Solar power generation system

Abstract

To improve the safety in a photovoltaic power generation system.SOLUTION: A photovoltaic power generation system 1, 1', 1'' comprises a string 2, 2', 2'', an inverter 3, a first breaker device 4, and second breaker devices 5A to 5D, 5A' to 5C', 5A'' to 5D''. The string is formed by series-connecting a plurality of solar battery modules 6. The first breaker device 4 turns off a first switching part 4a connected with an anode side terminal of the string and an anode side terminal of the inverter 3 and a second switching part 4b connected with a cathode side terminal of the string and a cathode side terminal of the inverter 3 depending on a first control signal S1 from the inverter 3. The second breaker devices output a second state signal to the first breaker device 4 depending on a second control signal S2 from the first breaker device 4 to disconnect a solar battery module group from the other solar battery modules 6 or the inverter 3.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] For the purpose of protecting firefighters from electric shock and the like in an emergency such as a fire, some solar power generation systems are provided with a function of immediately stopping power generation in an emergency (for example, see Patent Document 1). This function is called a rapid shutdown function. The rapid shutdown function is realized by a cutoff device that cuts off the electric circuit of a solar power generation system in response to a control signal generated in an emergency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a solar power generation system, the cutoff device is connected to the electric circuits of the anode-side terminals and the cathode-side terminals of a group including one or a plurality of solar cell modules connected in series. However, in a conventional cutoff device, only one of these two electric circuits can be cut off. Therefore, there is a problem regarding safety in an emergency.

[0005] An object of the present invention is to improve the safety of a solar power generation system.

Means for Solving the Problems

[0006] A photovoltaic power generation system according to one aspect of the present invention comprises a string, an inverter, a first circuit breaker, and a second circuit breaker. The string is formed by connecting a plurality of solar cell modules in series. The inverter is connected to the string and converts the DC power output from the string into AC power. The first circuit breaker has a first switching unit connected to the anode terminal of the string and the anode terminal of the inverter, and a second switching unit connected to the cathode terminal of the string and the cathode terminal of the inverter. The first circuit breaker turns off the first and second switching units in response to a first control signal from the inverter. The second circuit breaker is connected to a circuit connecting the solar cell module group to other solar cell modules or the inverter. The solar cell module group consists of one or a plurality of consecutive solar cell modules included in the string. The second circuit breaker outputs a second status signal to the inverter or the first circuit breaker in response to a second control signal from the first circuit breaker, thereby disconnecting the solar cell module group from other solar cell modules or the inverter.

[0007] In this solar power generation system, the first circuit breaker has a first switching unit connected to the anode terminal of the string and the anode terminal of the inverter, and a second switching unit connected to the cathode terminal of the string and the cathode terminal of the inverter. In response to a first control signal from the inverter, the first and second switching units are turned OFF. In other words, the first circuit breaker can interrupt both the circuit connecting the anode terminal of the string and the anode terminal of the inverter, and the circuit connecting the cathode terminal of the string and the cathode terminal of the inverter, in response to the first control signal. By interrupting both of the two circuits connecting the string and the inverter in this way, the string and the inverter can be electrically and reliably disconnected, thereby improving the safety of the solar power generation system in emergencies. In addition, the first circuit breaker or the inverter can monitor whether the second circuit breaker is operating normally.

[0008] The inverter or the first circuit breaker may output an abnormality signal if it determines that the second circuit breaker is malfunctioning in response to the second status signal output from the second circuit breaker. In this case, the first circuit breaker or inverter can notify the user or others of the malfunction of the second circuit breaker.

[0009] The second circuit breaker may output a second status signal to the inverter or the first circuit breaker via power line communication.

[0010] The second circuit breaker may output a second status signal to the inverter or the first circuit breaker via wireless communication.

[0011] The second circuit breaker may include a switch that opens and closes the connection between a group of solar cell modules and other solar cell modules. The second status signal output from the second circuit breaker may include information regarding the open / closed state of the switch. In this case, for example, the inverter or the first circuit breaker can monitor whether the switch is operating normally.

[0012] The inverter may monitor the first circuit breaker based on a first status signal output from the first circuit breaker. In this case, the inverter can monitor whether the first circuit breaker is operating normally.

[0013] The inverter may output an abnormality signal if it determines that the first circuit breaker is malfunctioning in response to the first status signal. In this case, the inverter can notify the user or others of the malfunction in the first circuit breaker.

[0014] The second circuit breaker may include a third switching unit connected to the anode terminal of the solar cell module group and the circuit to another solar cell module or inverter, and a fourth switching unit connected to the cathode terminal of the solar cell module group and the circuit to another solar cell module or inverter. In this case, the second circuit breaker can interrupt both the circuit connecting the anode terminal of the solar cell module group and another solar cell module group or inverter (hereinafter referred to as "other device"), and the circuit connecting the cathode terminal of the solar cell module group and the other device. As a result, the safety of the solar power generation system in emergencies can be improved.

[0015] The second circuit breaker may have a bypass element connected in parallel to the solar cell module group and capable of forming a circuit that bypasses the solar cell modules. In this case, when an abnormality occurs in the solar cell module group, power generated by other solar cell modules can bypass the bypass element and be supplied to the inverter.

[0016] The bypass element may be a diode having an anode connected to the cathode terminal of the solar cell module group and a cathode connected to the anode terminal of the solar cell module group. In this case, even without a command from an external signal, a circuit that bypasses the solar cell module group can be immediately formed when an abnormality occurs in the solar cell module group.

[0017] The first circuit breaker may be driven by power supplied from the commercial power source. In this case, the first circuit breaker can be operated regardless of whether or not power is supplied from the string. As a result, the string and inverter can be reliably disconnected in an emergency, thereby improving the safety of the solar power generation system in emergencies.

[0018] The second blocking device may be driven by the power generated by the solar cell module. In this case, the power generated by the solar cell module can be effectively utilized by using it for driving the second blocking device.

[0019] The inverter may output a first control signal to the first blocking device by power line communication. In this case, there is no need to provide an individual line for communication between the inverter and the first blocking device.

[0020] The inverter may output a first control signal to the first blocking device by wireless communication. In this case, a communication line between the inverter and the first blocking device becomes unnecessary.

