KR20210154365A - Arc detection method and apparatus using frequency analysis - Google Patents

Abstract

One embodiment of the present invention relates to a method for detecting an arc, which comprises: a step of acquiring a measurement value of a current flowing through a wire; and a step of evaluating that there is a high possibility of arc occurrence in the wire when magnitude by frequency in a pre-defined low frequency band increases in frequency analysis data for the measurement value.

Description

ARC DETECTION METHOD AND APPARATUS USING FREQUENCY ANALYSIS

This embodiment relates to a technique for detecting an arc.

The current flowing through the gas as a medium between two electrodes spaced apart or in unsafe contact is called an arc.

Arcs can be broadly classified into series arcs that occur in one conductor, parallel arcs that occur between two conductors, earth arcs that occur between ground and one conductor, and cross arcs that occur between other networks.

When such an arc occurs in the power system, some devices can fail. In particular, if the arc is left to occur continuously, since an electric fire may occur due to the deterioration caused by the arc discharge, it is necessary to detect the arc generation at an early stage and interrupt the corresponding power system so that an additional arc does not occur. .

International Patent Document WO2002/39561 introduces a technique for detecting an arc and interrupting the power system, but the technique has a problem.

Recently, power systems often include a power conversion device, but the technology has a problem in that it cannot distinguish between the noise and the arc caused by the power conversion device. Accordingly, there may be a problem in that the arc is erroneously detected according to the noise of the power conversion device even in a normal operating situation.

Against this background, an object of the present embodiment is to provide a technique for detecting an arc.

In another aspect, an object of the present embodiment is to provide a technique for discriminating between noise and arc generated in normal operation.

In order to achieve the above object, one embodiment provides a method for an apparatus to detect an arc, the method comprising: acquiring a measurement value of a current flowing in a conductor; And in the frequency analysis data for the measured value, when the magnitude (magnitude) for each frequency in a predefined low frequency band increases, it provides an arc detection method comprising the step of highly estimating the possibility of arc generation in the conducting wire.

The arc detection method may include determining that an arc has occurred in the conducting wire when the magnitude of each frequency in the low frequency band exceeds a reference value in the frequency analysis data.

The low frequency band may be defined within an audible frequency band.

The arc detection method may include a step of highly estimating the possibility of arc generation in the conducting wire when a magnitude for each frequency in a predefined high frequency band increases in the frequency analysis data.

In the arc detection method, frequency analysis is performed for N (N is a natural number of 2 or more) different time sections, and the magnitude of the variation in magnitude for each frequency in the low frequency band confirmed in the frequency analysis data in each time section is a reference value If it exceeds, it may include determining that an arc has occurred in the conducting wire.

The magnitude of the fluctuation may be calculated according to the variance or standard deviation of the magnitude for each frequency in each time period.

The reference value may be an average value of magnitudes for each frequency calculated in a time period before arc determination.

Another embodiment provides a method for a device to detect an arc, the method comprising: obtaining a measurement value of a current flowing in a conductor; In the frequency analysis data for the measured value, when the variability of the magnitude for each frequency in the low frequency band defined within the audible frequency band increases, the arc detection method comprising the step of highly estimating the possibility of arcing in the conducting wire provides

In the arc detection method, frequency analysis is performed for N (N is a natural number of 2 or more) different time sections, and the magnitude of the variation in magnitude for each frequency in the low frequency band confirmed in the frequency analysis data in each time section is a reference value If it exceeds, it may include determining that an arc has occurred in the conducting wire.

In the arc detection method, frequency analysis is performed on different M (M is a natural number greater than or equal to 2) time sections before the different N time sections, and the frequency in the low frequency band identified in the frequency analysis data in each time section The method may include setting the magnitude of the fluctuation of the magnitude of the star as the reference value.

Another embodiment, a measuring device for obtaining a measurement value for the current flowing through the wire to which the power conversion device is electrically connected to one side; a frequency analysis device for generating frequency analysis data for the measured value; In the frequency analysis data, when the variability of the magnitude (magnitude) for each frequency in the low frequency band defined within the audible frequency band increases, the arc determination device for highly evaluating the possibility of arc generation in the conducting wire; and a signal generating device for generating a control signal for blocking a current flowing through the conductive wire when the arc determining device determines that an arc has occurred in the conductive wire.

