Grid-connected and off-grid control method and power equipment

Abstract

The invention provides a grid-connected and off-grid control method and power equipment. The grid-connected and off-grid control method is applied to main power equipment. The main power device is in communication connection with at least one slave power device through a signal line and a protocol communication line, and each slave power device and the alternating current end of the main power device are connected with a power grid through a corresponding grid-connected switch. The method comprises the steps that when grid-connected operation is carried out and it is confirmed that a power grid is abnormal, a power grid abnormity notice is sent to slave power equipment through a protocol communication line, the power grid abnormity notice is used for configuring the slave power equipment to output a breaking signal through a signal line, and the breaking signal is used for indicating all power equipment to disconnect a grid-connected switch; when the breaking signal is detected, the grid-connected switch is controlled to be switched off; controlling the alternating current end to output off-grid alternating current voltage; and generating a synchronizing signal according to the output phase angle of the off-grid AC voltage, and outputting the synchronizing signal through a signal line, wherein the synchronizing signal is used for indicating each slave power device to perform off-grid phase synchronization. The control method provided by the invention can reduce the damage probability of the grid-connected switch.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a grid-connected and off-grid control method and power equipment. Background Technology

[0002] The increasing installation of distributed renewable energy and energy storage devices has brought about structural changes to modern power distribution systems. Microgrids based on energy storage systems can continue to supply power to regional loads without disconnecting from the transmission system during grid faults, maintaining off-grid operation. When the grid returns to normal, the microgrid exits off-grid operation mode and switches to grid-connected operation mode. Energy storage devices, such as power conversion systems (PCS), can be used for both off-grid operation with loads and grid-connected rectification and inversion, i.e., charge and discharge operation.

[0003] In particular, during grid-connected and off-grid operation, there are scenarios where the grid-side relays of energy storage devices may disconnect under load. If the grid-side relays of multiple energy storage devices disconnect asynchronously, the last grid-side relay to disconnect may bear a current exceeding its hardware capacity for a certain period of time, which may lead to the grid-side relay sticking and being damaged. Summary of the Invention

[0004] In view of this, this application provides a grid connection and off-grid control method and power equipment, which can better realize the synchronous disconnection of grid connection switches when multiple power devices switch from grid connection to off-grid, thereby reducing the probability of grid connection switch damage and improving the safety of power equipment.

[0005] The first aspect of this application provides a grid connection / off-grid control method applied to a master power device. The master power device is communicatively connected to at least one slave power device via a signal line and a protocol communication line. The AC terminals of each slave power device and the master power device are respectively connected to the power grid via corresponding grid-connected switches. The method includes: when operating in grid-connected mode and a grid anomaly is confirmed, sending a grid anomaly notification to the slave power devices via the protocol communication line. The grid anomaly notification is used to configure the slave power devices to output a disconnection signal via the signal line, and the disconnection signal is configured to instruct all power devices to disconnect their corresponding grid-connected switches; upon detecting the disconnection signal, controlling the grid-connected switch corresponding to the master power device to disconnect; after the grid-connected switch is disconnected, controlling the AC terminal of the master power device to output an off-grid AC voltage; generating a synchronization signal based on the output phase angle of the off-grid AC voltage and outputting it via the signal line. The effective edge of the synchronization signal corresponds to a preset phase of the output phase angle, and the synchronization signal is used to instruct each slave power device to perform off-grid phase synchronization.

[0006] In one embodiment, before controlling the main power equipment to output off-grid AC voltage after the grid-connected switch is opened, the method further includes: confirming that the grid-connected switch is open after a first preset time period following the detection of the disconnection signal.

[0007] In one embodiment, before controlling the AC terminal of the main power equipment to output off-grid AC voltage, the method further includes: controlling the AC terminal of the main power equipment to stop outputting when a disconnection signal is detected.

[0008] In one embodiment, the method further includes: controlling the grid connection switch to disconnect after a second preset time period following the sending of the grid anomaly notification.

[0009] In one embodiment, before sending a power grid anomaly notification to the slave power equipment via a protocol communication line, the method further includes: acquiring at least one of the actual grid voltage, actual grid current, and actual grid power; determining a power grid anomaly when an anomaly condition is met; wherein the anomaly condition includes at least one of the following conditions: the actual grid voltage is less than a first grid voltage, or the actual grid voltage is greater than a second grid voltage; the actual grid current is less than the first grid current, or the actual grid current is greater than the second grid current; the actual grid power is less than the first grid power, or the actual grid power is greater than the second grid power; and receiving power grid anomaly information reported by the slave power equipment.

[0010] A second aspect of this application provides a grid connection / off-grid control method applied to a slave power device. The slave power device is communicatively connected to a master power device via a signal line and a protocol communication line. Both the AC terminals of the slave power device and the master power device are connected to the power grid via corresponding grid-connected switches. The method includes: upon receiving a grid anomaly notification from the master power device via the protocol communication line, outputting a disconnection signal via the signal line, wherein the disconnection signal is configured to instruct all power devices to disconnect their corresponding grid-connected switches; upon detecting the disconnection signal, controlling the corresponding grid-connected switch of the slave power device to disconnect; after the grid-connected switch is disconnected, controlling the AC terminal of the slave power device to output an off-grid AC voltage; and upon detecting a synchronization signal via the signal line, performing off-grid phase synchronization based on the synchronization signal, wherein the effective edge of the synchronization signal corresponds to a preset phase of the output phase angle of the master power device.

[0011] In one embodiment, outputting a disconnect signal through the signal line includes: continuously pulling the signal line high for a third preset duration.

