Grid-connected anti-flow automatic test system

Abstract

This invention discloses an automated grid-connected anti-reverse current testing system, comprising a load simulation unit for simulating the load environment of actual power consumption scenarios; a power generation simulation unit for simulating a photovoltaic power generation network supplying power to the load simulation unit; an anti-reverse current device for connecting the load simulation unit and the power grid, and controlling the power generation of the power generation simulation unit based on real-time power measurements to prevent reverse current phenomena; and a power detection device for detecting the magnitude and direction of power between the anti-reverse current device and the power grid. In this invention, grid-connected anti-reverse current testing is performed using the load simulation unit and the power generation simulation unit. The testing system has a simple structure and low hardware cost.

Description

Technical Field

[0001] This invention belongs to the field of smart microgrids, and in particular relates to an automated test system for grid connection anti-reverse current. Background Technology

[0002] In grid-connected power generation systems that utilize renewable energy sources, such as photovoltaic grid-connected power generation systems, anti-reverse current control is a core requirement for meeting grid access standards. Especially in scenarios where policies restrict reverse power grid connection or transformer capacity is limited, the reliability of the anti-reverse current scheme directly determines system availability. Therefore, it is necessary to test the stability of the anti-reverse current system through a testing system to avoid the risk of current backflow into the grid during actual use. However, existing anti-reverse current testing systems are costly, and when performing complex tests such as multi-load switching, they still heavily rely on manual operation and intervention, resulting in cumbersome processes, low efficiency, and numerous inconveniences for testing work. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide an automated test system for grid connection anti-reverse current.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: An automated test system for grid-connected anti-reverse current, comprising: The load simulation unit is used to simulate the load environment of actual power consumption scenarios; The power generation simulation unit is used to simulate a photovoltaic power generation network supplying power to the load simulation unit. An anti-reverse current device is used to connect the load simulation unit and the power grid, and to control the power generation of the power generation simulation unit based on real-time power measurement to prevent reverse current from occurring; and A power detection device is used to detect the magnitude and direction of power between the anti-reverse current device and the power grid.

[0005] Furthermore, the load simulation unit includes a first combiner box, multiple loads, and multiple control switches. Each load is electrically connected to the first combiner box via a control switch. The first combiner box is also electrically connected to the power generation simulation unit and the anti-reverse current device.

[0006] Furthermore, the control switch is a time-controlled switch, which is a switch that performs timed power-on and timed power-off according to the set power-on and power-off times, and / or performs timed power-on and synchronous timing according to the set power-on and timing times, and turns off when the timing ends.

[0007] Furthermore, the anti-backflow device is a smart meter; and / or The power detection device is a bidirectional meter.

[0008] Furthermore, the power generation simulation unit includes a second combiner box, multiple inverter modules, and multiple power supply devices. The power supply devices are electrically connected to the inverter modules one by one. All the multiple inverter modules are electrically connected to the second combiner box, and the second combiner box is also electrically connected to the first combiner box of the load simulation unit.

[0009] Furthermore, the power supply device is a DC power supply.

[0010] Furthermore, the anti-reverse current device has a first communication module, and the inverter module has a second communication module. Both the first and second communication modules are Sub1G wireless communication modules with unique SN codes. The first communication module is fixed as a slave, and the second communication module determines the master and slave through a master contention mechanism, thereby forming a Sub1G communication network.

[0011] Furthermore, it also includes a cloud platform, and each of the inverter modules is connected to the cloud platform; the cloud platform stores the SN code of the anti-reverse current device in the anti-reverse current system, and each of the inverter modules obtains the corresponding SN code of the anti-reverse current device through the cloud platform.

[0012] Furthermore, the method by which the second communication module determines the master and slave devices through a master contention mechanism includes the following steps: S110. After each inverter module starts up, the second communication module first enters the standby mode. S120. In the waiting mode, each second communication module checks whether it receives a host contention message within a predetermined waiting time period. The host contention message includes the SN code of the anti-backflow device and the SN code of the second communication module that sent the message. If a host contention message is detected, step S130 is executed. If no host contention message is detected during the waiting time period, step S150 is executed. S130: The second communication module parses the SN code of the anti-reverse flow device from the host contention message. If it is the same as the SN code of the anti-reverse flow device obtained from the cloud platform, then step S140 is executed; otherwise, the host contention message is discarded, the waiting mode is maintained, and the execution of step S120 is returned. S140. The second communication module exits the standby mode, enters the slave working mode, and sends a network access request message to the host. S150, the second communication module exits the candidate mode and enters the host working mode, and sends host contention messages at intervals, and receives network access request messages from slave devices to form a network; After the anti-backflow device is activated, the first communication module first enters the waiting network access mode. After receiving the host contention message, it exits the waiting network access mode, enters the slave working mode, and sends a network access request message to the host.