[0021] The first blocking device may output a second control signal to the second blocking device by power line communication in response to receiving the first control signal from the inverter. In this case, there is no need to provide an individual line for communication between the first blocking device and the second blocking device.

[0022] The first blocking device may output a second control signal to the second blocking device by wireless communication in response to receiving the first control signal from the inverter. In this case, a communication line between the first blocking device and the second blocking device becomes unnecessary.

Advantages of the Invention

[0023] According to the present invention, the safety of the photovoltaic power generation system can be improved.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a diagram showing the configuration of a photovoltaic power generation system. [Figure 2] FIG. 2 is a diagram showing the configuration of the first blocking device. [Figure 3] FIG. 3 is a diagram showing the configuration of the second blocking device. [Figure 4] FIG. 4 is a diagram showing another example of the connection of the bypass element in the second blocking device. [Figure 5]Figure 5 shows the state of the first circuit breaker in each operating mode. [Figure 6] Figure 6 shows the state of the second circuit breaker in each operating mode. [Figure 7] Figure 7 shows another example of the configuration of a group of solar cell modules in a string. [Figure 8] Figure 8 shows yet another example of the configuration of a group of solar cell modules in a string. [Modes for carrying out the invention]

[0025] The photovoltaic power generation system 1 will be explained using Figure 1. Figure 1 is a diagram showing the configuration of the photovoltaic power generation system 1. The photovoltaic power generation system 1 comprises a string 2, an inverter 3, a first circuit breaker 4, and second circuit breakers 5A to 5D.

[0026] String 2 includes multiple solar cell modules 6 connected in series with each other. In this embodiment, String 2 consists of 16 solar cell modules 6. The photovoltaic power generation system 1 may also include a solar cell array in which multiple String 2s are connected in parallel.

[0027] String 2 includes multiple solar cell module groups. Each solar cell module group includes one or more consecutive solar cell modules 6. Each solar cell module group has an anode terminal and a cathode terminal. In a group containing one solar cell module 6, the anode of the solar cell module 6 becomes the anode terminal of the group, and the cathode of the solar cell module 6 becomes the cathode terminal of the group.

[0028] On the other hand, in a group containing multiple solar cell modules 6, the anode of the solar cell module 6 closest to the anode side of the inverter 3 becomes the anode terminal of that group, and the cathode of the solar cell module 6 closest to the cathode side of the inverter 3 becomes the cathode terminal of that group. In Figure 1, the anode terminal of each solar cell module group is represented by "+" and the cathode terminal by "-".

[0029] String 2 contains a total of eight solar cell module groups, from Group 1 6A to Group 8 6H. Groups 1 A, 3 C, 5 E, and 7 G each contain one solar cell module 6. On the other hand, Groups 2 B, 4 D, 6 F, and 8 H each contain three solar cell modules 6.

[0030] Groups 1A through 8H are connected in series within String 2. Specifically, the cathode terminal of Group 1A is connected to the anode terminal of Group 26B. The cathode terminal of Group 26B is connected to the anode terminal of Group 36C. The cathode terminal of Group 36C is connected to the anode terminal of Group 46D. The cathode terminal of Group 46D is connected to the anode terminal of Group 56E. The cathode terminal of Group 56E is connected to the anode terminal of Group 6F. The cathode terminal of Group 6F is connected to the anode terminal of Group 76G. The cathode terminal of Group 76G is connected to the anode terminal of Group 86H. The anode terminal of Group 16A is connected to the anode terminal of Inverter 3. The cathode terminal of Group 86H is connected to the cathode terminal of Inverter 3.

[0031] The solar cell module 6 generates electricity when it receives sunlight. The open-circuit voltage of the solar cell module 6 is, for example, 50V. The inverter 3 is connected to the string 2 via a power line. The inverter 3 converts the DC power output from the string 2, in which multiple solar cell modules 6 are connected in series, into AC power. The inverter 3 is connected to the power grid 7 and supplies the AC power to the commercial power grid and load devices.

[0032] Specifically, the inverter 3 includes a DC / DC converter 3a, a DC / AC inverter 3b, a control unit 3c, and a first control signal generation unit 3d. The DC / DC converter 3a converts the voltage of the power output from the string 2 into a predetermined voltage and inputs it to the DC / AC inverter 3b. The DC / AC inverter 3b converts the DC power output from the DC / DC converter 3a into AC power.

[0033] The control unit 3c is a computer system including a CPU, memory device, various interfaces, etc. The control unit 3c controls the DC / DC converter 3a and the DC / AC inverter 3b. The control unit 3c may also control the DC / DC converter 3a and the DC / AC inverter 3b using a program stored in the memory device. When the operation switch 8 is pressed, the first control signal generation unit 3d outputs the first control signal S1 to the first circuit breaker 4 via power line communication.

[0034] The first circuit breaker 4 is connected to the power line connecting the string 2 and the inverter 3. The first circuit breaker 4 disconnects the string 2 and the inverter 3 in response to the first control signal S1 from the inverter 3.

[0035] The second circuit breakers 5A to 5D are connected to the circuit connecting one solar cell module group to another solar cell module, or to the circuit connecting one solar cell module group to the inverter 3.

[0036] Specifically, the second circuit breaker 5A is connected to the circuit connecting the anode terminal of the first group 6A to the first circuit breaker 4, and is also connected to the circuit connecting the cathode terminal of the first group 6A to the anode terminal of the second group 6B. The second circuit breaker 5B is connected to the circuit connecting the anode terminal of the third group 6C to the cathode terminal of the second group 6B, and is also connected to the circuit connecting the cathode terminal of the third group 6C to the anode terminal of the fourth group 6D. The second circuit breaker 5C is connected to the circuit connecting the anode terminal of the fifth group 6E to the cathode terminal of the fourth group 6D, and is also connected to the circuit connecting the cathode terminal of the fifth group 6E to the anode terminal of the sixth group 6F. The second circuit breaker 5D is connected to the circuit connecting the anode terminal of the seventh group 6G and the cathode terminal of the sixth group 6F, and is also connected to the circuit connecting the cathode terminal of the seventh group 6G and the anode terminal of the eighth group 6H.

