JP7262014B2 - Arc detection circuits, breakers, power conditioners, solar panels, modules attached to solar panels, junction boxes - 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 DC power source 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 transmission lines connecting PV panels and power conditioners are damaged or broken due to external factors or aging deterioration. An arc (that is, an arc discharge) may occur due to such damage to the transmission line. Therefore, arc detection means for detecting arcs has been proposed (for example, Patent Document 1). The arc detection means disclosed in Patent Document 1 attempts to detect an arc based on the voltage and current applied to the transmission line.

JP 2011-7765 A

By the way, the signal that flows through the transmission line when an arc occurs contains not only the arc, which is an AC component, but also a DC component from the DC power supply. The DC component becomes an unnecessary component when detecting an arc (AC component), and the arc may not be accurately detected due to the influence of the DC component.

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 present invention provides an arc detection circuit that occurs in a transmission line that connects a DC power supply that generates DC power and a power converter that converts the DC power to AC power. An arc detection circuit for detecting an arc, comprising: a positive side transmission line connecting a positive side of the DC power supply in the transmission line and the power converter; and a negative side of the DC power supply in the transmission line. and the negative side transmission line connecting the power conversion device, arranged so as to be connected in parallel with the power conversion device, and the signal of the AC component contained in the signal flowing through the transmission line is transmitted to the transmission a resonance circuit for flowing from a path to the path, a resistor connected in series with the resonance circuit in the path and generating a voltage signal corresponding to the AC component signal, and the voltage signal generated in the resistor being input, A filter unit that passes a signal having a frequency corresponding to an arc, and an arc determination unit that determines occurrence of an arc based on the signal that has passed through the filter unit.

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 arc detection circuit described above.

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.

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 Embodiment 1 is applied. FIG. 2 is a configuration diagram showing another example of a system to which the arc detection circuit according to Embodiment 1 is applied. FIG. 3 is a configuration diagram showing an example of a system to which the arc detection circuit according to the modified example of Embodiment 1 is applied. FIG. 4 is a diagram for explaining an application example of the arc detection circuit according to the first embodiment and its modification.

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 and connection forms of the constituent elements, etc. 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 1)
An arc detection circuit according to Embodiment 1 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 Embodiment 1 is applied.

The arc detection circuit 10 is a circuit that detects an arc generated in a transmission line A that connects a solar panel 31 as a DC power source that generates DC power and a power conversion device 50 that converts the DC power into AC power. . The arc detection circuit 10 includes a resonance circuit 5, a resistor R1, an arc determination section 11 and a filter section 12. In the following description, an example of a DC power supply is the solar panel 31, but the DC power supply is not limited to the solar panel 31 as long as it generates DC power.

As shown in FIG. 1, the transmission line A connecting the solar panel 31 and the power conversion device 50 includes a positive transmission line A1 connecting the positive side of the solar panel 31 and the power conversion device 50, A negative side transmission line A2 that connects the negative side of the solar panel 31 and the power converter 50 is included. The positive transmission line A1 and the negative transmission line A2 are also called positive and negative DC (Direct Current) lines. A direct current from the solar panel 31 to the power converter 50 flows through the positive transmission line A1, and a direct current from the power converter 50 back to the solar panel 31 flows through the negative transmission line A2. The negative transmission line A2 is a transmission line that is not directly connected to the ground.

In the present embodiment, the power conversion device 50 is, for example, a part of the configuration of a power conditioner (power conditioner). The power conversion device 50 converts DC power supplied from the solar panel 31 via the transmission line A into AC power. The power converter 50 employs, for example, an MPPT (Maximum Power Point Tracking) method, and adjusts the current and voltage of the DC power supplied from the solar panel 31 to maximize the power. For example, the power converter 50 converts DC power into AC power with a voltage of 100 V and a frequency of 50 Hz or 60 Hz. The AC power is used in household electric appliances and the like.

It has been reported that the transmission line A 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 A or the like.

