MLPE equipment, control method thereof and photovoltaic system

Abstract

The invention provides MLPE equipment, a control method thereof and a photovoltaic system, and the MPLE equipment considers that signal reception is abnormal when judging that heartbeat signals are continuously interrupted and received from a first time point to a second time point. If the output current is smaller than the current threshold value, it is indicated that a safe turn-off scene is needed, and the output voltage is controlled to be smaller than the voltage threshold value or the output power is controlled to be smaller than the power threshold value. If it is judged that the output current is larger than or equal to the current threshold value, it is indicated that output can be kept in a communication signal unstable scene, and the output voltage is controlled to be larger than or equal to the voltage threshold value or the output power is controlled to be larger than or equal to the power threshold value from the second time point to the third time point so as to prolong the output time of the photovoltaic system; and the effective hours of the photovoltaic system are improved. And if the heartbeat signal is continuously interrupted and received from the second time point to the third time point, the signal receiving is not recovered to normal all the time, and the output voltage is controlled to be smaller than the voltage threshold value or the output power is controlled to be smaller than the power threshold value.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to an MLPE device, a control method thereof and a photovoltaic system. Background Art

[0002] Traditional photovoltaic systems use string or centralized inverter systems. On the DC side, multiple photovoltaic modules are connected in series and then in parallel to form a photovoltaic array. The output voltage of the photovoltaic array can reach hundreds of volts or even thousands of volts. This output voltage still exists when the inverter is turned off. When the photovoltaic system encounters a disaster, the continuous and unshutdown high voltage output will cause personal injury to the operation and maintenance personnel, and the spread of the fault will lead to asset losses.

[0003] Based on this, the current photovoltaic system can effectively solve the problem of photovoltaic array output voltage when the inverter is shut down by installing module-level power electronics (MLPE) devices on the photovoltaic module side. The MLPE devices support safe shutdown at the photovoltaic module level. The heartbeat mechanism is used between the inverter and the MLPE device to detect whether the behavior is normal or not. The inverter sends a heartbeat signal to the MLPE device at a regular interval. The MLPE device works normally after receiving the heartbeat signal. When the inverter is shut down, the MLPE device receives the heartbeat signal abnormally, and the MLPE device enters the safe mode, such as executing the shutdown operation, to meet the failure safety design. When the internal communication failure or power failure of the photovoltaic system caused by abnormal environmental changes will cause the heartbeat signal to be abnormal. In the distributed photovoltaic system, the common-mode and differential-mode interference caused by different installation environments will also cause the heartbeat signal to be abnormal. These situations will cause the MLPE device to enter the safe mode, which may trigger the frequent shutdown of the MPLE device, resulting in a decrease in the output time of the photovoltaic system and a reduction in the effective hours of the photovoltaic system. Summary of the invention

[0004] The present application provides an MLPE device, a control method thereof and a photovoltaic system, which are used to avoid frequent shutdown of the MLPE device and increase the effective hours of the photovoltaic system.

[0005] In the first aspect, the present application provides an MLPE device, including: a main circuit and a controller. The main circuit is connected to a photovoltaic module, and the main circuit is used to perform fine control on a single or multiple photovoltaic modules, mainly realizing functions such as inversion, monitoring, power optimization, and shutdown. The main circuit can be specifically an inverter circuit, an optimization circuit, or a shutdown circuit. The controller is used to receive and monitor the heartbeat signal, and determine whether the signal reception is abnormal according to the duration of the continuous interruption of the heartbeat signal. The controller starts timing from the first time point when the heartbeat signal is interrupted. If the heartbeat signal is continuously interrupted from the first time point to the second time point, it is considered that the signal reception is abnormal. The controller can determine the scene in which the MLPE device is located according to the magnitude of the output current of the main circuit at this time, and perform corresponding operations. Specifically, if it is determined that the output current of the main circuit is less than the current threshold, it means that the next-level device used to receive the output current of the MLPE device does not need a large input current at this time. The device may be in a standby state or a power-limited operation state. At this time, the MLPE device does not need to be in a large output voltage or output power condition. In other words, the MLPE device is in a scene that requires safe shutdown, and the output voltage of the main circuit is controlled to be less than the voltage threshold or the output power of the main circuit is less than the power threshold. If the output current is determined to be greater than or equal to the current threshold, it means that the next-level device used to receive the output current of the MLPE device requires a larger input current. The device may be in normal operation and requires the MLPE device to output a normal voltage or a normal output power. It is inferred that the MLPE device may be in a scene where the communication signal is unstable, resulting in abnormal heartbeat signal reception. The MLPE device can be controlled to maintain output, and the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold from the second time point to the third time point to extend the output time of the photovoltaic system and increase the effective hours of the photovoltaic system. If the heartbeat signal is continuously interrupted from the second time point to the third time point, it means that the signal reception has not returned to normal, and the output voltage needs to be controlled to be less than the voltage threshold or the output power needs to be controlled to be less than the power threshold.

