JP2021025843A - Ground fault detection system and ground fault detection device - Google Patents

Abstract

To provide a ground fault detection device with which it is possible to specify a point of DC ground fault in a short time.SOLUTION: A ground fault detection device (20) comprises an AC-DC converter ground fault detection unit (23), a collector box ground fault detection unit (24), a connection box ground fault detection unit (25) an a ground fault point specification unit (26). The AC-DC converter ground fault detection unit (23) turns only one of a plurality of primary circuit breakers off in order and determines the presence of a ground fault. The collector box ground fault detection unit (24) turns only one of a plurality of secondary circuit breakers of a collector box off in order that are connected to the primary circuit breaker which was in an off state when determined to be free of ground fault and determines the presence of a ground fault. The connection box ground fault detection unit (25) turns only one of a plurality of tertiary circuit breakers of a connection box off in order that are connected to the secondary circuit breaker that was in an off state when determined to be free of ground fault and determines the presence of a ground fault. The ground fault point specification unit (26) outputs a ground fault point specification signal that indicates the tertiary circuit breaker that was in an off state when determined to be free of ground fault.SELECTED DRAWING: Figure 3

Description

The present invention relates to a ground fault detection system and a ground fault detection device. In particular, the present invention relates to a ground fault detection system and a ground fault detection device suitable for identifying a ground fault location.

A photovoltaic power plant includes a large number of solar cells connected in parallel and a power conditioner (Power Conditioning System (PCS)). A power conditioner is an AC / DC converter that converts DC power generated by a solar cell into AC power. In a photovoltaic power plant, when a poor insulation occurs between a solar cell and a power conditioner due to humidity such as rain, snow, or morning dew, a DC ground fault (hereinafter, simply referred to as a ground fault) is detected. There is.

For example, Patent Document 1 discloses a ground fault detection device. According to the ground fault detection device, it is possible to detect the DC ground fault state of the photovoltaic power generation system.

Japanese Unexamined Patent Publication No. 9-285015

However, the ground fault detecting device of Patent Document 1 cannot specify at which position of a large number of solar cells connected in parallel the ground fault is detected. Therefore, in order to identify the location of the ground fault, it was necessary to manually investigate the power supply circuit between the solar cell and the power conditioner, one circuit at a time. In addition, when the ground fault recovers in a short time due to environmental changes such as temperature rise, it is difficult to identify the ground fault location.

The present invention has been made to solve the above-mentioned problems. An object of the present invention is to provide a ground fault detection system and a ground fault detection device capable of identifying the location of a DC ground fault in a short time.

The ground fault detection system according to the present invention is
An AC / DC converter that has multiple primary switches connected in parallel and converts DC power into AC power.
A plurality of current collector boxes each having a plurality of secondary switches connected to the plurality of primary switches and connected in parallel, and a plurality of current collector boxes.
A plurality of junction boxes each having a plurality of tertiary switches connected to the plurality of secondary switches and connected in parallel, and a plurality of junction boxes.
A plurality of solar cells connected to each of the plurality of tertiary switches and
The AC / DC conversion device, the plurality of current collector boxes, and a ground fault detection device connected to the plurality of junction boxes are provided.
The ground fault detection device is
When the ground voltage at the parallel connection point where the plurality of primary switches are connected in parallel is equal to or less than the threshold voltage, it is determined that there is a ground fault, and when the ground voltage is higher than the threshold voltage, it is determined that there is no ground fault. Ground fault judgment unit and
The AC / DC converter ground fault detection unit that turns off only one of the plurality of primary switches in order, determines the presence or absence of a ground fault by the ground fault determination unit, and returns the plurality of primary switches to the on state. When,
When the AC / DC converter ground fault detection unit determines that there is no ground fault, only one of the plurality of secondary switches of the current collector box connected to the primary switch in the off state is turned off in order. , The current collector box ground fault detection unit that determines the presence or absence of a ground fault by the ground fault determination unit and returns the plurality of secondary switches to the ON state.
When the current collector box ground fault detection unit determines that there is no ground fault, only one of the plurality of tertiary switches of the junction box connected to the secondary switch in the off state is turned off in order. A junction box ground fault detection unit that determines the presence or absence of a ground fault by the ground fault determination unit,
It is characterized by including a ground fault location identification unit that outputs a ground fault location identification signal indicating the tertiary switch in an off state when the junction box ground fault detection unit determines that there is no ground fault.

