Method and device for performing secure functions

Abstract

A processor according to an aspect: determines a need to switch to a secure mode during monitoring an operating condition; determining a target voltage for each of all devices based on the number of all devices connected to a photovoltaic (PV) module and a predefined safety voltage; and providing a turn-off signal to each of all the devices such that the output voltage of each of all the devices is controlled to be the target voltage.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for performing a security function. Background Art

[0002] Photovoltaic (PV) power generation systems must provide reliability by identifying possible anomalies and emergency situations in real time during operation. If an anomaly occurs in a PV power generation system, the inverter must detect it within a very short time and take protective measures to shut down the power supply. In this regard, increasingly stringent global industrial safety standards require rapid shutdown (RSD) functionality in PV systems.

[0003] In order to improve power generation efficiency, module-level power conversion equipment (or module-level power electronics (hereinafter, referred to as “MLPE”)) is being introduced into solar power generation systems.

[0004] In order to meet the safety voltage required by the standards of each country, MLPE is required to perform safety functions.

[0005] However, when passive components such as resistors and transient voltage suppressor (TVS) diodes are added to the output of an MLPE to perform safety functions, the unit cost of the MLPE increases. Furthermore, if the target voltage of the MLPE is fixed, any fault in the MLPE may not meet the safety voltage. Summary of the Invention

[0006] Technical issues

[0007] The present disclosure is intended to provide a method and apparatus for performing a security function. The present disclosure is also intended to provide a computer-readable recording medium having recorded thereon a program for performing the method on a computer. The technical problems to be solved are not limited to the above-mentioned technical problems, and other technical problems may exist.

[0008] Solution to the problem

[0009] According to one aspect, a processor is provided, configured to: determine whether a transition to a safety mode is required while monitoring an operating condition; determine a target voltage for each device in the total number of devices connected to a photovoltaic (PV) module and a selected safety voltage; and provide a shutdown signal to each device in the total number of devices so that the output voltage of each device in the total number of devices is controlled to the target voltage.

[0010] According to another aspect, a method for performing a safety function is provided, the method comprising: determining whether a transition to a safety mode is required while monitoring an operating condition; determining a target voltage for each device in the total number of devices connected to a photovoltaic (PV) module and a selected safety voltage; and providing a shutdown signal to each device in the total number of devices so that the output voltage of each device in the total number of devices is controlled to the target voltage.

[0011] According to another aspect, there is provided a computer-readable recording medium having recorded thereon a program for executing the above-described method on a computer.

[0012] Advantageous Effects of the Invention

[0013] This safety function can be enabled without adding any additional configuration to the PV power generation system. Therefore, the safety of the PV power generation system can be ensured and the manufacturing cost can be reduced.

[0014] Furthermore, even if a fault occurs in the MLPE group, the target voltage can be adjusted to meet the safe voltage condition, thus ensuring reliable operation of the photovoltaic power generation system.

[0015] Furthermore, a method is provided that can be used in a system having a 1-MLPE structure as well as a system having an n-MLPE structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a diagram illustrating an example photovoltaic (PV) power generation system according to an embodiment.

[0017] Figure 2 is a diagram illustrating an example device according to an embodiment.

[0018] Figure 3 is a flowchart illustrating an example method for a processor to perform a security function according to an embodiment.

[0019] Figure 4 1 is a diagram illustrating a situation where a device fails in the PV power generation system according to the embodiment.

[0020] Figure 5 is a flowchart illustrating an example of determining a target voltage by a processor according to an embodiment.

[0021] Figure 6 is a diagram illustrating an example PV power generation system according to an embodiment.

[0022] Figure 7 is a diagram illustrating an example sub-circuit of a device according to an embodiment. DETAILED DESCRIPTION

[0023] Best Mode for Carrying Out the Invention

[0024] According to one aspect, a processor may: determine whether a transition to a safety mode is required while monitoring operating conditions; determine a target voltage for each device in the total number of devices connected to a photovoltaic (PV) module and a selected safety voltage; and provide a shutdown signal to each device in the total number of devices so that the output voltage of each device in the total number of devices is controlled to the target voltage.

[0025] Implementation of the present invention

[0026] The terms used in the examples are selected as much as possible from commonly used general terms. However, these terms may vary according to the intentions, habits, emergence of new technologies, etc. of ordinary technicians in the field. The inventors may arbitrarily select some terms. In this case, the meanings of these terms will be described in detail in the appropriate sections. Therefore, the terms used in this specification are defined based on the meanings of the terms and the entire content of this specification, rather than simply based on the names of the terms.

