JP7117630B2 - Arc detection circuit, breaker, power conditioner, solar panel, module attached to solar panel, junction box, arc detection method and program - Google Patents

Description

The present invention relates to arc detection circuits and the like for detecting arcs in transmission lines.

2. Description of the Related Art Conventionally, a system is known in which DC power supplied from a power supply device such as a PV (Photo Voltaic) panel (solar panel) through a transmission line is converted into AC power by a power conditioner. It has been reported that a transmission line connecting a PV panel and an inverter is damaged or broken due to external factors, aged deterioration, or the like. An arc (that is, an arc discharge) may occur due to such damage to the transmission line. Therefore, an arc detection device for detecting arcs has been proposed (for example, Patent Document 1). The arc detection device disclosed in Patent Document 1 generates a power spectrum from the detection result of the current flowing through the transmission line, and compares the integrated value of the high-frequency power spectrum as a feature value with a predetermined threshold to detect the arc. To detect.

JP 2016-166773 A

However, in the arc detection device disclosed in Patent Document 1, for example, there are cases where noise caused by a breaker or the like, which momentarily increases in strength over the entire frequency band, is erroneously detected as noise caused by the generation of an arc. Accurate detection may not be possible.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an arc detection circuit or the like capable of accurately detecting an arc occurring in a transmission line.

In order to achieve the above object, one aspect of the arc detection circuit according to the present invention is a current detector that detects a current flowing through a transmission line, and frequency analysis of the current measurement result detected by the current detector, and an arc determination unit that determines the occurrence of an arc in the transmission line, wherein the arc determination unit determines, for each of a plurality of consecutive timings included in a predetermined time range, a predetermined calculating the ratio of the number of frequency components having a predetermined intensity or more to the total number of frequency components in the frequency band, and determining that the minimum ratio among the ratios for each of the plurality of calculated timings is a predetermined ratio or more , it is determined that an arc has occurred.

Further, in order to achieve the above object, one aspect of the arc detection circuit according to the present invention includes a current detector for detecting current flowing in a transmission line, and frequency analysis of the current measurement result detected by the current detector. and an arc determination unit that determines the occurrence of an arc in the transmission line, wherein the arc determination unit determines, in the current measurement result obtained by frequency analysis, for each of a plurality of consecutive timings included in a predetermined time range , in a predetermined frequency band, the number of frequency components having a predetermined intensity or more is calculated, and the minimum number of frequency components among the number of frequency components for each of the plurality of calculated timings is a predetermined minimum frequency component If the number is greater than or equal to the number, it is determined that an arc has occurred.

Moreover, in order to achieve the above object, one aspect of the breaker according to the present invention includes the arc detection circuit described above.

Moreover, in order to achieve the above object, one aspect of a power conditioner according to the present invention includes the above arc detection circuit.

Moreover, in order to achieve the above object, one aspect of the solar panel according to the present invention includes the above arc detection circuit.

In order to achieve the above object, one aspect of a solar panel attached module according to the present invention includes the arc detection circuit described above, and converts a signal output from the solar panel.

Moreover, in order to achieve the above object, one aspect of the junction box according to the present invention includes the arc detection circuit described above, and connects a solar panel and a power conditioner.

Further, in order to achieve the above object, one aspect of the arc detection method according to the present invention is an arc detection method for determining the occurrence of an arc in a transmission line, comprising a current detector for detecting a current flowing in the transmission line. frequency-analyzes the detected current measurement result, and in the frequency-analyzed current measurement result, for each of a plurality of consecutive timings included in a predetermined time range, a predetermined number of frequency components in a predetermined frequency band. A ratio of the number of frequency components having an intensity equal to or higher than the intensity is calculated, and if the minimum ratio among the ratios for each of the plurality of calculated timings is equal to or higher than a predetermined ratio, it is determined that an arc has occurred. judge.

In order to achieve the above object, one aspect of a program according to the present invention is a program that causes a computer to execute the above arc detection method.

According to one aspect of the present invention, an arc generated in a transmission line can be accurately detected.