[0013] Furthermore, the host sends a heartbeat signal once in each heartbeat cycle. If the second communication module in slave mode does not receive a heartbeat signal within n consecutive heartbeat cycles, it exits slave mode and enters standby mode; where n is a positive integer.

[0014] In this invention, grid-connected anti-reverse current testing is performed using a load simulation unit and a power generation simulation unit, resulting in a simple test system structure. A time-controlled switch is used to control load access, automatically connecting different combinations of loads at different times, thus covering multiple testing scenarios and more realistically simulating the changing load environment in actual power consumption scenarios. The time-controlled switch is low-cost, requires no network connection during use, is convenient to use, and eliminates the need for manual intervention during testing, greatly reducing the pressure on test personnel who would otherwise have to operate it for extended periods. The network utilizes Sub-1GHz wireless communication technology, providing excellent communication performance and strong signal penetration, ensuring effective communication. The network employs a distributed automatic contention and switching mechanism, avoiding the single-point-of-failure risk of traditional master-slave architectures. When the master fails, the slave can automatically compete to become the new master, significantly improving the system's robustness and availability. Furthermore, the equipment supports plug-and-play, achieving comprehensive optimization of performance, reliability, and economy. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a structural block diagram of an embodiment of the grid connection anti-reverse current automated testing system of the present invention.

[0016] Figure 2 This is a schematic diagram of automatic networking of communication modules based on host contention mechanism.

[0017] Figure 3 This is a flowchart illustrating a method for determining the master and slave devices through a master contention mechanism. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0019] Please see Figure 1 , Figure 1This is a structural block diagram of an embodiment of the automated grid-connected anti-reverse current testing system of the present invention. The automated grid-connected anti-reverse current testing system of this embodiment includes a load simulation unit, a power generation simulation unit, an anti-reverse current device, and a power detection device.

[0020] The load simulation unit is used to simulate the load environment of actual power consumption scenarios, such as the load environment in a household power consumption environment. In this embodiment, the load simulation unit includes a first combiner box, multiple loads, and multiple control switches. The multiple loads are used to simulate various electrical devices, and the size of each load can be different. Each load is electrically connected to the first combiner box through a control switch, so that the connection of the load can be controlled by the control switch. By connecting different combinations of loads at different time periods, test requirements for multiple scenarios can be explored, so as to more realistically simulate the variable load environment in actual power consumption scenarios such as household power consumption.

[0021] The first combiner box is also electrically connected to the power generation simulation unit and the anti-reverse current device, respectively, for providing the voltage output by the power generation simulation unit to each load, and for realizing the electrical connection between the load simulation unit, the power generation simulation unit and the anti-reverse current device.

[0022] The control switch is preferably a time-controlled switch. This time-controlled switch can perform timed power-on and timed power-off based on set power-on and power-off times. It can also perform timed power-on and synchronized timing based on set power-on times and timing periods, and power off when the timing ends. The time-controlled switch allows for pre-setting the access periods for each load, eliminating the need for manual intervention during testing. Furthermore, the time-controlled switch is low-cost, requires no network connection, and is easy to use, greatly reducing the workload for testing personnel who need to operate it for extended periods.

[0023] The power generation simulation unit is used to simulate a photovoltaic power generation network supplying power to the load simulation unit. In this embodiment, the power generation simulation unit includes a second combiner box, multiple inverter modules, and multiple power supply devices, each of which is electrically connected to a corresponding inverter module. The power supply devices are used to simulate photovoltaic equipment providing input power to the inverter modules. In this embodiment, the power supply devices preferably use DC power. All the multiple inverter modules are electrically connected to the second combiner box, which is also electrically connected to the first combiner box of the load simulation unit, thereby supplying power to the load connected to the first combiner box.

