A photovoltaic system and control method

Abstract

The application discloses a photovoltaic system and a control method. The photovoltaic system comprises an inverter and a plurality of shutdown devices. An input end of each of the plurality of shutdown devices is connected to a corresponding photovoltaic string. Output ends of the plurality of shutdown devices are connected in series to an input end of the inverter. Each of the shutdown devices is configured to control the internal switch action by using a preset pulse signal when an internal fault is identified. There is no communication between each of the shutdown devices and the inverter. The inverter is configured to determine that a fault occurs in the shutdown device when a voltage fluctuation corresponding to the preset pulse signal is detected in the input voltage, and to perform an alarm. The shutdown device in the photovoltaic system does not need to establish communication with the inverter, so that a low-cost shutdown device can be used. Since the photovoltaic system includes a large amount of shutdown device data, the cost of the photovoltaic system can be reduced as a whole.

Description

Technical Field

[0001] This application relates to the field of new energy technology, specifically to a photovoltaic system and control method. Background Technology

[0002] A photovoltaic (PV) system typically includes PV strings, a switch, and an inverter. The switch enhances the system's safety. Generally, multiple switches connected in series are connected to the inverter's input, with each switch connected to a corresponding PV string. When the inverter is turned off, the switches open, disconnecting all PV modules in the connected string and placing the inverter's input in a safe, low-voltage state.

[0003] In photovoltaic (PV) systems with circuit breakers, there is no communication connection between the circuit breaker and the inverter. If the circuit breaker malfunctions or is incorrectly wired between the circuit breaker and the PV string, the PV system continues to operate, making it difficult to detect the abnormality. For example, if a wiring error in the circuit breaker causes a short circuit in one PV string, the entire PV system can still operate. Because there is no communication between the circuit breaker and the inverter, the inverter cannot recognize the fault, resulting in that PV string remaining in a short-circuit state, posing a safety hazard. Summary of the Invention

[0004] In view of this, this application provides a photovoltaic system and control method that can promptly notify the inverter when the power-off switch fails, thereby improving the safety of the photovoltaic system.

[0005] To address the aforementioned issues, this application provides a photovoltaic system comprising: an inverter and multiple shutdown devices;

[0006] The input of each of the multiple switch-off devices is connected to the corresponding photovoltaic string;

[0007] The outputs of multiple circuit breakers are connected in series to the input of the inverter.

[0008] Each shut-off switch is used to control the internal switching action with a preset pulse signal when an internal fault is detected.

[0009] There is no communication between each switch and the inverter;

[0010] The inverter is used to detect voltage fluctuations in the input voltage that correspond to a preset pulse signal, determine that the shutdown device has malfunctioned, and issue an alarm.

[0011] Optionally, each shut-off switch is used to control the internal switching action with a pulse signal of a preset frequency when an internal fault is detected.

[0012] Optionally, the inverter is specifically used to detect the amplitude and / or frequency of the input voltage to determine whether the voltage fluctuation corresponds to a preset pulse signal.

[0013] Optionally, the shutdown device is used to identify whether an internal fault has occurred based on the port voltage and / or port current;

[0014] Internal faults include wiring errors or device malfunctions.

[0015] Optionally, each switch connects to the following two photovoltaic strings: a first photovoltaic string and a second photovoltaic string;

[0016] The circuit breaker includes: a first switch, a second switch, a third switch, and a fourth switch;

[0017] The first terminal of the first switch is connected to the positive terminal of the first photovoltaic string, the second terminal of the first switch is connected to the first terminal of the second switch, and the second terminal of the second switch is connected to the negative terminal of the first photovoltaic string.

[0018] The second terminal of the first switch is connected to the first output terminal of the circuit breaker;

[0019] The first end of the third switch is connected to the positive end of the second photovoltaic string, the second end of the third switch is connected to the second end of the second switch, the second end of the third switch is connected to the first end of the fourth switch, and the second end of the fourth switch is connected to the negative end of the second photovoltaic string.

[0020] The second terminal of the fourth switch is connected to the second output terminal of the circuit breaker;

[0021] The voltage at the second output terminal of the shutdown device is less than the voltage at the first output terminal.