[0006] In some embodiments of the present application, the controller is also used for: if a heartbeat signal is received between the second time point and the third time point, indicating that the signal reception may have returned to normal, the output voltage is continuously controlled to be greater than or equal to the voltage threshold or the output power is greater than or equal to the power threshold, so as to avoid false triggering of frequent shutdown of the MLPE device.

[0007] In some embodiments of the present application, the controller is also used to: when it is determined that the duration of continuous interruption of receiving the heartbeat signal is less than the duration between the first time point and the second time point, it is considered that the signal reception is normal, and the main circuit can be controlled to operate normally, that is, the output voltage of the main circuit is controlled to be greater than or equal to the voltage threshold or the output power of the main circuit is controlled to be greater than or equal to the power threshold.

[0008] In some embodiments of the present application, the main circuit includes: a switch tube connected to the photovoltaic module. When the controller controls the output voltage to be less than the voltage threshold or the output power to be less than the power threshold, the output voltage or output power can be reduced by turning off the switch tube to realize the main circuit shutdown operation.

[0009] In some embodiments of the present application, the MLPE device may be an optimizer, a switch or a micro inverter, etc.

[0010] In the second aspect, the present application provides a control method for MLPE equipment, including: when the heartbeat signal is continuously interrupted from the first time point to the second time point, it is considered that the signal reception is abnormal. If it is judged that the output current of the main circuit is less than the current threshold, it means that the next-level device used to receive the output current of the MLPE device does not need a large input current at this time, and the device may be in a standby state or a power-limited operation state. At this time, the MLPE device does not need to be in a large output voltage or output power condition. In other words, the MLPE device is in a scene that requires safe shutdown, and the output voltage of the main circuit is controlled to be less than the voltage threshold or the output power of the main circuit is less than the power threshold. If it is judged that the output current is greater than or equal to the current threshold, it means that the next-level device used to receive the output current of the MLPE device at this time needs a large input current, and the device may be in a normal operating state, requiring the MLPE device to have a normal output voltage or normal output power, then it is inferred that the MLPE device may be in a scene where the communication signal is unstable, resulting in abnormal heartbeat signal reception, and the MLPE device can be controlled to maintain output, then the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is greater than or equal to the power threshold from the second time point to the third time point, so as to extend the output time of the photovoltaic system and increase the effective hours of the photovoltaic system. If the heartbeat signal is continuously interrupted from the second time point to the third time point, it means that the signal reception has not returned to normal, and the output voltage needs to be controlled to be less than the voltage threshold or the output power needs to be controlled to be less than the power threshold.

[0011] In some embodiments of the present application, it also includes: if a heartbeat signal is received between the second time point and the third time point, it means that the signal reception may have returned to normal, and then the output voltage is continuously controlled to be greater than or equal to the voltage threshold or the output power is greater than or equal to the power threshold, so as to avoid false triggering of frequent shutdown of the MLPE device.

[0012] In some embodiments of the present application, it also includes: when the duration of continuous interruption of receiving the heartbeat signal is less than the duration between the first time point and the second time period, the signal reception is considered normal, and the main circuit can be controlled to work normally, that is, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold.

[0013] In some embodiments of the present application, controlling the output voltage to be less than a voltage threshold or the output power to be less than a power threshold includes: turning off the switch tube in the MLPE device used to connect to the photovoltaic module, reducing the output voltage or output power, and realizing the main circuit shutdown operation.

