KR102441745B1 - Apparatus for monitoring and interrupting arc and leakage current of electrical safety type solar junction box - Google Patents

Abstract

In accordance with the present invention, provided is an arc and leakage current monitoring and blocking device for an electrical safety solar junction box. The arc and leakage current monitoring and blocking device for an electrical safety solar junction box, includes: a first sensor unit disposed on a transmission line for transmitting a direct current generated by a plurality of solar cells, and detecting an arc signal from the direct current; a second sensor unit including a core disposed on the transmission line and a first coil wound around the core, applying an alternating current to the first coil and detecting a DC offset current induced by a leakage current flowing in the transmission line; and a control unit determining whether an arc is generated based on the arc signal, and determining whether the leakage current is generated based on the DC offset current. Therefore, the present invention is capable of embodying an electrical safety solar junction box by detecting and blocking arc and earthing accidents.

Description

ARC AND LEAKAGE CURRENT OF ELECTRICAL SAFETY TYPE SOLAR JUNCTION BOX

The present invention relates to a device for preventing a fire by monitoring and blocking the arc and leakage current of an electrical safety type solar junction box.

In a direct current (DC) terminal fire in a solar power plant, arcs occur in series or parallel form between damaged wires and between poles or lines with reduced insulation performance.

In the ungrounded system, the direct current (anode, cathode) of the solar power plant does not generate leakage current even if either pole is grounded, but when both ends are grounded, a short circuit begins to occur, which generates heat in a different form from the arc. lead to fire Therefore, it is possible to prevent a fire by detecting and blocking the arc and short circuit of the DC link of the solar power plant.

The conventional arc detection method extracts only the harmonic signal by applying a harmonic filter (HPF) to the current sensor (CT: Current Transformer) signal based on the harmonic characteristics of the arc and adjusts the size of the signal level or rms value (RMS: Root Mean Square) was used to detect the presence of arcs. However, when the harmonic characteristics are processed as signal levels or rms values in the time domain, there is a problem in that it is difficult to reflect the nonlinear characteristics of various harmonics.

In addition, since a direct current (DC) current flows differently from an alternating current in the direct current terminal of a solar power plant, when an alternating current sensor (CT) using magnetic material induced electromotive force is used, the magnetic material is saturated in one direction by the direct current flowing in one direction and is used as a sensor. There is a problem of losing the role.

In order to solve the problems of the prior art as described above, the present invention provides an arc and leakage current monitoring and interruption device of a solar junction box that can detect and block both arcs and short circuits, and has a simple and highly reliable system aim to do

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. There will be.

In order to solve the above problems, the present invention is a device for monitoring the arc and leakage current of a solar junction box, which is disposed on a transmission line for transmitting the DC current generated by a plurality of solar cells, and receives an arc signal from the DC current. It includes a first sensor unit for detecting, a core disposed on a transmission line, and a first coil wound around the core, applying an alternating current to the first coil and detecting a DC offset current induced by a leakage current flowing through the transmission line Arc and leakage current monitoring and blocking device of a solar junction box including a second sensor unit and a control unit for determining whether an arc is generated based on an arc signal, and determining whether a leakage current is generated based on a DC offset current provides

Here, the first sensor unit may include an air-core coil current sensor for detecting an arc signal, a gain adjusting unit for adjusting a gain of the arc signal, and a digital signal processing unit for digitally processing the arc signal of which the gain is adjusted.

In addition, the controller may determine the arc signal when the digital signal-processed arc signal has a size equal to or greater than a reference value and is detected to be greater than or equal to a reference time.

In addition, the digital signal processing unit includes a digital integrator that generates an integral signal by integrating the arc signal detected by the air-core coil current sensor, a Fourier transform unit that converts the integrated signal into a frequency domain, and a spectrum analysis that analyzes a spectrum in the frequency domain may include wealth.

In addition, the arc and leakage current monitoring and blocking device of the solar junction box of the present invention may further include a series arc processing unit connected in series to a transmission line, and a parallel arc processing unit connected to two transmission lines.