A photovoltaic panel or an energy storage device for generating a DC voltage may be electrically connected to the other side of the conducting wire.

The low frequency band may be determined according to a resonance frequency of an arc gap formed in the conducting wire.

The resonant frequency may be affected by the inductance of the conducting wire.

The arc determination device performs frequency analysis on different N (N is a natural number of 2 or more) time sections, and the magnitude of the change in magnitude for each frequency in the low frequency band confirmed in the frequency analysis data in each time section is When the reference value is exceeded, it may be determined that an arc has occurred in the conducting wire.

As described above, according to the present embodiment, there is an effect of detecting an arc generated in the power system and stably interrupting the power system based on this. In addition, according to the present embodiment, there is an effect that the frequency of arc misdetection can be reduced by distinguishing the arc from the noise generated in normal operation.

1 is a block diagram of an arc detection device according to an embodiment.
FIG. 2 is a view showing waveforms of current and voltage when an arc is generated in part A of FIG. 1 .
FIG. 3 is a diagram illustrating waveforms of current and voltage when part A of FIG. 1 is replaced with a resistor.
4 is a block diagram of an apparatus for measuring a small signal model for an arc gap.
5 is a diagram illustrating an impedance value measured by the measuring device of FIG. 4 as a Nyquist diagram.
FIG. 6 is a model of an arc gap according to the Nyquist diagram of FIG. 5 .
7 is a diagram illustrating an exemplary FFT waveform with respect to an arc current.
8 is a diagram showing the dispersion of magnitudes for each frequency in the FFT result of the arc current.
9 illustrates an audible sound appearing when an arc is generated in a conducting wire.
10 is a flowchart of an arc detection method according to an embodiment.
11 is a block diagram of a power device according to an embodiment.
12 is a diagram illustrating a test configuration of a power device according to an exemplary embodiment.
FIG. 13 is a view showing waveforms of arc current and arc voltage in a situation in which an arc is generated in the test of FIG. 12 .
FIG. 14 is a view showing waveforms of arc current and arc voltage when there is a change in load in the test of FIG. 12 .

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but another component is formed between each component. It should be understood that elements may also be “connected,” “coupled,” or “connected.”

1 is a block diagram of an arc detection device according to an embodiment.

Referring to FIG. 1 , the arc detecting device 100 may include a measuring device 110 , a frequency analyzing device 120 , an arc determining device 130 , a signal generating device 140 , and the like.

The measuring device 110 may acquire a measurement value of the sensor while being connected to a sensor disposed on the object. The measuring device 110 may acquire a measurement value of the current sensor 11 while being connected to the current sensor 11 disposed on the conducting wire 10 . Alternatively, the measuring device 110 may acquire a measured value of the voltage sensor (not shown) while being connected to a voltage sensor (not shown) disposed on the conducting wire 10 .

The measuring device 110 may obtain a measured value of the current ia flowing through the conducting wire 10 . The measured value of the current ia may be obtained through the current sensor 11 or may be obtained through another sensor (eg, a voltage sensor, etc.).

Noise sources 21 and 22 may affect the conductive wire 10 . The noise sources 21 and 22 may be directly connected to the conductive wire 10 or disposed around the conductive wire 10 .

The first noise source 21 that may be connected to one side of the conductive wire 10 may be a power supply. For example, the first noise source 21 may be a renewable energy source such as a solar panel, or may be an Energy Storage System (ESS). The first noise source 21 may introduce the first noise nos1 into the conducting wire 10 . In addition, the first noise nos1 may be included in or affect the current ia flowing through the conductive wire 10 .

The second noise source 22 that may be connected to the other side of the conductive wire 10 may be a power conversion device. For example, the second noise source 22 may be a DC/DC converter, a DC/AC converter (inverter), or the like. The second noise source 22 may introduce a second noise nos2 into the conducting wire 10 . In addition, the second noise nos2 may be included in or affect the current ia flowing through the conductive wire 10 .