Further, the ground fault detection device according to the present invention is
An AC / DC converter that has multiple primary switches connected in parallel and converts DC power into AC power.
A plurality of current collector boxes each having a plurality of secondary switches connected to the plurality of primary switches and connected in parallel, and a plurality of current collector boxes.
A plurality of junction boxes each having a plurality of tertiary switches connected to the plurality of secondary switches and connected in parallel, and the plurality of tertiary switches being connected to a plurality of solar cells, respectively. A ground fault detector to be connected
When the ground voltage at the parallel connection point where the plurality of primary switches are connected in parallel is equal to or less than the threshold voltage, it is determined that there is a ground fault, and when the ground voltage is higher than the threshold voltage, it is determined that there is no ground fault. Ground fault judgment unit and
The AC / DC converter ground fault detection unit that turns off only one of the plurality of primary switches in order, determines the presence or absence of a ground fault by the ground fault determination unit, and returns the plurality of primary switches to the on state. When,
When the AC / DC converter ground fault detection unit determines that there is no ground fault, only one of the plurality of secondary switches of the current collector box connected to the primary switch in the off state is turned off in order. , The current collector box ground fault detection unit that determines the presence or absence of a ground fault by the ground fault determination unit and returns the plurality of secondary switches to the ON state.
When the current collector box ground fault detection unit determines that there is no ground fault, only one of the plurality of tertiary switches of the junction box connected to the secondary switch in the off state is turned off in order. A junction box ground fault detection unit that determines the presence or absence of a ground fault by the ground fault determination unit,
It is characterized by including a ground fault location identification unit that outputs a ground fault location identification signal indicating the tertiary switch in an off state when the junction box ground fault detection unit determines that there is no ground fault.

According to these inventions, it is possible to identify in a short time at which part of a large number of solar cells connected in parallel a DC ground fault is detected. It is also possible to avoid the occurrence of major troubles in advance and ensure safety by disconnecting the location where the DC ground fault has occurred. Further, as compared with human work, not only the time required to identify the DC ground fault location but also the work cost can be reduced.

It is a figure for demonstrating the whole structure of the ground fault detection system in Embodiment 1 of this invention. It is a figure for demonstrating the circuit structure of the ground fault detection system in Embodiment 1 of this invention. It is a block diagram of the ground fault detection device in Embodiment 1 of this invention. It is a flowchart which shows the flow of the ground fault location identification processing in Embodiment 1 of this invention. It is a flowchart which shows the flow of the ground fault location identification processing in Embodiment 1 of this invention. It is a flowchart which shows the flow of the ground fault location identification processing in Embodiment 1 of this invention.

A mode for carrying out the present invention will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are designated by the same reference numerals. The duplicate description of the relevant part will be simplified or omitted as appropriate.

Embodiment 1.
(System configuration)
FIG. 1 is a diagram for explaining the overall configuration of the ground fault detection system according to the first embodiment of the present invention. FIG. 2 is a diagram for explaining the circuit configuration of the ground fault detection system according to the first embodiment of the present invention. As shown in FIG. 1, the ground fault detection system identifies a DC ground fault that has occurred at one location between the solar cell and the junction box.

The ground fault detection system 1 includes a power conditioner 10, a plurality of current collector boxes, a plurality of junction boxes, a plurality of solar cells, and a ground fault detection device 20. In the examples of FIGS. 1 and 2, the ground fault detection system 1 includes three current collector boxes (11, 12, 13). The ground fault detection system 1 includes nine junction boxes (111, 112, 113, 121, 122, 123, 131, 132, 133).

The power conditioner 10 is an AC / DC conversion device that converts DC power generated by a solar cell into AC power. The power conditioner 10 includes an inverter 10e and a plurality of primary switches (10a, 10b, 10c). A plurality of primary switches (10a, 10b, 10c) are connected in parallel. Each primary switch receives an open signal from the ground fault detection device 20 and turns on, and receives a close signal and turns off.

Specifically, one end of the primary switch 10a is connected to the current collector box 11. One end of the primary switch 10b is connected to the current collector box 12. One end of the primary switch 10c is connected to the current collector box 13. The other ends of the three primary switches (10a, 10b, 10c) are connected in parallel and connected to the DC side of the inverter 10e.