In addition, when an arc is generated, the controller may open the transmission line through the series arc processing unit or short-circuit the two transmission lines through the parallel arc processing unit.

Also, when the DC offset current is equal to or greater than the reference value, the controller may determine that the leakage current is generated.

Also, a coil current obtained by adding a DC offset current to an AC current may flow in the first coil when a leakage current is generated.

Also, the second sensor unit may calculate the DC offset current by removing the AC current from the coil current.

In addition, the arc and leakage current monitoring and blocking device of the solar junction box of the present invention includes a second coil wound on the core, and applies a compensation current corresponding to the alternating current and opposite to the alternating current to the second coil. It may further include a compensation unit.

According to the present invention, it is possible to implement an electric safety type smart solar junction box because it detects and blocks both arcs and grounding accidents, which are causes of fire in the direct current electric system of photovoltaic power generation.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art from the following description. will be.

1 is a view showing the overall configuration of a photovoltaic power generation system according to an embodiment of the present invention.
2 is a view for explaining a solar junction box according to an embodiment of the present invention.
3 is a detailed block diagram of an arc monitoring and blocking device of a solar junction box according to an embodiment of the present invention.
4 is a view for explaining an induced voltage according to the through current of the air-core coil current sensor according to an embodiment of the present invention.
5 is a diagram illustrating a graph comparing harmonic signals of an air-core coil current sensor and a general magnetic current sensor.
6 is a block diagram of a configuration for removing an arc of an arc monitoring device according to an embodiment of the present invention.
7 is a schematic circuit diagram of an apparatus for monitoring and blocking leakage current of a solar junction box according to an embodiment of the present invention.
8 is a detailed circuit diagram for forcibly applying an alternating current to a coil in the circuit diagram of FIG. 7 .
9 is a graph illustrating a waveform of a coil current flowing through a first coil.
10 is a graph illustrating a waveform obtained by removing an alternating current from the coil current of FIG. 9 .
11 is a detailed circuit diagram for compensating for an AC current forcibly applied to a coil in the circuit diagram of FIG. 7 .

In order to fully understand the configuration and effect of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various forms and various modifications may be made. However, the description of the present embodiment is provided so that the disclosure of the present invention is complete, and to fully inform those of ordinary skill in the art to which the present invention pertains the scope of the invention. In the accompanying drawings, components are enlarged in size than actual for convenience of description, and ratios of each component may be exaggerated or reduced.

Terms such as 'first' and 'second' may be used to describe various elements, but the elements should not be limited by the above terms. The above term may be used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a 'first component' may be termed a 'second component', and similarly, a 'second component' may also be termed a 'first component'. can Also, the singular expression includes the plural expression unless the context clearly dictates otherwise. Unless otherwise defined, terms used in the embodiments of the present invention may be interpreted as meanings commonly known to those of ordinary skill in the art.

1 is a view showing the overall configuration of a photovoltaic power generation system according to an embodiment of the present invention.

As shown in FIG. 1 , the photovoltaic power generation system according to an embodiment of the present invention includes a solar cell 110 , a photovoltaic junction box 120 , and a photovoltaic PCS 330 .

The solar cell 110 receives light from the sun and generates electricity by the photoelectric effect. Specifically, the solar cell 110 generates a direct current and transmits it to the solar junction box 120 .

The solar inverter 330 converts the DC current received from the solar junction box 120 into an AC current and supplies it to a transformer or the like.

2 is a view for explaining a solar junction box according to an embodiment of the present invention.

Referring to FIG. 2 , the photovoltaic junction box 120 is a facility in which photovoltaic electricity generated by a plurality of solar cells 110 is concentrated.

The photovoltaic junction box 120 is also a facility in which a fire frequently occurs when an electrical accident occurs, and has a characteristic of being burned out once a fire starts.

