A multi-grid-connection multi-device anti-flow control method

Abstract

The present application relates to the technical field of energy management, in particular to a multi-grid-connection-point multi-device anti-flow control method. The present application adopts a hierarchical energy storage redistribution power management method to manage multiple grid connection points and subordinate energy storage converters; by setting a first-level cache energy storage converter and a second-level cache energy storage converter, when the charging power of the user-side energy storage converter is greater than the discharging power, the user-side load is low, and the output power of the energy storage converter is excessive, the power can be stored in the second-level cache energy storage converter and the first-level cache energy storage converter layer by layer respectively. The present application solves the technical problems existing in the prior art, such as single grid connection point anti-flow processing, single means, and inability to transfer and utilize redundant power across grid connection points during reverse flow.

Description

Technical Field

[0001] This invention relates to the field of energy management technology, and more specifically, to a method for preventing backflow control of multiple grid connection points and multiple devices. Background Technology

[0002] With the accelerated advancement of energy transition, distributed energy generation technology has developed rapidly, and photovoltaic power generation and energy storage systems have been widely applied on the user side in industrial parks, commercial complexes, and public buildings. In practical engineering, due to the power consumption characteristics of different functional areas on the user side and the grid access requirements, the same user entity often sets up multiple independent grid connection points. For example, production workshops, office buildings, and dormitories are connected to the public grid through their respective grid connection points, forming an energy system architecture with multiple grid connection points. Backflow prevention control is one of the important technical means in the grid-connected operation of distributed energy. When the power generation capacity of distributed power sources, such as photovoltaics, exceeds the local load power consumption, the excess electricity will be fed back to the public grid through the grid connection point. This phenomenon is called "backflow." Backflow can cause problems such as increased grid voltage, malfunction of protection devices, and deterioration of power quality.

[0003] Currently, the main anti-backflow technologies are designed for single grid connection points. This involves configuring an energy management system at a single grid connection point. This system establishes a communication connection with all energy storage converters under that grid connection point, collects power data of the grid connection point in real time, and when the power of the grid connection point is detected to reach the warning threshold, the energy management system issues a power reduction command to all energy storage converters under that grid connection point until the backflow is eliminated. In addition, some solutions adopt a master-slave architecture, setting up a master controller and multiple slave devices, and physically grouping the inverters according to the grid connection point through communication networking to achieve zoned management.

[0004] Existing anti-reverse current methods can only prevent reverse current by limiting power, and cannot transfer and utilize electricity to prevent reverse current when the energy storage converter has energy redundancy, nor can they realize the utilization of electricity across grid connection points. In addition, existing anti-reverse current control mostly sets a single-layer threshold trigger logic, and directly reduces power when the risk of reverse current is detected, and the control method is relatively simple. Summary of the Invention

[0005] The purpose of this application is to provide a multi-grid-connection point and multi-device anti-backflow control method, which solves the technical problems existing in the prior art, such as the limited means of anti-backflow processing for a single grid connection point and the inability to transfer and utilize redundant electrical energy across grid connection points during backflow.

[0006] To solve the above-mentioned technical problems, the solution adopted in this application is as follows:

[0007] A method for preventing backflow in multiple grid connection points and multiple devices includes the following steps:

[0008] The system obtains the power status and charging status of the energy storage converters under the secondary grid connection point. If the power of any energy storage converter under the secondary grid connection point exceeds the second energy storage threshold and the energy storage converter is in the charging state, the secondary anti-reverse current operation is executed. Specifically, the energy storage converter with the power exceeding the second energy storage threshold charges the secondary buffer energy storage converter and transfers the electrical energy exceeding the second energy storage threshold of the energy storage converter to the secondary buffer energy storage converter.

[0009] If the power of any energy storage converter under the secondary grid connection point is lower than the second power failure threshold and the energy storage converter is in a discharging state, the secondary power transfer operation is executed, specifically: the secondary buffer energy storage converter charges the energy storage converter whose power is lower than its second power failure threshold.