FIG. 1 is a configuration diagram showing an example of a system to which an arc detection circuit according to an embodiment is applied. FIG. 2 is a flow chart showing an example of the operation of the arc detection circuit according to the embodiment. FIG. 3 is a spectrogram showing an example of a current measurement result frequency-analyzed by the arc determination unit according to the embodiment. FIG. 4 is a diagram schematically showing spectrograms at a plurality of consecutive timings. FIG. 5A is a diagram showing a frequency spectrum at timing T1. FIG. 5B is a diagram showing a frequency spectrum at timing T2. FIG. 5C is a diagram showing a frequency spectrum at timing T3. FIG. 5D is a diagram showing the frequency spectrum at timing T4. FIG. 5E is a diagram showing the frequency spectrum at timing T5. FIG. 6 is a diagram showing the ratio of the number of frequency components having a predetermined intensity or more to the total number of frequency components in a predetermined frequency band for each of a plurality of timings. FIG. 7 is a flow chart showing another example of the operation of the arc detection circuit according to the embodiment. FIG. 8A is a diagram schematically showing noise caused by an arc. FIG. 8B is a diagram schematically showing noise caused by a breaker or the like. FIG. 9 is a diagram for explaining an application example of the arc detection circuit according to the embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. All of the embodiments described below represent specific examples of the present invention. Therefore, the numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection forms, and the like shown in the following embodiments are examples and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in independent claims representing the highest level concept of the present invention will be described as optional constituent elements.

Each figure is a schematic diagram and is not necessarily strictly illustrated. Moreover, in each figure, the same code|symbol is attached|subjected to the substantially same structure, and the overlapping description is abbreviate|omitted or simplified.

(Embodiment)
Arc detection circuits according to embodiments will be described with reference to the drawings.

FIG. 1 is a configuration diagram showing an example of a system to which an arc detection circuit 10 according to an embodiment is applied.

The arc detection circuit 10 is a circuit that detects an arc that occurs in the power transmission line L1 from the power supply device to the power converter.

The power supply device is, for example, the solar panel 31 or the like, and is a device that supplies DC power generated by power generation or the like to the transmission line L1. The power converter is, for example, a power conditioner (power conditioner) 50 that converts DC power supplied from the power supply device through the transmission line L1 into AC power. The power conditioner 50 employs, for example, an MPPT (Maximum Power Point Tracking) system, and adjusts the current and voltage of the DC power supplied from the solar panel 31 to maximize the power. For example, the inverter 50 converts AC power with a voltage of 100 V and a frequency of 50 Hz or 60 Hz. The converted AC power is used in household electric appliances and the like.

It has been reported that the transmission line L1 is damaged or broken due to external factors, aged deterioration, and the like. An arc (that is, an arc discharge) may occur due to such damage to the transmission line L1.

The arc detection circuit 10 has an arc determination section 11 and a current detector 12 .

Current detector 12 detects the current flowing through transmission line L<b>1 connecting solar panel 31 and power conditioner 50 . The current detector 12 is composed of, for example, a resistive element having a minute resistance value. By inserting such a resistance element in the transmission line L1 and detecting the voltage applied to the resistance, a value corresponding to the current flowing through the transmission line L1 can be detected. The current detector 12 may be composed of a sensor such as an IC (Integrated Circuit). For example, the current detector 12 may consist of a sensor using a Hall element and a magnetic core. In this case, by arranging the magnetic core so that the transmission line L1 penetrates the magnetic core, a magnetic field corresponding to the current flowing through the transmission line L1 is generated in the magnetic core. A Hall element is placed in the magnetic field to generate a voltage corresponding to the magnetic field (that is, the current flowing through the transmission line L1). Thereby, the current detector 12 can detect a value corresponding to the current flowing through the transmission line L1.

The arc determination unit 11 performs frequency analysis on the current measurement result detected by the current detector 12 to determine the occurrence of an arc in the transmission line L1. The frequency analysis is, for example, calculating the frequency spectrum of the current signal by Fourier transforming the time waveform of the current measurement result (current signal), calculating the time change of the frequency spectrum, and calculating the frequency and time is to calculate a spectrogram (FIG. 3 to be described later) representing the relationship between .

The arc determination unit 11 is realized by, for example, a microcomputer (microcontroller). A microcomputer is a semiconductor integrated circuit or the like having ROM and RAM in which programs are stored, a processor (CPU: Central Processing Unit) for executing programs, a timer, an A/D converter, a D/A converter, and the like. For example, the functions of the arc determination unit 11 are realized by the processor operating according to a program.

