when the target alternating current component amplitude is not smaller than the first preset self-checking threshold value, the current sampling signal is judged not to meet the preset self-checking condition.

Optionally, the first preset self-checking threshold may also be used as a lower limit value of the second preset amplitude range, in this case, when the obtained average value is greater than the upper limit value of the second preset amplitude range, it is determined that an arc fault occurs, when the obtained average value is smaller than the first preset self-checking threshold, it is determined that the current sampling signal meets the preset self-checking condition, the arc detection apparatus is self-checked again, and when the obtained average value is within the second preset amplitude range, it is determined that no arc fault occurs.

Optionally, the execution process of S360-S380 may be implemented by referring to the execution process of S120-S140 in the embodiment shown in fig. 2; the execution processes of S350b-S350d can also be implemented with reference to the execution processes of S110b-S110d in the embodiment shown in fig. 2, and are not described herein again.

In summary, the arc detection device failure determination method provided in the embodiment of the present invention is implemented based on the FFT analysis result of the current acquisition signal, and particularly based on the arc characteristic spectrum analysis, and can also achieve the purpose of improving the reliability of the arc detection device and ensuring the operation safety of the photovoltaic power generation system.

Optionally, referring to fig. 5, fig. 5 is a flowchart of a fourth method for determining failure of an arc detection device according to an embodiment of the present invention, where the flowchart may include:

and S400, acquiring a current sampling signal after the arc detection device is powered on and passes self-detection.

Optionally, an optional implementation of S400 may be performed with reference to the content of S100 in the embodiment of fig. 2, and details are not described here.

S410, carrying out FFT analysis on the current sampling signal to obtain an analysis spectrogram.

Optionally, an optional implementation of S410 may be performed with reference to relevant content in S110b in the embodiment of fig. 2, and details are not described here.

And S420, determining the inverter switching frequency value as a target frequency value in the analytic spectrogram.

As described above, when the inverter operates, the current signal of the photovoltaic string contains the harmonic corresponding to the switching frequency of the inverter, and the harmonic current presents different frequency spectrum characteristics when the arc fault occurs and when the arc fault does not occur, so that the frequency value of the switching frequency of the inverter can be used as the target frequency value in the embodiment of the present invention.

S430, determining the alternating current component amplitude corresponding to the target frequency value as a target alternating current component amplitude.

After the target frequency value, that is, the inverter switching frequency value is obtained, according to the information recorded in the analytic spectrogram, the amplitude information of the alternating current component corresponding to the inverter switching frequency value, that is, the target alternating current component amplitude can be directly read and obtained.

S440a, judging whether the target alternating current component amplitude is larger than a second preset self-checking threshold value, if so, executing S450, and if not, executing S440 b.

Optionally, the amplitude of the alternating current component corresponding to the switching frequency of the inverter is much larger than the amplitudes of the alternating current components at other harmonic frequencies, so that when the preliminary judgment is performed according to the amplitude of the alternating current component of the switching frequency of the inverter, the value of the set second preset self-checking threshold is larger, and is often larger than the upper limit value of the second preset amplitude range.

If the target alternating current component amplitude is larger than a second preset self-checking threshold value, judging that the alternating current sampling signal meets a preset self-checking condition, executing S450, and performing self-checking on the arc detection device again; and if the target alternating current component amplitude is not greater than the second preset self-test threshold value, judging that the alternating current sampling signal does not meet the preset self-test condition, and executing S44 b.

Optionally, the execution processes of S450-S470 may be implemented by referring to the execution processes of S120-S140 in the embodiment shown in fig. 2; the execution processes of S440b-S440d can also be implemented with reference to the execution processes of S110b-S110d in the embodiment shown in fig. 2, and are not described herein again.

In summary, the method for determining the failure of the arc detection device provided by the embodiment of the invention is implemented based on the FFT analysis result of the current acquisition signal, and particularly based on the spectrum analysis of the inverter switching frequency, and can also achieve the purposes of improving the reliability of the arc detection device and ensuring the operation safety of the photovoltaic power generation system.

As can be seen from the combination of the embodiment shown in fig. 4 and the embodiment shown in fig. 5, both are performed based on the FFT analysis result, and therefore, the two embodiments can be combined to further improve the accuracy of the effective determination. Optionally, referring to fig. 6, fig. 6 is a flowchart of a fifth method for determining failure of an arc detection device according to an embodiment of the present invention, where the flowchart may include:

and S500, acquiring a current sampling signal after the arc detection device is powered on and passes self-detection.