Since the current output from the solar cell 110 is a maximum of 9A, even if an arc occurs in the solar junction box 120, it does not fall within the overcurrent operating range of the circuit breaker (MCCB), so the circuit breaker cannot directly protect against an arc accident . In addition, in the case of a parallel arc, even if the circuit breaker blocks the main line, since the solar cell 10 continues to supply energy, the arc is not removed and a fire may be caused.

In addition, in the photovoltaic power generation system, even if a ground fault occurs in which one transmission line is connected to the ground, the entire system is not insulated from the ground, so the fault current hardly flows. That is, even if a grounding fault occurs in one transmission line, the system can be used normally, but if a grounding fault occurs in another transmission line while no measures are taken, high fault current flows and the entire system blackout occurs. Therefore, in order to increase the reliability of the photovoltaic system, it is necessary to perform leakage current monitoring (insulation monitoring) before a system power outage, and to remove the fault by identifying which transmission line (point) has a grounding accident.

Arc and leakage current monitoring and blocking device of a solar junction box according to an embodiment of the present invention detects a series arc and a parallel arc generated in the solar junction box 120, and removes the series arc and parallel arc based on this and to prevent grounding accidents by detecting leakage current.

3 is a detailed block diagram of an arc monitoring and blocking device of a solar junction box according to an embodiment of the present invention.

2 and 3, the arc monitoring and blocking device of the solar junction box according to an embodiment of the present invention is disposed on a transmission line for transmitting the DC current generated by the plurality of solar cells 110, and the arc in the DC current and a first sensor unit 201 for detecting a signal.

Here, the first sensor unit 201 includes an aircore coil current sensor 210 and an arc detector 211 . The arc detector 211 includes a gain controller 220 , an analog-to-digital converter 230 , and a digital signal processor 240 .

The air-core coil current sensor 210 is positioned around the transmission line connected to the solar cell 110 , and detects an arc signal from the DC current output from the solar cell 110 . Here, the arc signal is a differential signal obtained by differentiating the harmonic current signal included in the DC current.

The gain adjusting unit 220 adjusts the differential signal output from the air-core coil current sensor 210 to a set size. For example, the gain control unit 220 increases or decreases the differential signal output from the air-core coil current sensor 210 to adjust the signal of a set size.

The analog-to-digital converter 230 converts the analog differential signal output from the gain adjuster 220 into a digital differential signal.

The digital signal processing unit 240 performs digital signal processing on the signal output from the analog-to-digital conversion unit 230 . Specifically, the digital signal processing unit 240 includes a digital integrator 241 , a Fast Fourier Transformation unit 242 , and a spectrum analysis unit 243 .

Here, the digital integrator 241 integrates the differential signal to restore the differential signal output from the analog-to-digital converter 230 to the original signal and converts the differential signal into an integral signal.

The Fourier transform unit 242 converts the integral signal output from the digital integrator 242 into a frequency domain.

The spectrum analyzer 243 analyzes the frequency domain of the integral signal transformed by the Fourier transform unit 242 and extracts a frequency magnitude value of a set range among the frequency domain. For example, the spectrum analyzer 243 may extract a frequency magnitude value in a range of 10 KHz to 200 KHz.

When a signal equal to or greater than the reference value is detected through the digital signal processing unit 240 , and a signal equal to or greater than the reference value is detected for more than the reference time, the controller 250 determines that the arc is an arc.

4 is a view for explaining an induced voltage according to the through current of the air-core coil current sensor according to an embodiment of the present invention, and FIG. 5 is a graph comparing the harmonic signals of the air-core coil current sensor and the general magnetic current sensor. It is a drawing.

4, the signal output from the air-core coil current sensor 210 according to the embodiment of the present invention is a waveform obtained by differentiating the harmonic current signal of the arc as shown in Equation 1 below.

[Equation 1]

Here, M means μ ₀ ×S × N, μ ₀ means air permeability π × 10 ^-7 H/m, S means the cross-sectional area (m ² ), and N is the number of turns /m stands for

The signal output from the air-core coil sensor 210 according to an embodiment of the present invention is a waveform obtained by differentiating the harmonic current signal of the arc. Specifically, in the present invention, an air-core coil current sensor 210 that is easy to measure harmonic alternating current without saturation in direct current due to the fact that the arc harmonic characteristic has a high frequency was used.