When the arc determination unit 11 determines that an arc has occurred, for example, it outputs a signal (arc generation signal) indicating that an arc has occurred to the outside. For example, the arc determination section 11 outputs an arc generation signal to the breaker control section 42 . The breaker control unit 42 acquires the arc generation signal from the arc determination unit 11 to operate the breaker 41 to cut off power transmission in the transmission line L1. As a result, power transmission can be suppressed when an arc is generated.

Next, details of the operation of the arc detection circuit 10 will be described.

FIG. 2 is a flow chart showing an example of the operation of the arc detection circuit 10 according to the embodiment.

First, the current detector 12 detects the current flowing through the transmission line L1, and the arc determination unit 11 performs frequency analysis on the current measurement result detected by the current detector 12 (step S11). Here, the frequency-analyzed current measurement results will be described with reference to FIG.

FIG. 3 is a spectrogram showing an example of a current measurement result frequency-analyzed by the arc determination unit 11 according to the embodiment. For example, the arc determination unit 11 derives a spectrogram as shown in FIG. 3 by frequency-analyzing the current measurement result detected by the current detector 12 . In FIG. 3, the x-axis is time, the y-axis is frequency, and the z-axis is intensity (the intensity component of the detected current).

Next, the arc determination unit 11 determines whether the current measurement result obtained by frequency analysis has a predetermined intensity or more with respect to the total number of frequency components in a predetermined frequency band for each of a plurality of consecutive timings included in a predetermined time range. Then, the ratio of the number of frequency components is calculated (step S12). The number of frequency components is the number of bins in the spectrum. FIG. 3 shows a predetermined time range T and a predetermined frequency band F. FIG.

The predetermined time range T can be changed by setting. A method for setting the predetermined time range T will be described later with reference to FIGS. 8A and 8B.

The predetermined frequency band F can be changed by setting. In other words, the upper limit frequency and lower limit frequency of the predetermined frequency band F can be changed by setting. The predetermined frequency band F is set, for example, to be a frequency band including a frequency at which noise due to an arc occurs when an arc occurs. The frequency at which arc-induced noise occurs can be obtained experimentally. Further, the predetermined frequency band F is set so as not to include the operating frequency of the inverter 50 or a multiple thereof, for example, in order to suppress the influence of noise from the inverter 50 as much as possible.

Here, in order to make the processing in step S12 easier to understand, it will be explained using FIG. 4 and FIGS. 5A to 5E.

FIG. 4 is a diagram schematically showing spectrograms at a plurality of consecutive timings. In FIG. 4, in order to simplify the explanation, the plurality of continuous timings included in the predetermined time range T are only timings T1 to T5 and five timings, and the total number of frequency components in the predetermined frequency band F is four. Only In practice, a plurality of continuous timings included in the predetermined time range T and the total number of frequency components in the predetermined frequency band F are determined by the time resolution and frequency resolution based on the performance of the arc determination unit 11 (microcomputer). The number of timings and the number of frequency components are determined accordingly. Further, FIG. 4 shows a predetermined strength A. As shown in FIG.

The predetermined intensity A can be changed by setting. The predetermined intensity A is set to a value higher than the intensity of the spectrum without noise and lower than the intensity of the spectrum with arc-induced noise. The predetermined strength A can be determined experimentally.

4 and FIGS. 5A to 5E, which will be described later, frequency components in a predetermined frequency band F are indicated by solid lines, and frequency components outside the predetermined frequency band F are indicated by dotted lines. The arc determination unit 11 determines, for each of a plurality of consecutive timings T1 to T5 included in a predetermined time range T, a predetermined intensity A or more for the total number of frequency components (here, four) in a predetermined frequency band F. When calculating the ratio of the number of frequency components, the frequency components outside the predetermined frequency band F indicated by the dotted line are not used, and the frequency components in the predetermined frequency band F indicated by the solid line are used. In FIG. 4, since it is difficult to see the frequency components having a predetermined intensity or more at each of the plurality of timings T1 to T5, the frequency spectrum of each timing is shown in FIGS. 5A to 5E.

5A to 5E are diagrams showing frequency spectra at timings T1 to T5.

As shown in FIGS. 5A to 5E, the number of frequency components having a predetermined intensity A or more in a predetermined frequency band F is 1 at timing T1, 3 at timing T2, 2 at timing T3, There are four at timing T4 and four at timing T5. From these, the ratio of the number of frequency components having a predetermined strength A or more to the total number of frequency components in the predetermined frequency band F for each of the plurality of timings T1 to T5 is summarized in FIG.