The resonance circuit 5 is arranged to be connected in parallel with the power conversion device 50 on a path connecting the positive transmission line A1 and the negative transmission line A2 of the transmission line A, and is included in the signal flowing through the transmission line A. This is a circuit for passing a signal of an AC component received from a transmission path A (transmission path A1 in this case) to a path A3. The resonance circuit 5 is composed of a coil L1 and a capacitor C1, and is a series resonance circuit in which the coil L1 and the capacitor C1 are connected in series in this embodiment. Since the resonance circuit 5 has a function of extracting an AC component signal corresponding to the resonance frequency of the resonance circuit 5, it extracts only the AC component corresponding to the resonance frequency from the signal flowing through the transmission path A, and outputs it to the path A3. can flow. The inductance value of the coil L1 and the capacitance value of the capacitor C1 are appropriately determined according to the target resonance frequency (that is, according to the frequency of the AC component to be extracted).

Resistor R1 is connected in series with resonant circuit 5 in path A3. A circuit in which the resonance circuit 5 and the resistor R1 are connected in series is connected in parallel with the power conversion device 50 . The resistor R1 is a resistive element having a minute resistance value that generates a voltage signal corresponding to an AC component signal. The voltage signal is a signal that indicates the potential difference that occurs in the resistor R1 when the signal (current) of the AC component flows through the resistor R1. Since the potential difference has a value corresponding to the current flowing through the path A3, the resistor R1 functions as a current sensor. If a sensor such as an IC (Integrated Circuit) is used as the current sensor, the arc detection circuit 10 will be large and costly. For example, when a Hall element or the like is used as the current sensor, the Hall element itself is often larger than the resistor R1, and a separate magnetic core or the like is required. It is also costly. On the other hand, by using the resistor R1, miniaturization and cost reduction can be realized.

A circuit in which the resonance circuit 5 and the resistor R1 are connected in series on the path A3 is connected in parallel with the power conversion device 50 . For example, the resonance circuit 5 is arranged on the positive transmission line A1 side, and the resistor R1 is arranged on the negative transmission line A2 side. The resonance circuit 5 may be arranged on the side of the negative transmission line A2, and the resistor R1 may be arranged on the side of the positive transmission line A1.

The filter unit 12 receives the voltage signal generated at the resistor R1 and has a filter that passes a signal having a frequency corresponding to the arc. Since arcs occur at specific broadband frequencies, the filter blocks signals other than the frequencies used for arc determination. The filter is, for example, an RLC filter or the like, but is not particularly limited. The pass band of the filter is appropriately determined according to the frequency of the arc that can occur, the frequency of noise other than the arc, and the like.

Arc determination unit 11 determines the occurrence of an arc based on the signal that has passed through filter unit 12 . The arc determination unit 11 is implemented by, for example, a microcomputer (microcontroller) having an AD conversion function, and acquires, for example, the voltage generated at the resistor R1 via the filter unit 12 . 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. Note that the filter unit 12 may have an amplifier circuit. As a result, the magnitude of the voltage generated at the resistor R1 can be amplified to a magnitude corresponding to the AD conversion function of the arc determination section 11, and the arc determination section 11 can correctly AD-convert the voltage.

Note that the arc determination unit 11 may be realized by a comparator. As a result, the arc determination unit 11 can be simplified compared to the case where it is realized by a microcomputer, and it is possible to reduce the size and cost.

When the arc detection circuit determines the occurrence of an arc directly from the signal flowing through the transmission path A, it is necessary to detect the arc from the signal containing the DC component unnecessary for arc detection, and the DC component cannot accurately detect the arc. Sometimes. Further, since the DC component flows through the resistor R1, it is necessary to prepare a resistor with a high withstand voltage as the resistor R1.

In contrast, in the present embodiment, the resonance circuit 5 is arranged on the path A3 connecting the positive transmission line A1 and the negative transmission line A2, so that the resonance circuit 5 DC power can be supplied from the DC power source such as the solar panel 31 to the power conversion device 50 without being affected by . Then, when an arc occurs, the resonance circuit 5 can extract only the arc (AC component) and allow it to flow through the path A3. That is, when an arc occurs in the transmission line A, the arc can be detected without being affected by the DC component, so the arc can be accurately detected. In addition, since the DC component does not flow through the resistor R1, a low withstand voltage resistor (that is, a small resistor) can be used as the resistor R1, and the arc detection circuit 10 can be miniaturized.

For example, if an arc is detected, the current flowing through transmission line A should be interrupted. On the other hand, by stopping the power conversion device 50 based on the determination result of the arc determination unit 11, the current flowing through the transmission line A can be interrupted.