The second noise source 22 may generate noise having a constant frequency. For example, the power converter may include a switch operated at a constant frequency, and switching noise having a constant frequency may occur in such a switch. In addition to the switching noise, the second noise source 22 may generate a plurality of noises having a constant frequency according to the wiring of the circuit or the impedance characteristic of the device.

These noises nos1 and nos2 may be included in the measurement value of the current ia acquired by the measuring device 110 . The measuring device 110 may minimize the influence of the noises nos1 and nos2 on the current ia while further including a processor such as a filter. For example, the measuring device 110 may reduce the components of the noises nos1 and nos2 in the measured value of the current ia while including a low-frequency filter, a band-pass filter, and a high-frequency filter.

However, if the frequency band of these noises (nos1, nos2) is the same as or similar to the frequency band of the arc to be observed, the use of the filter also attenuates the characteristic values to be observed along with the noises (nos1, nos2). This may not be valid.

In order to solve this problem, the arc detection apparatus 100 according to an embodiment may determine the occurrence of an arc by observing a frequency band in which the influence of the noises nos1 and nos2 is small. Alternatively, the arc detection device 100 may determine the occurrence of the arc by observing a frequency band in which the characteristics of the arc are better displayed. Alternatively, the arc detection apparatus 100 may minimize the possibility of misjudgment that may occur when only one frequency band is observed by observing a plurality of frequency bands.

The frequency analysis device 120 may generate frequency analysis data iF by performing a frequency analysis on the current measurement value iT received from the measuring device 110 . The current measurement value iT is a value that can be represented in the time domain and may have the form of time series data. The frequency analysis apparatus 120 may analyze the current measurement value iT acquired for a predetermined time and generate frequency analysis data iF that can be displayed in the frequency domain. The frequency analysis apparatus 120 may generate the frequency analysis data iF by, for example, performing a Fast Fourier Transform (FFT) analysis on the current measurement value iT.

The frequency analysis data iF may include a magnitude value for each frequency. The frequency analysis data iF may include a magnitude value for each frequency of a specific frequency band. For example, the frequency analysis data iF may include a magnitude value for each frequency of a predefined low frequency band. In addition, the frequency analysis data iF may include a magnitude value for each frequency of a predefined high frequency band.

Here, the low frequency band may be defined within the audible frequency band.

Among the conventional arc detection methods, there is a method of arranging a microphone near an arc generation point and determining an arc when the intensity of sound detected through the microphone exceeds a reference value. This conventional arc detection method was recognized as a method of detecting the occurrence of an arc well because it reflects the actual characteristic of the arc - the characteristic of generating an audible sound. However, such a conventional arc detection method has a problem in that it reacts sensitively to ambient noise in a situation in which an arc does not occur.

When analyzing such a conventional arc detection method, we can recognize the generation of audible sound in the audible frequency band as one of the characteristics of the arc. However, we can also admit that it is not appropriate to detect these audible sounds using a device such as a microphone and use the results to determine whether an arc has occurred due to the influence of ambient noise.

One embodiment uses the above-described characteristic of the arc - the characteristic that audible sound is generated - but detects it with a current sensor without detecting it with a sound detection device such as a microphone, so as to accurately arc without being affected by ambient noise, which is a problem of the prior art. It is possible to determine whether or not

On the other hand, the high-frequency band included in the frequency analysis data (iF) may be a band of 30KHz or 100KHz or more as known in various studies. In all of the conventional arc detection methods using frequency analysis, arc generation was determined using the magnitude for each frequency in this high-frequency band. It is known that when an arc occurs, the magnitude of a specific high frequency band, known as the arc frequency band, increases. The conventional arc detection method determines whether an arc is generated using these characteristics of the arc. However, as the number of devices generating noise in the same or similar band as the arc frequency band such as the noise sources 21 and 22 increases, the conventional arc detection method causes a lot of problems in false detection. In particular, since the frequency band of the switching noise of the power converter overlaps the arc frequency band in many parts, the arc cannot be accurately detected only by comparing the magnitude of each frequency in the high frequency band with a reference value.