FIG. 6 is a diagram showing the ratio of the number of frequency components whose intensity is greater than or equal to a predetermined intensity A to the total number of frequency components in a predetermined frequency band F for each of a plurality of timings T1 to T5.

As shown in FIG. 6, the ratio is 1/4 (25%) at timing T1, 3/4 (75%) at timing T2, 2/4 (50%) at timing T3, and 4/4 at timing T4. 4 (100%), and 4/4 (100%) at timing T5. The minimum ratio among the ratios for each of the plurality of timings T1 to T5 calculated by the arc determination unit 11 is 1/4 at the timing T1.

Then, the arc determination unit 11 determines whether or not the minimum ratio among the calculated ratios for each of the plurality of timings T1 to T5 is equal to or greater than a predetermined ratio (step S13).

The predetermined ratio can be changed by setting. The predetermined ratio is set to a value that is higher than the above ratio when noise is not generated and lower than the above ratio when noise is generated due to an arc. The predetermined ratio can be determined experimentally.

For example, if the predetermined ratio is set to 1/4 (25%), the minimum ratio at timing T1 is 1/4, so the minimum ratio is equal to or greater than the predetermined ratio. When the minimum ratio is equal to or greater than the predetermined ratio (Yes in step S23), the arc determination unit 11 determines that an arc has occurred (step S24). On the other hand, if the minimum ratio is not equal to or greater than the predetermined ratio (No in step S23), the arc determination unit 11 determines that no arc has occurred (step S25).

In addition, the arc determination unit 11 determines, for each of a plurality of consecutive timings T1 to T5 included in a predetermined time range T, the number of all frequency components in a predetermined frequency band F in the current measurement result obtained by frequency analysis. Although the ratio of the number of frequency components having the intensity A or higher of is calculated, the present invention is not limited to this. For example, the arc determination unit 11 determines that the current measurement result obtained by frequency analysis has a predetermined intensity A or more in a predetermined frequency band F at each of a plurality of consecutive timings T1 to T5 included in a predetermined time range T. It is also possible to calculate the number of frequency components present. The operation of the arc detection circuit 10 when the arc determination section 11 performs such processing will be described with reference to FIG.

FIG. 7 is a flow chart showing another example of the operation of the arc detection circuit 10 according to the embodiment. Note that steps S21, S24, and S25 are the same processes as steps S11, S14, and S15 in FIG. 2, so description thereof will be omitted.

The arc determination unit 11 determines that the current measurement result obtained by frequency analysis is equal to or greater than a predetermined intensity A in a predetermined frequency band F for each of a plurality of consecutive timings T1 to T5 included in a predetermined time range T. The number of frequency components is calculated (step S22). For example, when the total number of frequency components in the predetermined frequency band F is fixed, there is no need to calculate the ratio, and the ratio is calculated simply by calculating the number of frequency components having a predetermined intensity A or higher. because it would be the same as doing. Then, the arc determination unit 11 determines whether or not the minimum number of frequency components among the calculated numbers of frequency components for each of the plurality of timings T1 to T5 is equal to or greater than a predetermined minimum number of frequency components (step S23).

The predetermined minimum number of frequency components can be changed by setting. The specified minimum number of frequency components is a value higher than the minimum number of frequency components when noise is not generated, and a value lower than the minimum number of frequency components when noise is generated due to an arc. set. The predetermined minimum number of frequency components can be determined experimentally.

Specifically, if the total number of frequency components in the predetermined frequency band F is known to be 4, and the predetermined minimum number of frequency components is 1, then the predetermined minimum number of frequency components of 1 corresponds to the predetermined ratio of 1 in step S13. /4 (25%).

Thus, for example, when the total number of frequency components in the predetermined frequency band F is fixed, it is not necessary to calculate the above ratio, and it is sufficient to calculate the number of frequency components having a predetermined intensity A or more. .

Here, the predetermined time range T in step S12 or step S22 will be explained.