Note that the arc detection circuit 10 may be provided in the power conditioner as part of the configuration of the power conditioner. This will be described with reference to FIG.

FIG. 2 is a configuration diagram showing another example of a system to which the arc detection circuit 10 according to Embodiment 1 is applied.

As shown in FIG. 2 , arc detection circuit 10 is provided in power conditioner 51 and integrated with power converter 50 so as to be connected in parallel with power converter 50 within power conditioner 51 .

By integrally providing the arc detection circuit 10 and the power converter 50 in this way, it becomes easier to operate them in conjunction with each other. That is, when the arc detection circuit 10 detects an arc, the power conversion device 50 can be smoothly stopped.

Moreover, in the above-described embodiment, the resonance circuit 5 is a series resonance circuit in which the coil L1 and the capacitor C1 are connected in series, but the present invention is not limited to this. Another example of the resonance circuit will be described as a modification of the first embodiment with reference to FIG.

FIG. 3 is a configuration diagram showing an example of a system to which the arc detection circuit 10a according to the modification of the first embodiment is applied.

The arc detection circuit 10a differs from the arc detection circuit 10 in that it includes a resonance circuit 5a instead of the resonance circuit 5 and further includes a capacitor C2. Other points are the same as those of the arc detection circuit 10, so description thereof will be omitted.

The resonance circuit 5a is a parallel resonance circuit in which a coil L1 and a capacitor C1 are connected in parallel. Since the resonance circuit 5a has a function of extracting a signal of a component other than the AC component corresponding to the resonance frequency of the resonance circuit 5a, the signal of the component other than the AC component corresponding to the resonance frequency is extracted from the signal flowing through the transmission line A. It can be extracted and flowed to path A3. The inductance value of the coil L1 and the capacitance value of the capacitor C1 are appropriately determined according to the target resonance frequency (that is, according to the frequency of the AC component that is not desired to be extracted).

However, since the DC component also flows through the path A3 in the resonant circuit 5a alone, the arc detection circuit 10a further includes a capacitor C2 connected in series with the resonant circuit 5a in the path A3. Thereby, it is possible to extract a signal of an AC component other than the AC component corresponding to the resonance frequency of the resonance circuit 5a.

Note that the arc detection circuit 10 a may also be provided in the power conditioner 51 as a part of the configuration of the power conditioner 51 in the same manner as the arc detection circuit 10 .

As described above, arc detection circuit 10 according to the present embodiment connects a DC power supply (solar panel 31) that generates DC power and power converter 50 that converts DC power to AC power. A circuit for detecting an arc occurring on path A. The arc detection circuit 10 includes a positive transmission line A1 that connects the positive side of the DC power supply in the transmission line A and the power converter 50, and the negative side of the DC power supply in the transmission line A and the power converter 50. is arranged so as to be connected in parallel with the power conversion device 50 on the path A3 connecting the negative side transmission line A2 that connects the A resonance circuit 5 is provided for flowing the current. The arc detection circuit 10 is connected in series with the resonance circuit 5 on a path A3, receives a resistor R1 that generates a voltage signal corresponding to an AC component signal, and receives the voltage signal generated by the resistor R1 to detect an arc. and an arc determination unit 11 that determines arc generation based on the signal that has passed through the filter unit 12 .

According to this, the DC power can be supplied from the transmission line A to the power conversion device 50 without being affected by the resonance circuit 5 in normal times when no arc is generated. Then, when an arc occurs, the resonance circuit 5 can extract only the arc (AC component) from the transmission line A and allow it to flow through the path A3. That is, the arc determination unit 11 can detect arc generation without being affected by the DC component, and can accurately detect the arc generated in the transmission line A. Also, since the arc detection circuit 10 uses a resistor R1 that is smaller than a CT (Current Trans) or the like, the arc detection circuit 10 can be miniaturized. In addition, since a large DC component does not easily flow through the resistor R1 connected in series with the resonance circuit 5, a resistor with a low withstand voltage can be used as the resistor R1, and the arc detection circuit 10 can be further miniaturized.