[0010] The system obtains the power status and charging status of the secondary energy storage converters at the secondary grid-connected points under the primary grid-connected point. If the power of any secondary energy storage converter exceeds the second energy storage threshold and the secondary energy storage converter is in a charging state, the system performs a primary anti-reverse current operation. Specifically, the system enables the secondary energy storage converter with the power exceeding the second energy storage threshold to charge the primary energy storage converters under the primary grid-connected point, and transfers the power exceeding its second energy storage threshold in the secondary energy storage converter to the primary energy storage converter.

[0011] If the charge of any secondary energy storage converter is lower than the first power failure threshold and the secondary energy storage converter is in a discharging state, a primary energy transfer operation is performed, specifically: the primary energy storage converter charges the secondary energy storage converter whose charge is lower than its first power failure threshold.

[0012] The system detects the power status and charging status of the primary energy storage converter. If the power of the primary energy storage converter exceeds the maximum energy storage threshold and it is in a charging state, a power reduction operation is performed, specifically reducing the charging and discharging power of all energy storage converters.

[0013] Preferably, if the power of any energy storage converter under the secondary grid connection point exceeds the second energy storage threshold and the energy storage converter is in a charging state, the secondary anti-reverse current operation is performed. This step further includes:

[0014] Based on the excess power value, charging power, and user-side load power value of each energy storage converter, the excess power of all energy storage converters under the secondary grid connection point is sorted by priority to obtain the priority queue for excess power transfer.

[0015] According to the priority queue, the excess power of each energy storage converter is transmitted to the secondary buffer energy storage converter of the grid connection point to which the energy storage converter belongs;

[0016] During the excess power transfer process, the total user-side load power corresponding to all energy storage converters under the secondary grid connection point is collected, and the second energy storage threshold of the secondary buffer energy storage converters under the secondary grid connection point is dynamically adjusted according to the total load power.

[0017] Preferably, the dynamic adjustment of the second energy storage threshold of the secondary buffered energy storage converter under the secondary grid connection point includes the following steps:

[0018] Predict the future total load power based on the real-time total user-side load power and the historical total load power trend of the secondary grid connection point;

[0019] The second energy storage threshold is dynamically adjusted based on the difference between the real-time total user-side load power and the future total load power of the secondary grid connection point. Specifically, when the real-time total user-side load power of the secondary grid connection point is greater than the future total load power, the second energy storage threshold is increased; when the real-time total user-side load power of the secondary grid connection point is less than the future total load power, the second energy storage threshold is decreased.

[0020] Preferably, if the power level of any energy storage converter under the secondary grid connection point is lower than the second power failure threshold and the energy storage converter is in a discharging state, a secondary power transfer operation is performed. This step further includes:

[0021] Real-time traversal of the current remaining power, discharge power and working status of all energy storage converters under the secondary grid connection point, screening out energy storage converters whose power is lower than the second power failure threshold and are in a continuous discharge state, and marking them as energy storage converters to be replenished.

[0022] Based on the power loss, discharge rate, and user-side load power of each energy storage converter to be replenished, a replenishment priority sequence is established. According to the replenishment priority sequence, the secondary buffer energy storage converter charges the energy storage converter to be replenished.

[0023] Preferably, the secondary power transfer operation also includes:

[0024] If the power of the secondary energy storage converter is lower than the first power failure threshold and the energy storage converter still needs to be replenished, the power status of the primary energy storage converter is detected. If the power of the primary energy storage converter exceeds its minimum power threshold, the primary power transfer operation is triggered, and the primary energy storage converter charges the secondary energy storage converter.