[0024] The anti-reverse current device is used to connect the load simulation unit and the power grid, so that when the output power of the power generation simulation unit is lower than the total power consumption of the load simulation unit, the power grid can supplement the power supply to the load simulation unit. The anti-reverse current device is also used to control the power generation of the power generation simulation unit according to the real-time measured power, so as to avoid the reverse current phenomenon (i.e., the current of the power generation simulation unit and the load simulation unit flows back to the power grid).

[0025] The anti-backflow device is preferably a smart meter. A smart meter is a measurement terminal whose core functions are high-precision metering, data storage, and event logging. Smart meters generally have high-precision bidirectional power sensors that can provide millisecond-level power flow direction and magnitude data in real time, thus enabling bidirectional power measurement. Through the smart meter, the direction of power (positive power indicates current flowing from the grid into the load simulation unit, and negative power indicates current flowing back into the grid) and the magnitude of power can be measured in real time, thereby controlling the inverter module of the power generation simulation unit based on this information.

[0026] For example, when the measured power is negative, the inverter module's power output can be precisely adjusted to decrease based on the magnitude of the reverse power, thus quickly ending the reverse current phenomenon. Conversely, when the forward power is high, if the inverter module's power output is below its rated power, the inverter module's power output can be increased based on the magnitude of the forward power, ensuring that reverse current does not occur. This improves the inverter module's power generation efficiency and reduces grid power consumption. Thus, precise measurement and adjustment adapt to load changes in the load simulation unit.

[0027] The power detection device is used to detect the magnitude and direction of power between the anti-reverse current device and the power grid, that is, to detect whether the anti-reverse current device can prevent backflow and the severity of any backflow, thereby determining the effectiveness of the anti-reverse current control. In this embodiment, the power detection device is preferably a bidirectional meter. Existing power detection devices generally use power analyzers, but power analyzers are expensive, increasing the hardware cost of the testing system. In this embodiment, using a bidirectional meter at the power grid end can statistically determine whether there is backflow to the power grid within a certain period (e.g., one day) and how much electricity is flowing back, thus meeting the testing requirements for anti-reverse current detection and replacing the power analyzer. Moreover, the cost of a bidirectional meter is far lower than that of a power analyzer, making it more suitable for long-term aging tests.

[0028] In existing anti-reverse current testing systems, communication between the anti-reverse current device and the inverter module typically uses an RS485 communication architecture, achieving multi-machine power regulation via wired connection. However, this communication architecture suffers from high wiring costs and complex construction. Some manufacturers use Wi-Fi or Bluetooth networking to achieve communication between the anti-reverse current device and the inverter module, but Wi-Fi signals have weak penetration in complex building environments, limited communication distance (typically ≤10 meters), and insufficient stability when multiple devices communicate concurrently, making it difficult to adapt to the decentralized installation scenarios of residential distributed photovoltaic systems. Furthermore, existing solutions generally rely on fixed hosts or external data acquisition units for centralized control: when the fixed host fails, the entire system needs to be shut down for maintenance, resulting in insufficient reliability; while external data acquisition units not only increase equipment costs but also introduce additional communication delays. Therefore, it is necessary to improve the communication method.

[0029] Please see Figure 2 In this embodiment, the anti-reverse current device has a first communication module, and the inverter module has a second communication module. Both the first and second communication modules are Sub1G (i.e., radio wave bands with frequencies below 1GHz) wireless communication modules with unique serial numbers (SNs). The first communication module is fixed as the slave, and the second communication module determines the master and slave through a master contention mechanism. This allows the first communication module and each of the second communication modules to form a Sub1G communication network, through which data exchange and control command transmission between the anti-reverse current device and each inverter module are realized.

[0030] To facilitate parameter configuration of the inverter modules, a cloud platform is typically provided, and each inverter module is connected to the cloud platform. For example, each inverter module may also have a third communication module, which connects to the cloud platform. This third communication module can be a Wi-Fi communication module, but it can also be other wireless or wired communication modules. The cloud platform stores the SN code of the anti-reverse current device in the automated testing system (i.e., the SN code of the first communication module in the anti-reverse current device). Each inverter module can obtain the corresponding SN code of the anti-reverse current device (i.e., the SN code of the anti-reverse current device in its own automated testing system) through the cloud platform.