[0022] This application also provides a control method for a photovoltaic system, including: an inverter and a plurality of shutdown devices; the input terminal of each of the plurality of shutdown devices is connected to a corresponding photovoltaic string; the output terminals of the plurality of shutdown devices are connected in series and connected to the input terminal of the inverter; there is no communication between each shutdown device and the inverter;

[0023] The method includes:

[0024] When an internal fault is detected, each circuit breaker controls the internal switching action with a preset pulse signal.

[0025] When a voltage fluctuation corresponding to a preset pulse signal is detected in the input voltage, a fault is determined in the circuit breaker, and an alarm is triggered.

[0026] Optionally, the internal switching action is controlled by a preset pulse signal, specifically including:

[0027] The internal switching action is controlled by a pulse signal of preset frequency.

[0028] Optionally, detecting a voltage fluctuation in the input voltage corresponding to a preset pulse signal specifically includes:

[0029] The amplitude and / or frequency of the input voltage are detected to determine whether the voltage fluctuation corresponds to the preset pulse signal.

[0030] Optionally, it also includes:

[0031] The shutdown device identifies whether an internal fault has occurred based on the port voltage and / or port current.

[0032] Internal faults include wiring errors or device malfunctions.

[0033] Optionally, when a voltage fluctuation corresponding to a preset pulse signal is detected in the input voltage, a fault is determined to have occurred in the circuit breaker, specifically including:

[0034] When a square wave signal is detected in the input voltage, it is determined that the circuit breaker has malfunctioned.

[0035] Therefore, this application has the following beneficial effects:

[0036] The photovoltaic system provided in this application does not allow communication between the switch and the inverter. When the switch detects an internal fault, it controls its internal switching action with a preset pulse signal, causing the switch's output voltage to change regularly. Since the switch's output voltage affects the inverter's input voltage, this effectively informs the inverter that a fault has occurred within the switch. Specifically, when the inverter detects a voltage fluctuation in the input voltage corresponding to the preset pulse signal, it indicates that the switch is switching with the preset pulse signal, indicating a fault. The inverter can then issue an alarm promptly, enabling the photovoltaic system to quickly detect the internal fault in the switch and eliminate potential safety hazards. The switch in this photovoltaic system does not need to establish communication with the inverter, thus allowing the use of a low-cost switch. Because the photovoltaic system includes a large number of switch data points, the overall cost of the photovoltaic system can be reduced. Attached Figure Description

[0037] Figure 1 A schematic diagram of a photovoltaic system excluding a switch;

[0038] Figure 2 A schematic diagram of a photovoltaic system including a switch;

[0039] Figure 3 A schematic diagram of a photovoltaic system provided in this application embodiment;

[0040] Figure 4 A schematic diagram showing the correct connection between a switch and a photovoltaic module in an embodiment of this application;

[0041] Figure 5 A schematic diagram illustrating an incorrect connection between a switch and a photovoltaic module in an embodiment of this application;

[0042] Figure 6 A schematic diagram illustrating another incorrect connection between the switch and the photovoltaic module in an embodiment of this application;

[0043] Figure 7 This is a flowchart of a control method in a photovoltaic system provided in an embodiment of this application. Detailed Implementation

[0044] To enable those skilled in the art to better understand and implement the technical solutions of this application, specific application scenarios of this application are described below. The technical solutions provided in the embodiments of this application are applied to photovoltaic systems, and photovoltaic systems will be described first below.

[0045] See Figure 1 The figure is a schematic diagram of a photovoltaic system that does not include a power cut-off switch.

[0046] In this configuration, the positive terminal of photovoltaic string 1 is connected to the positive input terminal of the inverter, the negative terminal of photovoltaic string 1 is connected to the positive terminal of photovoltaic string 2, and so on, until the positive terminal of photovoltaic string n is connected, and the negative terminal of photovoltaic string n is connected to the negative input terminal of the inverter.

[0047] Regardless of whether the inverter is operational, the PV port voltage of the inverter is always the total voltage of the series-connected photovoltaic strings, which is a high-voltage condition. This continuous high-voltage condition at the inverter's PV port poses a certain safety hazard; therefore, a power cut-off switch is used to improve the safety of the photovoltaic system.

[0048] To ensure safety in photovoltaic systems, photovoltaic strings are typically connected to inverters via circuit breakers. One circuit breaker can connect to one photovoltaic string or multiple photovoltaic strings.

[0049] See Figure 2 The figure is a schematic diagram of a photovoltaic system including a switch.