[0012] In one embodiment, the method further includes: after receiving a power grid anomaly notification, controlling the grid connection switch to disconnect after a fourth preset time period.

[0013] In one embodiment, before controlling the output of off-grid AC voltage from the AC terminal of the power equipment after the grid-connected switch is disconnected, the method further includes: controlling the output to stop from the AC terminal of the power equipment when a disconnection signal is detected through a signal line.

[0014] A third aspect of this application provides an electrical device including a memory and a processor, wherein the processor is configured to execute a computer program stored in the memory to implement the grid connection / off-grid control method provided in the first aspect, or to implement the grid connection / off-grid control method provided in the second aspect.

[0015] The grid connection / off-grid control method provided in this application, when operating in grid connection and confirming a grid anomaly, sends a grid anomaly notification to the slave power equipment via a protocol communication line. Upon detecting a disconnection signal, it controls the corresponding grid connection switch of the master power equipment to disconnect. Then, after the grid connection switch is disconnected, it controls the AC terminal of the master power equipment to output an off-grid AC voltage. A synchronization signal is then generated based on the output phase angle of the off-grid AC voltage and output via a signal line. The grid anomaly notification is used to configure the slave power equipment to output a disconnection signal via the signal line, and the disconnection signal is configured to instruct all power equipment to disconnect their corresponding grid connection switches. In this way, compared to schemes that only achieve synchronous shutdown via a protocol communication line, the grid connection / off-grid control method provided in this application can reduce the delay caused by command transmission to the time difference of hardware capture of the disconnection signal on the signal line, thereby effectively reducing the time difference in shutdown of the grid connection switches by all power equipment and reducing the probability of damage to the grid connection switches. On the other hand, in the grid connection and off-grid control method provided in this application, after the main power equipment disconnects the grid connection switch and outputs off-grid AC voltage, it also outputs a synchronization signal through the signal line. The synchronization signal is used to instruct each slave power equipment to perform off-grid phase synchronization. In this way, the disconnection signal and the synchronization signal can be reused on the signal line, which is beneficial to reduce the manufacturing cost of power equipment and the installation cost of power supply system. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation on the scope of protection of this application. In the various drawings, similar components are numbered similarly.

[0017] Figure 1 This is a schematic diagram illustrating the application environment of the on-grid / off-grid control method provided in one embodiment of this application.

[0018] Figure 2 This is a schematic flowchart of a grid connection / off-grid control method for main power equipment provided in an embodiment of this application.

[0019] Figure 3 This is a schematic flowchart illustrating a grid connection / off-grid control method for power equipment, provided as an embodiment of this application.

[0020] Figure 4This is an embodiment of the present application showing the signal transmission and reception process between the master power equipment and the slave power equipment at different points in time when the grid connection and disconnection control method is executed.

[0021] Figure 5 This is a waveform diagram on the signal line during the execution of the on-grid and off-grid control method in one embodiment of this application.

[0022] Figure 6 This is a block diagram of a power equipment provided in an embodiment of this application.

[0023] Figure 7 A functional block diagram of a computer-readable storage medium provided in an embodiment of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0025] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have an intervening component. When a component is considered to be "placed" on another component, it can be directly placed on the other component or may also have an intervening component.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0028] Some embodiments will now be described with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0029] The increasing installation of distributed renewable energy and energy storage devices has brought about structural changes to modern power distribution systems. Microgrids based on energy storage systems can continue to supply power to regional loads without disconnecting from the transmission system during grid faults, maintaining off-grid operation. When the grid returns to normal, the microgrid exits off-grid operation mode and switches to grid-connected operation mode. Energy storage devices, such as power conversion systems (PCS), can be used for both off-grid operation with loads and grid-connected rectification and inversion, i.e., charge and discharge operation.

[0030] In particular, during grid-connected and off-grid operation, there are scenarios where the grid-side relays of energy storage devices may disconnect under load. If the grid-side relays of multiple energy storage devices disconnect asynchronously, the last grid-side relay to disconnect may bear a current exceeding its hardware capacity for a certain period of time, which may lead to the grid-side relay sticking and being damaged.

[0031] For example, please see Figure 1 , Figure 1 This is a schematic diagram illustrating the application environment of the grid connection / disconnection control method provided in one embodiment of this application. Understandably, the diagram is simplified for the purpose of illustration. Figure 1 The power supply system 100 shown includes only two power devices 10. In other embodiments, the power supply system 100 may include at least two power devices 10. This application does not limit the number of power devices 10 in the power supply system 100. Furthermore, one of the at least two power devices 10 serves as the master power device, and the remaining power devices 10 serve as slave power devices. This application does not limit the method for determining the master power device in the power supply system 100. In the embodiments of this application, using... Figure 1 The power equipment 10 above serves as the main power equipment. Figure 1 The electrical equipment 10 below is used as an example to illustrate the concept of electrical equipment.

[0032] The main power equipment is communicatively connected to at least one slave power equipment via signal line 20 and protocol communication line 30. The AC terminal of each slave power equipment and the AC terminal of the main power equipment are respectively connected to the power grid 50 via corresponding grid-connected switches S1. The AC terminal of each power equipment is also used to connect a load 40, for example, such as... Figure 1The AC terminals of the main power equipment and the slave power equipment shown are connected to the same load 40 to supply power to the same load 40. Thus, when the grid-connected switch S1 is closed, each power equipment 10 is connected to the power grid 50, i.e., both the main power equipment and each slave power equipment are connected to the power grid 50. When the grid-connected switch S1 is open, the corresponding power equipment 10 is disconnected from the power grid 50. In some embodiments, the AC terminal of the power equipment 10 is also provided with a protective switch S2 connected in series with the grid-connected switch S1. The load 40 is connected between the protective switch S2 and the grid-connected switch S1. When both the grid-connected switch S1 and the protective switch S2 are closed, the corresponding power equipment 10 is connected to the power grid 50; when the grid-connected switch S1 is open and the protective switch S2 is closed, the corresponding power equipment 10 is disconnected from the power grid 50 but connected to the load 40.