For example, the predetermined time range T shifts with the target range partially overlapping. Specifically, it is assumed that the predetermined time range is a range including four timings, and a plurality of consecutive timings advances to timings T1, T2, . . . according to time. Further, for example, if the current time is timing T4 and the predetermined time range T is the time range immediately preceding the current time, the predetermined time range at the current time is timings T1 to T4. That is, at the current time (timing T4), when performing the process in step S12 or step S22, the plurality of timings in the predetermined time range T are timings T1 to T4. Then, when the time progresses and the current time reaches timing T5, at the current time (timing T5), when performing the process in step S12 or step S22, the plurality of timings in the predetermined time range T are the timings T2 to T5. becomes. In other words, compared to timing T4, at timing T5, the oldest timing T1 is removed from the predetermined time range T, a new timing T5 is added, and timings T2 to T4 are still included. Note that the predetermined time range T may not be the time range immediately preceding the current time, and may be the time range immediately preceding the current time. In this case, for example, when performing the process in step S12 or step S22, at the current time (for example, timing T5), the plurality of timings in the predetermined time range T are timings T1 to T4, the time advances, and the current time At (timing T6), the plurality of timings in the predetermined time range T may be timings T2 to T5.

Further, for example, the predetermined time range T may be shifted according to time so that the target ranges do not overlap. Specifically, it is assumed that the predetermined time range is a range including four timings, and a plurality of consecutive timings advances to timings T1, T2, . . . according to time. Further, for example, if the current time is timing T4 and the predetermined time range T is the time range immediately preceding the current time, the predetermined time range at the current time is timings T1 to T4. Since the predetermined time range T shifts according to the time so that the target ranges do not overlap, when the time advances and the current time reaches timing T8, the predetermined time range at the current time shifts to timing T5. ~T8. In other words, the timing of performing the processing in step S12 or step S22 is such that timing T4 is followed by timing T8, and the predetermined time range T is shifted according to the time so that the target ranges do not overlap. can be

Next, the effect produced by the arc detection circuit 10 will be described.

FIG. 8A is a diagram schematically showing noise caused by an arc. FIG. 8B is a diagram schematically showing noise caused by a breaker or the like. Specifically, FIGS. 8A and 8B schematically show plots of intensity averages of spectra in a predetermined frequency band F. FIG. The intensity average, the ratio of the number of frequency components having a predetermined intensity A or more to the total number of frequency components, and the number of frequency components having a predetermined intensity A or more are correlated. Therefore, in FIGS. 8A and 8B, the larger the average intensity, the more the ratio of the number of frequency components having a predetermined intensity A or more to the total number of frequency components in the predetermined frequency band F, or the ratio of the number of frequency components having a predetermined intensity A or more. This means that the number of frequency components in the

In general, noise caused by a breaker or the like is instantaneous, as shown in FIG. 8B, whereas noise caused by an arc is continuous, as shown in FIG. 8A. FIG. 8A shows the pulse width ta of noise caused by an arc, and FIG. 8B shows the pulse width tb of noise caused by a breaker or the like, and it can be seen that pulse width ta>pulse width tb.

The predetermined time range T is set, for example, according to the pulse width ta of the noise caused by the arc and the pulse width tb of the noise caused by the breaker or the like. For example, as shown in FIGS. 8A and 8B, the predetermined time range T is set to be longer than the pulse width tb of noise caused by a breaker or the like and shorter than the pulse width ta of noise caused by an arc. be done.

Then, in the present invention, for each of a plurality of timings in a predetermined time range T, the ratio of the number of frequency components having a predetermined intensity A or more to the total number of frequency components in a predetermined frequency band F Focusing on the minimum ratio or the minimum number of frequency components among the number of frequency components having a predetermined intensity A or more, the minimum ratio or the minimum number of frequency components is the predetermined ratio or the predetermined minimum number of frequency components. (These are also referred to as predetermined criteria) or more, it is determined that an arc has occurred. In other words, it is determined that an arc has occurred when even the minimum ratio or the minimum number of frequency components in a predetermined time range T is equal to or greater than a predetermined reference.

