Device for performing safety function and photovoltaic system including the same

Abstract

A device for performing a safety function of a photovoltaic power generation system according to one embodiment of the present invention comprises: a safety function circuit including a switching element and a first resistor connected in parallel; and a second resistor connected in series to the parallel connection of the switching element and the first resistor; and a processor for controlling the safety function circuit according to the state of the photovoltaic power generation system, wherein, when switching to a safety mode is required, the processor inputs an off signal to the switching element to convert and output the output voltage of at least one PV (Photovoltaic) module applied to the safety function circuit into a safety voltage.

Description

Technology Field

[0001] The present invention relates to a safety function performing device and a photovoltaic power generation system including the same. Background Technology

[0002] It is essential for solar power generation systems to ensure stability by identifying potential abnormal conditions and emergency situations in real time during operation. In the event of an emergency, solar power systems must be equipped with safety functions that cut off the output of Photovoltaic (PV) modules for safety and control the voltage to below the safety voltage within a specific time frame, in accordance with the requirements of each country and product. In this regard, as global standards for industrial safety become more diverse, there is a growing trend requiring Rapid Shutdown (RSD) functions in solar power generation systems.

[0003] Meanwhile, recent solar power generation systems are introducing module-level power conversion devices (or module-level power control devices) (Module Level Power Electronics, MLPE), such as DC optimizers, to improve the performance of PV modules under specific conditions, such as when shading occurs, and to increase power production efficiency.

[0004] Currently, when an MLPE is provided, the output voltage of a PV module can be converted to a safe voltage by controlling the switching elements of a buck converter. In this case, a Pulse Width Modulation (PWM) controller must be provided to control the switching elements; however, if the PWM controller fails or an error occurs in the control algorithm, there are limitations in outputting and controlling the safe voltage. Furthermore, since the PWM controller and the switching elements are semiconductor integrated circuits (ICs), control and circuit implementation are not simple.

[0005] In the absence of an MLPE, the output voltage of the PV module can be converted to a safe voltage by controlling a separate regulator such as an LDO (Low Dropout). This method also uses semiconductor integrated circuits (ICs), so its configuration is complex, and there are limitations in outputting and controlling the safe voltage in abnormal conditions.

[0006] Therefore, there is a need to introduce a device that can reliably output a safe voltage in emergency situations and performs safety functions that are relatively easy to implement. The problem to be solved

[0007] The objective of the present invention is to provide a safety function performing device capable of performing safety functions more stably in emergency situations, and a photovoltaic power generation system including the same.

[0008] The objective of the present invention is to provide a safety function performing device capable of easily performing safety functions without complex configurations such as integrated circuits, and a photovoltaic power generation system including the same. means of solving the problem

[0009] A device for performing a safety function of a photovoltaic power generation system according to one embodiment of the present invention comprises: a safety function circuit including a switching element and a first resistor connected in parallel; and a second resistor connected in series to the parallel connection of the switching element and the first resistor; and a processor for controlling the safety function circuit according to the state of the photovoltaic power generation system, wherein, when switching to a safety mode is required, the processor inputs an off signal to the switching element to convert and output the output voltage of at least one PV (Photovoltaic) module applied to the safety function circuit into a safety voltage.

[0010] The above safety function circuit can output a safety voltage across the second resistor as the switching element turns off.

[0011] The above safety function circuit further includes a diode connected in series with the second resistor, and the safety function circuit can output a safety voltage applied to the second resistor and the diode as the switching element turns off.

[0012] The processor can monitor the status of the photovoltaic power generation system and identify whether a switch to the safety mode is required.

[0013] The first resistor has a resistance value greater than the second resistor.

[0014] In a photovoltaic power generation system according to one embodiment of the present invention, a plurality of safety function performing devices each comprising: a plurality of PV (Photovoltaic) modules; a switching element and a first resistor connected in parallel; a second resistor connected in series to the parallel connection of the switching element and the first resistor; and a processor that controls the safety function circuit according to the state of the photovoltaic power generation system; wherein each of the safety function performing devices inputs an off signal to the switching element to convert and output the output voltage of at least one PV module applied to the safety function circuit into a safety voltage when switching to a safety mode is required. Effects of the invention

[0015] According to one embodiment of the present invention, a safe voltage is output through a simple principle called the voltage divider rule using a resistor, thereby allowing the safety function to be performed safely without configuring a complex circuit.