[0033] Among them, the power equipment 10 includes a power conversion circuit ( Figure 1 (Not shown), and one end of the power conversion circuit is connected to the AC terminal, so that the power conversion circuit can output AC power or draw power through the AC terminal. The power conversion circuit may include, for example, a DC-AC conversion circuit, an AC-AC conversion circuit, etc., and this application does not limit the specific circuit structure of the power conversion circuit.

[0034] Signal line 20 is used to assist in the synchronous switching of all power devices 10 between off-grid and grid-connected modes. In this embodiment, signal line 20 is a hardware communication line. Specifically, signal line 20 transmits preset electrical signals between each power device 10 to achieve synchronous tracking of all power devices 10. Signal line 20 can be, for example, an I / O bus; in other embodiments, signal line 20 can also be an I2C bus or other signal buses.

[0035] The protocol communication line 30 is used to enable communication between power devices 10. The protocol communication line 30 can be, for example, a CAN (Controller Area Network) bus or an RS-485 serial bus.

[0036] In other embodiments, the electrical devices 10 may also communicate with each other via at least one of 3G (third-generation mobile information technology), 4G (fourth-generation mobile information technology), 5G (fifth-generation mobile information technology), Wi-Fi, Bluetooth or other wireless communication technologies.

[0037] The grid-connected switch S1 is used to establish a circuit connection between the power equipment 10 and the power grid 50. The grid-connected switch S1 may include a relay or other switching devices. The protective switch S2 may also include a relay or other switching devices. This application does not limit the specific circuit structure of the grid-connected switch S1 and the protective switch S2. In some embodiments, the grid-connected switch S1 and the protective switch S2 may be integrated into the power equipment 10 and closed or opened under the control of the processor of the power equipment 10.

[0038] Load 40 is used to draw power from electrical equipment 10 and / or power grid 50 to meet the power consumption required for operation. Load 40 can be various types of electrical equipment, and this application does not limit it.

[0039] The power grid 50 may be, for example, a municipal power grid or other power distribution system. This application does not limit the type of AC power in the power grid 50; for example, the power grid 50 may be single-phase AC, split-phase AC, three-phase AC, or other multi-phase AC.

[0040] In one embodiment, the power device 10 can be an inverter. In another embodiment, the power device 10 can also be a power conversion system, integrating an energy storage module to achieve bidirectional energy conversion. The energy storage module includes one or more battery cells connected in series and / or parallel. In another embodiment, the power device 10 also integrates a maximum power point tracking (MPPT) module, and the input terminal of the power device 10 is connected to the output terminal of a power generation device to convert the power output of the power generation device into AC output. The power generation device can be, for example, a generator, a photovoltaic power generation device, a wind power generation device, etc.

[0041] Please refer to it again. Figure 1 Obviously, in the power supply system 100, if the grid connection switch S1 of the power equipment is disconnected later than the grid connection switch S1 of the main power equipment, the grid connection switch S1 of the power equipment may bear all the load current for a period of time, thereby increasing the probability of damage to the grid connection switch S1 of the power equipment and reducing the safety of the power equipment.

[0042] To reduce the probability of damage to the grid-connected switch S1, related technologies generally select grid-connected switches S1 with high hardware parameter consistency to reduce the time difference between the disconnection of different grid-connected switches S1 during grid-to-off-grid transitions. However, in practical application scenarios, when installation forms, for example... Figure 1 In the power supply system 100 shown, the multiple grid-connected switches S1 do not all have the same hardware parameters. In addition, the breaking time test of the grid-connected switches S1 is relatively complex, and the record classification is also relatively complex, which further makes it impossible to guarantee the consistency of the hardware parameters of the multiple grid-connected switches S1.

[0043] On the other hand, related technologies also strive to maintain consistency at the software level when issuing disconnection commands to the grid-connected switch S1, in order to reduce the time difference in disconnection between the grid-connected switches S1 of the main power equipment and the slave power equipment caused by asynchronous command issuance. However, when the power grid is abnormal and the main power equipment issues disconnection commands to all slave power equipment through the protocol communication line 30, there is always a communication time difference between the main power equipment and the slave power equipment. For example, multiple interruption cycles will cause a time difference in disconnection between the grid-connected switches S1 of the main power equipment and the slave power equipment. Furthermore, when the communication data including the disconnection command is blocked or lost, the time difference in disconnection between the grid-connected switches S1 of the main power equipment and the slave power equipment will be even longer, thereby increasing the possibility of the last disconnected grid-connected switch S1 sticking and being damaged.

[0044] In summary, current technologies cannot adequately address the issue of synchronous disconnection of the grid-connected switch S1 when switching from grid connection to off-grid operation between the main and secondary power equipment.

[0045] Therefore, this application provides a grid connection / off-grid control method and power equipment, which can better realize the synchronous disconnection of grid connection switch S1 when multiple power devices switch from grid connection to off-grid, thereby reducing the probability of damage to grid connection switch S1 and improving the safety of power equipment.

[0046] It is worth noting that, Figure 1 Although the AC terminals of the main power device and the slave power device are shown connected to the same load 40, in other embodiments, the AC terminals of multiple power devices 10 may be connected to the corresponding loads 40 respectively, so that multiple power devices 10 supply power to different loads 40. This application does not limit the way in which multiple power devices 10 supply power to multiple loads 40.