[0027] As used herein, the terms "comprises," "comprising," "including," "having" and any variations thereof, unless explicitly described to the contrary, must be understood to cover a non-exclusive inclusion.

[0028] Ordinal terms such as "first" and "second" may be used in this specification to describe various elements, but these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0029] Hereinafter, example embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The detailed description described in conjunction with the accompanying drawings is intended to illustrate example embodiments of the present disclosure and is not intended to represent the only embodiment in which the present disclosure may be implemented. To clearly illustrate the present disclosure in the accompanying drawings, portions not relevant to the description may be omitted, and throughout the specification, the same or similar components may be denoted by the same reference numerals.

[0030] Figure 1 is a diagram illustrating an example photovoltaic (PV) power generation system according to an embodiment.

[0031] refer to Figure 1 , the PV power generation system 1 includes a PV module 110, a first device 120, a second device 130 and a power grid 140. Figure 1 In addition to the components shown in , the system 1 may also include general components.

[0032] The PV module 110 is a module that generates electricity using sunlight. For example, the system 1 may include a plurality of PV modules 110 .

[0033] The first devices 120 may be connected to the PV modules 110, respectively. For example, the number of PV modules 110 and the number of first devices 120 in the system 1 may be the same.

[0034] The first device 120 and / or the second device 130 may be an MLPE. For example, the first device 120 and / or the second device 130 may be an optimizer or a microinverter.

[0035] In an example, if the MLPE of system 1 is an optimizer, all second devices 130 of system 1 can collectively be a single inverter. In this case, the corresponding first devices 120 can optimize the power output by the PV modules 110 and output this power to a single inverter (e.g., a string inverter). The current converted by the inverter (e.g., from direct current (DC) to alternating current (AC)) can be output to a load or a grid 140.

[0036] In another example, if the MLPE of system 1 is a microinverter, first device 120 and second device 130 connected to a single PV module 110 can collectively be a microinverter. In other words, first device 120 and second device 130 can collectively be a single device. For example, system 1 can be configured so that a single microinverter is connected to a single PV module 110. In this case, first device 120 and second device 130 can convert the electricity generated by PV module 110. The converted current by first device 120 and second device 130 can be output to a load or grid 140.

[0037] Hereinafter, the term "device" is used to refer to the first device 120 and / or the second device 130. For example, in the case where the MLPE of the system 1 is an optimizer, the device may be the first device 120. In another example, in the case where the MLPE of the system 1 is an optimizer, the device may be both the first device 120 and the second device 130. That is, the first device 120 and the second device 130 may be collectively a single device. Figure 2 An example is described in which the first device 120 is an optimizer in the case where the MLPE of the system 1 is an optimizer.

[0038] like Figure 1As shown, a single device can be connected to a single PV module 110, but this is not limited to a single PV module 110. For example, depending on the structure used by the PV power generation system 1, the PV modules 110 and the devices can be arranged in a many-to-one relationship or a many-to-many relationship, and the arrangement is not limited to one of these relationships. In another embodiment, the power generation system 1 can also be configured so that a plurality of groups are connected in series, each of the plurality of groups including n PV modules 110 and n devices (where n is a natural number greater than or equal to 2). Figure 6 An example of the system 1 including a plurality of groups is described.

[0039] In the case where the MLPE of the system 1 is an optimizer, the first device 120 may be provided as a plurality of first devices 120 connected in series to one another, wherein the second device 130 may be connected to each of the plurality of first devices 120 connected in series.

[0040] In the case where the MLPE of the system 1 is an optimizer, the second device 130 may be provided in a power conversion system (PCS) to perform power conversion so as to supply power generated by the PV module 110 to a load or a grid 140 .

[0041] For example, the second device 130 can monitor the operating status of the PV power generation system 1 by analyzing various data received from the PV modules 110, the first devices 120, the load, the grid 140, etc. In the event of an abnormality, the second device 130 sends a shutdown signal to the plurality of first devices 120 to meet the safety voltage required by the standards of each country.

[0042] The present disclosure provides a PV power generation system 1 that can perform safety functions according to standards based on the structure of the PV power generation system 1 when a transition to a safety mode is required during monitoring of operating conditions. The present disclosure provides a PV power generation system 1 that can flexibly perform safety functions according to on-site conditions, such as when some of the first devices 120 have failed or are in a faulty state.