[0050] The input terminal of the switch 1 is connected to the photovoltaic string 1, the positive output terminal of the switch 1 is connected to the positive input terminal of the inverter, the negative output terminal of the switch 1 is connected to the positive output terminal of the switch 2, and so on, until it is connected to the positive output terminal of the switch n, and the negative output terminal of the switch n is connected to the negative input terminal of the inverter.

[0051] When the inverter is working normally, the switch is in the ON state, and the photovoltaic system is working normally; when the inverter is turned off, the switch is open, and each component in the series photovoltaic string is disconnected by the switch, forming a safe low-voltage state at the PV port of the inverter.

[0052] However, there is no communication connection between the switch and the inverter. If the system can still work normally under abnormal conditions such as abnormal damage to the switch or incorrect wiring between the switch and the photovoltaic module, it will be difficult to detect the abnormality of the switch. This will cause the switch to continue to work in an abnormal state, which poses a safety hazard.

[0053] Therefore, this application uses the switching on of the circuit breaker controlled by the preset pulse signal as a danger signal. When the inverter detects the voltage fluctuation corresponding to the preset pulse signal, it will issue an alarm, which can promptly detect the abnormal state of the circuit breaker and eliminate potential safety hazards.

[0054] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0055] See Figure 3 The figure is a schematic diagram of a photovoltaic system provided in an embodiment of this application.

[0056] The photovoltaic system 1000 provided in this embodiment includes: an inverter 100, multiple turn-off devices, and multiple photovoltaic strings, for example, n turn-off devices and n photovoltaic strings, where n is an integer greater than or equal to 2. The n turn-off devices are: first turn-off device 201, second turn-off device 202, third turn-off device 203, up to the nth turn-off device 20n; the n photovoltaic strings are: first photovoltaic string PV1, second photovoltaic string PV2, third photovoltaic string PV3, up to the nth photovoltaic string PVn. Each turn-off device is connected to its corresponding photovoltaic string, and the output terminals of the n turn-off devices are connected in series. The following is a detailed description of the attached... Figure 3 Detailed description.

[0057] like Figure 3 As shown, the input terminal of the first switch 201 is connected to the first photovoltaic string PV1, the positive output terminal of the first switch 201 is connected to the positive input terminal of the inverter 100, the negative output terminal of the first switch 201 is connected to the positive output terminal of the second switch 202, the input terminal of the second switch 202 is connected to the second photovoltaic string PV2, the negative output terminal of the second switch 202 is connected to the positive output terminal of the third switch 203, and so on, until it is connected to the positive output terminal of the nth switch 20n, the input terminal of the nth switch 20n is connected to the nth photovoltaic string PVn, and the negative output terminal of the nth switch 20n is connected to the negative output terminal of the inverter 100.

[0058] Under the above connection method, when the circuit breaker is turned on, all photovoltaic strings are connected to the inverter, and the photovoltaic system works normally. When the circuit breaker is turned off, for example, when circuit breaker 202 is turned off, the photovoltaic string PV2 connected to circuit breaker 202 is disconnected from the inverter, that is, the energy of photovoltaic string PV2 cannot reach the input terminal of the inverter, and other photovoltaic strings connected to the inverter still work normally. When the inverter is turned off, all circuit breakers are turned off, and all photovoltaic strings are disconnected from the inverter, so that the PV port of the inverter is in a low voltage state, which is safer.

[0059] Since there is no communication between each shutdown device and the inverter 100 provided in this application embodiment, when the shutdown device fails, it cannot notify the inverter 100 of the failure through communication.

[0060] Each of the multiple shutdown devices is used to control the internal switching action with a preset pulse signal when an internal fault is detected.

[0061] Each shutdown device uses a preset pulse signal to control its internal switching action, thus informing the inverter that a shutdown device has malfunctioned. Therefore, there is no need for communication between the shutdown device and the inverter, reducing the cost of establishing a communication connection.

[0062] The circuit breaker can identify whether an internal fault has occurred based on the port voltage and / or port current. Internal faults can be caused by wiring errors or device malfunctions. For example, wiring errors may include incorrect circuit breaker wiring leading to a short circuit in the photovoltaic string, while device malfunctions may involve a faulty switching transistor inside the circuit breaker.

[0063] See Figure 4 The diagram shows a correct connection between a circuit breaker and a photovoltaic module.

[0064] Each switch connects to the following two photovoltaic strings: the first photovoltaic string PV1 and the second photovoltaic string PV2, meaning that one switch can connect two photovoltaic strings in series.