Optionally, an optional implementation of S500 may be performed with reference to the content of S100 in the embodiment of fig. 2, and details are not described here.

And S510, carrying out FFT analysis on the current sampling signal to obtain an analysis spectrogram.

Optionally, an optional implementation of S510 may be performed with reference to relevant content in S110b in the embodiment of fig. 2, and is not described herein again.

S520, screening frequency values in the arc characteristic frequency range and inverter switching frequency values in the analytic spectrogram to obtain a plurality of target frequency values.

In this embodiment, the plurality of spectrograms obtained by simultaneously screening include a spectrogram corresponding to each frequency in the arc characteristic frequency range and a spectrogram corresponding to the inverter switching frequency, and the spectrogram obtained by screening is used as the target spectrogram.

S530, calculating the average value of the alternating current component amplitude corresponding to each frequency value in the arc characteristic frequency section to obtain a first target alternating current component amplitude.

Optionally, an optional implementation of S530 may be performed with reference to relevant content in S330 in the embodiment of fig. 4, and details are not described here.

And S540, determining the alternating current component amplitude corresponding to the inverter switching frequency value as a second target alternating current component amplitude.

It should be noted that, in the embodiment of the present invention, an average value of the ac component amplitudes corresponding to the frequency values in the arc characteristic frequency segment is referred to as a first target ac component amplitude, and the ac component amplitude corresponding to the inverter switching frequency is referred to as a second target ac component amplitude, which are for convenience of description only, and the two are represented in the same meaning as that in the foregoing embodiment.

And S550, judging whether the first target alternating current component amplitude is smaller than a first preset self-checking threshold value, if so, executing S570, and if not, executing S560 a.

Optionally, the setting and selecting of the first preset self-test threshold described in the embodiment of the present invention may be performed with reference to the embodiment shown in fig. 4, and details are not described here again.

And S560a, judging whether the second target alternating current component amplitude is larger than a second preset self-checking threshold value, if so, executing S570, and if not, executing S550 b.

And under the condition that the first target alternating current component amplitude is not smaller than the first preset self-detection threshold value, further judging whether the second target alternating current component amplitude is larger than a second preset self-detection threshold value, if the second target alternating current component amplitude is not larger than the second preset self-detection threshold value, executing S560b, and carrying out arc detection on the current sampling signal.

Optionally, the setting and selecting of the second preset self-test threshold described in the embodiment of the present invention may be performed with reference to the embodiment shown in fig. 5, and details are not described here again.

With reference to fig. 6, when the first target ac component amplitude is smaller than the first preset self-checking threshold, or the second target ac component amplitude is larger than the second preset self-checking threshold, the arc detection apparatus is self-checked again to verify whether the arc detection apparatus fails.

Optionally, the execution process of S570-S590 may be implemented by referring to the execution process of S120-S140 in the embodiment shown in fig. 2; the execution processes of S560b-S560d can also be implemented with reference to the execution processes of S110b-S110d in the embodiment shown in fig. 2, and are not described herein again.

In summary, the arc detection device failure determination method provided in the embodiment of the present invention combines the arc characteristic spectrum-based determination method and the inverter switching frequency spectrum-based determination method, and performs self-detection on the arc detection device again as long as one of the two methods meets the preset self-detection condition, so that the reliability of the arc detection device can be improved, and the operation safety of the photovoltaic power generation system can be ensured.

Alternatively, in addition to the embodiment shown in fig. 6, a plurality of determination methods provided in the above embodiments may be combined to obtain different failure determination methods. For example, the embodiment shown in fig. 3 and the embodiment shown in fig. 4 may be combined, the embodiment shown in fig. 3 and the embodiment shown in fig. 5 may be combined, and the embodiment shown in fig. 3 and the embodiment shown in fig. 6 may be combined. The present invention will not be described in detail with reference to the combination of the embodiment shown in fig. 3 and the embodiment shown in fig. 6, instead of the various combinations.

Optionally, referring to fig. 7, fig. 7 is a flowchart of a sixth method for determining failure of an arc detection device according to an embodiment of the present invention. In this embodiment, the three embodiments shown in fig. 3, fig. 4, and fig. 5 (the embodiment shown in fig. 4 and fig. 5 is combined to obtain the embodiment shown in fig. 6) are combined, and the process may include:

s600, acquiring a current sampling signal after the electric arc detection device is powered on and passes self-detection.