[0014] In a third aspect, the present application provides a photovoltaic system, including: including: an optimizer and a power converter, the input of the optimizer is used to connect to the photovoltaic module, the output of the optimizer is connected to the input of the power converter, and the output of the power converter is used to connect to the power grid or load. The optimizer can optimize the power of the connected photovoltaic module, and can track the maximum power point of the photovoltaic module in real time to achieve the maximum power output of the photovoltaic module. The power converter is used to send a heartbeat signal to the optimizer. For example, the power converter generally transmits the heartbeat signal to the optimizer every 4.7 seconds. The optimizer is used to receive and monitor the heartbeat signal, and judge whether the signal reception is abnormal according to the duration of the continuous interruption of the heartbeat signal. The optimizer starts timing from the first time point when the heartbeat signal is interrupted. If the heartbeat signal is continuously interrupted from the first time point to the second time point, it is considered that the signal reception is abnormal, and the scene where the optimizer is located can be determined according to the size of the output current at this time, and the corresponding operation is performed. Specifically, if it is judged that the output current is less than the current threshold, it means that the power converter does not need a large input current at this time, and the power converter may be in a standby state or a limited power operation state. At this time, the optimizer does not need to be in a condition of a large output voltage or output power. In other words, the optimizer is in a scene that requires safe shutdown, and the output voltage is controlled to be less than the voltage threshold or the output power is less than the power threshold. If it is judged that the output current is greater than or equal to the current threshold, it means that the power converter needs a large input current at this time, and the power converter may be in a normal operating state, and the optimizer needs a normal output voltage or normal output power. It is inferred that the optimizer is in a scene where the communication signal is unstable, which causes abnormal reception of the heartbeat signal. The optimizer can be controlled to maintain output, and the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is greater than or equal to the power threshold from the second time point to the third time point, so as to extend the output time of the photovoltaic system and increase the effective hours of the photovoltaic system. If the heartbeat signal is continuously interrupted from the second time point to the third time point, it means that the signal reception has not returned to normal, and the output voltage needs to be controlled to be less than the voltage threshold or the output power needs to be less than the power threshold.

[0015] In some embodiments of the present application, the optimizer is also used for: if a heartbeat signal is received between the second time point and the third time point, indicating that the signal reception may have returned to normal, then continuously controlling the output voltage to be greater than or equal to the voltage threshold or the output power to be greater than or equal to the power threshold, so as to avoid false triggering of frequent shutdown of the optimizer.

[0016] In some embodiments of the present application, the optimizer is also used to consider that the signal reception is normal and can operate normally when the duration of continuous interruption of the heartbeat signal is less than the duration between the first time point and the second time point, and to control the output voltage to be greater than or equal to the voltage threshold or the output power to be greater than or equal to the power threshold.

[0017] In some embodiments of the present application, the optimizer includes: a switch tube for connecting to a photovoltaic module. When the output voltage controlled by the optimizer is less than an output threshold or the output power is less than a power threshold, the output voltage or output power can be reduced by turning off the switch tube to realize the shutdown operation of the optimizer.

[0018] In some embodiments of the present application, a photovoltaic system generally includes multiple optimizers, and the outputs of the multiple optimizers are connected in series to the input of a power converter. The power converter can transparently transmit a heartbeat signal to each optimizer, and each optimizer monitors its own heartbeat signal to achieve the above operations.

[0019] In some embodiments of the present application, the power converter may be a direct current to direct current (DCDC) converter or a direct current to alternating current (DCAC) converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a timeline for the MLPE device to perform a judgment according to an embodiment of the present application;

[0021] Figure 2 A schematic diagram of a flow chart of a control method for an MLPE device provided in an embodiment of the present application;

[0022] Figure 3 A schematic diagram of the structure of a photovoltaic system provided in an embodiment of the present application;

[0023] Figure 4 A control flow chart of a photovoltaic system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as being limited to the embodiments described herein; on the contrary, these embodiments are provided to make the present application more comprehensive and complete, and to fully convey the concepts of the example embodiments to those skilled in the art. The same figure marks in the figures represent the same or similar structures, and thus their repeated descriptions will be omitted. The words expressing position and direction described in this application are all explained using the accompanying drawings as examples, but changes may be made as needed, and all changes are included in the scope of protection of this application. The drawings of this application are only used to illustrate the relative position relationship and do not represent the true proportions.

[0025] It should be noted that specific details are described in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in a variety of other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific implementation methods disclosed below. The subsequent description of the specification is a preferred implementation method for implementing the present application, but the description is for the purpose of illustrating the general principles of the present application and is not intended to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0026] In order to facilitate understanding of the embodiments of the present application, the relevant technologies involved in the embodiments of the present application are first introduced below.