[0043] The operation of the PV power generation system 1 will be described in detail below with reference to the accompanying drawings.

[0044] Figure 2 is a diagram illustrating an example device according to an embodiment.

[0045] refer to Figure 2 , the first device 120 may include a DC-DC converter 121 and a processor 122 .

[0046] For example, the DC-DC converter 121 may be implemented as a buck converter that steps down the voltage applied by the PV module 110 (i.e., the output voltage of the PV module 110). The detailed structure of the DC-DC converter 121 is not limited to any structure and may have any design by which the output voltage of the PV module 110 can be stepped down to a desired target voltage according to a defined protocol (e.g., 30 volts or less within 30 seconds).

[0047] The processor 122 may include, for example, a power control microcontroller unit (MCU). The processor 122 may execute software such as a program to control at least one other component (eg, hardware or software component) of the first device 120 and may perform various data processing or calculations.

[0048] The processor 122 may perform serial communication or power line communication (PLC) with the second device 130 to receive control signals, shutdown signals, etc. required for power optimization.

[0049] For example, the processor 122 may control the duty cycle of the DC-DC converter 121 to convert (or regulate) the output voltage of the first device 120 .

[0050] refer to Figure 2 , the second device 130 may include a power conversion circuit 131 and a processor 132 .

[0051] For example, the power conversion circuit 131 is a circuit that converts an output voltage (DC) applied from the PV module 110 or the equipment module 120 into an alternating current voltage (AC) for transmission to a load or the grid 140 .

[0052] For example, similar to the processor 122, the processor 132 may be implemented as a microcontroller unit (MCU) for power control, and may perform conversion control via the power conversion circuit 131, or monitor operating conditions by analyzing various data received from the PV module 110, the first device 120, the load, the grid 140, etc. For example, the processor 132 may operate as an energy management system (EMS).

[0053] As referenced above Figure 1As described above, when the MLPE of system 1 is a microinverter, the first device 120 and the second device 130 may be a single device. In this case, the processor 122 and the processor 132 may be implemented as a single processor, or may be implemented as separate processors.

[0054] Accordingly, hereinafter, the term "device" refers to the first device 120, or a single device that is a combination of the first device 120 and the second device 130. hereinafter, the term "processor" refers to the processor 132, or a single processor that is a combination of the processors 122 and 132.

[0055] Figure 3 is a flowchart illustrating an example method for a processor to perform a security function according to an embodiment.

[0056] Referring to operation S10 , the processor determines whether a transition to a safety mode is required while monitoring an operating condition.

[0057] For example, the processor may monitor the operating conditions of the PV power generation system 1 and recognize that a transition to a safe mode is required.

[0058] For example, the safety mode is a mode in which the operating power of the system 1 needs to be reduced due to an abnormality in the system 1 , and can also be considered as a step before the RSD mode.

[0059] For example, the processor can identify whether a transition to a safe mode is required by analyzing various data received from the PV module 110, devices, loads, the grid 140, etc. In addition, the need to transition to a safe mode can be identified by various methods, but is not limited to one of these methods.

[0060] In operation S20 , the processor is further configured to determine a target voltage for each of the devices based on the number of devices connected to the plurality of PV modules 120 and the selected safety voltage.

[0061] For example, the processor may determine a target voltage for each of the total devices based on the number of the total devices and the selected safety voltage.

[0062] For example, the total number of devices refers to the number of devices connected in series with each other, and may correspond to the number of cell strings of the PV module 120. Therefore, hereinafter, the total number of devices and the number of strings are used interchangeably.

[0063] The selected safety voltage refers to the total output voltage of the device required in safety mode according to country-specific standards. For example, the United States requires that the safety voltage within 30 seconds in safety mode must not exceed 30V.

[0064] In this case, since the number of strings in PV power generation system 1 is structurally recognized and national standards are also recognized, it is assumed that the processor knows the number of strings and the safety voltage. For example, the processor may receive information including the number of strings and the safety voltage via a server, a main controller, etc., or may receive user input for inputting the number of strings and the safety voltage. The method for obtaining information is not limited to one of these methods.

[0065] The target voltage for each device is the selected safety voltage divided by the total number of strings, k, as shown in Equation 1.

[0066] [Equation 1]

[0067]

[0068] According to the embodiment of the present disclosure, in order to more effectively perform the safety function, it is necessary to flexibly determine the target voltage of each device according to the operating conditions of the device. Figure 4 and Figure 5 An example is described in which the processor is further configured to determine a target voltage for each device according to an operating condition of the device.