[0016] According to one embodiment of the present invention, since the circuit utilizes the simple semiconductor characteristics of a diode, the safety voltage level can be easily adjusted and set in accordance with the forward characteristics of the diode.

[0017] According to one embodiment of the present invention, the safety function performing device can be operated stably without imposing a burden, such as power loss, on the entire system.

[0018] According to one embodiment of the present invention, a safe voltage can be output using simple semiconductor characteristics, bypassing the complex algorithm for setting a safe voltage through the control of a PWM controller.

[0019] According to one embodiment of the present invention, thanks to circuit features, instability in safety voltage control that may occur due to complex control algorithms and defects in semiconductor integrated circuits can be resolved.

[0020] According to one embodiment of the present invention, the required safety voltage level can be designed simply to match the diode's forward characteristics, allowing for agile circuit modifications in accordance with safety requirements from the market and users in the future. Brief explanation of the drawing

[0021] FIG. 1 is a schematic diagram illustrating a photovoltaic power generation system according to one embodiment of the present invention. FIG. 2 is a block diagram illustrating the configuration of a safety function performing device according to one embodiment of the present invention. FIG. 3 is a diagram illustrating a safety function circuit according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating a safety function circuit according to a second embodiment of the present invention. FIG. 5 is a diagram illustrating the operation flowchart of a safety function performing device according to one embodiment of the present invention. Specific details for implementing the invention

[0022] Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present invention and is not intended to represent the only embodiment in which the present invention can be practiced. In order to clearly explain the present invention in the drawings, parts unrelated to the description may be omitted, and the same reference numerals may be used for identical or similar components throughout the specification.

[0023] FIG. 1 is a schematic diagram illustrating a photovoltaic power generation system according to one embodiment of the present invention.

[0024] Referring to FIG. 1, the photovoltaic power generation system (1) includes a PV module (110) and a safety function performing device (120).

[0025] According to one embodiment of the present invention, the PV module (110) is a module that produces electricity using sunlight and may be provided in multiple numbers.

[0026] According to one embodiment of the present invention, the safety function performing device (120) is a device that converts the output voltage of a connected PV module (110) into a predefined safety voltage when an emergency situation occurs. The specific configuration of the safety function performing device (120) is described with reference to FIGS. 2 to 4.

[0027] The PV module (110) and the safety function performing device (120) can be connected in a one-to-one correspondence as shown in FIG. 1, but in addition to this, they can be installed in a many-to-one or many-to-many manner depending on the structure adopted by the photovoltaic power generation system (1), and the installation form is not limited to any one. In another embodiment, a group consisting of n PV modules (n is a natural number greater than or equal to 2) and n safety function performing devices (120) can be configured in a form in which multiple groups are connected in series.

[0028] Although not shown in FIG. 1, the photovoltaic power generation system (1) may include an MLPE, an inverter, and a grid.

[0029] According to one embodiment of the present invention, the MLPE can be implemented as a DC Optimizer, configured to be connected to a PV module (110) and to optimize the output power (output voltage) of the connected PV module (110).

[0030] A safety function performing device (120) according to one embodiment of the present invention may share resources such as a processor embedded in the MLPE. Accordingly, the MLPE may also be connected in a one-to-one correspondence with the PV module (110), just like the safety function performing device (120), but may be installed in a many-to-one or many-to-many manner depending on the structure adopted by the photovoltaic power generation system (1), and the installation form is not limited to any one.

[0031] MLPEs are provided in multiple numbers and connected in series with each other, and inverters are connected to both ends of the multiple MLPEs connected in series.

[0032] According to one embodiment of the present invention, the inverter is configured to be installed in a PCS (Power Conversion System) and perform power conversion to supply power produced from a PV module (110) to a load or grid.

[0033] The safety function execution device (120), MLPE, or inverter monitors the operating status of the photovoltaic power generation system (1) by analyzing various data received from the PV module (110), MLPE, load, grid, etc. If an abnormal situation occurs during monitoring, that is, if a switch to safety mode is required, the safety function execution device (120) can be used to output a safety voltage.