[0027] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be used as limitations on the present application. As used in the specification and appended claims of the present application, the singular expressions "one", "a kind of" and "the" are intended to also include expressions such as "one or more", unless there is a clear indication to the contrary in the context. It should also be understood that in the following embodiments of the present application, "at least one" refers to one, two or more than two.

[0028] References to "one embodiment" and the like described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in other embodiments", etc. that appear at different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0029] The embodiment of the present application provides an MLPE device, a control method thereof, and a photovoltaic system. Under the premise of meeting safety requirements, by judging the size of the output current of the MLPE device, the scenario in which the MLPE device is located is distinguished. When it is judged that the MLPE device is in a scenario that requires safe shutdown, the MLPE device is controlled to enter a safe mode, such as executing a shutdown operation. When it is judged that the MLPE device is in a scenario where the communication signal is unstable, the MLPE device can be controlled to maintain output, which can make up for the loss of output time of the photovoltaic system, increase the effective hours of the photovoltaic system, and also avoid frequent shutdown of the MLPE device.

[0030] The MLPE device provided in the embodiment of the present application may specifically include: a main circuit and a controller. The main circuit is connected to the photovoltaic module, and the main circuit is used to perform fine control on a single or multiple photovoltaic modules, mainly to realize functions such as inversion, monitoring, power optimization, and shutdown. The main circuit may specifically be an inverter circuit, an optimization circuit, or a shutdown circuit, etc. Correspondingly, the MLPE device may specifically be a micro inverter, an optimizer, or a shutdown device, etc. The controller is used to receive and monitor the heartbeat signal, and determine whether a signal reception abnormality occurs based on the duration of the continuous interruption of the heartbeat signal. Reference Figure 1 , the controller starts timing from the first time point when the heartbeat signal is interrupted. If the heartbeat signal is continuously interrupted within the first time period from the first time point to the second time point, it is considered that the signal reception is abnormal. The controller can determine the scene in which the MLPE device is located according to the magnitude of the output current of the main circuit at this time, and perform corresponding operations. Specifically, if it is determined that the output current of the main circuit is less than the current threshold, it means that the next-level device used to receive the output current of the MLPE device does not need a larger input current at this time. The device may be in a standby state or a power-limited operation state. At this time, the MLPE device does not need to be in a condition with a larger output voltage or output power. In other words, the MLPE device is in a scene that requires safe shutdown, and the output voltage of the main circuit is controlled to be less than the voltage threshold or the output power of the main circuit is controlled to be less than the power threshold. Exemplarily, the controller can turn off the switch tube connected to the photovoltaic module in the main circuit to reduce the output voltage or output power to achieve the shutdown operation of the main circuit. If it is judged that the output current is greater than or equal to the current threshold, it means that the next-level device for receiving the output current of the MLPE device needs a larger input current at this time. The device may be in normal operation and requires the MLPE device to output a normal voltage or a normal output power. It is inferred that the MLPE device is in a scene where the communication signal is unstable, which leads to abnormal reception of the heartbeat signal. The MLPE device can be controlled to maintain output. Then, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold within the second time period from the second time point to the third time point, so as to extend the output time of the photovoltaic system and increase the effective hours of the photovoltaic system. If the heartbeat signal is continuously interrupted during the second time period from the second time point to the third time point, it means that the signal reception has not returned to normal, and the output voltage needs to be controlled to be less than the voltage threshold or the output power needs to be less than the power threshold. Exemplarily, the controller can turn off the switch tube connected to the photovoltaic component in the main circuit to reduce the output voltage or output power to realize the shutdown operation of the main circuit.

[0031] Reference Figure 1 , in the present application, if a heartbeat signal is received within a second time period between the second time point and the third time point, for example Figure 1If a heartbeat signal is received at time point B, it indicates that signal reception may be restored to normal. Then, the output voltage is continuously controlled to be greater than or equal to the voltage threshold or the output power is greater than or equal to the power threshold, so as to avoid false triggering of frequent shutdown of the MLPE device.

[0032] Reference Figure 1 In this application, the controller starts timing from the first time point when the heartbeat signal is received during the interruption. If the duration of receiving the heartbeat signal during the continuous interruption is less than the first duration between the first time point and the second time point, for example Figure 1 If a heartbeat signal is received at time point A, it is considered that the signal reception is normal and the main circuit can be controlled to work normally, that is, the output voltage of the main circuit is controlled to be greater than or equal to the voltage threshold or the output power of the main circuit is controlled to be greater than or equal to the power threshold.