[0037] Each of the second circuit breakers 5A to 5D, in response to the second control signal S2 from the first circuit breaker 4, either disconnects the solar cell module group to which it is connected from other solar cell modules, or disconnects the solar cell module group to which it is connected from the inverter 3. Each of the second circuit breakers 5A to 5D outputs a status signal to the first circuit breaker 4 in response to the second control signal S2 from the first circuit breaker 4.

[0038] The specific configuration of the first circuit breaker 4 will be explained below using Figure 2. Figure 2 is a diagram showing the configuration of the first circuit breaker 4. The first circuit breaker 4 includes a first switching unit 4a, a second switching unit 4b, a first signal receiving unit 4c, a first drive unit 4d, and a first signal transmitting unit 4e.

[0039] The first switching unit 4a has one end connected to the anode terminal of string 2 and the other end connected to the anode terminal of the inverter. The "anode terminal of string 2" is the anode of the solar cell module 6 included in the first group 6A. The second switching unit 4b has one end connected to the cathode terminal of string 2 and the other end connected to the cathode terminal of the inverter. The "cathode terminal of string 2" is the cathode of the solar cell module 6 included in the eighth group 6H that is closest to the cathode side of the inverter 3. The first switching unit 4a and the second switching unit 4b are switching elements, such as semiconductor switches like relays and MOSFETs.

[0040] In this embodiment, the first switching unit 4a and the second switching unit 4b are simultaneously switched between an ON state and an OFF state by the control of the first drive unit 4d. This makes it possible to simultaneously disconnect the power line connecting the anode terminal of the string 2 and the anode terminal of the inverter 3, and the power line connecting the cathode terminal of the string 2 and the cathode terminal of the inverter 3.

[0041] To "turn the switching unit ON," it means to make the switching unit conductive, allowing the power line or circuit to which the switching unit is connected to to conduct electricity. On the other hand, to "turn the switching unit OFF," it means to make the switching unit insulated, electrically interrupting the power line or circuit to which the switching unit is connected.

[0042] In addition, the first switching unit 4a and the second switching unit 4b may each independently receive a drive signal from the first drive unit 4d and independently switch between an ON state and an OFF state. This increases the number of combinations of interruption for the power lines connecting the anode terminal of the string 2 and the anode terminal of the inverter 3, and the power lines connecting the cathode terminal of the string 2 and the cathode terminal of the inverter 3. For example, it is possible to interrupt both of the two power lines, or to interrupt only one of the two power lines. This ensures that even if one of the switching units does not operate properly, the other switching unit can interrupt one power line to reliably interrupt the connection between the string 2 and the inverter 3.

[0043] The first signal receiving unit 4c receives the first control signal S1 output from the inverter 3. When the first signal receiving unit 4c receives the first control signal S1, it outputs a signal to the first drive unit 4d indicating that the first control signal S1 has been received. In this embodiment, the first control signal S1 is output via power line communication to the power line connecting the inverter 3 and the first circuit breaker 4. Therefore, the first signal receiving unit 4c is a signal receiving circuit that can extract signals from the power line, for example, via power line communication.

[0044] The first drive unit 4d outputs drive signals to the first switching unit 4a and the second switching unit 4b to drive the first switching unit 4a and the second switching unit 4b. When connecting the string 2 and the inverter 3, the first drive unit 4d outputs drive signals to the first switching unit 4a and the second switching unit 4b to close them and turn them ON. On the other hand, when the first drive unit 4d receives a signal from the first signal receiving unit 4c indicating that the first control signal S1 has been received, the first drive unit 4d stops outputting the drive signal and opens the first switching unit 4a and the second switching unit 4b to turn them OFF. As a result, the first switching unit 4a and the second switching unit 4b can disconnect the string 2 and the inverter 3 in accordance with the first control signal S1.

[0045] Conversely, the first switching unit 4a and the second switching unit 4b may be in the OFF state when they receive a drive signal from the first drive unit 4d. In this case, the first drive unit 4d outputs a drive signal when it receives a signal from the first signal receiving unit 4c indicating that it has received the first control signal S1, and turns the first switching unit 4a and the second switching unit 4b OFF. On the other hand, when it does not receive a signal indicating that it has received the first control signal S1, the first drive unit 4d stops outputting the drive signal and turns the first switching unit 4a and the second switching unit 4b ON.

[0046] The first drive unit 4d is a signal generation circuit that generates drive signals for the first switching unit 4a and the second switching unit 4b when it receives a signal from the first signal receiving unit 4c, for example.

[0047] When the first drive unit 4d disconnects the string 2 and inverter 3 in response to the first control signal S1, it outputs a signal to the first signal transmission unit 4e indicating that the string 2 and inverter 3 have been disconnected. When the first signal transmission unit 4e receives the signal indicating that the string 2 and inverter 3 have been disconnected, it outputs a second control signal S2 to the power line connecting the first disconnection device 4 and the string 2. In this embodiment, the first signal transmission unit 4e outputs the second control signal S2 to the power line connecting the first disconnection device 4 and the string 2 via power line communication. Therefore, the first signal transmission unit 4e is a signal generation circuit that generates and outputs a signal to be transmitted, for example, via power line communication.

[0048] The first circuit breaker 4 is driven by an external commercial power supply 9. Specifically, the first drive unit 4d uses AC power supplied from the commercial power supply 9 to generate drive signals that drive the first switching unit 4a and the second switching unit 4b. For example, AC power from the commercial power supply 9 can be converted to DC power to generate drive power. The first signal receiving unit 4c and the first signal transmitting unit 4e are also driven by AC power supplied from the commercial power supply 9. This allows the first circuit breaker 4 to operate regardless of whether power is supplied from the string 2 or not.

[0049] The specific configurations of the second circuit breakers 5A to 5D will be explained below using Figure 3. Figure 3 shows the configurations of the second circuit breakers 5A to 5D. The second circuit breakers 5A to 5D have the same configuration. Therefore, in the following explanation, the configuration of the second circuit breaker 5A will be used as an example. The second circuit breaker 5A includes a third switching unit 5a, a fourth switching unit 5b, a second signal receiving unit 5c, a bypass circuit 5d, a power supply unit 5e, a second drive unit 5f, and a bypass element 5g.