[0034] In the present invention, a safety function performing device (120) capable of stably performing safety functions according to standards and easily performing safety functions without complex configurations such as integrated circuits, and a photovoltaic power generation system (1) including the same are proposed.

[0035] Hereinafter, the configuration and operation of a safety function performing device (120) according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0036] FIG. 2 is a block diagram illustrating the configuration of a safety function performing device according to one embodiment of the present invention.

[0037] According to one embodiment of the present invention, a safety function performing device (120) includes a safety function circuit (121) and a processor (122).

[0038] The safety function circuit (121) is a circuit that converts the output voltage of the PV module (110) into a safe voltage, and its specific configuration is explained with reference to FIGS. 3 and FIGS. 4.

[0039] The processor (122) is configured to control the safety function circuit (121) according to the state of the photovoltaic power generation system (1). The processor (122) may be a control device separately provided to perform the safety function of the safety function execution device (120), but is not limited thereto and may be a processor of an MLPE as described above. If the processor (122) is a processor of an MLPE, the internal configuration may be simpler and costs may be reduced. Hereinafter, for convenience of explanation, the processor (122) is described as a processor of an MLPE.

[0040] The processor (122) may include, for example, a power control MCU (Microcontroller Unit). The processor (122) can execute software, such as a program, to control at least one other component (e.g., a hardware or software component) of the safety function performing device (120) and MLPE, and can perform various data processing or operations.

[0041] The processor (122) can receive control signals, shutdown signals, etc. required for power optimization by communicating serially with the inverter or performing Power Line Communication (PLC).

[0042] At this time, the processor (122) may receive a shutdown signal from an inverter that monitors the overall operating status of the photovoltaic power generation system (1), but is not limited thereto.

[0043] For example, the processor (122) can generate a shutdown signal by detecting an abnormal situation by monitoring the operating status of each MLPE. Specifically, the processor (122) can also monitor the operating status by analyzing internal operation data of the MLPE or various data received from the PV module (110), load, grid, etc., and generate a shutdown signal when an abnormal situation occurs.

[0044] FIG. 3 is a diagram illustrating a safety function circuit according to the first embodiment of the present invention.

[0045] The safety function circuit (1211) of FIG. 3 is connected to at least one PV module (110) when switching to safety mode, and the output voltage (V) of the PV module (110) pv ) receives as input and safe voltage (V safety voltage Outputs as ).

[0046] The safety function circuit (1211) according to the present embodiment consists of a switching element (SW), a first resistor (R1), and a second resistor (R2). The switching element (SW) and the first resistor (R1) are connected in parallel, and the second resistor (R2) is connected in series to the parallel connection of the switching element (SW) and the first resistor (R1).

[0047] At this time, the position between the parallel connection of the switching element (SW) and the first resistor (R1) and the second resistor (R2) is not limited to any one. For example, in addition to the safety function circuit (1211) shown in FIG. 3, the parallel connection of the switching element (SW) and the first resistor (R1) can be placed on a line connected to the positive (+) output terminal of the PV module (110).

[0048] At this time, the switching element (SW) can be implemented as a FET (Field Effect Transistor), BJT (Bipolar Junction Transistor), etc., and in addition, it can be applied without limitation if it can be turned on or off by the control of the processor (122).

[0049] The processor (122) can control the safety function circuit (1211) according to the state of the photovoltaic power generation system (1). If switching to a safety mode is required, the processor (122) can input an off signal to the switching element (SW).

[0050] When the switching element (SW) is turned off, the output voltage (V) of the PV module (110) applied to the safety function circuit (1211) pv ) is distributed in proportion to the resistance values ​​of the first resistor (R1) and the second resistor (R2). The safety function circuit (1211) can output a safety voltage applied to the second resistor (R2) as the switching element (SW) operates off.

[0051] That is, the voltage across the second resistor (R2) is the safe voltage (V safety voltage As it is output as ), the resistance values ​​of the first resistor (R1) and the second resistor (R2) can be determined by considering the specifications for the safe voltage output of the photovoltaic power generation system (1) and the structure of the photovoltaic power generation system (1), and the first resistor (R1) can have a much larger resistance value than the second resistor (R2).