For example, assuming that the intensity average at point P in FIG. 8A corresponds to a predetermined standard, while shifting the predetermined time range T according to the time, the processing in steps S11 to S15 or steps S21 to step Suppose that the processing in S25 is repeated. Since the predetermined time range T is set to be shorter than the pulse width ta of the noise caused by the arc, when the noise caused by the arc occurs, the minimum ratio or the minimum number of frequency components exceeds the predetermined standard. Exceed. Specifically, in FIG. 8A, when the predetermined time range T shifts (moves to the right in FIG. 8A) according to time, the minimum ratio or the minimum When the number of frequency components exceeds a predetermined standard, it can be determined that an arc has occurred. On the other hand, the predetermined time range T is set to be longer than the pulse width tb of noise caused by a breaker or the like. The number of components does not exceed the prescribed criteria. Specifically, in FIG. 8B, even if the predetermined time range T shifts (moves to the right in FIG. 8B) according to time, the predetermined time range T has , there exists a level B in which the minimum ratio or the minimum number of frequency components does not exceed a predetermined standard, so it can be determined that no arc has occurred.

As a result, it becomes easier to determine that noise with a pulse width longer than the predetermined time range T is caused by an arc (that is, an arc is occurring), and noise with a pulse width shorter than the predetermined time range T is not caused by an arc (that is, no arc is generated). Therefore, it is possible to suppress erroneous detection of noise caused by a breaker or the like, which momentarily increases in strength over the entire frequency band, as noise caused by arc generation, and to accurately detect an arc generated in the transmission line L1.

Next, application examples of the arc detection circuit 10 will be described.

FIG. 9 is a diagram for explaining an application example of the arc detection circuit 10 according to the embodiment.

As described above, the arc detection circuit 10 is applied, for example, to a system in which the power conditioner 50 converts DC power supplied from the solar panel 31 through the transmission line L1 into AC power. In this application example, three solar panels 31 connected in series by one string 60 are arranged to form the solar cell array 30 . Each string 60 is grouped by the junction box 40 and connected to the power conditioner 50 .

For example, a breaker 41 is provided for each string 60 , here the breaker 41 is provided inside the junction box 40 . Note that the breaker 41 may not be provided inside the connection box 40 . For example, the breaker 41 may be provided between the junction box 40 and the solar cell array 30 , or may be provided between the junction box 40 and the power conditioner 50 instead of being provided for each string 60 .

The solar panel 31 has, for example, a solar panel attached module 32 that converts signals output from the solar panel 31 . Note that the solar panel 31 may not have the solar panel attached module 32 . The solar panel attached module 32 is, for example, a DC/DC converter that optimizes the power generation amount of each solar panel 31 .

For example, breaker 41 may include arc detection circuit 10 . In this case, the transmission line L1 becomes a transmission line (for example, the string 60) connected to the breaker 41, and can cut off the current flowing through the string 60 where the arc is generated. For example, when the arc determination unit 11 determines that an arc has occurred, the breaker 41 cuts off the current flowing through the string 60 in which the arc has occurred. Strings 60 that are not arcing can be used without interrupting the current.

Also, for example, the power conditioner 50 may include the arc detection circuit 10 . In this case, the transmission line L1 becomes a transmission line connected to the power conditioner 50, and the power conditioner 50 can be stopped in response to the occurrence of an arc. For example, the power conditioner 50 stops when the arc determination unit 11 determines that an arc has occurred.

Further, for example, the solar panel 31 or the solar panel attached module 32 may include the arc detection circuit 10 . In this case, the transmission line L1 becomes a transmission line (for example, the string 60) connected to the solar panel 31, and the output to the string 60 where the arc is generated can be stopped. For example, when the arc determination unit 11 determines that an arc has occurred, the solar panel 31 or the solar panel attached module 32 stops outputting to the string 60 where the arc has occurred. Strings 60 that are not arced can be used without stopping the output.

Also, for example, the junction box 40 may include the arc detection circuit 10 . In this case, the transmission line L1 becomes a transmission line (for example, the string 60) connected to the junction box 40, and the current flowing through the string 60 where the arc is generated can be interrupted via the breaker 41 or the like. For example, when the arc determination unit 11 determines that an arc has occurred, the connection box 40 cuts off the current flowing through the string 60 in which the arc has occurred. Strings 60 that are not arcing can be used without interrupting the current.

The arc detection circuit 10 is not limited to the system described above, and can be applied to any system that requires detection of arc generation.