One embodiment uses the above-described characteristics of the arc - the characteristics of increasing the magnitude in the high frequency band and the arc frequency band - while using a combination with other arc detection methods to minimize the influence of noises, or simply without observing whether or not the magnitude increases. It is possible to determine whether an arc has occurred by observing the variability of the

The arc determination device 130 may use the frequency analysis data iF to evaluate the possibility of arc generation in the conducting wire 10 and finally determine whether an arc is generated in the conducting wire 10 .

The arc determination device 130 may evaluate the possibility of arc generation in the conducting wire 10 by using the magnitude value for each frequency included in the frequency analysis data iF. For example, when the magnitude of each frequency increases in a specific frequency band, the arc determination device 130 may highly evaluate the possibility of arc generation in the conducting wire 10 . Here, the specific frequency band may be the aforementioned low frequency band or the aforementioned high frequency band.

The arc determination device 130 may determine whether an arc is generated by combining the possibility of arc generation in the low frequency band and the possibility of arc generation in the high frequency band. For example, in the arc determination device 130, when the magnitude for each frequency in the low frequency band exceeds the first reference value, and the magnitude for each frequency in the high frequency band exceeds the second reference value, it is determined that an arc has occurred in the conductor 10. can judge Here, when the magnitude of each frequency in a specific frequency band exceeds the reference value, it may be understood that the magnitude of all frequencies of the corresponding band does not exceed the reference value, but that the magnitude of some frequencies exceeds the reference value. From a graphical point of view, it can be understood that a part of the magnitude curve for each frequency in a specific frequency band is located above the curve composed of the reference value.

The reference value does not have a single value for all frequencies, but may have a different value for each frequency. The reference value may be a fixed value or a variable value. For example, the reference value may be an average value of magnitudes for each frequency calculated in the time period before the arc determination. The arc determination device 130 may determine the arc at a certain period, and set the reference value as the average value of the magnitudes for each frequency accumulated for a certain period of time before the arc determination.

The arc determination device 130 may check the variability of the magnitude for each frequency in the frequency analysis data, and if the variability increases, the possibility of arc generation in the conducting wire 10 may be highly evaluated. The variability of the magnitude or the magnitude of the fluctuation may be calculated according to a statistical value indicating the degree of dispersion of the magnitude (eg, variance or standard deviation).

The frequency analyzer 120 may perform frequency analysis for N (N is a natural number equal to or greater than 2) different time sections and generate frequency analysis data for each time section. Then, the arc determination device 130 calculates the variance or standard deviation of the magnitude for each frequency identified in the frequency analysis data in each time section, and can check the magnitude of the variability or the variation of the magnitude for each frequency according to the calculated value.

The arc determination device 130 may determine that an arc has occurred in the conducting wire 10 when the magnitude of the change in magnitude for each frequency exceeds a reference value. The arc determination device 130 may set the magnitude of the magnitude change for each frequency identified before the arc determination as a reference value. For example, the arc determination device 130 performs frequency analysis on different M (M is a natural number greater than or equal to 2) time sections before N different time sections, and the frequency identified in the frequency analysis data in each time section The magnitude of the fluctuation of the magnitude of a star can be set as a reference value.

The signal generating device 140 receives the arc determination result fa from the arc determination device 130, and when it is determined that an arc has occurred in the conducting wire 10 according to the arc determination result fa, flowing into the conducting line 10 It is possible to generate a control signal sa that cuts off the current. A circuit breaker (not shown) capable of blocking the current ia may be further disposed in the conductor 10 , and the circuit breaker (not shown) operates according to the control signal sa and the current ia flowing into the conductor 10 . ) can be controlled.

On the other hand, according to an embodiment, arc generation can be determined in a low frequency band where the influence of noise is minimized. Hereinafter, the characteristics of the arc in such a low frequency band are examined and the arc detection device is used to more accurately detect the arc according to the characteristics. Let's take a look at the components that can be added or modified in .

FIG. 2 is a view showing waveforms of current and voltage when an arc is generated in part A of FIG. 1 .