Referring to Equation 1, the DC current is canceled by the differential signal because there is no change. In addition, the AC harmonic current having a frequency component is output in the form of a differential signal.

As shown in FIG. 5 , the air-core coil sensor 210 according to an embodiment of the present invention is suitable for passing a frequency component of 1 MHz or less as a differential signal, so it may be suitable for detecting a harmonic current generated in a DC current. . In addition, since there is no magnetic saturation with respect to a direct current, the optimum performance can be exhibited.

Specifically, as shown in FIG. 5 , a general current sensor (CT) and an air-core coil current sensor according to an embodiment of the present invention exhibit similar signal characteristics, and when a direct current flows, the CT-Ferrite internal magnetic material is saturated. and arc signal output may not come out.

However, since the present invention uses an air-core coil current sensor and a digital signal processing unit, there is an advantage in that the arc determination can be made more reliably when the size of a specific band frequency is used.

The arc monitoring device of the solar junction box according to an embodiment of the present invention detects a series arc and a parallel arc generated in the solar junction box 120 through light (light), radio wave, and current signal analysis, and based on this, the series arc and parallel arcs.

A conventional solar junction box is equipped with a circuit breaker (MCCB). The overcurrent relay of the circuit breaker is a device to protect the circuit from overheating, and it performs the cutoff operation when several minutes have elapsed at 200% of the rated current to prevent fire. However, an arc accident occurs at a current lower than the rated current, but generates high heat, and the overcurrent relay of the existing circuit breaker cannot protect it. Moreover, the existing solar junction box is not equipped with an arc detection facility. Accordingly, the arc monitoring device according to an embodiment of the present invention detects the generation of a series arc using a sensor, and when an arc occurs, the solar cell 110 is separated from the solar junction box 120, and the main transmission line (eg, , connected to the solar inverter 330).

On the other hand, when a parallel arc occurs, even if the circuit breaker operates, the arc is continuously maintained due to the energy output from the solar cell 110 regardless of the circuit breaker, and thus a fire is inevitable. Therefore, the arc monitoring device according to an embodiment of the present invention removes the parallel arc by shorting the transmission line of the solar electricity 110 when a parallel arc occurs.

Then, in more detail, the arc monitoring device according to an embodiment of the present invention will be described with respect to a method of removing the arc.

6 is a block diagram of a configuration for removing an arc of an arc monitoring and interrupting device according to an embodiment of the present invention.

2 and 6 , the arc monitoring and blocking device according to an embodiment of the present invention includes a sensor unit 210 , a serial arc processing unit 214 , a parallel arc processing unit 213 , a communication unit 215 , and a control unit 250 . ) is included.

The sensor unit 210 may detect a harmonic current included in the DC current output from the solar cell 110 when an arc is generated.

The series arc processing unit 214 is connected in series to the transmission line of the solar cell 110 and may remove the series arc generated in the transmission line. Specifically, when a series arc occurs, the series arc processing unit 214 cuts off a transmission line connected in series under the control of the control unit 250 . The series arc processing unit 214 may be a switch or a relay circuit breaker connected in series to the transmission line of the solar cell 110 . That is, the series arc processing unit 214 removes the series arc by opening the corresponding transmission line when an arc is detected under the control of the controller 250 .

The parallel arc processing unit 213 is connected to two transmission lines of the solar cell 110 . That is, both ends of the parallel arc processing unit 213 are respectively connected to (+) and (-) transmission lines. In addition, the parallel arc processing unit 213 may remove the parallel arc generated between the two transmission lines.

On the other hand, as soon as the series arc processing unit 214 , that is, the circuit breaker is opened, all of the series arcs are removed, but the parallel arc may be maintained regardless of the series arc processing unit 120 . Therefore, even after removing the series arc, if the arc is still detected through the sensor unit 210, it can be determined that the parallel arc has occurred.