[0052] According to one embodiment of the present invention, a safe voltage is output through a simple principle called the voltage divider rule using a resistor, thereby allowing the safety function to be performed safely without configuring a complex circuit.

[0053] According to one embodiment of the present invention, thanks to circuit features, instability in safety voltage control that may occur due to complex control algorithms and defects in semiconductor integrated circuits (ICs) can be eliminated.

[0054] According to one embodiment of the present invention, when the output voltage range of a PV module is high, sufficient safe voltage control is possible using only resistor distribution.

[0055] FIG. 4 is a diagram illustrating a safety function circuit according to a second embodiment of the present invention.

[0056] The safety function circuit (1212) of FIG. 4 differs from the safety function circuit (1211) of FIG. 3 in that it further includes a diode (D). Therefore, the first resistor (R1), the second resistor (R2), and the switching element (SW) of the safety function circuit (1212) are identical to those of the safety function circuit (1211) of FIG. 3, so the specific description borrows from the description of FIG. 3 and focuses on the differences.

[0057] The diode (D) according to the present embodiment is connected in parallel with the switching element (SW) and the first resistor (R1), and in series with the second resistor (R2).

[0058] Similar to FIG. 3, the positions between the parallel connection of the switching element (SW) and the first resistor (R1) and the series connection of the second resistor (R2) and the diode (D) are not limited to either one. For example, in addition to the safety function circuit (1212) shown in FIG. 4, the parallel connection of the switching element (SW) and the first resistor (R1) can be placed on a line connected to the positive (+) output terminal of the PV module (110). Furthermore, the positions of the second resistor (R2) and the diode (D) are not limited to FIG. 4, and it is possible for their arrangement to be interchanged.

[0059] Likewise, the processor (122) can input an off signal to the switching element (SW) if it is necessary to switch to safe mode.

[0060] When the switching element (SW) is turned off, the output voltage (V) of the PV module (110) applied to the safety function circuit (1212) pv ) is distributed in proportion to the resistance values ​​of the first resistor (R1), the second resistor (R2), and the diode (D).

[0061] At this time, the output safety voltage (V safety voltage) is the sum of the forward voltage of the diode (D) and the voltage distributed to the second resistor (R2). That is, the safety function circuit (1212) can output a safety voltage across the second resistor (R2) and the diode (D) as the switching element (SW) turns off.

[0062] Accordingly, the resistance values ​​of the first resistor (R1) and the second resistor (R2) can be determined by considering the resistance value of the diode (D), the specifications for the safe voltage output of the photovoltaic power generation system (1), and the structure of the photovoltaic power generation system (1), and likewise, the first resistor (R1) can have a much larger resistance value than the second resistor (R2).

[0063] Meanwhile, generally, PV modules (panels) have an output voltage (V) depending on product characteristics such as manufacturer and material. pv )(In particular, maximum output voltage (V oc Since )) are different, the output voltage (V) of the PV module applied to the safety function performing device (120) according to the target PV module is different. pv The range is different.

[0064] When the safety function performing device (120) is equipped with a diode (D), since the forward voltage of the diode (D) is constant, the safety function performing device (120) has a required safety voltage (V) regardless of the manufacturer or product characteristics of the PV module (110). safety voltage It can reliably output ).

[0065] According to one embodiment of the present invention, since the circuit utilizes the simple semiconductor characteristics of a diode, the safety voltage level can be easily adjusted and set in accordance with the forward characteristics of the diode.

[0066] According to one embodiment of the present invention, since the voltage value applied to the diode has a constant value, it can be output more easily to match the magnitude of the safe voltage regardless of the PV module.

[0067] According to one embodiment of the present invention, a safe voltage can be output using simple semiconductor characteristics, bypassing the complex algorithm for setting a safe voltage through the control of a PWM controller.

[0068] According to one embodiment of the present invention, the required safety voltage level can be designed simply to match the diode's forward characteristics, allowing for agile circuit modifications in accordance with safety requirements from the market and users in the future.

[0069] FIG. 5 is a diagram illustrating the operation flowchart of a safety function performing device according to one embodiment of the present invention.

[0070] According to one embodiment of the present invention, the processor (122) identifies whether a switch to safe mode is required (S10).