Referring to FIG. 2 , the current ia is controlled to a constant value in the previous time centered on the time Ta when the arc is generated. However, at this previous time, a large ripple is seen in the current ia, and this ripple is due to the switching operation in the power converter. The arc voltage (Va) - the voltage across the arc gap of part A - at the time before the arc generation time (Ta) - represents 0V.

On the other hand, when an arc is generated, an impedance is formed in the arc gap-A portion-, and the arc voltage Va has an increased waveform. Then, the resonance waveform 201 appears in the current ia for a predetermined time from the time Ta when the arc is generated. The arc detection device according to an embodiment pays attention to this resonance waveform 201 of the arc current ia. In the resonance waveform 201 of the current ia that appears when the arc is generated, the resonance frequency is located in the low frequency band. More specifically, the resonant frequency is located in the audible frequency band. This resonance waveform 201 in the low frequency band - the audible frequency band - is a physical phenomenon that coincides with the generation of an audible sound when an arc is generated. According to this principle, the arc detection device according to an embodiment evaluates that if the frequency component-magnitude-of the low-frequency band in the arc current ia increases or its variability increases, the possibility that an arc has occurred in the conducting wire is high.

FIG. 3 is a diagram illustrating waveforms of current and voltage when part A of FIG. 1 is replaced with a resistor.

Conventional arc studies have shown that the arc gap can be modeled as resistance. In order to examine whether this theory is valid, the inventor assumed that an arc occurred in part A and conducted a test so that part A was replaced with a resistance when the arc occurred.

Referring to FIG. 3 , the waveforms of the current ia′ and the voltage Va′ before the time point Ta′ at which the arc is assumed to occur coincide with the waveforms of FIG. 2 . However, the resonance waveform does not appear in the current ia' after the time point Ta' at which the arc is assumed to have occurred - see reference numeral 301 -, and the voltage Va' is also different from the voltage Va in FIG. 2 It can be seen that the

From these experimental results, it can be seen that it is not feasible to model the arc gap as a simple resistance.

4 is a block diagram of an apparatus for measuring a small signal model for an arc gap.

Referring to FIG. 4 , the measuring device 400 includes a device (not shown) capable of forming an arc gap A in a conducting wire, and a voltage having an AC waveform voltage fluctuation Δvi in the arc gap A An amplifier 410 capable of supplying (Vi+Δvi) may be included, and a load 420 may be included.

The voltage (Vi + Δvi) supplied by the amplifier 410 is composed of a DC part (Vi) and an AC part (Δvi). According to this voltage waveform 430 , the current ia flowing in the arc gap A is also DC It has a part (Ii) and an AC part (Δii).

The impedance (Z) used in the small signal model may be determined according to the value obtained by dividing the AC voltage (Δvi) by the AC current (Δii).

If the impedance (Z) is represented as a nyquist plot, the detailed configuration of the impedance (Z) can be more accurately understood.

5 is a diagram illustrating an impedance value measured by the measuring device of FIG. 4 as a Nyquist diagram.

Referring to FIG. 5 , it can be seen that the arc gap has a semicircle part and a straight part in the Nyquist diagram, and it can be seen that the curve moves to the left along the real axis as the gap interval in the arc gap increases. have.

The detailed configuration of the impedance can be derived based on the shape of the Nyquist diagram of the arc gap. For example, the semicircle part can be modeled in RC parallel and the straight part can be modeled with an inductor.

FIG. 6 is a model of an arc gap according to the Nyquist diagram of FIG. 5 .

6, the arc gap is a series resistance (Rs), RC parallel part - first parallel resistor (Rp1) and first parallel capacitor (Ci) -, RL parallel part - second parallel resistance (Rp2) and parallel inductance (L)-, and can be modeled as a second parallel capacitor (Co). The connection relationship of each configuration can be seen with reference to FIG. 6 .

On the other hand, as confirmed in FIG. 6 , it appears that there are several resonance points in the arc gap. For example, the resonance of the first parallel capacitor (Ci) and the parallel inductance (L), the resonance of the second parallel capacitor (Co) and the parallel inductance (L), and the first parallel capacitor (Ci) / the second parallel capacitor Resonance of (Co) and parallel inductance (L) may appear in the arc gap.