[0050] The third switching unit 5a has one end connected to the anode terminal of the first group 6A and the other end connected to the first circuit breaker 4. The fourth switching unit 5b has one end connected to the cathode terminal of the first group 6A and the other end connected to the anode terminal of the second group 6B. The third switching unit 5a and the fourth switching unit 5b are switching elements, such as semiconductor switches like relays and MOSFETs. In this embodiment, the fourth switching unit 5b is an example of an opening / closing unit.

[0051] In this embodiment, the third switching unit 5a and the fourth switching unit 5b are simultaneously switched between an ON state and an OFF state by the control of the second drive unit 5f. As a result, the second circuit breaker 5A can simultaneously interrupt the circuit connecting the anode terminal of the first group 6A to the first circuit breaker 4, and the circuit connecting the cathode terminal of the first group 6A to the anode terminal of the second group 6B.

[0052] In addition, the third switching unit 5a and the fourth switching unit 5b may each independently receive a drive signal from the second drive unit 5f and be independently switched ON / OFF. This allows the second circuit breaker 5A to increase the number of combinations of circuit breakers for the circuit connecting the anode terminal of the first group 6A to the first circuit breaker 4 and the circuit connecting the cathode terminal of the first group 6A to the anode terminal of the second group 6B. For example, it is possible to break both of the two circuits, or to break only one of the two circuits. This allows the first group 6A to be isolated from other devices by breaking one circuit even if one of the switching units does not operate properly.

[0053] The second signal receiving unit 5c receives the second control signal S2 output from the first circuit breaker 4. When the second signal receiving unit 5c receives the second control signal S2, it outputs a signal to the second drive unit 5f indicating that the second control signal S2 has been received. In this embodiment, the second control signal S2 is output via power line communication to the circuit connecting the first circuit breaker 4 and the second circuit breaker 5A. Therefore, the second signal receiving unit 5c is a signal receiving circuit that can extract signals from the circuit, for example, via power line communication.

[0054] The bypass circuit 5d is a circuit for propagating the second control signal S2, which has propagated through one circuit of the second circuit breaker 5A, to the other circuit. Specifically, the bypass circuit 5d propagates the second control signal S2, which has propagated through the circuit to which the first circuit breaker 4 is connected, to the circuit connecting the cathode terminal of the first group 6A and the anode terminal of the second group 6B.

[0055] In this embodiment, the second control signal S2 propagates through the circuit via power line communication. That is, the second control signal S2 is a signal having a predetermined frequency. Therefore, the bypass circuit 5d is a circuit that allows signals of the predetermined frequency to pass through. Specifically, the bypass circuit 5d is, for example, a high-pass filter circuit that allows signals with frequencies above the predetermined frequency to pass through, or a band-pass filter circuit that allows only signals of the predetermined frequency to pass through. The bypass circuit 5d, which is a high-pass filter, can be realized, for example, by a capacitor element.

[0056] The power supply unit 5e generates power to drive the second circuit breaker 5A from the power generated by the solar cell modules included in the first group 6A. When DC power is used as the power to drive the second circuit breaker 5A, the power supply unit 5e is, for example, a regulator circuit.

[0057] The second drive unit 5f outputs drive signals to the third switching unit 5a and the fourth switching unit 5b, respectively, to drive the third switching unit 5a and the fourth switching unit 5b. The second drive unit 5f generates the above drive signals using power supplied from the power supply unit 5e and outputs them to the third switching unit 5a and the fourth switching unit 5b.

[0058] When it is desired to connect the solar cell module group to which the second circuit breaker 5A is connected to another device, the second drive unit 5f outputs a drive signal to the third switching unit 5a and the fourth switching unit 5b, which closes these switching units and turns them ON.

[0059] On the other hand, when the second drive unit 5f receives a signal from the second signal receiving unit 5c indicating that the second control signal S2 has been received, the second drive unit 5f stops outputting the drive signal and opens the third switching unit 5a and the fourth switching unit 5b to the OFF state. As a result, the third switching unit 5a and the fourth switching unit 5b can disconnect the solar cell module group from other devices in accordance with the second control signal S2. The second drive unit 5f also outputs a status signal to the first disconnection device 4 via power line communication, which includes information that the output of the drive signal has been stopped in accordance with the second control signal S2.

[0060] Conversely, the third switching unit 5a and the fourth switching unit 5b may be in the OFF state when they receive a drive signal from the second drive unit 5f. In this case, the second drive unit 5f outputs a drive signal when it receives a signal from the second signal receiving unit 5c indicating that it has received the second control signal S2, and turns the third switching unit 5a and the fourth switching unit 5b OFF. On the other hand, when it does not receive a signal indicating that it has received the second control signal S2, the second drive unit 5f stops outputting the drive signal and turns the third switching unit 5a and the fourth switching unit 5b ON.

[0061] The second drive unit 5f is a signal generation circuit that, for example, when it receives a signal from the second signal receiving unit 5c, uses power supplied from the power supply unit 5e to generate drive signals for the third switching unit 5a and the fourth switching unit 5b.

[0062] The second control signal S2 is output after the first circuit breaker 4 receives the first control signal S1 and disconnects the string 2 and inverter 3. Therefore, the circuit interruption by the second circuit breaker 5A is performed after the string 2 and inverter 3 have been disconnected.

[0063] The bypass element 5g is connected in parallel to the first group 6A to which the second circuit breaker 5A is connected. The bypass element 5g forms a circuit that bypasses the solar cell module group to which the second circuit breaker 5A is connected. As shown in Figure 3, the bypass element 5g is a diode having an anode connected to the cathode terminal of the first group 6A and a cathode connected to the anode terminal of the first group 6A.

[0064] When an abnormality such as a sudden power drop or abnormal heat generation occurs in the first group 6A to which the second circuit breaker 5A is connected, and the first group 6A can no longer output sufficient power, the bypass element 5g forms a circuit that transmits power generated by other solar cell module groups, "bypassing" the abnormal first group 6A. Specifically, when an abnormality occurs in the first group 6A, the bypass element 5g of the second circuit breaker 5A forms a path that transmits power generated in groups 6B to 6H from the second group 6B to the inverter 3 (first circuit breaker 4).