[0069] In operation S30 , the processor provides a shutdown signal to each device so that an output voltage of each device is controlled to be a target voltage.

[0070] For example, the device may control the duty cycle of the DC-DC converter 121 to optimize the output voltage of the PV module 110. When the device receives a shutdown signal, the processor may control the device to control the duty cycle of the DC-DC converter 121 so that the output voltage of the device is the target voltage.

[0071] Specifically, when the device receives a shutdown signal, the processor may control the duty cycle of the DC-DC converter using a duty cycle determined based on the output voltage Vpv and the target voltage of the PV module 110. For example, the processor may use Equation 2 to calculate the duty cycle.

[0072] [Equation 2]

[0073]

[0074] According to the embodiment of the present disclosure, the system 1 can perform a safety function without adding an additional configuration to the system 1. Therefore, the safety of the system 1 can be ensured and the manufacturing cost of the system 1 can be reduced.

[0075] Figure 4 1 is a diagram illustrating a situation where a device fails in a PV power generation system according to an embodiment.

[0076] refer to Figure 4In the case where a transition to a safe mode is required, the processor 132 may send a shutdown signal to cause the first device 120 to reduce the output voltage to a target voltage. In this case, the processor 132 may send the shutdown signal to the first device 120 via a communication line.

[0077] like Figure 4 As shown, at least one first device 410 among the plurality of first devices 120 may fail. The failed first device 410 fails to control the output voltage to the target voltage in response to the shutdown signal, which is referred to as being in a fault state or having failed.

[0078] For example, the processor 132 may identify the faulty first device 410 based on various configurations of the system 1 or data received from an external source. In another example, the processor 132 may receive status information from the faulty first device 410. Furthermore, the process of the processor 132 identifying whether the first device 410 is in a normal state or a faulty state may be performed in various ways and is not limited to any one of these ways.

[0079] In order to meet the safety voltage required in the safety mode when at least one first device 410 among the plurality of first devices 120 has failed, the remaining first devices among the plurality of first devices 120 are required to share the voltage amount not controlled by the first device 410 .

[0080] Also, in the case where a voltage higher than 0V is applied to the failed first device 410, the target voltage of the remaining first devices needs to be lowered. Figure 5 A specific method for determining the target voltage will be described.

[0081] Figure 5 is a flowchart illustrating an example of determining a target voltage by a processor according to an embodiment.

[0082] As reference Figure 3 Operation S20 and Figure 4 As described, the processor can determine the target voltage for each device based on specifications and site conditions. Figure 5 Shown in more detail Figure 3 Operation S20, and in some features with Figure 3 and Figure 4 If the features are the same as in , the description of these features is omitted.

[0083] In operation S21 , the processor is further configured to identify whether at least one device has failed.

[0084] For example, the processor may obtain the target voltage in three different ways depending on whether a device has failed and whether the voltage is being applied to the failed device.

[0085] First, in a case where none of the plurality of devices is identified as having failed (No in operation S21), the processor is further configured to: in operation S22, identify the number of the plurality of devices as a variable A, and identify the selected safety voltage as a variable B. In this case, both A and B are variables used to calculate the target voltage of each device in operation S27.

[0086] Thereafter, if at least one device among the plurality of devices is identified as having failed (Yes in Operation S21), in Operation S23, the processor may identify the difference between the number of the plurality of devices and the number of the at least one device (i.e., the device that has failed) as a variable A. That is, the processor subtracts the number of failed devices from the total number of devices.

[0087] Thereafter, the processor is further configured to, in operation S24, identify whether voltage is being applied to at least one faulty device. If the voltage applied to at least one faulty device is zero (no in operation S24), there is no effect on the target voltage. In this case, in operation S25, the processor may identify the selected safety voltage as variable B. Here, if multiple devices have failed, the processor is further configured to identify the selected safety voltage as variable B only when the voltage applied to all normal devices is zero.

[0088] If a voltage (having a level greater than 0V and referred to as a first voltage) is applied to at least one faulty device (yes in operation S24), in operation S26, the processor may identify the difference between the selected safety voltage and the first voltage applied to the at least one device as a variable B. Here, if multiple devices have failed, the processor regards the sum of the voltages applied to all faulty devices as the first voltage. That is, the processor subtracts the voltage that is fixedly applied to the device due to the failure from the safety voltage.