The arc detection apparatus according to an embodiment may determine whether an arc is generated by observing these resonance points in the current. Some of these resonance points may appear in a low frequency band, and some may appear in a high frequency band.

The designer of the arc detection device can model the arc gap through the measuring device of FIG. 4 and find the resonance point according to the model of the arc gap. And, it is possible to set the resonance frequency or observation frequency band to be observed by the arc detection device according to the resonance point.

7 is a diagram illustrating an exemplary FFT waveform with respect to an arc current.

Referring to FIG. 7 , in the FFT waveform 710 of the arc current, a characteristic waveform 712 in the low frequency band - 0 to fa (Hz) - appears.

The arc detection device compares the FFT waveform (710 or 712) of the arc current with the reference line 720 in a predefined low frequency band -0 to fa (Hz)-, and compares the FFT waveform (710 or 712) of the arc current with the reference line 720 ), it can be evaluated that there is a high possibility that an arc has occurred in the conductor.

8 is a diagram showing the dispersion of magnitudes for each frequency in the FFT result of the arc current.

Referring to FIG. 8 , it can be seen that the dispersion value of the magnitude for each frequency in the waveform 710 when the arc is generated is greater than the dispersion value of the magnitude by frequency in the waveform 720 when the arc does not occur, in particular , it can be seen that the difference is more clear in the low frequency band - 0~fa(Hz)-.

The arc detection device calculates the dispersion or standard deviation of the magnitude for each frequency of the FFT result in a predefined low frequency band - 0 to fa (Hz) - and compares it with the reference value or the value when no arc occurs. It can be determined whether or not this has occurred.

9 illustrates an audible sound appearing when an arc is generated in a conducting wire.

Researchers have found empirically that an arc in a conductor produces an audible sound. However, researchers tended to check these audible sounds only through sound sensing devices such as microphones. Since it is difficult to distinguish the audible sound generated from the arc from the ambient noise, the sound detection device was difficult to be used as an accurate device for judging the arc.

One embodiment proposes a method of observing the audible frequency band in the arc current and judging the arc according to the observation result in order to solve this problem in the prior art. In addition, the inventor devised a small signal device to present the rationale for this method, modeled the impedance of the arc gap, and confirmed that the resonance point of the audible frequency band appears in the arc gap according to the modeling result.

10 is a flowchart of an arc detection method according to an embodiment.

Referring to FIG. 10 , the arc detection device may acquire a measurement value of the current flowing through the conducting wire (S1002). The arc detection device may directly measure a current measured value using a current sensor, or may receive a current measured value measured by another device through communication or a signal. The current measurement value is a value measured in the time domain and may be a value measured in a constant time unit. Current measurement values acquired for a certain period of time may form time series data.

The arc detection device may frequency-analyze the time series data for the current measurement value (S1004). Frequency analysis may be performed by an analog circuit or a digital circuit, and may be performed by a method of FFT (Fast Fourier Transform) in a device having computational capability.

Frequency analysis may be performed only once, or may be performed periodically at regular time intervals. For example, time series data may be generated as a collection of current measurement values measured during the time period of the TU, and frequency analysis may be performed on this time series data. and perform frequency analysis.

Frequency analysis data generated in frequency analysis may include a magnitude for each frequency. Magnitude is also called a frequency component, and can be understood as indicating the energy level for each frequency of a value to be analyzed.

The arc detection device may evaluate the possibility of arc generation in the conducting wire using the frequency analysis data (S1006).

The arc detection device can highly evaluate the possibility of arcing in the conducting wire when the magnitude of each frequency in a predefined low frequency band increases in the frequency analysis data.

The arc detection device may determine that an arc has occurred in the conducting wire when the magnitude of each frequency in the low frequency band exceeds the reference value in the frequency analysis data.

The arc detection device can highly evaluate the possibility of arcing in the conducting wire when the magnitude of each frequency in a predefined high-frequency band increases in the frequency analysis data.

The arc detection device performs frequency analysis for N different time sections (N is a natural number greater than or equal to 2), and the magnitude of the change in magnitude for each frequency in the low frequency band identified in the frequency analysis data in each time section exceeds the reference value. In this case, it can be determined that an arc has occurred in the conducting wire.