The plurality of current collector boxes (11, 12, 13) are connected to the plurality of primary switches (10a, 10b, 10c), respectively. Each of the plurality of current collector boxes (11, 12, 13) has a plurality of secondary switches. A plurality of secondary switches are connected in parallel. Each secondary switch receives an open signal from the ground fault detection device 20 and turns on, and receives a close signal and turns off.

In the example shown in FIG. 1, each current collector box (11, 12, 13) has three secondary switches. The current collector box 11 has three secondary switches (11a, 11b, 11c). The current collector box 12 has three secondary switches (12a, 12b, 12c). The current collector box 13 has three secondary switches (13a, 13b, 13c).

As an example, the configuration of the current collector box 11 will be specifically described. One end of the secondary switch 11a is connected to the junction box 111. One end of the secondary switch 11b is connected to the junction box 112. One end of the secondary switch 11c is connected to the junction box 113. The other ends of the three secondary switches (11a, 11b, 11c) are connected in parallel and connected to the primary switch 10a. Since the configurations of the current collector box 12 and the current collector box 13 are the same as the configurations of the current collector box 11 as shown in FIG. 2, the description thereof will be omitted.

The plurality of junction boxes (111, 112, 113, 121, 122, 123, 131, 132, 133) have a plurality of secondary switches (11a, 11b, 11c, 12a, 12b, 12c, 13a, 13b, 13c). Connect to each. The plurality of junction boxes (111, 112, 113, 121, 122, 123, 131, 132, 133) each have a plurality of tertiary switches. A plurality of tertiary switches are connected in parallel. In the example shown in FIG. 1, each junction box (111, 112, 113, 121, 122, 123, 131, 132, 133) has three tertiary switches. Each tertiary switch receives an open signal from the ground fault detection device 20 and turns on, and receives a close signal and turns off.

As an example, the configuration of the junction box 111 will be specifically described. The junction box 111 has three tertiary switches (111a, 111b, 111c). One end of the tertiary switch 111a is connected to the solar cell 111d. One end of the tertiary switch 111b is connected to the solar cell 111e. One end of the tertiary switch 111c is connected to the solar cell 111f. The other ends of the three tertiary switches (111a, 111b, 111c) are connected in parallel and connected to the secondary switch 11a. Since the configuration of the junction box (112, 113, 121, 122, 123, 131, 132, 133) is the same as that of the junction box 111 as shown in FIG. 2, the description thereof will be omitted.

A plurality of solar cells (111d, 111e, 111f, ..., 133d, 133e, 133f) are connected to a plurality of tertiary switches (111a, 111b, 111c, ..., 133a, 133b, 133c), respectively. .. In the present specification, the solar cell is a string in which a plurality of solar cell modules are wired in series.

(Ground fault detector)
Next, the function of the ground fault detection device 20 will be described with reference to FIGS. 1 and 3. FIG. 3 is a block diagram of the ground fault detection device 20 according to the first embodiment of the present invention. Further, in FIG. 1, as an example of a DC ground fault, an abnormal circuit in which a DC ground fault has occurred between the solar cell 121e and the tertiary switch 121b of the junction box 121 is drawn.

The ground fault detection device 20 is connected to the power conditioner 10, a plurality of current collector boxes (11, 12, 13), and a plurality of junction boxes (112, 113, 121, 122, 123, 131, 132, 133). .. In addition, the ground fault detection device 20 can individually transmit an open signal or a close signal to each switch.

The ground fault detection device 20 includes a ground voltage measurement unit 21, a ground fault determination unit 22, an AC / DC conversion device ground fault detection unit 23, a current collector box ground fault detection unit 24, a connection box ground fault detection unit 25, and a ground fault location identification unit. 26, a ground fault location cutting portion 27 is provided.

The ground voltage measuring unit 21 measures the ground voltage between the parallel connection point 10d in which a plurality of primary switches (10a, 10b, 10c) are connected in parallel and the reference potential point (grounding point or grounding side electric wire). ..

The ground fault determination unit 22 determines that there is a ground fault when the ground voltage with respect to the parallel connection point 10d is equal to or less than the threshold voltage. Further, the ground fault determination unit 22 determines that there is no ground fault when the ground voltage at the parallel connection point 10d is higher than the threshold voltage. Since all the solar cells are connected in parallel, the threshold voltage may be a fixed value regardless of the increase or decrease of the solar cells.