Here, the parallel arc processing unit 213 removes the parallel arc by shorting the two transmission lines in which the parallel arc is detected. In this way, when the two transmission lines in which the parallel arc is generated are short-circuited, the voltage between the two transmission lines becomes 0V, and accordingly, the arc is removed because the plasma material that activates the parallel arc is no longer generated. .

After removing the parallel arc, the parallel arc processing unit 213 separates the two transmission lines to restore insulation performance between the two transmission lines to restore the original state. As such, the parallel arc processing unit 213 may be a relay, a switch, etc. that can cause a short circuit of two transmission lines and return.

The communication unit 215 is for communication with other devices including a manager device (not shown), and performs communication through various communication connection methods. The communication unit 215 may select and communicate with any one of communication functions of various communication connection methods.

The control unit 250 may transmit a report indicating that the arc has been generated and removed to the manager device through the communication unit 215 .

Then, the communication unit 215 may convert the report received from the control unit 250 into a wireless signal and transmit it through a wireless channel.

The controller 250 may control the overall operation of the arc monitoring device and the signal flow between internal components of the arc monitoring device, and may perform a data processing function of processing data. The control unit 250 may be a central processing unit (CPU), a graphic processing unit (GPU), a digital signal processor (DSP), or the like.

7 is a schematic circuit diagram of an apparatus for monitoring and blocking leakage current of a solar junction box according to an embodiment of the present invention.

Referring to FIG. 7 , the leakage current monitoring and blocking device may include a sensor unit 130 , a compensation unit 140 , and a control unit 250 .

The sensor unit 130 is disposed on the transmission lines L1 and L2 and may detect a DC offset current induced by the leakage current I _p when a ground fault occurs.

The controller 250 may monitor the ground fault based on the DC offset current. That is, when the DC offset current is detected, the control unit 150 may determine the ground fault, or if the DC offset current is equal to or greater than the reference value, it may determine the ground fault.

8 is a detailed circuit diagram for forcibly applying an alternating current to a coil in the circuit diagram of FIG. 7 . Also, FIG. 9 is a graph illustrating a waveform of a coil current flowing through the first coil, and FIG. 10 is a graph illustrating a waveform in which an AC current is removed from the coil current of FIG. 9 . And, FIG. 11 is a detailed circuit diagram for compensating for the AC current forcibly applied to the coil in the circuit diagram of FIG. 7 .

7 and 8 , the sensor unit 130 is a current sensor using the principle of AC induction electromotive force, and may be a current transformer (CT), and a core 131 disposed on the transmission lines L1 and L2. and a first coil 132 wound around the core 131 .

On the other hand, when the solar cell 110 continuously outputs a DC current to the transmission lines L1 and L2, the core 131 of the sensor unit 130 disposed on the transmission lines L1 and L2 is saturated and is no longer It cannot perform the role of a current transformer.

Accordingly, the sensor unit 130 prevents the core 131 from being saturated by applying the AC voltage (alternating voltage) Vs to the first coil 132 . At this time, an AC current is flows through the first coil 132 due to the AC voltage Vs.

Specifically, the sensor unit 130 applies the AC current is to the first coil 132 , the first operational amplifier op1 , the first resistor R1 , the second resistor R2 , and the first It may be configured to include a current controller 133 .

Here, the first current controller 133 is connected to one end of the first coil 132 wound around the core 131 , and the first and second current controllers 133 are connected between one end of the first coil 132 and the first current controller 133 . The second resistors R1 and R2 are connected in series. And, the non-inverting terminal (+) of the first operational amplifier op1 is connected between the first and second resistors R1 and R2, and the inverting terminal (-) of the first operational amplifier op1 is the first coil It is connected to the other end of (132).

Here, the number of turns of the first coil 132 may be adjusted according to the detection range of the DC offset current.