[0065] The bypass element 5g, which is a diode, can immediately form a circuit that bypasses the malfunctioning first group 6A based on its electrical characteristics when the first group 6A can no longer output sufficient power, even without a command from an external signal.

[0066] Furthermore, as long as the second circuit breaker 5A can bypass the first group 6A to which it is connected, and at least one of the terminals of the bypass element 5g is connected to the first group 6A without going through the third switching unit 5a or the fourth switching unit 5b, the connection positions of the two terminals of the bypass element 5g can be arbitrarily set. For example, as shown in Figure 4, the anode of the bypass element 5g, which is a diode, can be connected to the circuit connecting the anode terminal of the second group 6B and the fourth switching unit 5b, and the cathode can be connected to the circuit connecting the anode terminal of the first group and the third switching unit 5a. Figure 4 shows another example of the connection of the bypass element 5g in the second circuit breaker 5A.

[0067] The first circuit breaker 4 monitors the second circuit breakers 5A to 5D based on the status signals output from the second circuit breakers 5A to 5D. If the first circuit breaker 4 determines that the second circuit breakers 5A to 5D are malfunctioning based on the status signals output from the second circuit breakers 5A to 5D, it outputs a malfunction signal to the inverter 3 via power line communication. For example, the first circuit breaker 4 determines that the second circuit breakers 5A to 5D are malfunctioning if it cannot receive a status signal from the second circuit breakers 5A to 5D corresponding to the second control signal S2. When the inverter 3 receives a malfunction signal from the first circuit breaker 4, the inverter 3 notifies the inverter 3 via the display unit 10 connected to the inverter 3 that the second circuit breakers 5A to 5D are malfunctioning.

[0068] Next, an example of the operation of the first circuit breaker 4 and the second circuit breakers 5A to 5D will be explained using Figures 5 and 6. Figure 5 shows the state of the first circuit breaker 4 in each operating mode. Figure 6 shows the state of the second circuit breakers 5A to 5D in each operating mode. The operating modes in the photovoltaic power generation system 1 include three operating modes: start mode, active mode, and safety mode. The safety mode includes normal circuit breaker mode and emergency safety circuit breaker mode.

[0069] The start mode is the mode when sunlight first hits the solar cell module 6. At this time, the solar cell module 6 generates electricity from the sunlight. In start mode, the inverter 3 does not output the first control signal S1 (first control signal "none"), so the first drive unit 4d of the first circuit breaker 4 outputs drive signals to the first switching unit 4a and the second switching unit 4b. As a result, the first switching unit 4a and the second switching unit 4b are turned ON (relay operation mode "ON"), and the string 2 and the inverter 3 are connected. Since the first control signal S1 is not output, the first signal transmission unit 4e does not output the second control signal S2.

[0070] Meanwhile, in the second circuit breakers 5A to 5D, the power supply unit 5e generates power to drive the second circuit breakers 5A to 5D using the power generated by the solar cell module group. Also, since the first circuit breaker 4 does not output the second control signal S2 (second control signal "none"), the second drive unit 5f generates a drive signal using the power generated by the power supply unit 5e and outputs it to the third switching unit 5a and the fourth switching unit 5b. As a result, the third switching unit 5a and the fourth switching unit 5b become ON (relay operation mode "ON"), and the solar cell module group connected to the second circuit breakers 5A to 5D is connected to other devices.

[0071] As described above, in start mode, the power generated in string 2 is supplied to inverter 3 via the first circuit breaker 4. The DC power supplied from string 2 is converted to AC power by inverter 3 and supplied to power grid 7.

[0072] The active mode is the state in which the solar cell module 6 generates electricity by receiving sunlight during the day, and is essentially the same as the start mode. Specifically, in the active mode, the first control signal S1 is not output (first control signal "none"), and the first switching unit 4a and the second switching unit 4b of the first circuit breaker 4 are in the ON state (relay operation mode "ON"). Also, the second control signal S2 is not output (second control signal "none"), and the third switching unit 5a and the fourth switching unit 5b of the second circuit breakers 5A to 5D are in the ON state. As a result, the power generated in string 2 is supplied to inverter 3 via first circuit breaker 4. The DC power supplied from string 2 is converted to AC power by inverter 3 and supplied to the power grid 7.

[0073] The normal shutdown mode is the mode used when the solar cell module 6 is not receiving sunlight due to nighttime or bad weather such as rain. Therefore, in the normal shutdown mode, the solar cell module 6 is not generating power. In the normal shutdown mode, the inverter 3 outputs the first control signal S1 (first control signal "present"). As a result, the first switching unit 4a and the second switching unit 4b of the first shutdown device 4 are in the OFF state (relay operation mode "OFF").

[0074] On the other hand, in the second circuit breakers 5A to 5D, the second control signal S2 is output (second control signal "present"), so the third switching unit 5a and the fourth switching unit 5b are in the OFF state (relay operation mode "OFF"). Note that in normal circuit breaker mode, the second circuit breakers 5A to 5D are not supplied with power from the solar cell module group, so the second drive unit 5f cannot generate a drive signal to output to the third switching unit 5a and the fourth switching unit 5b.

[0075] Furthermore, in the normal shutdown mode, if the power generation of the solar cell module 6 is unstable due to reasons such as unstable weather, the first control signal S1 is not output (first control signal "none"), and the first switching unit 4a and the second switching unit 4b of the first shutdown device 4 are in the ON state (relay operation mode "ON"). On the other hand, in the second shutdown devices 5A to 5D, the second control signal S2 is not output (second control signal "none"), so the third switching unit 5a and the fourth switching unit 5b are in the ON state / OFF state depending on the power supplied from the solar cell module group connected to the second shutdown devices 5A to 5D (relay operation mode "ON / OFF").

[0076] As a result, in normal interruption mode, either string 2 cannot supply power to inverter 3, or the power supply to inverter 3 is frequently interrupted.

[0077] The emergency safety shutoff mode is a mode that cuts off the power supply from string 2 to inverter 3 during start mode or active mode. The emergency safety shutoff mode is started when the operation switch 8 is operated during start mode or active mode.

[0078] Specifically, when the operation switch 8 is operated, the first control signal generation unit 3d of the inverter 3 transmits the first control signal S1 to the first circuit breaker 4 via power line communication (first control signal "present"). Thus, in this embodiment, the first control signal S1 is output only when the emergency safety shutdown mode is initiated.