The AC / DC converter ground fault detection unit 23 turns off only one of the plurality of primary switches (10a, 10b, 10c) in order, and the ground fault determination unit 22 determines the presence or absence of a ground fault. After that, the AC / DC converter ground fault detection unit 23 returns the plurality of primary switches (10a, 10b, 10c) to the ON state.

The current collector box ground fault detection unit 24 is connected to the current collector box (10b in the example of FIG. 1) in the off state when the AC / DC converter ground fault detection unit 23 determines that there is no ground fault. In the example of FIG. 1, only one of the plurality of secondary switches (12a, 12b, 12c in the example of FIG. 1) of 12) is turned off in order, and the ground fault determination unit 22 determines the presence or absence of a ground fault. After that, the current collector box ground fault detection unit 24 returns the plurality of secondary switches (12a, 12b, 12c in the example of FIG. 1) to the ON state.

The junction box ground fault detection unit 25 is connected to the secondary switch (12a in the example of FIG. 1) in the off state when the current collector box ground fault detection unit 24 determines that there is no ground fault (FIG. 1). In the example of 121), only one of the plurality of tertiary switches (121a, 121b, 121c in the example of FIG. 1) is turned off in order, and the ground fault determination unit 22 determines the presence or absence of a ground fault. After that, the junction box ground fault detection unit 25 returns the plurality of tertiary switches (121a, 121b, 121c in the example of FIG. 1) to the ON state.

The ground fault location identification unit 26 outputs a ground fault location identification signal indicating a tertiary switch (121b in the example of FIG. 1) in the off state when the junction box ground fault detection unit 25 determines that there is no ground fault. ..

The ground fault location separation portion 27 outputs an open signal that turns off the tertiary switch (121b in the example of FIG. 1) in response to the ground fault location identification signal. The tertiary switch that receives the open signal is turned off.

(Flow of ground fault location identification process)
Next, with reference to FIGS. 4 to 6, a routine for ground fault location identification processing executed by the ground fault detection device 20 will be described. This routine is executed when the ground fault detection device 20 is operated by an operator or when the ground fault detection device 20 receives a ground fault location identification command from the outside. Further, as a specific example of the ground fault location identification process, a case where a ground fault occurs between the solar cell 121e shown in FIG. 1 and the tertiary switch 121b of the junction box 121 will be described together.

First, in step S100, the ground fault detection device 20 turns on all the switches.

In step S101, the ground voltage measuring unit 21 measures the ground voltage with all switches turned on.

In step S102, the ground fault determination unit 22 determines that there is a ground fault when the ground voltage is equal to or less than the threshold voltage, and determines that there is no ground fault when the ground voltage is higher than the threshold voltage. When it is determined that there is a ground fault, the ground fault detection device 20 executes the processes after step S103 in order to identify the ground fault location. On the other hand, when it is determined that there is no ground fault, no ground fault has occurred between any of the solar cells and the power conditioner 10, so the ground fault detection device 20 ends this routine.

In step S103, the AC / DC converter ground fault detection unit 23 substitutes 1 for the variable i.

In step S104, the AC / DC converter ground fault detection unit 23 turns off only the i-th primary switch. For example, when i = 1, the AC / DC converter ground fault detection unit 23 turns 10a, which is the first primary switch, off, and 10b and 10c on.

In step S105, the ground voltage measuring unit 21 measures the ground voltage.

In step S106, the AC / DC conversion device ground fault detection unit 23 detects the presence or absence of a ground fault by the ground fault determination unit 22. The ground fault determination unit 22 determines that there is a ground fault when the ground voltage is equal to or less than the threshold voltage, and determines that there is no ground fault when the ground voltage is higher than the threshold voltage. When it is determined that there is a ground fault, there is a normal circuit between the i-th primary switch turned off and the solar cell connected to the primary switch. In this case, it is suspected that an abnormality has occurred in the circuit connected to the other primary switch. Therefore, the AC / DC converter ground fault detection unit 23 executes the processes after step S107 in order to identify which of the other primary switches is connected to the abnormal circuit. On the other hand, when it is determined that there is no ground fault, an abnormality has occurred between the i-th primary switch turned off and the solar cell connected to the primary switch. In this case, the AC / DC converter ground fault detection unit 23 executes the process of step S109.

In step S107, the AC / DC converter ground fault detection unit 23 turns on the i-th primary switch. As a result, all the primary switches are turned on.