[0031] Please see Figure 3 The method by which the second communication module determines the master and slave devices through a master contention mechanism includes the following steps: S110. After each inverter module starts up, the second communication module first enters the waiting mode and begins the host competition mechanism.

[0032] S120. In the waiting mode, each second communication module checks whether it has received a host contention message within a predetermined waiting period. The host contention message sent by the second communication module includes the SN code of the anti-reverse current device and the SN code of the second communication module itself, and generally also includes other relevant information such as a timestamp, current power generation, and communication signal strength. If the second communication module detects the host contention message, step S130 is executed. If the second communication module still does not detect the host contention message during the waiting period, step S150 is executed. Of course, after detecting the host contention message, the slave device will also perform time alignment based on the timestamp.

[0033] Interference may occur when two or more automated testing systems are located in the same area. For example, when the automated testing systems are powered on simultaneously, the inverter module and the anti-reverse current device may not be able to accurately identify each other, or the inverter module may identify the same model of anti-reverse current device in another automated testing system. That is, the inverter module in automated testing system a cannot identify the anti-reverse current device in automated testing system a, or incorrectly identifies the anti-reverse current device in automated testing system b, thus causing the two or more automated testing systems in close proximity to be unable to operate normally independently. To avoid the above situation, this embodiment writes the SN code of the anti-reverse current device in its own testing system into the host contention message.

[0034] S130: The second communication module parses the SN code of the anti-reverse current device from the host contention message. If it is the same as the SN code of the anti-reverse current device obtained from the cloud platform, it means that the host contention message was sent by the second communication module of the inverter module in the same anti-reverse current system. Therefore, step S140 is executed to respond. Otherwise, it means that the host contention message was sent by the second communication module of the inverter module in another automated test system. No response is required. Therefore, the host contention message is discarded, the waiting mode is maintained, and step S120 is executed.

[0035] By writing the SN code of the anti-backflow device in the automated testing system into the cloud platform and writing the SN code of the anti-backflow device in the automated testing system into the host contention message, the inverter modules in different automated testing systems can be distinguished to ensure that the inverter modules in the network are all located in the same automated testing system and to eliminate interference caused by devices in other automated testing systems.

[0036] S140. The second communication module exits the candidate mode and enters the slave working mode (i.e., the second communication module is set as a slave, and at this time, it no longer responds to the host contention message), and sends a network access request message to the host. It should be noted that, except for the second communication module that did not win the host contention, the first communication module is also a slave.

[0037] S150: The second communication module exits the candidate mode and enters the master working mode (i.e., sets the second communication module as the master), and sends master contention messages at intervals (e.g., at 1 second intervals); and receives network access request messages from slave devices to form a network. Therefore, there is only one master device when forming a network, and the other second communication modules are all slave devices.

[0038] Since the first communication module is fixed as a slave module, after the anti-backflow device is activated, the first communication module first enters the waiting network access mode. After receiving the host contention message, it exits the waiting network access mode, enters the slave working mode, and sends a network access request message to the host, which then arranges the network access.

[0039] The specific process of setting up a network may include the following steps: S160. The host divides the time into multiple time slices according to pre-set parameters and generates a device information table. The device information table is used to record the serial number (SN) code and allocated time slice of each slave device in each channel. Each time slice corresponds one-to-one with a channel. Time slice is a resource scheduling method in network communication that divides continuous communication time into fixed or variable-length, periodically repeating time segments and allocates them to different devices to achieve orderly and conflict-free data transmission.

[0040] In one-to-many communication networks, time-slicing is a core technology for coordinating multiple devices to share the same channel (such as a wireless frequency or bus). Time-slicing can be understood as a time-division multiplexing strategy, essentially dividing the communication timeline into multiple fixed time slots, each of which is a time slice. The master allocates one or more fixed time slots to each slave device. Only during its assigned time slot can a slave device send data; other slave devices must remain silent or sleep. As the time cycle repeats, each device can regularly obtain communication opportunities.

[0041] S170. The host sends a slave sequence message, which includes a device information table, i.e., whether each channel is occupied, and the device information used to occupy the channel, so that the slave can determine whether there is a free channel according to the device information table.

[0042] S180. After receiving the slave sequence message, each slave device checks the device information table to see if there are any available channels. If there are available channels, it means that the device can join the network, and then sends a network entry request message to the host to request network entry.