Specifically, the resonant circuit 5 may be composed of a coil L1 and a capacitor L1. More specifically, the resonance circuit 5 may be a series resonance circuit in which a coil L1 and a capacitor C1 are connected in series. Further, as in the modification, the resonance circuit 5a may be a parallel resonance circuit in which the coil L1 and the capacitor C1 are connected in parallel, and the arc detection circuit 10a further includes a parallel resonance circuit (resonance There may be a capacitor C2 connected in series with the circuit 5a).

With such a circuit configuration, the resonance circuits 5 and 5a can be realized.

(Embodiment 2)
Embodiment 2 describes an application example of the arc detection circuits 10 and 10a.

FIG. 4 is a diagram for explaining application examples of the arc detection circuits 10 and 10a according to the first embodiment and its modification.

As described above, the arc detection circuits 10 and 10a, for example, convert DC power supplied from the solar panel 31 through the transmission line A into AC power by the power conditioner (power conditioner) 51 configured by the power conversion device 50. Applies to systems that convert to electrical 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 51 .

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 51 instead of being provided for each string 60 .

The solar panel 31 has, for example, a solar panel attachment 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 circuits 10, 10a. In this case, the transmission line A 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 in which the arc has occurred. 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.

Further, for example, the power conditioner 51 may include the arc detection circuits 10 and 10a as described with reference to FIG. In this case, a circuit in which the resonance circuit 5 and the resistor R1 are connected in series on the path A3 in the inverter 51 is connected in parallel with the power converter 50 . Also, the transmission line A becomes a transmission line connected to the power conditioner 51, and the power conditioner 51 can be stopped in response to the occurrence of an arc. For example, the power conditioner 51 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 circuits 10 and 10a. In this case, the transmission line A 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 circuits 10, 10a. In this case, the transmission line A 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, for example. 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 circuits 10 and 10a are not limited to the above system, and can be applied to any system that requires detection of arc generation.

Thus, the breaker 41 may include arc detection circuits 10, 10a. The power conditioner 51 may also include arc detection circuits 10 and 10a. Moreover, the solar panel 31 may be provided with the arc detection circuits 10 and 10a. Moreover, the solar panel attached module 32 may include the arc detection circuits 10 and 10 a and convert the signal output from the solar panel 31 . Also, the junction box 40 may include the arc detection circuits 10 and 10 a to connect the solar panel 31 and the power conditioner 51 .

(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.

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

Further, for example, in the above embodiments, the resonance circuits 5 and 5a are LC resonance circuits, but the invention is not limited to this. For example, it may be an RLC resonant circuit that combines resistors, coils and capacitors.

In addition, it can be realized by applying various modifications to each embodiment that a person skilled in the art can think of, or 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.

5, 5a resonance circuit 10, 10a arc detection circuit 11 arc determination unit 12 filter unit 31 solar panel 32 solar panel attached module 40 junction box 41 breaker 50 power converter 51 power conditioner (power conditioner)
C1, C2 Capacitor A Transmission line A1 Positive transmission line A2 Negative transmission line A3 Path R1 Resistor

Claims (9)

An arc detection circuit for detecting an arc generated in a transmission line connecting a DC power supply that generates DC power and a power conversion device that converts the DC power to AC power,
A positive side transmission line that connects the positive side of the DC power supply and the power conversion device of the transmission line, and a negative side of the transmission line that connects the negative side of the DC power supply and the power conversion device. a resonance circuit that is arranged to be connected in parallel with the power conversion device on a path connecting a transmission line, and that causes a signal of an AC component included in a signal flowing through the transmission line to flow from the transmission line to the path;
a resistor connected in series with the resonant circuit in the path and generating a voltage signal corresponding to the AC component signal;
a filter unit that receives the voltage signal generated in the resistor and passes a signal having a frequency corresponding to the arc;
an arc determination unit that determines the occurrence of an arc based on the signal that has passed through the filter unit;
Arc detection circuit. The resonant circuit is composed of a coil and a capacitor,
The arc detection circuit of Claim 1. The resonant circuit is a series resonant circuit in which the coil and the capacitor are connected in series,
3. The arc detection circuit of claim 2. The resonant circuit is a parallel resonant circuit in which the coil and the capacitor are connected in parallel,
the arc detection circuit further comprising a capacitor connected in series with the parallel resonant circuit in the path;
3. The arc detection circuit of claim 2. 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.

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