Next, in step S108, the AC / DC converter ground fault detection unit 23 increments the variable i by 1. As a result, in the subsequent processing in step S104 and subsequent steps, the processing can proceed using the incremented variable i. Specifically, when i = 2 by the process of step S108, the presence or absence of a ground fault can be determined by turning off only the second primary switch 10b in the following steps S104 to S106.

In the example of FIG. 1, when i = 2, that is, when only the second primary switch 10b is turned off, it is determined in step S106 that there is no ground fault. As a result, it is detected that a ground fault has occurred between the primary switch 10b and the solar cells (121d, 121e, 121f, ..., 123d, 123e, 123f) connected to the primary switch 10b.

If it is determined in step S106 that there is no ground fault, then in step S109, the i-th primary switch (10b in the example of FIG. 1) is turned on. As a result, all the primary switches are turned on. In order to further narrow down the ground fault location, the process proceeds to the process after step S110 in FIG.

With reference to FIG. 5, the narrowing down of the ground fault location by the current collector box ground fault detection unit 24 will be described.

In step S110, the current collector box ground fault detection unit 24 substitutes 1 for the variable j.

In step S111, the current collector box ground fault detection unit 24 is connected to the primary switch (10b in the example of FIG. 1) in the off state when the AC / DC converter ground fault detection unit 23 determines that there is no ground fault. Only the j-th secondary switch of the current collector box (12 in the example of FIG. 1) is turned off. For example, when j = 1, the current collector box ground fault detection unit 24 turns 12a, which is the first secondary switch of the current collector box 12, in the off state, and 12b and 12c in the on state.

In step S112, the ground voltage measuring unit 21 measures the ground voltage.

In step S113, the current collector box ground fault detection unit 24 detects the presence or absence of a ground fault by the ground fault determination unit 22. The ground fault determination unit 22 determines that there is a ground fault when the ground voltage is equal to or less than the threshold voltage, and determines that there is no ground fault when the ground voltage is higher than the threshold voltage. When it is determined that there is a ground fault, there is a normal circuit between the j-th secondary switch turned off and the solar cell connected to the secondary switch. In this case, it is suspected that an abnormality has occurred in the circuit connected to the other secondary switch. Therefore, the current collector box ground fault detection unit 24 executes the processes after step S114 in order to identify which of the other secondary switches is connected to the abnormal circuit. On the other hand, when it is determined that there is no ground fault, an abnormality has occurred between the j-th secondary switch turned off and the solar cell connected to the secondary switch. In this case, the current collector box ground fault detection unit 24 executes the process of step S116.

In step S114, the current collector box ground fault detection unit 24 turns on the j-th secondary switch. As a result, all secondary switches are turned on.

Next, in step S115, the current collector box ground fault detection unit 24 increments the variable j by 1. As a result, in the subsequent processing in step S111 and subsequent steps, the processing can proceed using the incremented variable j. Specifically, when j = 2 is obtained by the process of step S115, the presence or absence of a ground fault can be determined by turning off only the second secondary switch 12b in the following steps S111 to S113.

In the example of FIG. 1, when j = 1, that is, when only the first secondary switch 12a is turned off, it is determined in step S113 that there is no ground fault. As a result, it is detected that a ground fault has occurred between the secondary switch 12a and the solar cells (121d, 121e, 121f) connected to the secondary switch 12a.

If it is determined in step S113 that there is no ground fault, then in step S116, the j-th secondary switch (12a in the example of FIG. 1) is turned on. As a result, all secondary switches are turned on. In order to further narrow down the ground fault location, the process proceeds to the process after step S117 in FIG.

With reference to FIG. 6, the narrowing down of the ground fault location by the junction box ground fault detection unit 25 will be described.

In step S117, the junction box ground fault detection unit 25 substitutes 1 for the variable k.

In step S118, the connection box ground fault detection unit 25 is connected to the secondary switch (12a in the example of FIG. 1) in the off state when the current collector box ground fault detection unit 24 determines that there is no ground fault. Only the kth tertiary switch of the box (121 in the example of FIG. 1) is turned off. For example, when k = 1, the junction box ground fault detection unit 25 turns 121a, which is the first tertiary switch of the junction box 121, in the off state, and 121b and 121c in the on state.

In step S119, the ground voltage measuring unit 21 measures the ground voltage.