[0025] Preferably, if the power of any secondary energy storage converter exceeds the second energy storage threshold and the secondary energy storage converter is in a charging state, the first-level anti-reverse current operation is executed. This step further includes:

[0026] In real time, iterate through all secondary grid-connected points under the primary grid-connected point and collect their current remaining power, charging power, charging status and the number of the secondary grid-connected point to which they belong. Select the secondary grid-connected point whose power exceeds the second energy storage threshold and is in the charging state, and mark it as a primary anti-reverse current energy storage converter to be dispatched.

[0027] A multi-level scheduling priority sequence is established based on the excess power, charging power, and total user-side load power of each primary anti-reverse flow energy storage converter to be dispatched, as well as the total user-side load power of its respective secondary grid connection point.

[0028] According to the multi-level scheduling priority sequence, the secondary buffer energy storage converter charges the primary buffer energy storage converter in order of priority from high to low.

[0029] Preferably, if the power of any secondary energy storage converter exceeds the second energy storage threshold and the secondary energy storage converter is in a charging state, the first-level anti-reverse current operation is executed. This step further includes:

[0030] When charging the primary energy storage converter, the power of the primary energy storage converter is monitored in real time. If the stored power of the primary energy storage converter reaches its maximum energy storage threshold, the primary anti-reverse operation is stopped and the power reduction operation is performed.

[0031] Preferably, the step of performing a first-level power transfer operation if the power of any secondary energy storage converter is lower than the first power failure threshold and the secondary energy storage converter is in a discharging state further includes:

[0032] Real-time monitoring of the current remaining power and discharge power of the secondary buffer energy storage converters corresponding to all secondary grid connection points under the primary grid connection point; screening out the secondary buffer energy storage converters whose power is lower than the first power outage threshold and are in a continuous discharge state; marking them as primary energy replenishment devices; and recording their respective secondary grid connection point number and current power outage status parameters.

[0033] Based on the current remaining power, discharge power, and total user-side load power of the primary energy-replenishing equipment and its corresponding secondary grid connection point, the primary energy-replenishing equipment is prioritized for energy replenishment.

[0034] According to the order of charging priority from high to low, the first-level buffer energy storage converter charges the second-level buffer energy storage converter in sequence.

[0035] Preferably, the step of performing a first-level power transfer operation if the power of any secondary energy storage converter is lower than the first power failure threshold and the secondary energy storage converter is in a discharging state further includes:

[0036] When the primary energy storage converter charges the secondary energy storage converter in sequence, the power of the primary energy storage converter is monitored in real time. If the power of the primary energy storage converter reaches its minimum energy storage threshold, the primary energy transfer operation is stopped.

[0037] Preferably, the step of detecting the power status and charging status of the primary energy storage converter, and performing a power reduction operation if the power status of the primary energy storage converter exceeds the maximum energy storage threshold and is in a charging state, further includes:

[0038] When performing power reduction operations, a graded gradient power reduction strategy is adopted; specifically:

[0039] Based on the difference between the current power of the primary energy storage converter and the maximum energy storage threshold, multiple power reduction intervals are defined.

[0040] When the difference is within the first preset range, the charging power and discharging power of each energy storage converter are reduced according to the first preset power gradient.

[0041] When the difference is in the second preset range which is greater than the first preset range, the charging power and discharging power of each energy storage converter are reduced according to the second preset power gradient which is greater than the first preset power gradient.

[0042] After each stage of power regulation is completed, the power of the first-stage energy storage converter is monitored in real time until the power of the first-stage energy storage converter drops below the maximum energy storage threshold.