[0065] The circuit breaker 200 includes: a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4.

[0066] The specific connection method between the switch 200 and the photovoltaic string is as follows:

[0067] The first terminal of the first switch Q1 is connected to the IN1+ terminal of the circuit breaker 200. The positive terminal PV+ of the first photovoltaic string PV1 is connected to the IN1+ terminal of the circuit breaker 200. The second terminal of the first switch Q1 is connected to the first terminal of the second switch Q2. The second terminal of the second switch Q2 is connected to the IN1- terminal of the circuit breaker 200. The negative terminal PV- of the first photovoltaic string PV1 is connected to the IN1- terminal of the circuit breaker 200.

[0068] The second terminal of the first switch Q1 is connected to the OUT+ terminal of the circuit breaker 200. The first output terminal of the circuit breaker 200 is connected to the OUT+ terminal of the circuit breaker 200.

[0069] The first terminal of the third switch Q2 is connected to the IN2+ terminal of the circuit breaker 200. The positive terminal PV+ of the second photovoltaic string PV2 is connected to the IN2+ terminal of the circuit breaker 200. The second terminal of the third switch Q3 is connected to the second terminal of the second switch Q2. The second terminal of the third switch Q3 is connected to the first terminal of the fourth switch. The second terminal of the fourth switch Q4 is connected to the IN2- terminal of the circuit breaker 200. The negative terminal PV- of the second photovoltaic string PV2 is connected to the IN2- terminal of the circuit breaker 200.

[0070] The second terminal of the fourth switch Q4 is connected to the OUT- terminal of the circuit breaker 200. The second output terminal of the circuit breaker 200 is connected to the OUT- terminal of the circuit breaker 200.

[0071] The following examples illustrate several scenarios of incorrect circuit breaker wiring. (See below) Figure 5 The diagram shows an incorrect connection between a circuit breaker and a photovoltaic module.

[0072] The difference from the correct wiring method is that the negative terminal PV- of the first photovoltaic string PV1 is connected to the OUT+ terminal of the switch 200, and the first output terminal of the switch 200 is connected to the IN1- terminal of the switch 200. Because the first terminal of the first switch is connected to the positive terminal PV+ of the first photovoltaic string PV1 through the IN1+ terminal of the switch 200, and the second terminal of the first switch is connected to the negative terminal PV- of the first photovoltaic string PV1 through the OUT+ terminal of the switch 200, the first photovoltaic string PV1 is short-circuited.

[0073] See Figure 6 The diagram shows another example of an incorrect connection between the circuit breaker and the photovoltaic module string.

[0074] The difference from the correct wiring method is that the positive terminal PV+ of the second photovoltaic string PV2 is connected to the IN1+ terminal of the switch 200, and the positive terminal PV+ of the first photovoltaic string PV1 is connected to the IN2+ terminal of the switch 200. Because the first terminal of the third switch is connected to the positive terminal PV+ of the first photovoltaic string PV1 through the IN2+ terminal of the switch 200, the second terminal of the third switch is connected to the second terminal of the second switch, and the second terminal of the second switch is connected to the negative terminal PV- of the first photovoltaic string PV1 through the IN1- terminal of the switch 200, the first photovoltaic string PV1 is short-circuited.

[0075] When an internal fault occurs in the circuit breaker, the circuit breaker controls its internal switching action with a preset pulse signal. This changes the circuit breaker's output voltage so that the inverter can identify the input voltage and determine if a fault has occurred. The preset pulse signal can be implemented in several ways; for example, it can be set with a preset frequency, or no preset frequency can be set.

[0076] Inverter 100 is used to detect a voltage fluctuation in the input voltage corresponding to a preset pulse signal, determine that the shutdown device has malfunctioned, and issue an alarm.

[0077] Since the inverter 100 has a predefined preset pulse signal, when the inverter 100 detects a voltage fluctuation in the input voltage corresponding to the preset pulse signal, it indicates that the circuit breaker has malfunctioned. The circuit breaker switches on and off using the preset pulse signal to cause voltage fluctuations; therefore, the inverter can determine that the circuit breaker has malfunctioned.

[0078] The inverter 100 can determine whether the voltage fluctuation corresponds to the preset pulse signal by detecting the amplitude and / or frequency of the input voltage.