[0033] In some embodiments of the present application, the second duration may be greater than the first duration, so as to fully eliminate frequent shutdown operations caused by unstable communication signals. For example, the first duration may be selected from an appropriate value between 1 second and 30 seconds, such as 30 seconds; the second duration may be selected from an appropriate value between 1 minute and 30 seconds, such as 2 minutes.

[0034] Reference Figure 2 The present application also provides a method for controlling an MLPE device, comprising the following steps:

[0035] S1. Receive and detect heartbeat signal.

[0036] S2. Control the output voltage to be greater than or equal to a voltage threshold or the output power to be greater than or equal to a power threshold.

[0037] S3, starting timing from the first time point when the heartbeat signal is interrupted, determining whether the heartbeat signal is continuously interrupted from the first time point to the second time point. When it is determined that the heartbeat signal is continuously interrupted from the first time point to the second time point, executing step S4.

[0038] S4, determine whether the output current is less than the current threshold. When it is determined that the output current is less than the current threshold, execute step S5. When it is determined that the output current is greater than or equal to the current threshold, execute step S6.

[0039] S5. Control the output voltage to be less than the voltage threshold or the output power to be less than the power threshold. For example, the switch connected to the photovoltaic module in the main circuit can be turned off to reduce the output voltage or output power to achieve the shutdown operation of the main circuit.

[0040] S6. Control the output voltage to be greater than or equal to a voltage threshold or the output power to be greater than or equal to a power threshold within a period from the second time point to the third time point.

[0041] S7, determine whether the heartbeat signal is continuously interrupted from the second time point to the third time point. If it is determined that the heartbeat signal is continuously interrupted from the second time point to the third time point, execute step S5. If it is determined that the heartbeat signal is received from the second time point to the third time point, execute step S8.

[0042] S8. Continuously control the output voltage to be greater than or equal to the voltage threshold or the output power to be greater than or equal to the power threshold.

[0043] Reference Figure 3, the embodiment of the present application also provides a photovoltaic system, specifically including: an optimizer and a power converter. The input of the optimizer is used to connect to the photovoltaic module, the output of the optimizer is connected to the input of the power converter, and the output of the power converter is used to connect to the power grid or the load. The optimizer can optimize the power of the connected photovoltaic module, and can track the maximum power point of the photovoltaic module in real time to achieve the maximum power output of the photovoltaic module. The power converter is used to send a heartbeat signal to the optimizer. For example, the power converter generally transmits the heartbeat signal to the optimizer periodically, for example, every 4.7 seconds. The optimizer is used to receive and monitor the heartbeat signal, and determine whether the signal reception is abnormal according to the duration of the continuous interruption of receiving the heartbeat signal. The optimizer starts timing from the first time point when the heartbeat signal is interrupted. If the heartbeat signal is continuously interrupted within the first time period from the first time point to the second time point, it is considered that the signal reception is abnormal, and the scene where the optimizer is located can be determined according to the size of the output current at this time, and the corresponding operation is performed. Specifically, if it is judged that the output current is less than the current threshold, it means that the power converter does not need a larger input current at this time, and the power converter may be in a standby state or a limited power operation state. At this time, the optimizer does not need to be in a condition of a larger output voltage or output power. In other words, the optimizer is in a scene that requires safe shutdown, and the output voltage is controlled to be less than the voltage threshold or the output power is less than the power threshold. Exemplarily, the switch tube connected to the photovoltaic component can be turned off to reduce the output voltage or output power to achieve the shutdown operation of the optimizer. If it is judged that the output current is greater than or equal to the current threshold, it means that the power converter needs a larger input current at this time, and the power converter may be in a normal operating state, and the optimizer needs a normal output voltage or normal output power. It is inferred that the optimizer is in a scene where the communication signal is unstable, resulting in abnormal reception of the heartbeat signal, and the optimizer can be controlled to maintain output. Then, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is greater than or equal to the power threshold in the second time period from the second time point to the third time point, so as to extend the output time of the photovoltaic system and increase the effective hours of the photovoltaic system. If the heartbeat signal is continuously interrupted from the second time point to the third time point, it means that the signal reception has not returned to normal, and the output voltage needs to be controlled to be less than the voltage threshold or the output power needs to be controlled to be less than the power threshold. For example, the switch connected to the photovoltaic module can be turned off to reduce the output voltage or output power to achieve the optimizer shutdown operation.