[0089] Finally, in operation S27 , the processor may determine a target voltage for each device using the variable A and the variable B identified by the three cases.

[0090] For example, a method of obtaining a target voltage using the variables of operation S22 may be represented by Equation 1, and a method of obtaining a target voltage using the variables of operation S25 may be represented by Equation 3.

[0091] [Equation 3]

[0092]

[0093] (Safety voltage: selected safety voltage; k: number of multiple devices; Number of faults: number of faulty devices)

[0094] Similarly, a method of obtaining a target voltage using the variables of operation S26 may be represented by Equation 4.

[0095] [Equation 4]

[0096]

[0097] (Safety voltage: selected safety voltage; Fault voltage: voltage applied to a faulty device; k: number of multiple devices; Number of faults: number of faulty devices)

[0098] According to an embodiment of the present disclosure, the system's higher-level processor instructions allow for flexible responses based on module installation site conditions and the safety standards required by each country.

[0099] According to the embodiments of the present disclosure, even in the event of a device failure, a safe voltage condition can be satisfied by adjusting the target voltage, thereby achieving reliability.

[0100] Figure 6 is a diagram illustrating an example PV power generation system according to an embodiment.

[0101] As mentioned above Figure 1 As described, the system 1 may be configured such that a plurality of groups are connected in series, each of the plurality of groups including n PV modules 110 and n devices (where n is a natural number greater than or equal to 2).

[0102] The processor can determine the target voltage for each group in the group and can compare it with the above reference voltage. Figures 3 to 5 The same method described applies to the basic target voltage determination process.

[0103] However, if Figure 6 As shown, the determined target voltage corresponds to the target voltage of each group in the group. Therefore, in the event that any device in each group fails, the target voltage required between the devices in the group needs to be adjusted.

[0104] For example, if the processor is further configured to identify at least one faulty device among the n devices in each group, the processor can use the difference between n and the number of at least one faulty device to determine the target voltage for the remaining devices in each group. Mathematically, this is the same as Equation 3, except that n is used instead of k because the unit is group.

[0105] Furthermore, when a voltage (having a level greater than 0V and referred to as a second voltage) is applied to a faulty device in each group, the processor can determine the target voltages for the remaining devices using the difference between the target voltage for each group and the second voltage. Mathematically, this is the same as Equation 4, where n is used instead of k because the unit is group.

[0106] In the event that all devices in any group have failed, neither Equation 3 nor Equation 4 is applied, and the target voltage of each group is re-determined based on whether a voltage is applied to the corresponding group.

[0107] refer to Figure 6 ,The PV power generation system includes multiple groups, each group includes three PV modules and three devices.,The processor assigns the target voltage to the corresponding group according to the,safe voltage required by the system.

[0108] According to an embodiment of the present disclosure, even in the event that any one device in a group fails, the processor can adjust the target voltage to meet a safe voltage condition.

[0109] According to an embodiment of the present disclosure, a security function can be applied to a system that is extended to n device structures as well as 1 device structure.

[0110] In the following, reference Figure 7 Describe the subcircuits of the 3 device systems.

[0111] Figure 7 is a diagram illustrating an example sub-circuit of a device according to an embodiment.

[0112] refer to Figure 7 , shows three devices 710, 720, and 730 included in a group. The three devices 710, 720, and 730 share the target voltage required by the group by each taking one-third of the target voltage.

[0113] The subcircuits of devices 710, 720, and 730 are implemented as DC-DC converters, and each of devices 710, 720, and 730 controls the duty cycle of the DC-DC converter to reduce the applied output voltage Vpv of the PV module to target voltage / 3, i.e., one-third of the target voltage. The duty cycle is calculated in the same manner as described above using Equation 2. In this case, the target voltage in Equation 2 is replaced by target voltage / 3.

[0114] As mentioned above Figure 6 As described above, in the event that any one of the devices 710 , 720 , and 730 fails, it may be necessary to adjust the target voltage required between the devices in the group.

[0115] For example, if device 720 has failed, the processor can cause devices 710 and 730 to adjust their target voltages from target voltage / 3 to target voltage / 2. Here, if the second voltage is applied to device 720, the processor can cause the target voltages of devices 710 and 730 to adjust from target voltage / 3 to (target voltage-second voltage) / 2. For example, the processor can use Equations 3 and 4.

[0116] According to an embodiment of the present disclosure, a processor may adjust voltage only for a group including a faulty device, thereby reducing a calculation process and speeding up execution of a safety function.

