Power conditioner system

Abstract

A power conditioner system includes: a power conditioner that converts DC power output from a string into AC power; and an arc detection device that detects generation of an arc in an electric path connecting the string and the power conditioner. The arc detection device includes a current sensor, an arc determination unit, a recording unit, and a communication unit. The current sensor detects a current flowing through the electric path. The arc determination unit outputs a first control signal for switching an opening / closing device from the closed state to the open state when it is determined that the arc has been generated. The recording unit records the data used by the arc determination unit to determine the generation of the arc. The communication unit transmits the determination result and the determination data of the arc determination unit when the arc determination unit determines that the arc has been generated.

Description

Power Conditioner System

[0001] The present invention relates to a power conditioner system.

[0002] A power conditioner system equipped with an arc detection device has been known. When the arc detection device determines that an arc is occurring, it activates a breaker via a breaker control unit, thereby interrupting the electrical path connecting the solar cell module and the power conditioner.

[0003] Patent No. 7117630

[0004] In a conventional power conditioner system, when a circuit connecting a solar cell module and a power conditioner is interrupted by a breaker, the cause must be identified at the site where the arc detection device is installed, and the administrator of the power conditioner system cannot verify the details of the arc detection event at a location away from the site where the arc detection device is installed. In other words, it is difficult for the administrator of the power conditioner system to immediately grasp the urgency and situation of the event at the site where the arc detection device is installed.

[0005] An object of the present invention is to provide a power conditioner system that makes it possible to verify the details of an event in which an arc is detected by an arc detection device at a location away from the site where the arc detection device is installed.

[0006] A power conditioner system according to one aspect of the present invention is a power conditioner system for outputting power output from at least one string including a plurality of solar cell modules to a load or a power grid. The power conditioner system includes a power conditioner, an arc detection device, and a switching device. The power conditioner converts DC power output from the at least one string into AC power. The arc detection device detects the occurrence of an arc in an electric circuit connecting the at least one string and the power conditioner. The switching device includes a switching unit and opens and closes the electric circuit. The at least one arc detection device includes a current sensor, an arc determination unit, a recording unit, and a communication unit. The current sensor detects a current flowing in the electric circuit. The arc determination unit determines the occurrence of an arc based on the detection result of the current sensor, and outputs a first control signal for switching the switching unit from a closed state to an open state when it determines that an arc has occurred. The recording unit records determination data used by the arc determination unit to determine the occurrence of an arc. The communication unit transmits the determination result and the determination data of the arc determination unit when the arc determination unit determines that an arc has occurred.

[0007] In this power conditioner system, the determination result of the arc determination unit and the determination data used by the arc determination unit to determine the occurrence of an arc are transmitted by the communication unit. As a result, for example, an administrator of the power conditioner system can receive the data transmitted from the communication unit and verify the details of the event in which the arc detection device detected an arc at a location away from the site where the arc detection device is installed.

[0008] The opening and closing device may further include a control unit that controls the opening and closing unit. The control unit may be capable of receiving a second control signal output from an external device for switching the opening and closing unit from an open state to a closed state. In this case, for example, if an administrator examines the details of an event in which an arc is detected by the arc detection device and determines that the arc detection device is malfunctioning, the administrator can operate the external device to send the second control signal to the control unit, thereby restoring the opening and closing device.

[0009] The switching device may include a holding circuit for holding the switching unit in an open state. In this case, when the switching unit is switched from a closed state to an open state as determined by the arc determination unit, the open state of the switching unit can be held by the holding circuit.

[0010] The power conditioner may convert DC power output from a plurality of strings including a first string and a second string into AC power. The at least one arc detection device may include a first arc detection device that detects an arc occurrence in an electric circuit connecting the first string and the power conditioner, and a second arc detection device that detects an arc occurrence in a second electric circuit connecting the second string and the power conditioner. In this case, it is possible to shut off only the string in which an arc is detected, thereby reducing downtime of the power conditioner.

[0011] The determination result of the arc determination unit of the second arc detection device and the determination data recorded by the recording unit of the second arc detection device may be output via the communication unit of the first arc detection device. In this case, the communication line with the external device can be unified using the communication unit of the first arc detection device.