[0043] S190. After receiving the network access request message, the host checks the device information table for available channels. If there are available channels, the host responds to the slave's network access request, allocates a time slice for it, and fills its SN code and time slice into an available channel, then accepts the slave's network access. Otherwise, it means that the channel is full and no more slaves can be arranged to join the network, so the host does not respond to the slave's network access request.

[0044] For example, when the pre-set network capacity is 10 devices, the host will divide the network into 9 time slices to form 9 channels. When all 9 channels are occupied, it means that the network has reached its maximum capacity and can no longer accept slave devices to join the network.

[0045] To prevent communication interruptions caused by the inverter module containing the host malfunctioning due to weak light or equipment failure, in this embodiment, the host sends a heartbeat signal once per heartbeat cycle (the heartbeat signal is a short data packet used to announce to the slave that the host is still online and working normally). For example, the heartbeat cycle can be 3 seconds. If the second communication module in slave mode does not receive a heartbeat signal within n consecutive heartbeat cycles, it determines that the host has left the network and needs to be re-networked, where n is a positive integer. At this time, the second communication module exits slave mode and enters waiting mode, re-determining the host and slave through the host contention mechanism to continue data transmission. Since data packet loss needs to be considered, n is generally set to an integer greater than 1; for example, n=3 times.

[0046] In addition, to avoid incomplete networking due to unexpected situations where more than two hosts appear simultaneously (i.e., some second communication modules cannot join the network because they are in host working mode), when a host continuously receives host contention messages from other second communication modules (i.e., another host) in the same automated testing system, all hosts will exit host working mode and enter waiting mode, thereby restarting the host contention mechanism to form a network.

[0047] After the network is set up, the anti-backflow control phase begins, and the following steps are performed: S210. The host obtains the net power P_meter and power direction (i.e., forward or reverse) of the smart meter, as well as the current generating power P_i and rated output power P_ei of each slave unit through the Sub-1G communication network, and calculates the power control coefficient of the inverter module. To prevent reverse current, P_meter ≥ 0 (i.e., the power direction is reversed to forward). When P_meter < 0, the inverter module needs to be controlled to reduce its generating power to reverse the power direction to forward. Additionally, if a large value of P_meter is detected when the inverter module is not generating at full load, the inverter module also needs to be controlled to increase its generating power to improve the utilization rate of photovoltaic power generation.

[0048] The method for calculating the power control coefficient is as follows: First, calculate the required power adjustment value P_cut based on the net power P_meter. The sign of the power value P_cut indicates the direction of power adjustment. Theoretically, the net power P_meter can be used as the power value to be adjusted, i.e., P_cut = P_meter. However, since power cannot remain absolutely stable, this would result in frequent adjustments. Therefore, a buffer value P_buffer can be set (for example, P_buffer = 50W), and adjustments can be made when P_meter < 0 or P_meter > P_buffer.

[0049] Next, the target total power generation P_target is calculated based on the current total power generation ΣP_i and the power value P_cut. Finally, the power control coefficient K is calculated based on the total rated output power ΣP_ei and the target total power generation P_target, where 0 ≤ K ≤ 1.

[0050] S220: The master unit sends the power control coefficient to each slave unit via a control command message.

[0051] S230. Each slave unit adjusts its power generation according to the power control coefficient in the control command message and feeds back the execution result to the master unit via a message. After adjustment, the output power of each inverter module should be K×P_ei.

[0052] In this embodiment, grid-connected anti-reverse current testing is conducted using a load simulation unit and a power generation simulation unit, resulting in a simple test system structure. A time-controlled switch is employed to control load access, automatically connecting different combinations of loads at different time periods. This allows for the exploration of various testing scenarios, more realistically simulating the changing load environment in actual power consumption scenarios. The time-controlled switch is low-cost, requires no network connection during use, is easy to operate, and eliminates the need for manual intervention during testing, significantly reducing the workload for testing personnel who would otherwise need to operate it for extended periods.