[0079] When the first signal receiving unit 4c receives the first control signal S1, the first drive unit 4d stops outputting drive power to the first switching unit 4a and the second switching unit 4b. As a result, the first switching unit 4a and the second switching unit 4b are turned OFF, and the string 2 and the inverter 3 are disconnected (relay operation mode "OFF"). At the moment the first switching unit 4a and the second switching unit 4b are turned OFF, the first signal transmitting unit 4e outputs the second control signal S2 to the string 2 via power line communication (second control signal "present").

[0080] When the second signal receiving unit 5c of the second circuit breaker 5A to 5D receives the second control signal S2, the second drive unit 5f stops outputting drive power to the third switching unit 5a and the fourth switching unit 5b. As a result, the third switching unit 5a and the fourth switching unit 5b enter the OFF state, and the solar cell module group connected to the second circuit breaker 5A to 5B is disconnected from other devices (relay operation mode "OFF"). In other words, the voltage output from all solar cell modules 6 included in string 2 is disconnected. When the second drive unit 5f receives the second control signal S2 and stops outputting the drive signals that drive the third switching unit 5a and the fourth switching unit 5b, it outputs a status signal to the first circuit breaker 4 that includes information indicating that it has stopped outputting the drive signals to the third switching unit 5a and the fourth switching unit 5b. The first circuit breaker 4 determines that the second circuit breaker 5A to 5D are malfunctioning if it cannot receive a status signal from the second circuit breaker 5A to 5D corresponding to the second control signal S2.

[0081] As described above, in emergency safety shutdown mode, the first shutdown device 4 can shut off the string 2 and the inverter 3, and the second shutdown devices 5A to 5D can shut off each group of solar cell modules included in the string 2. Specifically, the second shutdown device 5A can shut off the connection between the first group 6A and the second group 6B. The second shutdown device 5B can shut off the connection between the second group 6B and the third group 6C, and the connection between the third group 6C and the fourth group 6D. The second shutdown device 5C can shut off the connection between the fourth group 6D and the fifth group 6E, and the connection between the fifth group 6E and the sixth group 6F. The second shutdown device 5D can shut off the connection between the sixth group 6F and the seventh group 6G, and the connection between the seventh group 6G and the eighth group 6H.

[0082] Therefore, in the photovoltaic power generation system 1, the cost of installing a shut-off device can be reduced compared to installing a shut-off device for each solar cell module 6. Furthermore, in the emergency safety shut-off mode, not only is the string 2 shut off for each group of solar cell modules, but the connection between the string 2 and the inverter 3 is also shut off, providing a more safe photovoltaic power generation system.

[0083] In the solar power generation system 1, the first circuit breaker 4 has a first switching unit 4a connected to the anode terminal of the string 2 and the anode terminal of the inverter 3, and a second switching unit 4b connected to the cathode terminal of the string 2 and the cathode terminal of the inverter 3. In response to a first control signal S1 from the inverter 3, the first switching unit 4a and the second switching unit 4b are turned OFF. In other words, the first circuit breaker 4 can disconnect both the power line connecting the anode terminal of the string 2 and the anode terminal of the inverter 3, and the power line connecting the cathode terminal of the string 2 and the cathode terminal of the inverter 3, in response to the first control signal S1. By disconnecting both of the two power lines connecting the string 2 and the inverter 3 in this way, the string 2 and the inverter 3 can be electrically and reliably disconnected. As a result, the safety of the solar power generation system 1 in emergencies can be improved.

[0084] The second circuit breakers 5A to 5D include a third switching unit 5a connected to the anode terminal of the solar cell module group and the circuit to another solar cell module 6 or inverter 3, and a fourth switching unit 5b connected to the cathode terminal of the solar cell module group and the circuit to another solar cell module 6 or inverter 3. As a result, the second circuit breakers 5A to 5D can interrupt both the circuit connecting the anode terminal of the solar cell module group to another solar cell module group or inverter 3, and the circuit connecting the cathode terminal of the solar cell module group to another solar cell module group or inverter 3. This improves the safety of the solar power generation system 1 in emergencies.

[0085] The second circuit breakers 5A to 5D output a status signal to the first circuit breaker 4 in response to the second control signal S2 from the first circuit breaker 4. Therefore, when the operation switch 8 is operated, the first circuit breaker 4 can detect that the second circuit breakers 5A to 5D are operating normally. As a result, a safer solar power generation system 1 can be provided.

[0086] The second circuit breakers 5A to 5D are connected in parallel to the solar cell module group and have a bypass element 5g that can form a circuit that bypasses the solar cell module. This allows power generated by other solar cell modules to bypass the bypass element and be supplied to the inverter 3 when an abnormality occurs in the solar cell module group.

[0087] The first circuit breaker 4 is powered by electricity supplied from the commercial power supply 9. This allows the first circuit breaker 4 to operate regardless of whether or not power is supplied from the string 2. As a result, the string 2 and the inverter 3 can be reliably shut off in an emergency, thereby improving the safety of the solar power generation system 1 in emergencies.

[0088] The second circuit breakers 5A to 5D are driven by the electricity generated by the solar cell module 6. This allows the electricity generated by the solar cell module 6 to be effectively utilized to drive the second circuit breakers 5A to 5D.

[0089] The inverter 3 outputs a first control signal S1 to the first circuit breaker 4 via power line communication. This eliminates the need to provide separate lines for communication between the inverter 3 and the first circuit breaker 4.

[0090] The first circuit breaker 4 may, upon receiving the first control signal S1 from the inverter 3, output a second control signal S2 to the second circuit breakers 5A to 5D via power line communication. This eliminates the need to provide separate lines for communication between the first circuit breaker 4 and the second circuit breakers 5A to 5D.

[0091] 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 spirit of the invention. The method of grouping solar cell module groups in String 2, and the number of solar cell modules 6 included in each group, can be arbitrarily determined based on factors such as the open-circuit voltage at which String 2 is shut off during emergency safety shutdown mode. For example, in emergency safety shutdown mode, it is preferable that the open-circuit voltage of String 2 is divided to 165V or less. If the open-circuit voltage of one solar cell module 6 is 50V, it is preferable to shut off String 2 for each group containing three solar cell modules 6.