[0043] The technical solution of this application has at least the following advantages and beneficial effects:

[0044] 1. This invention employs a tiered energy storage and redistribution power management method to manage multiple grid-connected points and their subordinate energy storage converters. By setting up primary and secondary buffer energy storage converters, when the charging power of the user-side energy storage converter exceeds the discharging power, resulting in a low user-side load and excess output power of the energy storage converter, the excess power can be stored layer by layer in the secondary and primary buffer energy storage converters. Compared to existing methods that directly reduce power and discharge when the output power of the energy storage converter exceeds the user-side load, this method stores the excess power and, when the energy storage converter's power is low, outputs the power from the secondary buffer energy storage converter to charge it. Furthermore, when the power of the secondary buffer energy storage converter is low, outputs the power from the primary buffer energy storage converter to charge it. Finally, when the charge of the primary energy storage converter exceeds its maximum energy storage threshold, all energy storage converters under the secondary grid connection point are reduced in power to prevent them from continuously outputting excess power at their original power level, thus preventing the excess power from flowing back to the grid through the secondary and primary energy storage converters. Attached Figure Description

[0045] Figure 1 This is a schematic flowchart of the method of the present invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] This invention discloses a multi-grid-connected point and multi-device anti-backflow control method, applied to an energy system architecture containing a primary grid-connected point and multiple secondary grid-connected points. The specific implementation method includes the following steps:

[0048] The system obtains the power status and charging status of the energy storage converters under the secondary grid connection point. If the power of any energy storage converter under the secondary grid connection point exceeds the second energy storage threshold and the energy storage converter is in the charging state, the secondary anti-reverse current operation is executed. Specifically, the energy storage converter with the power exceeding the second energy storage threshold charges the secondary buffer energy storage converter and transfers the electrical energy exceeding the second energy storage threshold of the energy storage converter to the secondary buffer energy storage converter.

[0049] If the power of any energy storage converter under the secondary grid connection point is lower than the second power failure threshold and the energy storage converter is in a discharging state, the secondary power transfer operation is executed, specifically: the secondary buffer energy storage converter charges the energy storage converter whose power is lower than its second power failure threshold.

[0050] The system obtains the power status and charging status of the secondary energy storage converters at the secondary grid-connected points under the primary grid-connected point. If the power of any secondary energy storage converter exceeds the second energy storage threshold and the secondary energy storage converter is in a charging state, the system performs a primary anti-reverse current operation. Specifically, the system enables the secondary energy storage converter with the power exceeding the second energy storage threshold to charge the primary energy storage converters under the primary grid-connected point, and transfers the power exceeding its second energy storage threshold in the secondary energy storage converter to the primary energy storage converter.

[0051] If the charge of any secondary energy storage converter is lower than the first power failure threshold and the secondary energy storage converter is in a discharging state, a primary energy transfer operation is performed, specifically: the primary energy storage converter charges the secondary energy storage converter whose charge is lower than its first power failure threshold.

[0052] The system detects the power status and charging status of the primary energy storage converter. If the power of the primary energy storage converter exceeds the maximum energy storage threshold and it is in a charging state, a power reduction operation is performed, specifically reducing the charging and discharging power of all energy storage converters.

[0053] As described above, by setting up a primary and a secondary energy storage converter, when the charging power of the user-side energy storage converter exceeds the discharging power, resulting in a low user-side load and excess output power of the energy storage converter, the excess power can be stored layer by layer in the secondary and primary energy storage converters. Compared to the existing method of directly reducing power and discharging when the output power of the energy storage converter exceeds the user-side load, this method stores the excess energy and, when the energy storage converter's power is low, outputs the energy from the secondary energy storage converter to charge it. Furthermore, when the energy storage converter's power is low, it can output the energy from the primary energy storage converter to charge the secondary energy storage device. Finally, when the charge of the primary energy storage converter exceeds its maximum energy storage threshold, all energy storage converters under the secondary grid connection point are reduced in power to prevent them from continuously outputting excess power at their original power level, thus preventing the excess power from flowing back to the grid through the secondary and primary energy storage converters.