As described above, the arc detection circuit 10 according to the present embodiment includes the current detector 12 that detects the current flowing through the transmission line L1, and the frequency analysis of the current measurement result detected by the current detector 12. and an arc determination unit 11 that determines occurrence of an arc in the transmission line L1. The arc determination unit 11 determines that the current measurement result obtained by frequency analysis is equal to or greater than a predetermined intensity A for all frequency components in a predetermined frequency band F for each of a plurality of consecutive timings included in a predetermined time range T. Calculate the ratio of the number of frequency components that are Then, the arc determination unit 11 determines that an arc has occurred when the minimum ratio among the calculated ratios for each of the plurality of timings is greater than or equal to a predetermined ratio. Alternatively, the arc detection circuit 10 according to the present embodiment includes a current detector 12 that detects the current flowing through the transmission line L1, and frequency analysis of the current measurement result detected by the current detector 12 to detect the current in the transmission line L1. and an arc determination unit 11 that determines occurrence of an arc. The arc determination unit 11 determines the number of frequency components having a predetermined intensity A or more in a predetermined frequency band F for each of a plurality of consecutive timings included in a predetermined time range T in the current measurement result obtained by frequency analysis. Calculate Then, the arc determination unit 11 determines that an arc has occurred when the minimum number of frequency components among the numbers of frequency components for each of the calculated plurality of timings is greater than or equal to a predetermined minimum number of frequency components. do.

According to this, it becomes easy to determine that noise with a pulse width longer than the predetermined time range T is caused by the arc, and noise with a pulse width shorter than the predetermined time range T is not caused by the arc. Easier to determine if there is. Therefore, it is possible to suppress erroneous detection of noise caused by a breaker or the like, which momentarily increases in strength over the entire frequency band, as noise caused by arc generation, and to accurately detect an arc generated in the transmission line L1.

Also, the predetermined time range T, the predetermined frequency band F, the predetermined intensity A, and the predetermined ratio may be changed by setting. Alternatively, the predetermined time range T, the predetermined frequency band F, the predetermined intensity A, and the predetermined minimum number of frequency components may be changed by setting.

According to this, the predetermined time range T, the predetermined frequency band F, the predetermined intensity A, the predetermined ratio, and the minimum number of frequency components can be flexibly optimized according to the environment in which the arc detection circuit 10 is placed. Can be set.

Also, the breaker 41 may include the arc detection circuit 10 . Also, the power conditioner 50 may include the arc detection circuit 10 . The solar panel 31 may also include the arc detection circuit 10 . Further, the solar panel attached module 32 may include the arc detection circuit 10 to convert the signal output from the solar panel. Also, the junction box 40 may include the arc detection circuit 10 and connect the solar panel 31 and the power conditioner 50 .

(Other embodiments)
Although the arc detection circuit 10 and the like according to the embodiments have been described above, the present invention is not limited to the above embodiments.

For example, in the above embodiment, the predetermined time range T, the predetermined frequency band F, the predetermined intensity A, the predetermined ratio, and the predetermined minimum number of frequency components can be changed by setting. may be specified by inputting or selecting a value or the like through an input/output interface (display, keyboard, mouse, touch panel, etc.) of the device including the arc detection circuit 10 .

Further, the present invention can be realized not only as the arc detection circuit 10 but also as an arc detection method including steps (processes) performed by each constituent element of the arc detection circuit 10 .

Specifically, as shown in FIG. 2, the arc detection method is a method for determining the occurrence of an arc in the transmission line L1. frequency-analyzed current measurement results (step S11), and in the frequency-analyzed current measurement results, for each of a plurality of consecutive timings included in a predetermined time range T, for the total number of frequency components in a predetermined frequency band F , the ratio of the number of frequency components having a predetermined intensity A or higher is calculated (step S12), and the minimum ratio among the calculated ratios for each of the plurality of timings is a predetermined ratio or higher Then (Yes in step S13), it is determined that an arc has occurred (step S14).

For example, those steps may be performed by a computer (computer system). The present disclosure can be realized as a program for causing a computer to execute the steps included in those methods. Furthermore, the present disclosure can be implemented as a non-temporary computer-readable recording medium such as a CD-ROM recording the program.

Although the arc detection circuit 10 according to the above-described embodiment is realized in software by a microcomputer, it may be realized in software in a general-purpose computer such as a personal computer. Furthermore, the arc detection circuit 10 may be implemented in hardware by a dedicated electronic circuit composed of A/D converters, logic circuits, gate arrays, D/A converters, and the like.

In addition, it is realized by applying various modifications to each embodiment that a person skilled in the art can think of, and by arbitrarily combining the constituent elements and functions of each embodiment without departing from the spirit of the present invention. Forms are also included in the present invention.