[0047] It is understood that the grid connection and off-grid control method provided in this application, in addition to being applied to Figure 1 The power equipment 10 in the power supply system 100 shown can also be applied to other application environments that require the implementation of multiple power devices and off-grid control. Figure 1 The illustrated application environment diagram does not limit the on-grid and off-grid control methods provided in this application.

[0048] Please see Figure 2 , Figure 2 This is a schematic flowchart illustrating a grid connection / disconnection control method provided in an embodiment of this application. It is understood that the grid connection / disconnection control method provided in this application is applied to the main power equipment and is controlled by the processor of the main power equipment (…). Figure 1 (Not shown) is executed. The method includes the following steps S201-S204.

[0049] Step S201: When the grid is in operation and a grid anomaly is confirmed, a grid anomaly notification is sent to the slave power equipment through the protocol communication line. The grid anomaly notification is used to configure the slave power equipment to output a disconnection signal through the signal line, and the disconnection signal is configured to instruct all power equipment to disconnect the corresponding grid-connected switch.

[0050] Understandably, the power equipment 10 includes two operating modes: grid-connected operation mode and off-grid operation mode. Grid-connected operation mode refers to the operating mode when the power equipment 10 is connected to the power grid 50, i.e., when the grid-connected switch S1 corresponding to the power equipment 10 is closed. Off-grid operation mode refers to the operating mode when the power equipment 10 is disconnected from the power grid 50, i.e., when the grid-connected switch S1 corresponding to the power equipment 10 is open. For example, when the power grid 50 is normal, by controlling the grid-connected switch S1 to close, the power equipment 10 can supply power to the load 40 and / or transmit electrical energy to the power grid 50, or the power grid 50 can supply power to the load 40; in this case, the power equipment 10 is in grid-connected operation mode. When the power grid 50 is abnormal, by controlling the grid-connected switch S1 to open, the power equipment 10 can disconnect from the power grid 50, while maintaining power supply to the load 40.

[0051] Power grid anomalies refer to various phenomena that deviate from the normal and stable operating state of the power grid, such as overvoltage, undervoltage, voltage waveform distortion, abnormal grid connection, or other abnormal power grid phenomena. In some embodiments, each power device 10 in the power supply system 100 is equipped with a sampling circuit to collect power grid parameters to determine whether a power grid anomaly has occurred. Each slave power device, upon determining that a power grid anomaly has occurred, will report the anomaly information to the master power device. The master power device may actively determine that a power grid anomaly has occurred, or upon receiving power grid anomaly information reported by any slave power device, send a power grid anomaly notification to the slave power device via the protocol communication line 30. The power grid anomaly notification may be a specific string or other data format; this application does not limit the specific data content and format of the power grid anomaly notification.

[0052] The disconnection signal in step S201 can be an electrical signal with specific characteristics transmitted through signal line 20, such as a preset level signal, an electrical signal with a voltage exceeding a preset threshold, or a signal with a preset signal edge. Thus, the master power device and each slave power device can sample at their respective ports used to connect to signal line 20 to determine whether a disconnection signal has been detected.

[0053] Step S202: When an interruption signal is detected, the grid-connected switch corresponding to the main power equipment is disconnected.

[0054] Understandably, due to delays or blockages in the protocol communication line, when the power supply system 100 includes at least two slave power devices, the time at which different slave power devices receive the grid anomaly notification may differ. Consequently, the time at which different slave power devices output a disconnection signal on the signal line 20 based on the grid anomaly notification may also differ. In some embodiments, the master power device and each slave power device in the power supply system 100 control the corresponding grid-connected switch to disconnect based on the first disconnection signal on the signal line 20. That is, when the master power device and the slave power device detect the first disconnection signal on the signal line 20, they control their corresponding grid-connected switch S1 to disconnect.

[0055] In some embodiments, each power device 10 has an interface for connecting to the signal line 20, which is provided with a disconnection signal sampling circuit for detecting disconnection signals. This application does not limit the specific circuit of the disconnection signal sampling circuit.

[0056] Thus, by executing steps S201 to S202, the master power equipment sends a grid anomaly notification to each slave power equipment, and then the slave power equipment outputs a disconnection signal through signal line 20 to instruct all power equipment 10 to disconnect their corresponding grid-connected switches S1. Therefore, compared to asynchronous shutdown caused by delays or data congestion when synchronous shutdown is achieved solely through protocol communication line 30, executing steps S201-S202 can instruct all power equipment's corresponding grid-connected switches S1 to disconnect via the disconnection signal on signal line 20, reducing the delay caused by command transmission to the time difference of hardware signal capture, thereby effectively reducing the time difference in shutdown of all power equipment's grid-connected switches S1. On the other hand, compared to the scheme where all main power equipment and slave power equipment do not send and receive grid anomaly notifications, but directly control the corresponding grid-connected switch S1 to disconnect based on the disconnection signal on signal line 20, the execution steps S201-S202 can achieve a preliminary judgment of grid anomaly through the grid anomaly notification sent by the main power equipment. In this way, when the main power equipment sends the grid anomaly notification, the synchronous disconnection operation is performed based on the disconnection signal on signal line 20, which can reduce the probability of misjudgment of the disconnection signal caused by signal fluctuations or interference on signal line 20 and improve the accuracy of synchronous disconnection.

[0057] Step S203: After the grid connection switch is disconnected, control the AC terminal of the main power equipment to output off-grid AC voltage.

[0058] In step S203, the voltage-controlled oscillator in the main power equipment provides phase by self-oscillation at a preset frequency, and outputs off-grid AC voltage according to the phase.