As described above, an alternating current is is applied to the first coil 132 , and a direct current I _CC is output from the solar cell 110 to the transmission lines L1 and L2 . At this time, when a ground fault occurs, the primary side DC current ip further flows through the transmission line L1 due to the ground fault resistance, and the first coil 132 receives a DC offset by the primary side DC current ip. current is induced.

Referring to FIG. 9 , if a ground fault does not occur, the coil current i _ST flowing in the first coil 132 includes only the alternating current is (a). However, when a grounding accident occurs, a coil current i _ST in which a DC offset current is added to an AC current is flows in the first coil 132 (b).

At this time, in order to measure the coil current i _ST , a shunt resistor Rs may be connected between the other end of the first coil 132 and the inverting terminal (-) of the first operational amplifier op1, and the sensor unit When 130 measures the voltage (V _ST ) across the shunt resistor (Rs), the coil current (i _ST ) can be measured according to Ohm's law (V _ST /Rs).

The sensor unit 130 may calculate the DC offset current by removing the AC current is from the coil current i _ST . At this time, referring to FIG. 10 , if a grounding fault does not occur, the DC offset current is almost zero (0) (a), and when a grounding fault occurs, it can be confirmed that a DC offset current of a certain value or more appears ( b).

The sensor unit 130 may provide the calculated DC offset current to the control unit 250 .

Then, the control unit 250 may determine whether a ground fault has occurred based on the DC offset current provided from the sensor unit 130 . That is, when the DC offset current is detected, it can be determined as a grounding fault. In this case, if the DC offset current is equal to or greater than the reference value, it may be determined as a ground fault.

On the other hand, when the AC current is forcibly applied to the first coil 132 , the current Icc flowing through the transmission lines L1 and L2 is also affected. Accordingly, it is preferable to remove the influence on the transmission lines L1 and L2 by flowing the compensation current i _T in the opposite direction to the AC current is applied to the first coil 132 .

To this end, the compensator 140 includes a second coil 141 wound around the core 131 , and applies a compensating voltage V _T to the second coil 141 in response to an alternating current is. can do. Accordingly, the compensation current (i _T ) according to the compensation voltage (V _T ) flows in the second coil 141 in the opposite direction to the AC current (is), so that the AC current (is) flowing in the first coil 131 is It is possible to remove the influence on the transmission lines (L1, L2).

7 and 11 , the compensator 140 includes a low-pass filter 142 , an integrator 143 , and a second operational amplifier op2 to apply a compensation current i _T to the second coil 141 . ) and a second current controller 144 .

One end of the second coil 141 is connected to the second current controller 144 , and the second current controller is connected to the output terminal of the second operational amplifier op2 . Then, the integrator 143 is input to the non-inverting terminal (+) of the second operational amplifier op2 , and the low-pass filter 142 is connected to the integrator 143 . And, the other end of the second coil 141 is connected to the inverting terminal (-) of the second operational amplifier (op2).

Here, when the voltage (V _ST ) across the shunt resistor (Rs) is input to the non-inverting terminal (+) of the second operational amplifier (op2) through the low-pass filter 142 and the integrator 143, the second coil ( 141), the compensation current i _T flows.

In order to measure the compensation current i _T , a measurement resistance R _T may be connected between the other end of the second coil 132 and the inverting terminal (−) of the first operational amplifier op1 , and the sensor unit 130 . ) can measure the compensation current (i _T ) flowing through the second coil 141 according to Ohm's law (V _T / R _T ) by measuring the voltage (V _T ) across the measurement resistance ( _RT ).

Meanwhile, the photovoltaic power generation system may be configured to include a plurality of transmission lines branched from the busbar, and the sensor unit 130 may be provided in each of the plurality of transmission lines located at different positions.

The control unit 250 may receive each of the DC offset currents from the plurality of sensor units 130 to monitor the ground fault and its location.

Specifically, when the DC offset current is received or the received DC offset current is equal to or greater than a reference value, the controller 250 may determine the grounding fault.