REFERENCE SIGNS LIST 10 arc detection circuit 11 arc determination unit 12 current detector 31 solar panel 32 solar panel attached module 40 junction box 41 breaker 42 breaker control unit 50 power conditioner (power conditioner)
L1 Transmission line A Predetermined intensity F Predetermined frequency band T Predetermined time range

Claims (11)

a current detector that detects current flowing through the transmission line;
an arc determination unit that determines the occurrence of an arc in the transmission line by frequency-analyzing the current measurement result detected by the current detector;
The arc determination unit
In the frequency-analyzed current measurement result, for each of a plurality of consecutive timings included in a predetermined time range, the ratio of the number of frequency components having a predetermined intensity or more to the total number of frequency components in a predetermined frequency band calculate,
determining that an arc has occurred when a minimum ratio among the ratios for each of the plurality of calculated timings is equal to or greater than a predetermined ratio;
the predetermined time range is shorter than the pulse width of the noise caused by the arc;
The predetermined frequency band is a frequency band including a frequency at which noise due to an arc occurs when an arc occurs,
The predetermined intensity is a value higher than the intensity in a state where noise is not generated and a value lower than the intensity in a state where noise caused by an arc is generated,
The predetermined ratio is a value higher than the minimum ratio when no noise is generated and a value lower than the minimum ratio when noise caused by an arc is generated.
Arc detection circuit. The predetermined time range, the predetermined frequency band, the predetermined intensity and the predetermined ratio can be changed by setting,
2. The arc detection circuit of claim 1. a current detector that detects the current flowing through the transmission line;
an arc determination unit that determines the occurrence of an arc in the transmission line by frequency-analyzing the current measurement result detected by the current detector;
The arc determination unit
calculating the number of frequency components having a predetermined intensity or more in a predetermined frequency band for each of a plurality of consecutive timings included in a predetermined time range in the current measurement result obtained by frequency analysis;
determining that an arc has occurred when the minimum number of frequency components among the number of frequency components for each of the plurality of calculated timings is equal to or greater than a predetermined minimum number of frequency components;
the predetermined time range is shorter than the pulse width of the noise caused by the arc;
The predetermined frequency band is a frequency band including a frequency at which noise due to an arc occurs when an arc occurs,
The predetermined intensity is a value higher than the intensity in a state where noise is not generated and a value lower than the intensity in a state where noise caused by an arc is generated,
The predetermined minimum number of frequency components is a value higher than the minimum number of frequency components when noise is not generated, and the minimum frequency when noise caused by an arc is generated. which is lower than the number of components,
Arc detection circuit. The predetermined time range, the predetermined frequency band, the predetermined intensity and the predetermined minimum number of frequency components can be changed by setting,
4. The arc detection circuit of claim 3. Equipped with the arc detection circuit according to any one of claims 1 to 4,
breaker. Equipped with the arc detection circuit according to any one of claims 1 to 4,
power conditioner. Equipped with the arc detection circuit according to any one of claims 1 to 4,
solar panel. Equipped with the arc detection circuit according to any one of claims 1 to 4,
converts the signal output from the solar panel,
Module with solar panel. Equipped with the arc detection circuit according to any one of claims 1 to 4,
connecting solar panels and inverters,
junction box. An arc detection method for determining the occurrence of an arc in a transmission line,
frequency-analyzing a current measurement result detected by a current detector that detects a current flowing through the transmission line;
In the frequency-analyzed current measurement result, the ratio of the number of frequency components having a predetermined intensity or more to the total number of frequency components in a predetermined frequency band for each of a plurality of consecutive timings included in a predetermined time range. to calculate
determining that an arc has occurred when a minimum ratio among the ratios for each of the plurality of calculated timings is equal to or greater than a predetermined ratio;
the predetermined time range is shorter than the pulse width of the noise caused by the arc;
The predetermined frequency band is a frequency band including a frequency at which noise due to an arc occurs when an arc occurs,
The predetermined intensity is a value higher than the intensity in a state where noise is not generated and a value lower than the intensity in a state where noise caused by an arc is generated,
The predetermined ratio is a value higher than the minimum ratio when no noise is generated and a value lower than the minimum ratio when noise caused by an arc is generated.
Arc detection method. A program that causes a computer to execute the arc detection method according to claim 10 .

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