[0054] Furthermore, the power status and charging status of the energy storage converters under the secondary grid connection point are obtained. If the power of any energy storage converter under the secondary grid connection point exceeds the second energy storage threshold and the energy storage converter is in a charging state, a secondary anti-reverse current operation is executed. Specifically, the energy storage converter with the power exceeding the second energy storage threshold charges the secondary buffer energy storage converter, transferring the electrical energy exceeding the second energy storage threshold of the energy storage converter to the secondary buffer energy storage converter. This step also includes:

[0055] Based on the excess power value, charging power, and user-side load power value of each energy storage converter, the excess power of all energy storage converters under the secondary grid connection point is sorted by priority to obtain the priority queue for excess power transfer.

[0056] According to the priority queue, the excess power of each energy storage converter is transmitted to the secondary buffer energy storage converter of the grid connection point to which the energy storage converter belongs;

[0057] During the excess power transfer process, the total user-side load power value corresponding to all energy storage converters under the secondary grid connection point is collected, and the second energy storage threshold of the secondary buffer energy storage converters under the secondary grid connection point is dynamically adjusted according to the total load power value.

[0058] Furthermore, dynamically adjusting the second energy storage threshold of the secondary buffered energy storage converter under the secondary grid connection point includes the following steps:

[0059] Predict the future total load power based on the real-time total user-side load power and the historical total load power trend of the secondary grid connection point;

[0060] The second energy storage threshold is dynamically adjusted based on the difference between the real-time total user-side load power and the future total load power of the secondary grid connection point. Specifically, when the real-time total user-side load power of the secondary grid connection point is greater than the future total load power, the second energy storage threshold is increased; when the real-time total user-side load power of the secondary grid connection point is less than the future total load power, the second energy storage threshold is decreased.

[0061] As described above, when the total real-time user-side load power at the secondary grid connection point is greater than the total future load power, it indicates that the current load consumption capacity is strong and more electrical energy is needed. In this case, the second energy storage threshold of the secondary buffer energy storage converter should be increased to improve its energy storage capacity and reduce the frequency of triggering the primary anti-reverse operation. When the total real-time user-side load power at the secondary grid connection point is less than the total future load power, it indicates that the current load consumption capacity is weak and there is a risk of excess electrical energy and reverse flow. In this case, the second energy storage threshold should be lowered to trigger the primary anti-reverse operation earlier, transferring excess electrical energy upwards in advance and avoiding local energy storage overload.

[0062] Furthermore, if the charge of any energy storage converter under the secondary grid connection point is lower than the second power failure threshold and the energy storage converter is in a discharging state, a secondary power transfer operation is performed, specifically: the secondary buffer energy storage converter charges the energy storage converter whose charge is lower than its second power failure threshold; this step also includes:

[0063] Real-time traversal of the current remaining power, discharge power and working status of all energy storage converters under the secondary grid connection point, screening out energy storage converters whose power is lower than the second power failure threshold and are in a continuous discharge state, and marking them as energy storage converters to be replenished.

[0064] Based on the power loss, discharge rate, and user-side load power of each energy storage converter to be replenished, a replenishment priority sequence is established. According to the replenishment priority sequence, the secondary buffer energy storage converter charges the energy storage converter to be replenished.

[0065] Furthermore, secondary power transfer operations also include:

[0066] If the power of the secondary energy storage converter is lower than the first power failure threshold and the energy storage converter still needs to be replenished, the power status of the primary energy storage converter is detected. If the power of the primary energy storage converter exceeds its minimum power threshold, the primary power transfer operation is triggered, and the primary energy storage converter charges the secondary energy storage converter.

[0067] Furthermore, the system obtains the power status and charging status of the secondary energy storage converters at the secondary grid-connected points under the primary grid-connected point. If the power of any secondary energy storage converter exceeds the second energy storage threshold and the secondary energy storage converter is in a charging state, a primary anti-reverse current operation is executed. Specifically, the secondary energy storage converter with the power exceeding the second energy storage threshold charges the primary energy storage converters under the primary grid-connected point, transferring the power exceeding its second energy storage threshold from the secondary energy storage converter to the primary energy storage converter. This step also includes:

[0068] In real time, iterate through all secondary grid-connected points under the primary grid-connected point and collect their current remaining power, charging power, charging status and the number of the secondary grid-connected point to which they belong. Select the secondary grid-connected point whose power exceeds the second energy storage threshold and is in the charging state, and mark it as a primary anti-reverse current energy storage converter to be dispatched.