Optionally, an optional implementation of S600 may be performed with reference to the content of S100 in the embodiment of fig. 2, and details are not described here.

S610, judging whether the current sampling signal is in a preset sampling range, and if not, executing S620.

Optionally, an optional implementation of S610 may be performed with reference to S210a in the embodiment of fig. 3, and details are not described here.

If the current sampling signal is within the preset sampling range, the subsequent analysis process based on the spectrum characteristics is continued, and S630 is executed.

S620, judging whether the duration of the current sampling signal which is not in the preset sampling range is larger than or equal to a preset duration threshold, if so, executing S690, otherwise, executing S630.

Optionally, an optional implementation of S620 may be performed with reference to the content of S220 in the embodiment of fig. 3, and details are not described here.

S630, carrying out FFT analysis on the current sampling signal to obtain an analysis spectrogram.

Optionally, an optional implementation of S630 may be performed with reference to relevant content in S110b in the embodiment of fig. 2, and details are not described here.

And S640, screening frequency values in the arc characteristic frequency band and inverter switching frequency values in the analytic spectrogram to obtain a plurality of target frequency values.

In this embodiment, the target frequency values obtained by simultaneous filtering include frequency values in the arc characteristic frequency range and inverter switching frequency values.

S650, calculating the average value of the alternating current component amplitude values corresponding to the frequency values in the arc characteristic frequency section to obtain a first target alternating current component amplitude value.

Optionally, an optional implementation of S650 may be performed with reference to relevant content in S330 in the embodiment of fig. 4, and details are not described here.

And S660, determining the alternating current component amplitude corresponding to the inverter switching frequency value as a second target alternating current component amplitude.

Optionally, an optional implementation of S660 may be performed with reference to relevant content in S430 in the embodiment of fig. 5, and details are not described here.

And S670, judging whether the first target alternating current component amplitude is smaller than a first preset self-detection threshold value, if so, executing S690, and if not, executing S680 a.

Optionally, the setting and selecting of the first preset self-test threshold described in the embodiment of the present invention may be performed with reference to the embodiment shown in fig. 4, and details are not described here again.

S680a, determining whether the second target ac component amplitude is greater than a second preset self-checking threshold, if so, performing S690, and if not, performing S680 b.

Optionally, an optional implementation of S680a may be performed with reference to relevant content in S440a in the embodiment of fig. 5, and is not described herein again.

Optionally, the setting and selecting of the second preset self-test threshold described in the embodiment of the present invention may be performed with reference to the embodiment shown in fig. 5, and details are not described here again.

Optionally, the execution process of S690-S710 may be implemented by referring to the execution process of S120-S140 in the embodiment shown in fig. 2; the execution processes of S680b-S680d can also be implemented with reference to the execution processes of S110b-S110d in the embodiment shown in fig. 2, and are not described herein again.

With reference to fig. 7, when the first target ac component amplitude is smaller than the first preset self-checking threshold, or the second target ac component amplitude is larger than the second preset self-checking threshold, or the duration of the current sampling signal not within the preset sampling range is greater than or equal to the preset duration threshold, the arc detection apparatus is self-checked again to verify whether the arc detection apparatus fails.

It should be noted that, in the embodiments provided in the present invention, the arc detection process and the failure determination process performed based on the sampling current spectrum feature are both implemented based on FFT analysis, so that after performing FFT analysis on the current sampling signal to obtain the analytic spectrogram, the execution sequence of the arc detection process and the failure determination process performed based on the sampling current spectrum feature may be adjusted, for example, the arc detection may be performed first, and the failure determination process may be performed again on the premise that it is determined that no arc fault occurs. Obviously, the method obtained after adjusting the execution sequence of the steps also belongs to the protection scope of the present invention.

Optionally, an embodiment of the present invention further provides an arc detection apparatus, where the arc detection apparatus includes: a self-checking circuit, a group current sampling circuit, an amplifying and filtering circuit and a controller, wherein,

the self-checking circuit is used for outputting a self-checking signal with arc frequency spectrum characteristics after receiving a self-checking instruction; wherein the self-test instruction is at least from the controller;

the group of serial current sampling circuits are used for outputting current sampling signals;

the amplifying and filtering circuit is used for amplifying and filtering the received current sampling signal, or the self-checking signal and the current sampling signal, and sending the processed signal to the controller;

the controller is used for executing the failure determination method of the arc detection device provided by any one of the above embodiments.

The embodiments of the invention are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments can be referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.