[0059] Step S204: Generate a synchronization signal based on the output phase angle of the off-grid AC voltage and output it through the signal line. The effective edge of the synchronization signal corresponds to the preset phase of the output phase angle, and the synchronization signal is used to instruct each slave power device to perform off-grid phase synchronization.

[0060] In step S204, the phase-locked loop in the main power equipment can phase-lock the output off-grid AC voltage to obtain the output phase angle. Furthermore, the output phase angle of the off-grid AC voltage output by the main power equipment can be used as the phase target value of the output voltage of each slave power equipment, ensuring that the off-grid AC voltage output by the main power equipment is phase-synchronized with the output voltage at the AC terminal of each slave power equipment. This achieves off-grid synchronization, reducing the probability of parallel circulating current caused by phase asynchrony when multiple power equipment 10 are operating off-grid.

[0061] The effective edge of the synchronization signal corresponds to the preset phase of the output phase angle, which can mean that the phase difference between the effective edge and the preset phase is within a preset range. Understandably, this preset range can be a small range, such that the effective edge of the synchronization signal is approximately aligned with the preset phase of the output phase angle. The preset phase can be, for example, the phase corresponding to the zero-crossing or π-crossing point of the off-grid AC voltage output by the main power equipment, or it can be other preset phases. This application does not limit the specific value of the preset phase.

[0062] This application does not limit the specific shape of the effective edge of the synchronization signal. For example, the effective edge can be a rising edge, a falling edge, or other edges. It can be understood that when the power equipment detects the effective edge of the synchronization signal through the signal line 20, it can confirm that the output phase angle of the main power equipment is currently at a preset phase, and thus adjust the phase of its own AC terminal output voltage to the preset phase to achieve off-grid phase synchronization.

[0063] In summary, the grid connection / off-grid control method provided in this application, when operating in grid connection and confirming a grid anomaly, sends a grid anomaly notification to the slave power equipment via a protocol communication line. Upon detecting a disconnection signal, it controls the corresponding grid connection switch S1 of the master power equipment to disconnect. Then, after the grid connection switch S1 disconnects, it controls the AC terminal of the master power equipment to output an off-grid AC voltage. A synchronization signal is then generated based on the output phase angle of the off-grid AC voltage and output via a signal line. The grid anomaly notification is used to configure the slave power equipment to output a disconnection signal via the signal line, and the disconnection signal is configured to instruct all power equipment to disconnect their corresponding grid connection switches S1. In this way, compared to a scheme that only achieves synchronous shutdown via the protocol communication line 30, the grid connection / off-grid control method provided in this application can reduce the delay caused by command transmission to the time difference of hardware capture of the disconnection signal on the signal line 20, thereby effectively reducing the time difference in shutdown of the grid connection switch S1 by all power equipment and reducing the probability of damage to the grid connection switch S1. On the other hand, in the grid connection and off-grid control method provided in this application, after the main power equipment disconnects the grid connection switch S1 and outputs the off-grid AC voltage, it also outputs a synchronization signal through the signal line 20. The synchronization signal is used to instruct each slave power equipment to perform off-grid phase synchronization. In this way, the disconnection signal and the synchronization signal can be multiplexed to the signal line 20, which is beneficial to reduce the manufacturing cost of the power equipment 10 and the installation cost of the power supply system 100.

[0064] In some embodiments, each slave power device also performs off-grid amplitude synchronization based on the off-grid AC voltage output by the master power device, further reducing the probability of parallel circulating current. When the AC terminal of the master power device is also equipped with a protection switch S2, the master power device controls the protection switch S2 to close after confirming that each slave power device has completed off-grid phase synchronization and off-grid amplitude synchronization, so as to realize power supply to the load 40. In this way, the probability of multiple power devices 10 generating parallel circulating current during the process of switching from grid-connected operation to off-grid operation can be further reduced.

[0065] In some embodiments, before performing step S203, the off-grid control method further includes: After a first preset time following the detection of the disconnection signal, the grid-connected switch is confirmed to be disconnected.

[0066] Thus, after detecting the disconnection signal, a first preset time is elapsed before confirming that the grid-connected switch S1 is open, and the AC terminal is controlled to output off-grid AC voltage. Simultaneously, each slave power device also confirms that the grid-connected switch S1 is open after the first preset time is elapsed after detecting the disconnection signal, and controls its AC terminal to output off-grid AC voltage. It is understood that the opening of the grid-connected switch S1 typically requires a certain disconnection time. This ensures that all power devices have received the disconnection signal and controlled their corresponding grid-connected switches S1 to open, thereby improving the synchronization between the master and slave power devices when outputting off-grid AC voltage and reducing the probability of parallel circulating current. It also prevents power devices from starting to output off-grid AC power before being disconnected from the grid, which could cause the off-grid AC power output to affect the grid. In some embodiments, the first preset time is at least longer than the time it takes for the grid-connected switch to open; this application does not limit the specific duration of the first preset time.

[0067] In some embodiments, before performing step S203, the off-grid control method further includes: When a disconnection signal is detected, the AC terminal of the main power equipment stops outputting.

[0068] When a disconnection signal is detected, it indicates that each power device 10 has started to execute the disconnection operation of the grid-connected switch S1 and enter off-grid operation. At this time, stopping the AC terminal output can reduce the probability of the main power equipment being affected by the abnormality of the power grid 50, so as to protect the main power equipment.

[0069] In some embodiments, the off-grid control method further includes: After a second preset time following the sending of a power grid anomaly notification, the grid-connected switch is disconnected.