[0069] A multi-level scheduling priority sequence is established based on the excess power, charging power, and total user-side load power of each primary anti-reverse flow energy storage converter to be dispatched, as well as the total user-side load power of its respective secondary grid connection point.

[0070] According to the multi-level scheduling priority sequence, the secondary buffer energy storage converter charges the primary buffer energy storage converter in order of priority from high to low.

[0071] Furthermore, this step also includes:

[0072] When charging the primary energy storage converter, the power of the primary energy storage converter is monitored in real time. If the stored power of the primary energy storage converter reaches its maximum energy storage threshold, the primary anti-reverse operation is stopped and the power reduction operation is performed.

[0073] Furthermore, if the charge of any secondary energy storage converter is lower than the first power-off threshold and the secondary energy storage converter is in a discharging state, a primary energy transfer operation is performed, specifically: the primary energy storage converter charges the secondary energy storage converter whose charge is lower than its first power-off threshold; this step also includes:

[0074] Real-time monitoring of the current remaining power and discharge power of the secondary buffer energy storage converters corresponding to all secondary grid connection points under the primary grid connection point; screening out the secondary buffer energy storage converters whose power is lower than the first power outage threshold and are in a continuous discharge state; marking them as primary energy replenishment devices; and recording their respective secondary grid connection point number and current power outage status parameters.

[0075] Based on the current remaining power, discharge power, and total user-side load power of the primary energy-replenishing equipment and its corresponding secondary grid connection point, the primary energy-replenishing equipment is prioritized for energy replenishment.

[0076] According to the order of charging priority from high to low, the first-level buffer energy storage converter charges the second-level buffer energy storage converter in sequence.

[0077] Furthermore, this step also includes:

[0078] When the primary energy storage converter charges the secondary energy storage converter in sequence, the power of the primary energy storage converter is monitored in real time. If the power of the primary energy storage converter reaches its minimum energy storage threshold, the primary energy transfer operation is stopped.

[0079] Furthermore, the power status and charging status of the primary energy storage converter are detected. If the power status of the primary energy storage converter exceeds the maximum energy storage threshold and it is in a charging state, a power reduction operation is performed, specifically: reducing the charging and discharging power of all energy storage converters; this step also includes:

[0080] When performing power reduction operations, a graded gradient power reduction strategy is adopted; specifically:

[0081] Based on the difference between the current power of the primary energy storage converter and the maximum energy storage threshold, multiple power reduction intervals are defined.

[0082] When the difference is within the first preset range, the charging power and discharging power of each energy storage converter are reduced according to the first preset power gradient.

[0083] When the difference is in the second preset range which is greater than the first preset range, the charging power and discharging power of each energy storage converter are reduced according to the second preset power gradient which is greater than the first preset power gradient.

[0084] After each stage of power regulation is completed, the power of the first-stage energy storage converter is monitored in real time until the power of the first-stage energy storage converter drops below the maximum energy storage threshold.

[0085] The various embodiments of the present invention have now been described in detail. To avoid obscuring the concept of the invention, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solutions of this invention based on the above description, and the scope of the invention is defined by the appended claims.