[0092] For example, in the photovoltaic power generation system 1' shown in Figure 7, string 2' contains 18 solar cell modules 6 connected in series, and includes 6 solar cell module groups 6A' to 6F'. Each solar cell module group 6A' to 6F' consists of three consecutive solar cell modules 6. Furthermore, second circuit breakers 5A', 5B', and 5C' are connected to solar cell module groups 6A', 6C', and 6E', respectively. Figure 7 shows another example of the configuration of solar cell module groups in a string.

[0093] Furthermore, for example, in the photovoltaic power generation system 1'' shown in Figure 8, string 2'' includes 12 solar cell modules 6 connected in series, and contains 4 solar cell module groups 6A'' to 6D''. Each solar cell module group 6A'' to 6D'' consists of 3 consecutive solar cell modules 6. In addition, a second circuit breaker 5A'' to 5D'' is connected to each solar cell module group 6A'' to 6D''. Figure 8 shows yet another example of the configuration of solar cell module groups in a string.

[0094] In addition, in photovoltaic power generation systems 1' and 1'', only the configuration of the solar cell module groups in strings 2' and 2'' differs from that of photovoltaic power generation system 1; the other configurations in photovoltaic power generation systems 1' and 1'' are the same as those in photovoltaic power generation system 1.

[0095] Switching from start mode or active mode to emergency safety shutdown mode may be performed when an abnormality is detected from the output state of the solar cell module 6 included in string 2. In this case, for example, the photovoltaic power generation system 1 is equipped with a sensor that detects the output state of the solar cell module 6, and when an abnormality is detected from the output state of the solar cell module 6 detected by the sensor, the first control signal generation unit 3d of the inverter 3 outputs the first control signal S1, thereby performing the switch to emergency safety shutdown mode. Alternatively, for example, a fire alarm or fire detector is connected to the inverter 3, and when the inverter 3 receives a signal from the fire alarm or fire detector, the first control signal generation unit 3d outputs the first control signal S1, thereby performing the switch to emergency safety shutdown mode.

[0096] The first control signal S1 and / or the second control signal S2 can be transmitted and received by methods other than power line communication. For example, the first control signal S1 and / or the second control signal S2 may be transmitted and received by wireless communication. Alternatively, the first control signal S1 may be transmitted and received by power line communication while the second control signal S2 is transmitted and received by wireless communication. When the second control signal S2 is transmitted and received by wireless communication, it is not necessary to provide a bypass circuit 5d in the second circuit breaker. The second circuit breakers 5A to 5D may output status signals to the first circuit breaker 4 by wireless communication. The second circuit breakers 5A to 5D may be connected to the first circuit breaker 4 so as to enable bidirectional communication by wireless communication. The first circuit breaker 4 may output an abnormal signal to the inverter 3 by wireless communication. The first circuit breaker 4 may be configured to output an abnormal signal to the user's mobile terminal by wireless communication.

[0097] The status signals output from the second circuit breakers 5A to 5D may include at least one of the following: the voltage of the second circuit breakers 5A to 5D, the current, or information regarding the open / closed state of the fourth switching unit 5b. The first circuit breaker 4 may determine that the second circuit breakers 5A to 5D are abnormal based on the information regarding the open / closed state of the fourth switching unit 5b. For example, if the fourth switching unit 5b is composed of a mechanical relay, the first circuit breaker 4 may detect welding of the fourth switching unit 5b by monitoring the voltage between the contacts of the fourth switching unit 5b based on the status signals output from the second circuit breakers 5A to 5D, and determine that the second circuit breakers 5A to 5D are abnormal. If the status signals output from the second circuit breakers 5A to 5D include information regarding the open / closed state of the fourth switching unit 5b, the status signals output from the second circuit breakers 5A to 5D may further include information regarding the open / closed state of the third switching unit 5a. The status signals output from the second circuit breakers 5A to 5D may also include information indicating that the second circuit breakers 5A to 5D are abnormal. In other words, the second circuit breakers 5A to 5D may be configured to monitor their own voltage and other parameters and detect any abnormalities in the second circuit breakers 5A to 5D themselves.

[0098] In the above embodiment, the second circuit breakers 5A to 5D were configured to output a status signal to the first circuit breaker 4 in response to the second control signal S2 from the first circuit breaker 4. However, if the status signal includes at least one of the voltage, current, or open / closed state of the second circuit breakers 5A to 5D, the second circuit breakers 5A to 5D may periodically or continuously output a status signal to the first circuit breaker 4 in active mode.

[0099] In the above embodiment, the second circuit breakers 5A to 5D were configured to output status signals to the first circuit breaker 4. However, the second circuit breakers 5A to 5D may be configured to output status signals to the inverter 3 via power line communication or wireless communication. In this case, the inverter 3 may determine if there is an abnormality in the second circuit breakers 5A to 5D based on the status signals output from the second circuit breakers 5A to 5D, and notify the inverter 3 of the abnormality of the second circuit breakers 5A to 5D via the display unit 10.

[0100] The first circuit breaker 4 may output a status signal to the inverter 3 via power line communication or wireless communication. The inverter 3 may monitor the first circuit breaker 4 based on the status signal output from the first circuit breaker 4. If the inverter 3 determines that the first circuit breaker 4 is abnormal based on the status signal output from the first circuit breaker 4, it may output an abnormality signal to the display unit 10 or the user's mobile terminal to notify that the first circuit breaker 4 is abnormal. The status signal output from the first circuit breaker 4 may contain the same information as the status signals output from the second circuit breakers 5a to 5c. The status signal output from the first circuit breaker 4 may, for example, be feedback to the inverter regarding the output of a signal to the first switching unit 4a or the second switching unit 4b in response to the first control signal, or it may include at least one of the following: the voltage of the first circuit breaker 4, the current, or the open / closed state of the first switching unit 4a or the second switching unit 4b, or it may include information indicating that the first circuit breaker 4 is abnormal.

[0101] The first control signal S1 and / or the second control signal S2 may represent multiple types of information. That is, the decision of whether or not to switch to emergency safety shutdown mode is not limited to the presence or absence of the first control signal S1 and the second control signal S2, but may also be made based on the type of information indicated by the first control signal S1 and / or the second control signal S2.