[0070] In this way, when the disconnection signal fails, the grid-connected switch S1 can be controlled to disconnect in a timely manner after the power grid is abnormal, ensuring that the power equipment can eventually be disconnected from the grid and reducing the probability of damage to the main power equipment.

[0071] In some embodiments, the off-grid control method further includes, before sending a grid anomaly notification to the power equipment via a protocol communication line: Obtain at least one of the actual grid voltage, actual grid current, and actual grid power. A power grid anomaly is determined when abnormal conditions are met; wherein the abnormal conditions include at least one of the following: The actual grid voltage is less than the first grid voltage, or the actual grid voltage is greater than the second grid voltage; The actual grid current is less than the first grid current, or the actual grid current is greater than the second grid current; The actual grid power is less than the first grid power, or the actual grid power is greater than the second grid power; Received power grid anomaly information reported from power equipment.

[0072] In some embodiments, the sampling circuit provided at the AC terminal of each power device 10 may include, for example, a voltage sampling circuit and a current sampling circuit, or a power sampling circuit, to sample the electrical parameters of the power grid 50 through at least one of the voltage sampling circuit, the current sampling circuit, and the power sampling circuit, thereby determining whether an abnormality has occurred in the power grid 50.

[0073] In this system, the first grid voltage can be the grid undervoltage threshold, the second grid voltage can be the grid overvoltage threshold, the first grid current can be the grid undercurrent threshold, and the second grid current can be the grid overcurrent threshold. The first grid power and the second grid power are used together to define the normal grid power. When the actual grid power exceeds the range defined by the first and second grid power, it can be determined that the grid power is abnormal. In summary, by performing the above steps, it is possible to effectively determine whether a grid anomaly has occurred.

[0074] Please see Figure 3 , Figure 3 This is a schematic flowchart of a grid connection / off-grid control method provided in an embodiment of this application. Figure 3 The grid connection / off-grid control method shown is applied to power equipment and controlled by the processor of the power equipment. Figure 1 (Not shown) is executed. The method includes the following steps S301-S304.

[0075] Step S301: When a power grid abnormality notification is received from the main power equipment via the protocol communication line, a disconnection signal is output via the signal line, and the disconnection signal is configured to instruct all power equipment to disconnect the corresponding grid-connected switch.

[0076] Step S302: When an interruption signal is detected, the grid-connected switch corresponding to the power equipment is disconnected.

[0077] Step S303: After the grid connection switch is disconnected, control the output of off-grid AC voltage from the AC terminal of the power equipment.

[0078] Step S304: When a synchronization signal is detected through the signal line, off-grid phase synchronization is performed based on the synchronization signal, wherein the effective edge of the synchronization signal corresponds to the preset phase of the output phase angle of the main power equipment.

[0079] For a detailed description of steps S301-S304, please refer to the relevant content of steps S201-S204, which will not be repeated here. Furthermore, this application does not limit the specific algorithm for off-grid phase synchronization based on the synchronization signal in step S304.

[0080] In summary, the grid connection / off-grid control method provided in this application, upon receiving a grid anomaly notification from the main power equipment via the protocol communication line 30, outputs a disconnection signal via the signal line 20. Upon detecting the disconnection signal, it controls the corresponding grid connection switch S1 of the power equipment to disconnect. Then, after the grid connection switch S1 is disconnected, it controls the output of an off-grid AC voltage from the AC terminal of the power equipment. Finally, upon detecting a synchronization signal via the signal line 20, it performs off-grid phase synchronization based on the synchronization signal. The disconnection signal is configured to instruct all power equipment to disconnect their corresponding grid connection switches S1. In this way, compared to a scheme that only achieves synchronous shutdown via the protocol communication line 30, the grid connection / off-grid control method provided in this application can reduce the delay caused by command transmission to the time difference of hardware capture of the disconnection signal on the signal line 20, thereby effectively reducing the time difference in shutdown of the grid connection switch S1 by all power equipment and reducing the probability of damage to the grid connection switch S1. On the other hand, in the grid connection and off-grid control method provided in this application, after the power equipment disconnects the grid connection switch S1 and outputs off-grid AC voltage, off-grid phase synchronization is also performed through a synchronization signal. In this way, the disconnection signal and the synchronization signal can be multiplexed on the signal line 20, which is beneficial to reduce the manufacturing cost of the power equipment 10 and the installation cost of the power supply system 100.

[0081] In some embodiments, the step S301 of outputting a disconnect signal via a signal line includes: The signal line is continuously pulled high for the third preset duration.

[0082] At this time, the disconnect signal can be a high-level signal. The third preset duration can be, for example, 1ms (milliseconds). Thus, by pulling the signal line 20 high within the third preset duration, a high-level disconnect signal can be output, reducing the probability of misjudgment of the disconnect signal caused by glitches on the signal line 20.

[0083] In some embodiments, the off-grid control method further includes: After receiving a power grid anomaly notification, the grid connection switch is disconnected after a fourth preset time interval.

[0084] In some embodiments, the fourth preset duration may be equal to the second preset duration, for example, both being 1 ms (milliseconds). In other embodiments, the fourth preset duration may not be equal to the second preset duration. For example, considering communication delay, the fourth preset duration may be less than the second preset duration, as long as the time when the power equipment and the main power equipment control grid-connected switch S1 are disconnected is close. This application does not limit the specific duration of the fourth preset duration.

[0085] In some embodiments, before performing step S303, the off-grid control method further includes: When a disconnection signal is detected through the signal line, the control stops the output from the AC terminal of the power equipment.