[0012] The current sensor of at least one arc detection device may also serve as a current sensor for detecting the output current of the power conditioner, which can reduce the cost of the power conditioner system.

[0013] According to the present invention, it is possible to provide a power conditioner system that makes it possible to verify the details of an event in which an arc is detected by an arc detection device at a location away from the site where the arc detection device is installed.

[0014] It is a block diagram showing typically the configuration of a power conditioner system. It is a block diagram showing typically the configuration of a first arc detection device. It is a block diagram showing typically the configuration of a first switching device. It is a block diagram showing typically the configuration of a power conditioner system according to another embodiment.

[0015] Hereinafter, a power conditioner system 1 according to an embodiment will be described with reference to the drawings. Fig. 1 is a block diagram schematically showing the configuration of the power conditioner system 1. The power conditioner system 1 is a system for outputting power output from at least one string including a plurality of solar cell modules to a load or a power grid.

[0016] The power conditioner system 1 includes a plurality of strings 2 , a power conditioner 3 , an arc detection device 4 , and a switching device 5 .

[0017] Each of the multiple strings 2 includes multiple solar cell modules connected in series. Each solar cell module includes multiple solar cell cells (not shown) connected in series. The multiple strings 2 form a solar cell array 10. The multiple strings 2 are connected to a power conditioner 3 via a junction box 13. In this embodiment, the multiple strings 2 include first to fourth strings 2a to 2d.

[0018] The power conditioner 3 converts DC power output from the plurality of strings 2 into AC power and outputs the AC power. The power conditioner 3 is connected to a load and a power grid 8 (not shown).

[0019] The power conditioner 3 has a conventional configuration and includes circuits (not shown) such as a converter circuit, an inverter circuit, and a charge / discharge circuit. The power conditioner 3 also includes a linked operation circuit that controls connection with the power grid 8, and an independent operation circuit that supplies the AC voltage generated by the inverter circuit to a load when, for example, the power grid 8 experiences a power outage.

[0020] The arc detector 4 detects the occurrence of an arc in an electric path connecting the plurality of strings 2 and the power conditioner 3. In this embodiment, the arc detector 4 is disposed in the output path of each of the strings 2a to 2d. That is, in this embodiment, the arc detector 4 includes first to fourth arc detectors 4a to 4d. The arc detector 4 is disposed in the connection box 13.

[0021] 2 is a block diagram illustrating a configuration of the first arc detector 4a. The first arc detector 4a detects the occurrence of an arc in the first electrical circuit 30a connecting the first string 2a and the power conditioner 3.

[0022] The first arc detection device 4 a includes a current sensor 21 , an amplifier 22 , a filter 23 , an A / D conversion unit 24 , an arc determination unit 25 , a recording unit 26 , and a communication unit 27 .

[0023] The current sensor 21 detects the current flowing through the first electrical circuit 30a connecting the first string 2a and the power conditioner 3. The amplifier 22 amplifies the current detected by the current sensor 21. The filter 23 is a bandpass filter (BPF) that passes only current within a predetermined frequency range from the current output from the amplifier 22. For example, the frequency range passed by the filter 23 is 40 kHz to 100 kHz. The A / D converter 24 converts the analog current signal that has passed through the filter 23 into a digital signal and outputs it to the arc determination unit 25.

[0024] The arc determination unit 25 is a functional configuration realized by the CPU, and is realized by the CPU executing a program stored in the ROM, RAM, etc. The arc determination unit 25 determines the occurrence of an arc in the first electric circuit 30a based on the detection result of the current sensor 21, and outputs a first control signal S1 for switching the switching device 5 from a closed state to an open state when it determines that an arc has occurred.

[0025] Arc determination unit 25 performs an FFT on the digital signal output from A / D conversion unit 24 to generate a power spectrum of the current, and uses the generated power spectrum to determine whether an arc has occurred. Note that arc determination unit 25 may also use the frequency spectrum of the current signal obtained by Fourier transforming the time waveform of the current signal output from current sensor 21 to determine whether an arc has occurred.