In the frequency analysis data, the arc detection device can highly evaluate the possibility of arcing in the conducting wire when the variability of the magnitude for each frequency in the low frequency band defined within the audible frequency band increases.

The arc detection device performs frequency analysis for N different time sections (N is a natural number greater than or equal to 2), and the magnitude of the change in magnitude for each frequency in the low frequency band identified in the frequency analysis data in each time section exceeds the reference value. In this case, it can be determined that an arc has occurred in the conducting wire. Here, the arc detection device performs frequency analysis on different M (M is a natural number greater than or equal to 2) time sections before N different time sections, and each frequency in the low frequency band identified in the frequency analysis data in each time section The magnitude of the magnitude change may be set as a reference value.

When it is determined that an arc has occurred, the arc detection device may generate a control signal for blocking the current flowing through the conducting wire (S1008).

11 is a block diagram of a power device according to an embodiment.

Referring to FIG. 11 , a power device 1100 may include a power supply device 1121 , a power conversion device 1122 , a current sensor 1111 , and an arc detection device 100 .

The power supply 1121 may be a renewable energy device such as a solar panel or an energy storage device such as a battery.

The power conversion device 1122 is a device for converting power, and may convert a DC voltage (DC) into an AC voltage (AC) to transmit power to the grid.

The power supply device 1121 and the power converter 1122 may be connected through a conductive wire, and a current sensor 1111 may be disposed on the conductive wire.

The arc detection device 100 may acquire a current measurement value flowing through the conducting wire while being connected to the current sensor 1111 .

The arc detection device 100 obtains a measurement value of the current flowing through the conducting wire, generates frequency analysis data for the measurement value, and in the frequency analysis data, the magnitude ( magnitude), the possibility of arcing in the conductor can be highly evaluated. And, when it is determined that an arc has occurred in the conducting wire, the arc detection device 100 may generate a control signal for blocking the current flowing through the conducting wire.

Here, the low frequency band may be determined according to the resonance frequency of the arc gap formed in the conductive wire, and the resonance frequency may be affected by the inductance of the conductive wire.

12 is a test configuration diagram of a power device according to an embodiment.

In order to evaluate the arc detection capability of the power device according to an embodiment, a test device simulating the power device was configured. The test device 1200 includes a solar panel simulator 1221 , a solar inverter 1222 , a current sensor 1211 , a current measurement value preprocessing device 1232 , a DSP device 1231 , and an arc gap generating device 1212 . was composed

The photovoltaic panel simulator 1221 and the photovoltaic inverter 1222 are connected by a conducting wire, and an arc gap generating device 1212 is disposed in the middle of the conducting wire. The arc gap generating device 1212 is a device capable of generating an arc gap in a part of the conducting wire, and can also measure the voltage across the arc gap.

In the DSP device 1231, the above-described arc detection method was programmed and performed, and the DSP device 1231 obtained a current measurement value flowing through the conductor from the current measurement value preprocessing unit 1232 connected to the current sensor 1211. .

FIG. 13 is a diagram showing waveforms of arc current and arc voltage in a situation in which an arc is generated in the test of FIG. 12 .

Referring to FIG. 13 , it can be seen that a resonance waveform appears in the arc current ia at the time point Ta when the arc is generated, and it can be confirmed that the arc voltage Va is increased.

The DSP device 1231 performs a frequency analysis on the current measurement value accumulated for a certain period of time, and increases the control signal Sa at a time point Tb 83 ms after the arc generation according to the frequency analysis.

The difference between the arc generation time (Ta) and the control signal generation time (Tb) is the time that occurs according to the accumulation of current measurement values for frequency analysis, which is 83 ms, which is much shorter than the arc energy accumulation time for fire. it can be seen that

FIG. 14 is a view showing waveforms of arc current and arc voltage when there is a change in load in the test of FIG. 12 .

In order to test whether the arc detection device erroneously judges the change in the load as an arc, the load was changed at a time point Tc during the test, but it can be confirmed that the control signal Sa is not affected by the change in the load.