In step S120, the junction box ground fault detection unit 25 detects the presence or absence of a ground fault by the ground fault determination unit 22. The ground fault determination unit 22 determines that there is a ground fault when the ground voltage is equal to or less than the threshold voltage, and determines that there is no ground fault when the ground voltage is higher than the threshold voltage. When it is determined that there is a ground fault, there is a normal circuit between the k-th tertiary switch turned off and the solar cell connected to the third switch. In this case, it is suspected that an abnormality has occurred in the circuit connected to the other tertiary switch. Therefore, the junction box ground fault detection unit 25 executes the processes after step S121 in order to identify which of the other tertiary switches is connected to the abnormal circuit. On the other hand, when it is determined that there is no ground fault, an abnormality has occurred between the k-th tertiary switch turned off and the solar cell connected to the third switch. In this case, the junction box ground fault detection unit 25 executes the process of step S123.

In step S121, the junction box ground fault detection unit 25 turns on the kth tertiary switch. As a result, all tertiary switches are turned on.

In step S122, the junction box ground fault detection unit 25 increments the variable k by 1. As a result, in the subsequent processing in step S118 and subsequent steps, the processing can proceed using the incremented variable k. Specifically, when k = 2 by the process of step S122, the presence or absence of a ground fault can be determined by turning off only the second tertiary switch 121b in the following steps S118 to S120.

In the example of FIG. 1, when k = 2, that is, when only the second tertiary switch 121b is turned off, it is determined in step S120 that there is no ground fault. As a result, it is detected that a ground fault has occurred between the tertiary switch 121b and the solar cell 121e connected to the tertiary switch 121b.

If it is determined in step S120 that there is no ground fault, then in step S123, the kth tertiary switch (121b in the example of FIG. 1) is turned on. As a result, all secondary switches are turned on.

Next, in step S124, the ground fault location identification unit 26 outputs a ground fault location identification signal indicating the tertiary switch (121b in the example of FIG. 1) in the off state when it is determined in step S120 that there is no ground fault. To do. In another routine, the ground fault detection device 20, the power conditioner 10, or the host computer (not shown) receives the ground fault location identification signal, notifies the ground fault location by voice or display, or notifies the ground fault location. Store in the storage unit.

In step S125, the ground fault location separating portion 27 outputs an open signal that turns off the tertiary switch (121b in the example of FIG. 1) in response to the ground fault location identification signal. The tertiary switch (121b in the example of FIG. 1) that received the open signal is turned off, and the solar cell (121e in the example of FIG. 1) is disconnected.

As described above, according to the ground fault detection system 1 and the ground fault detection device 20 according to the present embodiment, each power supply device configured between the solar cell and the power conditioner 10 is automatically remotely controlled and measured. Monitor. According to this, it is possible to automatically identify in a short time at which part of a large number of solar cells connected in parallel a DC ground fault is detected. It is also possible to avoid the occurrence of major troubles in advance and ensure safety by disconnecting the location where the DC ground fault has occurred. Further, as compared with human work, not only the time required to identify the DC ground fault location but also the work cost can be reduced.

By the way, in the system of the first embodiment described above, the ground fault detection device 20 is arranged outside the power conditioner 10, but is not limited to this. The ground fault detection device 20 may be mounted on the power conditioner 10.

Further, in the system of the first embodiment described above, each switch is arranged on the P line, but the present invention is not limited to this. Each switch may be arranged on the N line. In this case, the ground fault detection device 20 is connected to the N line.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be variously modified and implemented without departing from the spirit of the present invention.

1 Ground fault detection system 10 Power conditioners 10a, 10b, 10c Primary switch 10d Parallel connection point 10e Inverters 11, 12, 13 Current collector boxes 11a, 11b, 11c Secondary switches 12a, 12b of the current collector box 11 , 12c Secondary switch 13a, 13b, 13c of the current collector box 12 Secondary switch of the current collector box 13 20 Ground fault detection device 21 Ground voltage measurement unit 22 Ground fault determination unit 23 AC / DC converter Ground fault detection unit 24 Current collecting box Ground fault detection unit 25 Connection box Ground fault detection unit 26 Ground fault location identification unit 27 Ground fault location separation unit 111, 112, 113, 121, 122, 123, 131, 132, 133 Connection box 111a, 111b , 111c The tertiary switch 112a, 112b, 112c of the junction box 111 The tertiary switch 113a, 113b, 113c of the junction box 112 The tertiary switch 121a, 121b, 121c of the junction box 113 has 3 Secondary switches 122a, 122b, 122c Secondary switches 123a, 123b, 123c included in the junction box 122 Tertiary switches 131a, 131b, 131c included in the junction box 123 Tertiary switches 132a, 132b, 132c included in the junction box 131 Tertiary switches 133a, 133b, 133c included in the junction box 132 Tertiary switches 111d, 111e, 111f, 112d, 112e, 112f, 113d, 113e, 113f, 121d, 121e, 121f, 122d, 122e included in the junction box 133 , 122f, 123d, 123e, 123f, 131d, 131e, 131f, 132d, 132e, 132f, 133d, 133e, 133f Solar cell