Claims

1. A method for preventing backflow control of multiple grid connection points and multiple devices, characterized in that, Includes the following steps: The system obtains the power status and charging status of the energy storage converters under the secondary grid connection point. If the power of any energy storage converter under the secondary grid connection point exceeds the second energy storage threshold and the energy storage converter is in the charging state, the secondary anti-reverse current operation is executed. Specifically, the energy storage converter with the power exceeding the second energy storage threshold charges the secondary buffer energy storage converter and transfers the electrical energy exceeding the second energy storage threshold of the energy storage converter to the secondary buffer energy storage converter. If the power of any energy storage converter under the secondary grid connection point is lower than the second power failure threshold and the energy storage converter is in a discharging state, the secondary power transfer operation is executed, specifically: the secondary buffer energy storage converter charges the energy storage converter whose power is lower than its second power failure threshold. The system obtains the power status and charging status of the secondary energy storage converters at the secondary grid-connected points under the primary grid-connected point. If the power of any secondary energy storage converter exceeds the second energy storage threshold and the secondary energy storage converter is in a charging state, the system performs a primary anti-reverse current operation. Specifically, the system enables the secondary energy storage converter with the power exceeding the second energy storage threshold to charge the primary energy storage converters under the primary grid-connected point, and transfers the power exceeding its second energy storage threshold in the secondary energy storage converter to the primary energy storage converter. If the charge of any secondary energy storage converter is lower than the first power failure threshold and the secondary energy storage converter is in a discharging state, a primary energy transfer operation is performed, specifically: the primary energy storage converter charges the secondary energy storage converter whose charge is lower than its first power failure threshold. The system detects the power status and charging status of the primary energy storage converter. If the power of the primary energy storage converter exceeds the maximum energy storage threshold and it is in a charging state, a power reduction operation is performed, specifically reducing the charging and discharging power of all energy storage converters.

2. The method for preventing backflow of multiple grid-connected devices according to claim 1, characterized in that, If the power of any energy storage converter under the secondary grid connection point exceeds the second energy storage threshold and the energy storage converter is in a charging state, a secondary anti-reverse current operation is performed. This step also includes: Based on the excess power value, charging power, and user-side load power value of each energy storage converter, the excess power of all energy storage converters under the secondary grid connection point is sorted by priority to obtain the priority queue for excess power transfer. According to the priority queue, the excess power of each energy storage converter is transmitted to the secondary buffer energy storage converter of the grid connection point to which the energy storage converter belongs; During the excess power transfer process, the total user-side load power corresponding to all energy storage converters under the secondary grid connection point is collected, and the second energy storage threshold of the secondary buffer energy storage converters under the secondary grid connection point is dynamically adjusted according to the total load power.

3. The method for preventing backflow of multiple grid-connected devices according to claim 2, characterized in that, The dynamic adjustment of the second energy storage threshold of the secondary buffered energy converter under the secondary grid connection point includes the following steps: Predict the future total load power based on the real-time total user-side load power and the historical total load power trend of the secondary grid connection point; The second energy storage threshold is dynamically adjusted based on the difference between the real-time total user-side load power and the future total load power of the secondary grid connection point. Specifically, when the real-time total user-side load power of the secondary grid connection point is greater than the future total load power, the second energy storage threshold is increased; when the real-time total user-side load power of the secondary grid connection point is less than the future total load power, the second energy storage threshold is decreased.

4. The method for preventing backflow in multiple grid-connected devices according to claim 1, characterized in that, If the charge of any energy storage converter under the secondary grid connection point is lower than the second power failure threshold and the energy storage converter is in a discharging state, a secondary power transfer operation is performed. This step also includes: Real-time traversal of the current remaining power, discharge power and working status of all energy storage converters under the secondary grid connection point, screening out energy storage converters whose power is lower than the second power failure threshold and are in a continuous discharge state, and marking them as energy storage converters to be replenished. Based on the power loss, discharge rate, and user-side load power of each energy storage converter to be replenished, a replenishment priority sequence is established. According to the replenishment priority sequence, the secondary buffer energy storage converter charges the energy storage converter to be replenished.

5. The method for preventing backflow in multiple grid-connected devices according to claim 4, characterized in that, Secondary power transfer operations also include: If the power of the secondary energy storage converter is lower than the first power failure threshold and the energy storage converter still needs to be replenished, the power status of the primary energy storage converter is detected. If the power of the primary energy storage converter exceeds its minimum power threshold, the primary power transfer operation is triggered, and the primary energy storage converter charges the secondary energy storage converter.