[0026] The recording unit 26 is a non-volatile memory, such as an EEPROM. The recording unit 26 records determination data related to the determination result of the arc determination unit 25. The determination data is data used by the arc determination unit 25 to determine whether an arc has occurred. The determination data includes data related to the current signal output from the current sensor 21 and data generated based on the current signal. The determination data includes, for example, the arc current value during the period in which it was determined that an arc has occurred, the FFT calculation value, the analysis results of the power spectrum, and data related to the number of times the occurrence of an arc has been detected.

[0027] When the arc determination unit 25 determines that an arc has occurred, the communication unit 27 transmits the determination result of the arc determination unit 25 and the determination data stored in the recording unit 26. The communication unit 27 transmits the determination result of the arc determination unit 25 and the determination data stored in the recording unit 26 to, for example, a management terminal 40 (an example of an external device) that manages the power conditioner system 1. In this case, the communication unit 27 is connected to the management terminal 40 so as to be able to communicate via wired or wireless communication using a serial communication method or the like. The determination result of the arc determination unit 25 and the determination data stored in the recording unit 26 may be transmitted from the communication unit 27 to the management terminal 40 via the power conditioner 3. The communication unit 27 may transmit the determination result of the arc determination unit 25 and the determination data stored in the recording unit to a communication terminal (an example of an external device) used by a user of the power conditioner system 1.

[0028] The second arc detector 4b detects the occurrence of an arc in the second electric circuit 30b connecting the second string 2b and the power conditioner 3. The third arc detector 4c detects the occurrence of an arc in the third electric circuit 30c connecting the third string 2c and the power conditioner 3. The fourth arc detector 4d detects the occurrence of an arc in the fourth electric circuit 30d connecting the fourth string 2d and the power conditioner 3.

[0029] The first to fourth arc detectors 4a to 4d have the same functional configuration except that they detect arcs in different strings, and therefore detailed descriptions of the second to fourth arc detectors 4b to 4d will be omitted.

[0030] The switching devices 5 are arranged in the first to fourth electrical circuits 30a to 30d, respectively. The switching devices 5 are relays or contactors. The switching devices 5 include first to fourth switching devices 5a to 5d.

[0031] 3 is a block diagram illustrating the configuration of the first switching device 5a. The first switching device 5a opens and closes the first electrical circuit 30a. The first switching device 5a includes a switching unit 51 and a control unit 52. The switching unit 51 can be in a closed state in which the first string 2a is connected to the power conditioner 3, or in an open state in which the first string 2a is disconnected from the power conditioner 3.

[0032] The control unit 6 controls the opening / closing unit 51. The control unit 52 is supplied with power from a control power supply 42. The control power supply 42 may be generated from power generated by a solar cell, or may also serve as the control power supply for the power conditioner 3. The control power supply for the power conditioner 3 may be supplied from the power grid 8, or may be generated from power generated by the multiple strings 2. In this embodiment, the arc detection device 4 is supplied with power from the control power supply 42.

[0033] The control unit 52 switches the switching unit 51 from a closed state to an open state in response to a first control signal S1 output from the arc determination unit 25. The control unit 6 is capable of receiving a second control signal S2 for switching the switching unit 51 from an open state to a closed state, which is output from the management terminal 40. The control unit 52 switches the switching unit 51 from an open state to an open state in response to the second control signal S2.

[0034] The first switching device 5a includes a holding circuit 53 for holding the switching unit 51 in an open state. The holding circuit 53 includes a latch relay. The switching unit 51 operates in conjunction with the latch relay. The control unit 52 outputs a signal for switching the latch relay from an on state to an off state in response to a first control signal S1 output from the arc determination unit 25. As a result, the latch relay turns off, switching the switching unit 51 from a closed state to an open state, and the holding circuit 53 holds the switching unit 51 in an open state. The control unit 52 outputs a signal for switching the latch relay from an off state to an on state in response to a second control signal S2. As a result, the latch relay turns on, switching the switching unit 51 from an open state to a closed state.

[0035] The second switching device 5b opens and closes the second electrical circuit 30b. The third switching device 5c opens and closes the third electrical circuit 30c. The fourth switching device 5d opens and closes the fourth electrical circuit 30d. The first to fourth switching devices 5a to 5d have the same functions except that they open and close different electrical circuits. Therefore, detailed descriptions of the second to fourth switching devices 5b to 5d will be omitted.