[0086] When a disconnection signal is detected, it indicates that each power device 10 has started to execute the disconnection operation of the grid-connected switch S1 and enter off-grid operation. At this time, stopping the AC terminal output can reduce the probability of the power device being affected by the abnormality of the power grid 50, so as to protect the power device.

[0087] Please continue reading. Figure 4 and Figure 5 , Figure 4 This embodiment of the present application describes the signal transmission and reception process between the master power equipment and the slave power equipment at different points in time during the execution of the grid connection and disconnection control method. Figure 5 This is a schematic diagram of the waveforms on signal line 20 during the execution of the on / off network control method in one embodiment of this application. We will continue from... Figure 1 , Figure 4 and Figure 5 Let's take an example to illustrate the coordination between the master power equipment and the slave power equipment during the implementation of the grid connection and disconnection control method.

[0088] Specifically, at time t0, an anomaly occurs in power grid 50. Subsequently, the slave power equipment determines that power grid 50 is abnormal based on the collected power grid parameters, and thus reports the power grid anomaly information to the master power equipment via protocol communication line 30 at time t1. The master power equipment receives the power grid anomaly information at time t2 and sends a power grid anomaly notification to each slave power equipment via protocol communication line 30 at time t3. It can be understood that in other embodiments, the master power equipment may determine that power grid 50 is abnormal based on the collected power grid parameters and send a power grid anomaly notification to each slave power equipment before time t1. The slave power equipment receives the power grid anomaly notification at time t4, and thus pulls the signal line 20 high at time t5 to output a disconnection signal. The master power equipment at time t... 6-0 The disconnection signal is captured on signal line 20 at all times, almost simultaneously from the power equipment at t 6-1 The disconnection signal is constantly captured on signal line 20. Thus, when the main power equipment and the slave power equipment detect the disconnection signal, they control the corresponding grid-connected switch S1 to open and control the corresponding AC terminal to stop outputting AC voltage. After the grid-connected switch S1 opens, they control the corresponding AC terminal to output off-grid AC voltage. Specifically, the main power equipment controls the corresponding grid-connected switch S1 to open at time t7, a second preset time after sending the grid anomaly notification at time t3. The slave power equipment controls the corresponding grid-connected switch S1 to open at time t8, a fourth preset time after receiving the grid anomaly notification at time t4. Therefore, the main power equipment and each slave power equipment can prevent the grid-connected switch S1 from failing to open due to the failure of the disconnection signal on signal line 20. Clearly, by implementing the grid connection / off-grid control method of this application, the disconnection time difference between the main power equipment and the slave power equipment can be reduced to t.6-0 Time and t 6-1 The time difference between moments is reduced, thus significantly reducing the disconnection time difference and enabling synchronous disconnection between the main power equipment and the slave power equipment.

[0089] Please continue reading. Figure 5 , Figure 5 The solid lines in the waveform represent the signal waveform actively output by the corresponding main power equipment or slave power equipment. Figure 5 The dashed waveform in the diagram represents the signal waveform passively detected by the corresponding main power equipment or slave power equipment. As mentioned above, the slave power equipment at t 6-1 The disconnection signal is constantly captured on signal line 20, and the disconnection signal is actively output from the power equipment. Almost simultaneously, the main power equipment at t 6-0 The interruption signal is constantly captured on signal line 20. This interruption signal can be, for example, a high-level signal lasting for a third preset duration, such as 1 ms. This effectively reduces interference from glitches on signal line 20, lowering the probability of false alarms. This allows all power devices connected to signal line 20 to synchronously control the corresponding grid-connected switch S1 to open upon detecting the interruption signal. Simultaneously, when the main power device and the slave power device detect the interruption signal, they control the corresponding AC terminal to stop outputting. Furthermore, after a first preset duration (e.g., 15 ms) following the detection of the interruption signal, the main power device and the slave power device confirm the opening of the corresponding grid-connected switch S1 and control the corresponding AC terminal to output off-grid AC voltage, thus initially achieving off-grid synchronization of the main power device and the slave power device. Further, to achieve off-grid phase synchronization, the main power device also generates a synchronization signal based on the output phase angle of its own off-grid AC voltage and... 9-0 The signal is output via signal line 20 at all times. Almost simultaneously, the power supply is activated at t... 9-1 A synchronization signal is constantly detected. This synchronization signal can be, for example, a square wave signal with a synchronization period of 20 ms (milliseconds). It is understood that since the timing of the interruption signals sent by different slave power devices differs, to reduce interference from later-sent interruption signals on the synchronization signal for off-grid phase synchronization, the slave power devices may perform off-grid phase synchronization based on the synchronization signal only after a preset number of synchronization periods. For example, the slave power device may perform off-grid phase synchronization based on the synchronization signal of the third synchronization period only after two synchronization periods. In summary, through the signal transmission and reception between the master and slave power devices on signal line 20, signal line 20 can be multiplexed for synchronization interruption and off-grid phase synchronization. In some embodiments, the slave power device may also perform off-grid amplitude synchronization based on the synchronization signal. This application does not limit the specific off-grid phase synchronization algorithm or off-grid amplitude synchronization algorithm.

[0090] Please see Figure 6 An embodiment of this application also provides a power device 10, including a memory 101 and a processor 102. The processor 102 is used to execute a computer program stored in the memory 101 to implement the grid connection / disconnection control method executed by the master power device as described in any of the above claims, or to implement the grid connection / disconnection control method executed by the slave power device as described in any of the above claims.

[0091] Understandably, the power equipment 10 can be an energy storage converter, a photovoltaic inverter, or other grid-connected equipment, and this application does not limit the specific type of the power equipment 10. The processor 102 mentioned in this application can be a microcontroller unit, a central processing unit, or a digital signal processor, etc. The memory 101 can be a Flash chip, a read-only memory, a disk, an optical disk, a USB flash drive, or a portable hard drive, etc.