6. The method for preventing backflow in multiple grid-connected devices according to claim 1, characterized in that, If the charge of any secondary energy storage converter exceeds the second energy storage threshold and the secondary energy storage converter is in a charging state, a first-level anti-reverse current operation is performed. This step also includes: In real time, iterate through all secondary grid-connected points under the primary grid-connected point and collect their current remaining power, charging power, charging status and the number of the secondary grid-connected point to which they belong. Select the secondary grid-connected point whose power exceeds the second energy storage threshold and is in the charging state, and mark it as a primary anti-reverse current energy storage converter to be dispatched. A multi-level scheduling priority sequence is established based on the excess power, charging power, and total user-side load power of each primary anti-reverse flow energy storage converter to be dispatched, as well as the total user-side load power of its respective secondary grid connection point. According to the multi-level scheduling priority sequence, the secondary buffer energy storage converter charges the primary buffer energy storage converter in order of priority from high to low.

7. A method for preventing backflow in multiple grid-connected devices according to claim 6, characterized in that, If the charge of any secondary energy storage converter exceeds the second energy storage threshold and the secondary energy storage converter is in a charging state, a first-level anti-reverse current operation is performed. This step also includes: When charging the primary energy storage converter, the power of the primary energy storage converter is monitored in real time. If the stored power of the primary energy storage converter reaches its maximum energy storage threshold, the primary anti-reverse operation is stopped and the power reduction operation is performed.

8. A method for preventing backflow in multiple grid-connected devices according to claim 1, characterized in that, If the charge of any secondary energy storage converter is lower than the first power failure threshold and the secondary energy storage converter is in a discharging state, a primary power transfer operation is performed. This step further includes: Real-time monitoring of the current remaining power and discharge power of the secondary buffer energy storage converters corresponding to all secondary grid connection points under the primary grid connection point; screening out the secondary buffer energy storage converters whose power is lower than the first power outage threshold and are in a continuous discharge state; marking them as primary energy replenishment devices; and recording their respective secondary grid connection point number and current power outage status parameters. Based on the current remaining power, discharge power, and total user-side load power of the primary energy-replenishing equipment and its corresponding secondary grid connection point, the primary energy-replenishing equipment is prioritized for energy replenishment. According to the order of charging priority from high to low, the first-level buffer energy storage converter charges the second-level buffer energy storage converter in sequence.

9. A method for preventing backflow in multiple grid-connected devices according to claim 8, characterized in that, If the charge of any secondary energy storage converter is lower than the first power failure threshold and the secondary energy storage converter is in a discharging state, a primary power transfer operation is performed. This step further includes: When the primary energy storage converter charges the secondary energy storage converter in sequence, the power of the primary energy storage converter is monitored in real time. If the power stored in the primary energy storage converter reaches its minimum energy storage threshold, the primary energy transfer operation is stopped.

10. A method for preventing backflow in multiple grid-connected devices according to claim 9, characterized in that, The step of detecting the power status and charging status of the primary energy storage converter, and if the power status of the primary energy storage converter exceeds the maximum energy storage threshold and is in a charging state, performing a power reduction operation, further includes: When performing power reduction operations, a graded gradient power reduction strategy is adopted; specifically: Based on the difference between the current power of the primary energy storage converter and the maximum energy storage threshold, multiple power reduction intervals are defined. When the difference is within the first preset range, the charging power and discharging power of each energy storage converter are reduced according to the first preset power gradient. When the difference is in the second preset range which is greater than the first preset range, the charging power and discharging power of each energy storage converter are reduced according to the second preset power gradient which is greater than the first preset power gradient. After each stage of power regulation is completed, the power of the first-stage energy storage converter is monitored in real time until the power of the first-stage energy storage converter drops below the maximum energy storage threshold.

Images