[0071] The processor (122) monitors the status of the photovoltaic power generation system (1) and can identify whether a transition to a safety mode is necessary depending on whether an abnormal situation occurs. At this time, the safety mode may include an RSD mode.

[0072] In addition, the processor (122) can identify that switching to safety mode is required when it receives a shutdown signal from the inverter.

[0073] Additionally, the safety function performing device (120) according to one embodiment of the present invention can be used to check whether the DC optimizer is faulty even when there is no emergency situation. In this case, it is switched to a safety mode through operation by a manager, such as an installer, and the fault of the DC optimizer can be checked through the safety voltage output by the safety function performing device (120).

[0074] If it is identified that a safe mode switch is required (Yes in S10), the processor (122) inputs an off signal to the switching element (SW).

[0075] As the switching element (SW) turns off, the previously described safety function circuit (1211) outputs a safety voltage across the second resistor (R2), and the safety function circuit (1212) outputs a safety voltage across the second resistor (R2) and the diode (D).

[0076] If it is not identified that a safety mode switch is required (No of S10), this algorithm is terminated. When the photovoltaic power generation system (1) is operating normally, the switching element (SW) of the safety function circuit (1211, 1212) is basically in ON operation.

[0077] When the switching element (SW) is turned on, the switching element (SW) has an ON resistance (R), which is the resistance value between the drain and source. DS(ON) has ).

[0078] Since the first resistor (R1) and the switching element (SW) are in a parallel relationship, the combined resistance has a value smaller than the ON resistance (a very small value), so the output voltage of the PV module (110) is applied directly to the second resistor (R2). That is, when the switching element (SW) is turned ON, the safety function execution device (120) does not affect the entire photovoltaic power generation system (1).

[0079] According to one embodiment of the present invention, the safety function performing device can be operated stably without imposing a burden, such as power loss, on the entire system. Explanation of the symbols

[0080] 1: Solar power generation system 110: PV Module 120: Safety function performing device 121: Safety function circuit 122: Processor

Claims

Claim 1 A safety function performing device for a photovoltaic power generation system, comprising: a safety function circuit including a switching element and a first resistor connected in parallel; and a second resistor connected in series to the parallel connection of the switching element and the first resistor; and a processor that controls the safety function circuit according to the state of the photovoltaic power generation system, wherein, when switching to a safety mode is required, the processor inputs an off signal to the switching element to convert and output the output voltage of at least one PV (Photovoltaic) module applied to the safety function circuit into a safety voltage, and the safety function circuit outputs a safety voltage applied to the second resistor as the switching element operates off, and the safety voltage is determined in proportion to the resistance values ​​of the first resistor and the second resistor. Claim 2 delete Claim 3 In claim 1, the safety function circuit further includes a diode connected in series with the second resistor, and the safety function circuit is a safety function performing device that outputs a safety voltage across the second resistor and the diode as the switching element is turned off. Claim 4 In claim 1, the processor is a safety function performing device that monitors the state of the photovoltaic power generation system and identifies whether a transition to the safety mode is required. Claim 5 A safety function performing device according to claim 1, wherein the first resistor has a resistance value greater than the second resistor. Claim 6 A photovoltaic power generation system comprising: a plurality of photovoltaic (PV) modules; a safety function circuit including a switching element and a first resistor connected in parallel; and a second resistor connected in series to the parallel connection of the switching element and the first resistor; and a plurality of safety function performing devices each comprising a processor that controls the safety function circuit according to the state of the photovoltaic power generation system; wherein, when switching to a safety mode is required, each safety function performing device inputs an off signal to the switching element to convert and output the output voltage of at least one PV module applied to the safety function circuit into a safety voltage, and the safety function circuit outputs a safety voltage applied to the second resistor as the switching element operates off, and the safety voltage is determined in proportion to the resistance values ​​of the first resistor and the second resistor. Claim 7 delete Claim 8 In claim 6, the safety function circuit further includes a diode connected in series with the second resistor, and the safety function circuit outputs a safety voltage across the second resistor and the diode as the switching element is turned off. Claim 9 In claim 6, the processor monitors the state of the photovoltaic power generation system and identifies whether a transition to the safety mode is required. Claim 10 In claim 6, a photovoltaic power generation system in which the first resistance has a resistance value greater than the second resistance.

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