Claims (4)

An AC / DC converter that has multiple primary switches connected in parallel and converts DC power into AC power.
A plurality of current collector boxes each having a plurality of secondary switches connected to the plurality of primary switches and connected in parallel, and a plurality of current collector boxes.
A plurality of junction boxes each having a plurality of tertiary switches connected to the plurality of secondary switches and connected in parallel, and a plurality of junction boxes.
A plurality of solar cells connected to each of the plurality of tertiary switches and
The AC / DC conversion device, the plurality of current collector boxes, and a ground fault detection device connected to the plurality of junction boxes are provided.
The ground fault detection device is
When the ground voltage at the parallel connection point where the plurality of primary switches are connected in parallel is equal to or less than the threshold voltage, it is determined that there is a ground fault, and when the ground voltage is higher than the threshold voltage, it is determined that there is no ground fault. Ground fault judgment unit and
The AC / DC converter ground fault detection unit that turns off only one of the plurality of primary switches in order, determines the presence or absence of a ground fault by the ground fault determination unit, and returns the plurality of primary switches to the on state. When,
When the AC / DC converter ground fault detection unit determines that there is no ground fault, only one of the plurality of secondary switches of the current collector box connected to the primary switch in the off state is turned off in order. , The current collector box ground fault detection unit that determines the presence or absence of a ground fault by the ground fault determination unit and returns the plurality of secondary switches to the ON state.
When the current collector box ground fault detection unit determines that there is no ground fault, only one of the plurality of tertiary switches of the junction box connected to the secondary switch in the off state is turned off in order. A junction box ground fault detection unit that determines the presence or absence of a ground fault by the ground fault determination unit,
A ground fault location identification unit that outputs a ground fault location identification signal indicating the tertiary switch in the off state when the junction box ground fault detection unit determines that there is no ground fault.
A ground fault detection system characterized by being equipped with. The ground fault detection system according to claim 1, further comprising a ground fault location separation portion that turns off the tertiary switch in response to the ground fault location identification signal. An AC / DC converter that has multiple primary switches connected in parallel and converts DC power into AC power.
A plurality of current collector boxes each having a plurality of secondary switches connected to the plurality of primary switches and connected in parallel, and a plurality of current collector boxes.
A plurality of junction boxes each having a plurality of tertiary switches connected to the plurality of secondary switches and connected in parallel, and the plurality of tertiary switches being connected to a plurality of solar cells, respectively. A ground fault detector to be connected
When the ground voltage at the parallel connection point where the plurality of primary switches are connected in parallel is equal to or less than the threshold voltage, it is determined that there is a ground fault, and when the ground voltage is higher than the threshold voltage, it is determined that there is no ground fault. Ground fault judgment unit and
The AC / DC converter ground fault detection unit that turns off only one of the plurality of primary switches in order, determines the presence or absence of a ground fault by the ground fault determination unit, and returns the plurality of primary switches to the on state. When,
When the AC / DC converter ground fault detection unit determines that there is no ground fault, only one of the plurality of secondary switches of the current collector box connected to the primary switch in the off state is turned off in order. , The current collector box ground fault detection unit that determines the presence or absence of a ground fault by the ground fault determination unit and returns the plurality of secondary switches to the ON state.
When the current collector box ground fault detection unit determines that there is no ground fault, only one of the plurality of tertiary switches of the junction box connected to the secondary switch in the off state is turned off in order. A junction box ground fault detection unit that determines the presence or absence of a ground fault by the ground fault determination unit,
A ground fault location identification unit that outputs a ground fault location identification signal indicating the tertiary switch in the off state when the junction box ground fault detection unit determines that there is no ground fault.
A ground fault detection device characterized by being provided with. The ground fault detecting device according to claim 3, further comprising a ground fault location separating portion that turns off the tertiary switch in response to the ground fault location identification signal.

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