As described above, according to the present embodiment, there is an effect of detecting an arc generated in the power system and stably interrupting the power system based on this. In addition, according to the present embodiment, there is an effect of reducing the frequency of arc misdetection by distinguishing the arc from the noise generated in normal operation.

Terms such as "include", "comprise" or "have" described above mean that the corresponding component may be embedded unless otherwise stated, so it does not exclude other components. It should be construed as being able to further include other components. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, unless otherwise defined. Terms commonly used, such as those defined in the dictionary, should be interpreted as being consistent with the meaning of the context of the related art, and are not interpreted in an ideal or excessively formal meaning unless explicitly defined in the present invention.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (15)

A method for a device to detect an arc, comprising:
obtaining a measurement value of the current flowing through the conductor; and
In the frequency analysis data for the measured value, when the magnitude (magnitude) for each frequency in a predefined low frequency band increases, highly evaluating the possibility of arcing in the conducting wire
Arc detection method comprising a. According to claim 1,
In the frequency analysis data, if the magnitude of each frequency in the low frequency band exceeds a reference value, further comprising the step of determining that an arc has occurred in the conducting wire
Arc detection method. According to claim 1,
The low frequency band is an arc detection method defined within an audible frequency band. According to claim 1,
In the frequency analysis data, when the magnitude for each frequency in a predefined high frequency band increases, further comprising the step of highly estimating the possibility of arcing in the conducting wire
Arc detection method. According to claim 1,
When frequency analysis is performed on N different (N is a natural number of 2 or more) time sections, and the magnitude of the fluctuation of the magnitude for each frequency in the low frequency band identified in the frequency analysis data in each time section exceeds the reference value, Determining that an arc has occurred in the conducting wire
further comprising
Arc detection method. 6. The method of claim 5,
The magnitude of the fluctuation is calculated according to the dispersion or standard deviation of the magnitude for each frequency in each time period. 3. The method of claim 2,
The reference value is an arc detection method that is an average value of the magnitudes for each frequency calculated in the time period before the arc determination. A method for a device to detect an arc, comprising:
obtaining a measurement value of the current flowing through the conductor;
In the frequency analysis data for the measured value, if the variability of the magnitude (magnitude) for each frequency in the low frequency band defined within the audible frequency band increases, estimating the possibility of arcing in the conducting wire highly
Arc detection method comprising a. 9. The method of claim 8,
When frequency analysis is performed on N different (N is a natural number of 2 or more) time sections, and the magnitude of the fluctuation of the magnitude for each frequency in the low frequency band identified in the frequency analysis data in each time section exceeds the reference value, Further comprising the step of determining that an arc has occurred in the conducting wire
Arc detection method. 10. The method of claim 9,
Frequency analysis is performed on different M (M is a natural number of 2 or more) time sections before the different N time sections, and the variation of the magnitude of each frequency in the low frequency band confirmed in the frequency analysis data in each time section Further comprising the step of setting the size as the reference value
Arc detection method. a measuring device for obtaining a measurement value of a current flowing through a wire to which the power converter is electrically connected to one side;
a frequency analysis device for generating frequency analysis data for the measured value;
In the frequency analysis data, when the variability of the magnitude (magnitude) for each frequency in the low frequency band defined within the audible frequency band increases, the arc determination device for highly evaluating the possibility of arc generation in the conducting wire; and
When the arc determination device determines that an arc has occurred in the conducting wire, a signal generating device for generating a control signal to block the current flowing through the conducting wire
An arc detection device comprising a. 12. The method of claim 11,
An arc detection device to which a photovoltaic panel or an energy storage device for generating a DC voltage is electrically connected to the other side of the conducting wire. 12. The method of claim 11,
The low frequency band is an arc detection device that is determined according to the resonance frequency of the arc gap formed in the conducting wire. 14. The method of claim 13,
The resonant frequency is affected by the inductance of the wire arc detection device. 12. The method of claim 11,
The arc determination device,
When frequency analysis is performed on N different (N is a natural number of 2 or more) time sections, and the magnitude of the fluctuation of the magnitude for each frequency in the low frequency band identified in the frequency analysis data in each time section exceeds the reference value, An arc detection device that determines that an arc has occurred in the conducting wire.

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