[0053] By employing Sub-1GHz wireless communication technology for networking, the system boasts excellent communication performance and strong signal penetration, ensuring effective communication. The networking method utilizes a distributed automatic contention and failover mechanism, avoiding the single point of failure risk of traditional master-slave architectures. In the event of a master failure, a slave device can automatically compete to become the new master, significantly improving system robustness and availability. Furthermore, the equipment supports plug-and-play functionality, achieving comprehensive optimization of performance, reliability, and cost-effectiveness.

[0054] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. An automated test system for grid-connected anti-reverse current, characterized in that: include The load simulation unit is used to simulate the load environment of actual power consumption scenarios; The power generation simulation unit is used to simulate a photovoltaic power generation network supplying power to the load simulation unit. The anti-backflow device is used to connect the load simulation unit and the power grid, and to control the power generation of the power generation simulation unit according to the real-time measured power to avoid backflow. as well as A power detection device is used to detect the magnitude and direction of power between the anti-reverse current device and the power grid.

2. The automated test system for grid connection anti-reverse current as described in claim 1, characterized in that: The load simulation unit includes a first combiner box, multiple loads, and multiple control switches. Each load is electrically connected to the first combiner box via a control switch. The first combiner box is also electrically connected to the power generation simulation unit and the anti-reverse current device.

3. The automated test system for grid connection anti-reverse current as described in claim 2, characterized in that: The control switch is a time-controlled switch, which is a switch that turns on the device at a set time based on the set power-on time and power-off time, and / or turns on the device at a set time based on the set power-on time and timing time, and turns it off when the timing ends.

4. The automated test system for grid connection anti-reverse current as described in claim 1, characterized in that: The backflow prevention device is a smart meter; and / or The power detection device is a bidirectional meter.

5. The automated test system for grid connection anti-reverse current as described in claim 1, characterized in that: The power generation simulation unit includes a second combiner box, multiple inverter modules, and multiple power supply devices. The power supply devices are electrically connected to the inverter modules one by one. All the multiple inverter modules are electrically connected to the second combiner box, which is also electrically connected to the first combiner box of the load simulation unit.

6. The automated test system for grid connection anti-reverse current as described in claim 5, characterized in that: The power supply device is a DC power supply.

7. The automated test system for grid connection anti-reverse current as described in any one of claims 1 to 6, characterized in that: The anti-reverse current device has a first communication module, and the inverter module has a second communication module. Both the first and second communication modules are Sub1G wireless communication modules with unique SN codes. The first communication module is fixed as a slave, and the second communication module determines the master and slave through a master contention mechanism, thereby forming a Sub1G communication network.

8. The automated test system for grid connection anti-reverse current as described in claim 7, characterized in that: It also includes a cloud platform, and each of the inverter modules is connected to the cloud platform; the cloud platform stores the SN code of the anti-reverse current device in the anti-reverse current system, and each of the inverter modules obtains the corresponding SN code of the anti-reverse current device through the cloud platform.

9. The automated test system for grid connection anti-reverse current as described in claim 8, characterized in that, The method by which the second communication module determines the master and slave devices through a master contention mechanism includes the following steps: S110. After each inverter module starts up, the second communication module first enters the standby mode. S120. In the waiting mode, each second communication module checks whether it receives a host contention message within a predetermined waiting time period. The host contention message includes the SN code of the anti-backflow device and the SN code of the second communication module that sent the message. If a host contention message is detected, step S130 is executed. If no host contention message is detected during the waiting time period, step S150 is executed. S130: The second communication module parses the SN code of the anti-reverse flow device from the host contention message. If it is the same as the SN code of the anti-reverse flow device obtained from the cloud platform, then step S140 is executed; otherwise, the host contention message is discarded, the waiting mode is maintained, and the execution of step S120 is returned. S140. The second communication module exits the standby mode, enters the slave working mode, and sends a network access request message to the host. S150, the second communication module exits the candidate mode and enters the host working mode, and sends host contention messages at intervals, and receives network access request messages from slave devices to form a network; After the anti-backflow device is activated, the first communication module first enters the waiting network access mode. After receiving the host contention message, it exits the waiting network access mode, enters the slave working mode, and sends a network access request message to the host.

10. The automated test system for grid connection anti-reverse current as described in claim 9, characterized in that: The host sends a heartbeat signal once in each heartbeat cycle. If the second communication module in slave mode does not receive a heartbeat signal within n consecutive heartbeat cycles, it exits slave mode and enters standby mode; where n is a positive integer.

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