[0117] The above method can be constructed as a program executable on a computer and can be implemented on a general-purpose digital computer that runs the program using a computer-readable recording medium. In addition, the data structure used in the above-described method can be recorded on a computer-readable recording medium in various ways. Computer-readable recording media include storage media, for example, magnetic storage media (for example, read-only memory (ROM), random access memory (RAM), universal serial bus (USB), floppy disk and hard disk), optical reading media (for example, compact disc read-only memory (CD-ROM) and digital versatile disc (DVD)), etc.

[0118] Those skilled in the art will appreciate that various modifications are possible without departing from the essential features of the present disclosure. Therefore, the disclosed method is to be regarded as illustrative rather than restrictive, and the scope of rights should be interpreted as being defined by the claims, rather than by the preceding description, and encompassing all equivalent differences.

Claims

1. A processor, the processor being configured to: While monitoring the operation, determine whether it is necessary to switch to safe mode; determining a target voltage for each device in the total number of devices connected to the photovoltaic PV module based on the number of devices and the selected safety voltage; and A shutdown signal is provided to each of the total devices so that an output voltage of each of the total devices is controlled to a target voltage.

2. The processor according to claim 1, wherein: In the event that at least one device in the total number of devices is identified as having failed, the processor is further configured to determine a target voltage for each device in the total number of devices using a difference between the number of the total number of devices and the number of the at least one failed device.

3. The processor according to claim 2, wherein: The processor is further configured to determine a target voltage for each of the total devices based on whether voltage is applied to the at least one faulty device.

4. The processor according to claim 3, wherein: In a case where a first voltage is applied to the at least one faulty device, the processor is further configured to determine a target voltage for each of the total devices using a difference between the safety voltage and the first voltage.

5. The processor according to claim 1, wherein: The PV modules and the overall device include a plurality of groups, each group including n PV modules and n devices, where n is a natural number greater than or equal to 2; and The processor is further configured to: determining a target voltage for each of the plurality of groups; and In a case where at least one device among n devices included in each group is identified as having failed, target voltages of remaining devices included in each group are determined using a difference between n and the number of the at least one failed device. The processor according to claim 5 , wherein: In a case where a second voltage is applied to the at least one faulty device, the processor is further configured to determine the target voltages of the remaining devices using a difference between the target voltage of each group and the second voltage.

7. The processor according to claim 1, wherein: When each device in the total device receives the shutdown signal, the processor is further configured to: control the duty cycle of the DC-DC converter using a duty cycle determined based on the output voltage of the PV modules respectively connected to the total device and the target voltage.

8. A method for performing a security function, the method comprising: While monitoring the operation, determine whether it is necessary to switch to safe mode; determining a target voltage for each device in the total number of devices connected to the photovoltaic PV module based on the number of devices and the selected safety voltage; as well as A shutdown signal is provided to each of the total devices so that an output voltage of each of the total devices is controlled to a target voltage.

9. The method according to claim 8, wherein In a case where at least one device in the total number of devices is identified as having failed, the determining includes determining a target voltage for each device in the total number of devices using a difference between the number of the total number of devices and the number of the at least one failed device.

10. The method according to claim 9, wherein: In the determination, A target voltage for each of the total devices is determined based on whether voltage is applied to the at least one faulty device.

11. The method according to claim 10, wherein: In a case where a first voltage is applied to the at least one faulty device, the determining includes determining a target voltage of each of the total devices using a difference between the safety voltage and the first voltage.

12. The method according to claim 9, wherein The PV modules and the overall device include a plurality of groups, each group including n PV modules and n devices, where n is a natural number greater than or equal to 2; and The method further comprises: determining a target voltage for each of the plurality of groups; and In a case where at least one device among n devices included in each group is identified as having failed, target voltages of remaining devices included in each group are determined using a difference between n and the number of the at least one failed device.

13. The method according to claim 12, wherein: In a case where a second voltage is applied to the at least one faulty device, determining the target voltages for the remaining devices includes determining the target voltages for the remaining devices using a difference between a target voltage for each group and the second voltage.

14. The method according to claim 8, further comprising: When each of the collective devices receives the shutdown signal, a duty cycle of a DC-DC converter is controlled using a duty cycle determined based on the output voltages of the PV modules respectively connected to the collective device and the target voltage. 15 . A computer-readable recording medium having recorded thereon a program for causing a computer to execute the method according to claim 8 .

Images