[0044] In the present application, if a heartbeat signal is received between the second time point and the third time point, indicating that the signal reception may have returned to normal, the output voltage is continuously controlled to be greater than or equal to the voltage threshold or the output power is greater than or equal to the power threshold, so as to avoid false triggering of frequent shutdown of the optimizer.

[0045] In the present application, timing starts from the first time point when the heartbeat signal is received during the interruption. If the duration of receiving the heartbeat signal during the continuous interruption is less than the duration between the first time point and the second time point, the signal reception is considered normal, and the main circuit can be controlled to work normally, that is, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold.

[0046] In some embodiments of the present application, a photovoltaic system generally includes multiple optimizers, and the outputs of the multiple optimizers are connected in series to the input of a power converter. The power converter can transparently transmit a heartbeat signal to each optimizer, and each optimizer monitors its own heartbeat signal to achieve the above operations.

[0047] In some embodiments of the present application, the power converter may specifically be a direct current to direct current (DCDC) converter or a direct current to alternating current (DCAC) converter.

[0048] The control process of the photovoltaic system provided in the embodiment of the present application is explained below with a specific example.

[0049] Reference Figure 4 , the photovoltaic system includes an optimizer and an inverter, the input of the optimizer is connected to the photovoltaic module, the output of the optimizer is connected to the input of the inverter, and the output of the inverter is connected to the power grid or the load. The inverter includes a monitoring module, an inverter module and a transparent transmission (CCO) module, and the optimizer includes a main circuit and a controller (STA). The monitoring module of the inverter broadcasts a heartbeat power-on command, which is transparently transmitted to the STA of the optimizer through the CCO module timing cycle. After receiving the heartbeat power-on command, the STA of the optimizer controls the main circuit to start and run. The STA of the optimizer detects the heartbeat signal, starts timing from the first time point when the heartbeat signal is interrupted, determines that there is no heartbeat signal continuously within the first time period from the first time point to the second time point, and detects the output current. If the output current is less than the current threshold, the STA sends a shutdown command to the main circuit, and the switch tube connected to the photovoltaic module in the main circuit is turned off. If the output current is greater than or equal to the current threshold, STA waits for a second period of time from the second time point to the third time point, and if there is no heartbeat signal within the second period of time, STA sends a shutdown command to the main circuit, and the switch tube connected to the photovoltaic component in the main circuit is turned off.

[0050] The above-mentioned MLPE device, its control method and photovoltaic system provided by the present application, when the MPLE device determines that the heartbeat signal is continuously interrupted from the first time point to the second time point, it is considered that the signal reception is abnormal, and the scene can be determined according to the size of the output current at this time to distinguish the execution operation behavior. If it is judged that the output current is less than the current threshold, it means that the next-level device used to receive the output current of the MLPE device does not need a larger input current at this time. The device may be in a standby state or a limited power operation state. At this time, the MLPE device does not need to be in a condition with a larger output voltage or output power. In other words, the MLPE device is in a scene that requires safe shutdown, and the output voltage is controlled to be less than the voltage threshold or the output power is less than the power threshold. If the output current is determined to be greater than or equal to the current threshold, it means that the next-level device for receiving the output current of the MLPE device needs a larger input current. The device may be in normal operation and requires the MLPE device to output a normal voltage or a normal output power. It is inferred that the MLPE device is in a communication signal unstable scenario, which leads to abnormal reception of the heartbeat signal. The MLPE device can be controlled to maintain output. In the second time period from the second time point to the third time point, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold, so as to extend the output time of the photovoltaic system and increase the effective hours of the photovoltaic system. If the heartbeat signal is continuously interrupted from the second time point to the third time point, it means that the signal reception has not returned to normal, and the output voltage needs to be controlled to be less than the voltage threshold or the output power needs to be controlled to be less than the power threshold.

[0051] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A component-level electronic MLPE device, characterized in that: include: A main circuit and a controller, wherein the main circuit is used to connect to a photovoltaic module; The controller is used to: when the heartbeat signal is continuously interrupted from the first time point to the second time point, if the output current of the main circuit is less than the current threshold, control the output voltage of the main circuit to be less than the voltage threshold or the output power of the main circuit to be less than the power threshold; If the output current is greater than or equal to the current threshold, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold between the second time point and the third time point; if the heartbeat signal is continuously interrupted from the second time point to the third time point, the output voltage is controlled to be less than the voltage threshold or the output power is controlled to be less than the power threshold.