[0092] Please refer to it again. Figure 1 An embodiment of this application also provides a power supply system 100, including at least two power devices 10, wherein one of the power devices 10 serves as a master power device, and the other power devices 10 serve as slave power devices. The master power device is used to execute the grid connection / disconnection control method executed by the master power device as described in any of the above claims, and the slave power devices are used to execute the grid connection / disconnection control method executed by the slave power devices as described in any of the above claims.

[0093] Please see Figure 7 This application also provides a computer-readable storage medium 200 storing a computer program 210 thereon. When executed by a processor 102, the computer program 210 implements the on-grid / off-grid control method described in the above technical solutions. The computer-readable storage medium may be a portable compact disc read-only memory (CD-ROM) and include program code, and may run on a terminal device, such as a personal computer. However, the program product of this invention is not limited thereto. In this document, the readable storage medium may be any tangible medium containing or storing a program that may be used by or in conjunction with an instruction execution system, apparatus, or device.

[0094] The above-described program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0095] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium, capable of sending, propagating, or transmitting programs for use by or in conjunction with an instruction execution system, apparatus, or device.

[0096] The program code contained on the readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0097] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0098] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0099] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A grid-connected / off-grid control method, applied to main power equipment, characterized in that, The main power equipment is communicatively connected to at least one slave power equipment via signal lines and protocol communication lines. The AC terminal of each slave power equipment and the AC terminal of the main power equipment are respectively connected to the power grid via corresponding grid-connected switches. The method includes: When the grid is in operation and the grid abnormality is confirmed, a grid abnormality notification is sent to the slave power device through the protocol communication line. The grid abnormality notification is used to configure the slave power device to output a disconnection signal through the signal line, and the disconnection signal is configured to instruct all power devices to disconnect the corresponding grid-connected switch. When the disconnection signal is detected, the grid-connected switch corresponding to the main power equipment is controlled to disconnect. After the grid-connected switch is disconnected, the AC terminal of the main power equipment is controlled to output off-grid AC voltage; A synchronization signal is generated based on the output phase angle of the off-grid AC voltage and output through the signal line. The effective edge of the synchronization signal corresponds to the preset phase of the output phase angle, and the synchronization signal is used to instruct each of the slave power devices to perform off-grid phase synchronization.

2. The grid connection / disconnection control method according to claim 1, characterized in that, The process further includes the following steps: after the grid-connected switch is disconnected, but before controlling the main power equipment to output off-grid AC voltage: After a first preset time period following the detection of the disconnection signal, it is confirmed that the grid-connected switch is disconnected.

3. The grid connection / disconnection control method according to claim 1, characterized in that, Before controlling the AC terminal of the main power equipment to output off-grid AC voltage, the method further includes: When the disconnection signal is detected, the AC terminal of the main power equipment is controlled to stop output.

4. The grid connection / disconnection control method according to claim 1, characterized in that, The method further includes: After a second preset time following the sending of the power grid anomaly notification, the grid-connected switch is controlled to disconnect.

5. The grid connection / disconnection control method according to claim 1, characterized in that, Before sending the power grid anomaly notification to the slave power equipment via the protocol communication line, the method further includes: Obtain at least one of the actual grid voltage, actual grid current, and actual grid power of the power grid; When an abnormal condition is met, the power grid is determined to be abnormal; wherein the abnormal condition includes at least one of the following conditions: The actual grid voltage is less than the first grid voltage, or the actual grid voltage is greater than the second grid voltage; The actual grid current is less than the first grid current, or the actual grid current is greater than the second grid current; The actual grid power is less than the first grid power, or the actual grid power is greater than the second grid power; The power grid anomaly information reported from the power equipment was received.

6. A grid-connected / off-grid control method, applied to power equipment, characterized in that, The slave power device is communicatively connected to the master power device via signal lines and protocol communication lines. The AC terminals of both the slave power device and the master power device are connected to the power grid via corresponding grid-connected switches. The method includes: When a power grid anomaly notification is received from the main power equipment via the protocol communication line, a disconnection signal is output via the signal line, and the disconnection signal is configured to instruct all power equipment to disconnect the corresponding grid-connected switch; When the disconnection signal is detected, the grid-connected switch corresponding to the power equipment is controlled to disconnect. After the grid-connected switch is disconnected, the off-grid AC voltage is output from the AC terminal of the power equipment. When a synchronization signal is detected through the signal line, off-grid phase synchronization is performed based on the synchronization signal, wherein the effective edge of the synchronization signal corresponds to a preset phase of the output phase angle of the main power equipment.

7. The grid connection / disconnection control method according to claim 6, characterized in that, The step of outputting a disconnect signal through the signal line includes: The signal line is continuously pulled high for a third preset duration.

8. The grid connection / disconnection control method according to claim 6, characterized in that, The method further includes: After receiving the power grid anomaly notification, the grid-connected switch is controlled to disconnect after a fourth preset time period.

9. The grid connection / disconnection control method according to claim 6, characterized in that, Before controlling the output of off-grid AC voltage from the AC terminal of the power equipment after the grid-connected switch is disconnected, the method further includes: When the disconnection signal is detected through the signal line, the AC terminal of the power equipment is controlled to stop output.

10. An electrical device, characterized in that, The power equipment includes a memory and a processor, wherein the processor is used to execute a computer program stored in the memory to implement the grid connection / disconnection control method as described in any one of claims 1 to 5, or to implement the grid connection / disconnection control method as described in any one of claims 6 to 9.

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