[0079] To enable those skilled in the art to better understand the technical solution of this application, the following is an explanation with reference to a specific example. For example, inverter 100 is connected to 10 switch-off devices, and each switch-off device corresponds to a photovoltaic string, that is, it corresponds to 10 photovoltaic strings.

[0080] Assuming the voltage of each photovoltaic string is 20V, then when the photovoltaic system is working normally, the input voltage of the inverter should be 20V×10=200V.

[0081] If a circuit breaker detects an internal fault, a preset pulse signal, such as a square wave with a frequency of 50Hz, is used to control the switching action inside the faulty circuit breaker.

[0082] When the switch is turned on, the photovoltaic string connected to it is normally connected to the photovoltaic system, and the inverter's input voltage is 200V; when the switch is turned off, the photovoltaic string connected to it is not connected to the photovoltaic system, so the inverter's input voltage is 20V×9=180V.

[0083] Since the switching of the circuit breaker is controlled by a periodic preset pulse signal, the input voltage of the inverter should also be periodic, with the amplitude changing between 180V and 200V with a period of 1 / 50Hz = 0.2s, and the waveform is similar to a square wave.

[0084] The photovoltaic system provided in this application does not allow communication between the switch and the inverter. When the switch detects an internal fault, it controls its internal switching action with a preset pulse signal, causing the switch's output voltage to change regularly. Since the switch's output voltage affects the inverter's input voltage, this effectively informs the inverter that a fault has occurred within the switch. Specifically, when the inverter detects a voltage fluctuation in the input voltage corresponding to the preset pulse signal, it indicates that the switch is switching with the preset pulse signal, indicating a fault. The inverter can then issue an alarm promptly, enabling the photovoltaic system to quickly detect the internal fault in the switch and eliminate potential safety hazards. The switch in this photovoltaic system does not need to establish communication with the inverter, thus allowing the use of a low-cost switch. Because the photovoltaic system includes a large number of switch data points, the overall cost of the photovoltaic system can be reduced.

[0085] Based on the photovoltaic system provided in the above embodiments, this application also provides a control method in the photovoltaic system, which will be described in detail below with reference to the accompanying drawings.

[0086] See Figure 7 The figure is a flowchart of a control method in a photovoltaic system provided in an embodiment of this application.

[0087] The control method in the photovoltaic system provided in this embodiment is applied to the photovoltaic system described in the above embodiments. The photovoltaic system includes: an inverter, multiple turn-off devices, and multiple photovoltaic strings. The input terminal of each turn-off device is connected to the corresponding photovoltaic string. The output terminals of the turn-off devices are connected in series and connected to the input terminal of the inverter. There is no communication between each turn-off device and the inverter.

[0088] The method includes:

[0089] S701: The shut-off device identifies whether an internal fault has occurred. If so, proceed to step S702.

[0090] The circuit breaker identifies whether an internal fault has occurred, specifically by using port voltage and / or port current to determine if an internal fault has occurred. For example, port voltage may include input voltage and / or output voltage, and port current may include input current and / or output current.

[0091] Internal faults can specifically include: wiring errors or device malfunctions.

[0092] S702: The shut-off device controls the internal switching action with a preset pulse signal.

[0093] The circuit breaker controls the internal switching action with a preset pulse signal, specifically including: the circuit breaker controls the internal switching action with a preset pulse signal of a preset frequency.

[0094] S703: The inverter detects whether the input voltage shows a voltage fluctuation corresponding to the preset pulse signal. If so, proceed to step S704.

[0095] The inverter detects whether the input voltage shows a voltage fluctuation corresponding to a preset pulse signal. Specifically, this can include: detecting the amplitude and / or frequency of the input voltage to determine whether the voltage fluctuation corresponds to the preset pulse signal.

[0096] S704: The inverter detects a fault in the shutdown device and issues an alarm.

[0097] The inverter detects whether the input voltage shows a voltage fluctuation corresponding to a preset pulse signal to determine if the shutdown device has malfunctioned. Specifically, this can include: when the inverter detects a square wave signal in the input voltage, it determines that the shutdown device has malfunctioned.