The control unit 250 may determine that a grounding accident has occurred at a location of a transmission line in which the sensor unit 130 outputting the DC offset current is disposed. In this case, the sensor unit 130 may transmit the DC offset current together with its own identification code in order to distinguish each sensor unit 130 .

The control unit 250 may include a display unit (not shown) that displays the DC offset current in numbers for each of the plurality of transmission lines. In this case, the display unit distinguishes between a normal transmission line and a transmission line in which a grounding accident has occurred with an LED or the like. can be displayed.

In this way, the leakage current monitoring and blocking device of the solar junction box according to an embodiment of the present invention is a simple system compared to the AC detection signal application and AC current detection method in detecting the leakage current, and can provide high reliability .

As described above, the arc and leakage current monitoring and interruption device of the solar junction box according to the embodiment of the present invention detects and blocks both arc and ground accidents that are the cause of the fire of the DC electric system of solar power generation, so electrical safety A type smart solar junction box can be implemented.

In the detailed description of the present invention, although specific embodiments have been described, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention is not limited to the described embodiments, and should be defined by the following claims and their equivalents.

110: solar cell
210: first sensor unit
130: second sensor unit
140: compensation unit
250: control unit

Claims (10)

A device for monitoring and blocking the arc and leakage current of a solar junction box,
a first sensor unit disposed on a transmission line for transmitting the DC current generated by the plurality of solar cells and detecting an arc signal from the DC current;
a first coil comprising a core disposed to pass through the transmission line and a first coil wound around the core, applying an alternating current to the first coil and detecting a DC offset current induced by a leakage current flowing through the transmission line 2 sensor unit;
a control unit that determines whether the arc is generated based on the arc signal and determines whether the leakage current is generated based on the DC offset current; and
a second coil wound around the core, and applying a compensating current corresponding to the alternating current and opposite to the alternating current to the second coil so that the alternating current flowing through the first coil affects the transmission line Compensation to eliminate influence
Arc and leakage current monitoring and interruption device of an electrical safety type solar junction box comprising a.
The method of claim 1,
The first sensor unit
an air-core coil current sensor detecting the arc signal;
a gain control unit for adjusting a gain of the arc signal;
Digital signal processing unit for digital signal processing the arc signal of which the gain is adjusted
Arc and leakage current monitoring and interruption device of an electrical safety type solar junction box comprising a.
3. The method of claim 2,
the control unit
When the digital signal-processed arc signal is greater than or equal to a reference value and detected for more than a reference time, it is determined as the arc.
Arc and leakage current monitoring and interruption device for electrical safety photovoltaic junction box.
3. The method of claim 2,
The digital signal processing unit
a digital integrator that integrates the arc signal detected by the air-core coil current sensor to generate an integrated signal;
a Fourier transform unit converting the integral signal into a frequency domain;
A spectrum analyzer that analyzes the spectrum in the frequency domain
Arc and leakage current monitoring and interruption device of an electrical safety type solar junction box comprising a.
The method of claim 1,
a serial arc processing unit connected in series to the transmission line; and
Parallel arc processing unit connected to the two transmission lines
Arc and leakage current monitoring and interruption device of the electrical safety-type solar junction box further comprising a.
6. The method of claim 5,
the control unit
When the arc is generated, the transmission line is opened through the series arc processing unit, or the two transmission lines are short-circuited through the parallel arc processing unit.
Arc and leakage current monitoring and interruption device for electrical safety photovoltaic junction box.
The method of claim 1,
the control unit
If the DC offset current is greater than or equal to a reference value, it is determined that the leakage current occurs.
Arc and leakage current monitoring and interruption device for electrical safety photovoltaic junction box.
The method of claim 1,
The first coil has
When the leakage current is generated, a coil current in which the DC offset current is added to the AC current flows
Arc and leakage current monitoring and interruption device for electrical safety photovoltaic junction box.
9. The method of claim 8,
The second sensor unit
calculating the DC offset current by removing the AC current from the coil current
Arc and leakage current monitoring and interruption device for electrical safety photovoltaic junction box.
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