2. The MLPE device according to claim 1, characterized in that The controller is further used for: if the heartbeat signal is received between the second time point and the third time point, continuously controlling the output voltage to be greater than or equal to the voltage threshold or the output power to be greater than or equal to the power threshold.

3. The MLPE device according to claim 1 or 2, characterized in that: The controller is also used to: when the duration of continuous interruption of receiving the heartbeat signal is less than the duration between the first time point and the second time point, control the output voltage to be greater than or equal to the voltage threshold or the output power to be greater than or equal to the power threshold.

4. The MLPE device according to any one of claims 1 to 3, characterized in that: The main circuit includes: a switch tube connected to the photovoltaic module; The controller is used to turn off the switch tube to control the output voltage to be less than the voltage threshold or the output power to be less than the power threshold.

5. The MLPE device according to any one of claims 1 to 4, characterized in that: The MLPE device is an optimizer, a switch or a micro inverter.

6. A control method for component-level electronic MLPE equipment, characterized in that: include: When the heartbeat signal is continuously interrupted from the first time point to the second time point, if it is determined that the output current of the main circuit is less than the current threshold, the output voltage of the main circuit is controlled to be less than the voltage threshold or the output power of the main circuit is controlled to be less than the power threshold; If it is determined that the output current is greater than or equal to the current threshold, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold between the second time point and the third time point; if the heartbeat signal is continuously interrupted from being received between the second time point and the third time point, the output voltage is controlled to be less than the voltage threshold or the output power is controlled to be less than the power threshold.

7. The control method according to claim 6, characterized in that: Also includes: If the heartbeat signal is received between the second time point and the third time point, the output voltage is continuously controlled to be greater than or equal to the voltage threshold or the output power is continuously controlled to be greater than or equal to the power threshold.

8. The control method according to claim 6 or 7, characterized in that: Also includes: When the duration of continuous interruption of receiving the heartbeat signal is less than the duration between the first time point and the second time point, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold.

9. The control method according to any one of claims 6 to 8, characterized in that: Controlling the output voltage to be less than the voltage threshold or the output power to be less than the power threshold includes: turning off a switch tube in the MLPE device that is used to connect to a photovoltaic component.

10. A photovoltaic system, characterized in that: include: An optimizer and a power converter, wherein the input of the optimizer is used to be connected to a photovoltaic module, the output of the optimizer is connected to the input of the power converter, and the output of the power converter is used to be connected to a power grid or a load; The optimizer is used to track the maximum power point of the photovoltaic module; The power converter is used to: send a heartbeat signal to the optimizer; The optimizer is used to: when the heartbeat signal is continuously interrupted from the first time point to the second time point, if it is determined that the output current is less than the current threshold, control the output voltage to be less than the voltage threshold or the output power to be less than the power threshold; If it is determined that the output current is greater than or equal to the current threshold, the output voltage is controlled to be greater than or equal to the voltage threshold or the output power is controlled to be greater than or equal to the power threshold between the second time point and the third time point; if the heartbeat signal is continuously interrupted from being received between the second time point and the third time point, the output voltage is controlled to be less than the voltage threshold or the output power is controlled to be less than the power threshold.

11. The photovoltaic system according to claim 10, characterized in that: The optimizer is further used for: if the heartbeat signal is received between the second time point and the third time point, continuously controlling the output voltage to be greater than or equal to the voltage threshold or the output power to be greater than or equal to the power threshold.

12. The photovoltaic system according to claim 10 or 11, characterized in that: The optimizer is also used to: when the duration of continuous interruption of receiving the heartbeat signal is less than the duration between the first time point and the second time point, control the output voltage to be greater than or equal to the voltage threshold or the output power to be greater than or equal to the power threshold.

13. The photovoltaic system according to any one of claims 10 to 12, characterized in that: The optimizer includes: a switch tube connected to the photovoltaic assembly; The optimizer includes: the optimizer is used to turn off the switch tube to control the output voltage to be less than the output threshold or the output power to be less than the power threshold.

14. The photovoltaic system according to any one of claims 10 to 13, characterized in that: The photovoltaic system includes a plurality of optimizers, and the outputs of the plurality of optimizers are connected in series and then connected to the input of the power converter.

15. The photovoltaic system according to any one of claims 10 to 14, characterized in that: The power converter is a DC to DC (DCDC) converter or a DC to AC (DCAC) converter.

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