[0098] The control method in the photovoltaic system provided in this application embodiment, when communication between the switch-off device and the inverter is impossible, allows the switch-off device to control its internal switching action with a preset pulse signal when an internal fault is detected. This causes the output voltage of the switch-off device to change regularly. Since the output voltage of the switch-off device affects the input voltage of the inverter, it is equivalent to the switch-off device informing the inverter that an internal fault has occurred. Specifically, when the inverter detects a voltage fluctuation in the input voltage corresponding to the preset pulse signal, it indicates that the switch-off device is switching with the preset pulse signal, indicating a fault. The inverter can then issue an alarm in a timely manner, enabling the photovoltaic system to quickly detect the internal fault of the switch-off device and eliminate potential safety hazards. The switch-off device in this photovoltaic system does not need to establish communication with the inverter, thus allowing the use of a low-cost switch-off device. Because the photovoltaic system includes a large amount of switch-off data, the overall cost of the photovoltaic system can be reduced.

[0099] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photovoltaic system, characterized in that, include: Inverter and multiple shutdown devices; The input terminal of each of the plurality of switch-off devices is connected to the corresponding photovoltaic string. The output terminals of the plurality of shut-off devices are connected in series and then connected to the input terminal of the inverter. Each of the circuit breakers is used to control the internal switching action with a preset pulse signal when an internal fault is detected, to connect or disconnect the corresponding photovoltaic string and change the input voltage of the inverter. There is no communication between each of the shutdown devices and the inverter; The inverter is used to detect a voltage fluctuation in the input voltage corresponding to the preset pulse signal, determine that the shutdown device has malfunctioned, and issue an alarm.

2. The photovoltaic system according to claim 1, characterized in that, Each of the circuit breakers is used to control the internal switching action with a pulse signal of a preset frequency when an internal fault is detected.

3. The photovoltaic system according to claim 1, characterized in that, The inverter is specifically used to detect the amplitude and / or frequency of the input voltage to determine whether the voltage fluctuation corresponds to the preset pulse signal.

4. The photovoltaic system according to claim 1, characterized in that, The shutdown device is used to identify whether an internal fault has occurred based on the port voltage and / or port current. The internal faults include wiring errors or device malfunctions.

5. The photovoltaic system according to any one of claims 1-4, characterized in that, Each switch is connected to the following two photovoltaic strings: the first photovoltaic string and the second photovoltaic string; The shut-off device includes: a first switch, a second switch, a third switch, and a fourth switch; The first end of the first switch is connected to the positive end of the first photovoltaic string, the second end of the first switch is connected to the first end of the second switch, and the second end of the second switch is connected to the negative end of the first photovoltaic string. The second end of the first switch is connected to the first output end of the circuit breaker. The first end of the third switch is connected to the positive end of the second photovoltaic string, the second end of the third switch is connected to the second end of the second switch, the second end of the third switch is connected to the first end of the fourth switch, and the second end of the fourth switch is connected to the negative end of the second photovoltaic string. The second terminal of the fourth switch is connected to the second output terminal of the shut-off device; The voltage at the second output terminal of the switch is less than the voltage at the first output terminal.

6. A control method for a photovoltaic system, characterized in that, include: An inverter and multiple turn-off devices; the input of each of the multiple turn-off devices is connected to the corresponding photovoltaic string; The output terminals of the plurality of shutdown devices are connected in series and then connected to the input terminal of the inverter; there is no communication between each shutdown device and the inverter; The method includes: When each switch detects an internal fault, it controls the internal switching action with a preset pulse signal to connect or disconnect the corresponding photovoltaic string, thereby changing the input voltage of the inverter. When a voltage fluctuation corresponding to the preset pulse signal is detected in the input voltage, it is determined that the circuit breaker has malfunctioned and an alarm is triggered.

7. The method according to claim 6, characterized in that, The control of internal switching actions by a preset pulse signal specifically includes: The internal switching action is controlled by a pulse signal of preset frequency.

8. The method according to claim 6, characterized in that, The detection of a voltage fluctuation in the input voltage corresponding to the preset pulse signal specifically includes: The amplitude and / or frequency of the input voltage are detected to determine whether the voltage fluctuation corresponds to the preset pulse signal.

9. The method according to claim 6, characterized in that, Also includes: The shutdown device identifies whether an internal fault has occurred based on the port voltage and / or port current. The internal faults include wiring errors or device malfunctions.

10. The method according to any one of claims 6-9, characterized in that, When a voltage fluctuation corresponding to the preset pulse signal is detected in the input voltage, it is determined that the shut-off device has malfunctioned, specifically including: When a square wave signal is detected in the input voltage, it is determined that the shutdown device has malfunctioned.

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