[0036] In the above-described power conditioner system 1, the determination result of the arc determination unit 25 and the determination data used by the arc determination unit 25 to determine the occurrence of an arc are transmitted by the communication unit 27. As a result, for example, an administrator of the power conditioner system 1 can receive the data transmitted from the communication unit 27 and verify the details of the event in which the arc was detected by the arc detection device 4 (e.g., determine the urgency, etc.) at a location remote from the site where the arc detection device 4 is installed. Furthermore, if the administrator determines that the arc detection device 4 has malfunctioned based on the data transmitted from the communication unit 27, the administrator can restore the switch without going to the site where the arc detection device 4 is installed.

[0037] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0038] The number of strings in the power conditioner system 1 may be one or more. The connection box 13 may be omitted. In this case, the arc detection device 4 and the switchgear 5 may be disposed in the power conditioner 3. In addition, the control power supply 42 and the management terminal 40 may be disposed in the power conditioner 3.

[0039] The arc detection device 4 may be configured to collectively detect the occurrence of arcs in a plurality of strings 2. The switchgear 5 may be configured by a single switchgear including four switchgear units 51, for example.

[0040] The current sensor 21 may also serve as a current sensor that detects the output current of the power conditioner 3 .

[0041] As shown in FIG. 4 , the second arc detection device 4b may be communicatively connected to the first arc detection device 4a via wired or wireless communication using a serial communication system or the like. That is, the communication unit 27 of the second arc detection device 4b may be configured to communicate with the first arc detection device 4a. In this case, the determination result of the arc determination unit 25 of the second arc detection device 4b and the determination data recorded by the recording unit 26 of the second arc detection device 4b may be output via the communication unit 27 of the first arc detection device 4a. The third arc detection device 4c and the fourth arc detection device 4d may also be communicatively connected to the first arc detection device 4a. The first arc detection device 4a functions as a master with respect to the second to fourth arc detection devices 4b to 4d, and the second to fourth arc detection devices 4b to 4d function as slaves with respect to the first arc detection device 4a. That is, the arc detection device 4a may be configured to monitor the second to fourth arc detection devices 4b to 4d.

[0042] 1: Power conditioner system, 2: String, 3: Power conditioner, 4: Arc detection device, 5: Switching device, 21: Current sensor, 25: Arc determination unit, 27: Communication unit, 51: Switching unit, 52: Control unit, 53: Holding circuit

Claims

1. A power conditioner system for outputting power output from at least one string including a plurality of solar cell modules to a load or a power grid, comprising: a power conditioner that converts DC power output from the at least one string into AC power; at least one arc detection device that detects the occurrence of an arc in an electric circuit connecting the at least one string and the power conditioner; and a switching device that includes a switching unit and opens and closes the electric circuit, wherein the at least one arc detection device includes: a current sensor that detects a current flowing in the electric circuit; an arc determination unit that determines the occurrence of an arc based on the detection result of the current sensor, and outputs a first control signal for switching the switching unit from a closed state to an open state when it determines that the arc has occurred; a recording unit that records determination data used by the arc determination unit to determine the occurrence of the arc; and a communication unit that transmits the determination result of the arc determination unit and the determination data when the arc determination unit determines that the arc has occurred.

2. The power conditioner system according to claim 1, wherein the opening and closing device further includes a control unit that controls the opening and closing unit, and the control unit is capable of receiving a second control signal output from an external device for switching the opening and closing unit from the open state to the closed state.

3. The power conditioner system according to claim 1 or 2, wherein the switching device includes a holding circuit for holding the switching unit in the open state.

4. The power conditioner system according to claim 1 or 2, wherein the power conditioner converts DC power output from a plurality of strings including a first string and a second string into AC power, and the at least one arc detection device includes a first arc detection device that detects the occurrence of an arc in an electric circuit connecting the first string and the power conditioner, and a second arc detection device that detects the occurrence of an arc in a second electric circuit connecting the second string and the power conditioner.

5. The power conditioner system according to claim 4, wherein the determination result of the arc determination unit of the second arc detection device and the determination data recorded by the recording unit of the second arc detection device are output via the communication unit of the first arc detection device.

6. The power conditioner system according to claim 1 or 2, wherein the current sensor of the at least one arc detection device also serves as a current sensor for detecting an output current of the power conditioner.

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