[0102] For example, the first control signal S1 and the second control signal S2 may be capable of representing two types of values ​​(referred to as the first value and the second value) in binary. In this case, for example, if the first control signal S1 and the second control signal S2 indicate the first value, it may be decided to switch to emergency safety shutdown mode (shutting off the connection between string 2 and inverter 3, and / or shutting off the connections between solar cell module groups within string 2), and if they indicate the second value, it may be decided not to switch to emergency safety shutdown mode (maintaining the connection between string 2 and inverter 3, and / or maintaining the connections between solar cell module groups within string 2).

[0103] In modes other than the emergency safety shutdown mode, the first control signal S1 and the second control signal S2 are always output, and in the emergency safety shutdown mode, the output of the first control signal S1 and the second control signal S2 may be stopped. In this case, the first shutdown device and the second shutdown device close their switching units when they receive the first control signal S1 and the second control signal S2, and open their switching units when they do not receive the first control signal S1 and the second control signal S2. [Industrial applicability]

[0104] This invention can be widely applied to photovoltaic power generation systems equipped with a rapid shutdown function. [Explanation of Symbols]

[0105] 1, 1', 1'' Solar power generation system 2, 2', 2'' strings 3 Inverter 3a DC / DC converter 3b DC / AC Inverter 3c Control Unit 3d First control signal generation unit 4. First circuit breaker 4a First switching section 4b Second Switching Section 4c First signal receiving section 4d First drive unit 4e First signal transmission unit 5A~5D Second circuit breaker 5A'~5C' 2nd shutoff device 5A''~5D'' Second circuit breaker 5a Third switching section 5b Fourth switching section 5c Second signal receiving section 5d Bypass Circuit 5e Power supply 5f Second drive unit 5g bypass element 6. Solar cell modules 6A~6H Solar Panel Module Group 6A'~6F' Solar Cell Module Group 6A''~6D'' Solar Panel Module Group 7 Power system 8. Operation switches 9 Commercial power supply S1 First control signal S2 Second control signal

Claims

1. A string of multiple solar modules connected in series, An inverter connected to the string, which converts the DC power output from the string into AC power, A first switch unit comprising a first switching unit connected to the anode terminal of the string and the anode terminal of the inverter, and a second switching unit connected to the cathode terminal of the string and the cathode terminal of the inverter, wherein the first switch unit and the second switching unit are turned OFF in response to a first control signal from the inverter, A second circuit breaker is connected to a circuit connecting a solar cell module group, which consists of one or more consecutive solar cell modules included in the string, to other solar cell modules or the inverter, and outputs a second status signal to the inverter or the first circuit breaker in response to a second control signal from the first circuit breaker, thereby disconnecting the solar cell module group from the other solar cell modules or the inverter. Equipped with, The first switching unit is positioned in the anode-side circuit extending between the anode-side terminal of the string and the anode-side terminal of the inverter, and opens and closes the anode-side circuit. The second switching unit is positioned in a cathode-side circuit extending between the cathode-side terminal of the string and the cathode-side terminal of the inverter, and opens and closes the cathode-side circuit. The first switching unit and the second switching unit can each be turned ON / OFF independently. The second circuit breaker has a switching unit connected to the solar cell module group and the circuit to the other solar cell module or the inverter, The second status signal includes information regarding the voltage, current, or the open / closed state of the second circuit breaker, The inverter or the first circuit breaker determines an abnormality in the second circuit breaker based on the second status signal. Solar power generation system.

2. If the inverter or the first circuit breaker determines that the second circuit breaker is malfunctioning in response to the second status signal, it outputs an abnormality signal. The photovoltaic power generation system according to claim 1.

3. The second circuit breaker outputs the second status signal to the inverter or the first circuit breaker via power line communication. The photovoltaic power generation system according to claim 1 or 2.

4. The second circuit breaker outputs the second status signal to the inverter or the first circuit breaker via wireless communication. The photovoltaic power generation system according to claim 1 or 2.

5. The second disconnection device includes a switch that opens and closes the connection between the solar cell module group and other solar cell modules. The second status signal includes information regarding the open / closed state of the opening / closing part, A solar power generation system according to any one of claims 1 to 4.

6. The inverter monitors the first circuit breaker based on a first status signal output from the first circuit breaker. A solar power generation system according to any one of claims 1 to 5.

7. The inverter, when it determines that the first circuit breaker is malfunctioning in response to the first status signal, outputs an abnormality signal. The solar power generation system according to claim 6.

8. The photovoltaic power generation system according to any one of claims 1 to 7, wherein the switching unit of the second circuit breaker comprises a third switching unit connected to the anode terminal of the solar cell module group and a circuit to the other solar cell module or the inverter, and a fourth switching unit connected to the cathode terminal of the solar cell module group and a circuit to the other solar cell module or the inverter.

9. The photovoltaic power generation system according to any one of claims 1 to 8, wherein the second circuit breaker is connected in parallel to the solar cell module group and has a bypass element capable of forming an electrical circuit that bypasses the solar cell module group.

10. The photovoltaic power generation system according to claim 9, wherein the bypass element is a diode having an anode connected to the cathode-side terminal of the solar cell module group and a cathode connected to the anode-side terminal of the solar cell module group.

11. The photovoltaic power generation system according to any one of claims 1 to 10, wherein the first circuit breaker is driven by power supplied from a commercial power source.

12. The photovoltaic power generation system according to any one of claims 1 to 11, wherein the second circuit breaker is driven by the power generated by the solar cell module.

13. The photovoltaic power generation system according to any one of claims 1 to 12, wherein the inverter outputs the first control signal to the first circuit breaker via power line communication.

14. The solar power generation system according to any one of claims 1 to 12, wherein the inverter outputs the first control signal to the first circuit breaker via wireless communication.

15. The photovoltaic power generation system according to any one of claims 1 to 14, wherein the first circuit breaker outputs a second control signal to the second circuit breaker via power line communication in response to receiving a first control signal from the inverter.

16. The photovoltaic power generation system according to any one of claims 1 to 14, wherein the first circuit breaker outputs a second control signal to the second circuit breaker via wireless communication in response to receiving a first control signal from the inverter.

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