Countercurrent prevention control system and method based on transformer area flexible direct current interconnection

Abstract

The invention provides an anti-countercurrent control system and method based on transformer area flexible direct current interconnection, belongs to the technical field of power distribution network and new energy fusion control, and is suitable for direct current flexible interconnection and green energy collaborative utilization of heterogeneous transformer areas such as expressways, parks and urban and rural fusion areas. The system comprises an energy route management module, a transformer area capacity marking module, an energy monitoring module, a flexible direct current interconnection scheduling module, an anti-countercurrent module and an intelligent scheduling strategy module, and the control method comprises the steps of initializing the state of a transformer area, collecting data in real time, judging redundant power and scheduling the redundant power to the transformer area without power generation / grid connection capacity, and executing an anti-countercurrent strategy. And parameters and strategies are optimized based on an intelligent self-learning mechanism. The method achieves the preferential local consumption of new energy, prevents power countercurrent, guarantees the safety of a power grid, improves the adaptability and economical efficiency of the system, and is adaptive to a complex multi-source distributed energy scene.

Description

Technical Field

[0001] This invention relates to the field of power distribution network and new energy integrated control technology, specifically to an anti-reverse current control system and method based on flexible DC interconnection of distribution areas. Background Technology

[0002] With the continuous expansion of new energy access, distributed power sources are widely deployed in distribution substations, especially in linear areas such as highway service areas, toll stations, and logistics hubs. Multiple substations often exhibit a mixed state, with some having power generation capacity and others not, some grid-connected and others not. Under traditional operating models, each substation operates independently, and the load between substations cannot be mutually adjusted or supplemented, leading to waste of electricity generated by new energy sources. Substations without power generation capacity cannot obtain local green energy and can only rely on the main grid for power supply, which undoubtedly increases the operational pressure on the main grid. At the same time, some substations with grid-connected capacity also face the risk of reverse power transmission, affecting the safe operation of the grid. Flexible DC interconnection, as a new type of substation interconnection method, enables bidirectional DC power flow between different substations. However, when multiple substations have different structures, without effective control measures, the problem of power flowing back into the public grid is prone to occur. Therefore, there is an urgent need for a flexible DC interconnection system with anti-reverse-current function to balance power supply efficiency and grid security.

[0003] To address this, a reverse current prevention control system and its method based on flexible DC interconnection of transformer substations are proposed. Summary of the Invention

[0004] The present invention aims to solve the problems mentioned in the background art by providing an anti-reverse current control system and method based on flexible DC interconnection of transformer substations.

[0005] The specific technical solution is as follows: A reverse current prevention control system based on flexible DC interconnection of transformer substations includes a transformer substation capacity identification module, an energy monitoring unit, a flexible DC interconnection scheduling module, a reverse current prevention control module, and an intelligent scheduling strategy module, wherein: The energy monitoring unit is used to collect real-time power generation output data, load power data, energy storage status data, and power flow data at the grid connection point of each transformer area. The input terminal of the transformer area capability identification module is connected to the output terminal of the energy monitoring unit. It is used to identify the power generation capacity and grid connection capacity of each transformer area based on the collected data, and to divide the transformer area into power supply type transformer areas with power generation and grid connection capabilities and power receiving type transformer areas without power generation and grid connection capabilities. The input terminal of the intelligent scheduling strategy module is connected to the output terminal signals of the energy monitoring unit and the transformer area capability identification module, respectively, and is used to perform multi-objective optimization decisions based on historical operating data and real-time collected data; The input terminal of the flexible DC interconnection scheduling module is connected to the output terminal signals of the transformer area capability identification module and the intelligent scheduling strategy module, respectively, and is used to prioritize the scheduling of redundant power generated by the power supply type transformer area to the power receiving type transformer area according to the optimization decision results. The input terminal of the anti-reverse flow control module is connected to the output terminal signals of the energy monitoring unit and the intelligent scheduling strategy module, respectively, and communicates bidirectionally with the flexible DC interconnection scheduling module. It is used to monitor the reverse power flow status based on the power flow direction data at the grid connection point, and execute the anti-reverse flow strategy when a reverse flow trend occurs to prevent electrical energy from flowing back to the public power grid.

[0006] The aforementioned anti-reverse current control system based on flexible DC interconnection of distribution areas includes an energy storage management unit, a photovoltaic power limiting controller, and a grid-connected isolating switch. The energy storage management unit, photovoltaic power limiting controller, and grid-connected disconnect switch respond to the anti-backflow command in sequence according to a preset priority order, with the energy storage management unit having the highest response priority, the photovoltaic power limiting controller having the second highest response priority, and the grid-connected disconnect switch having the lowest response priority. The energy storage management unit is used to actively absorb redundant power from the power supply area when a reverse flow trend is detected. The photovoltaic power generation limit controller is used to dynamically adjust the photovoltaic output of the power supply area when the energy storage management unit has insufficient absorption capacity; The grid-connected disconnect switch is used to disconnect the grid-connected branch of the power supply substation from the public power grid after the energy storage management unit reaches its upper limit and the photovoltaic power limiting controller is adjusted to its limit.

[0007] The aforementioned anti-reverse current control system based on flexible DC interconnection of distribution areas includes a multi-objective optimization decision-making mechanism for the intelligent scheduling strategy module, which includes three core optimization objectives: maximizing the renewable energy absorption rate, ensuring the safety margin of the public power grid, and improving the utilization rate of the energy storage system. The intelligent scheduling strategy module uses a dynamic optimization algorithm based on supply and demand forecasting to execute the decision.

[0008] The aforementioned anti-reverse current control system based on flexible DC interconnection of distribution areas includes an intelligent scheduling strategy module with a built-in intelligent self-learning mechanism. This mechanism uses historical operating data, system response data under different operating conditions, and fault handling data as training samples to continuously optimize scheduling parameters and the execution threshold of the anti-reverse current strategy.

[0009] The aforementioned anti-reverse current control system based on flexible DC interconnection of power distribution areas, wherein the flexible DC interconnection scheduling module adopts a dynamic allocation algorithm based on the real-time load-bearing capacity of the power receiving area when scheduling redundant power. The dynamic allocation algorithm accurately allocates redundant power according to the load gap size, power supply distance and line loss of each power receiving area.

[0010] In the aforementioned anti-reverse current control system based on flexible DC interconnection of distribution areas, the energy monitoring unit acquires power flow data at the grid connection point with an accuracy of not less than 0.5%, and the anti-reverse current control module presets a reverse power judgment threshold. When the reverse power value at the grid connection point exceeds the reverse power judgment threshold for 3 consecutive seconds, it is determined that a reverse current trend has occurred.

[0011] The aforementioned anti-reverse current control system based on flexible DC interconnection of distribution areas includes an energy storage management unit whose charging and discharging control strategy is related to the energy storage state of charge and the magnitude of the reverse current power. When the energy storage state of charge is below 80%, it absorbs 100% of the reverse current power. When the energy storage state of charge is between 80% and 90%, it absorbs 50% to 80% of the reverse current power. When the energy storage state of charge is above 90%, it stops actively absorbing energy and triggers the photovoltaic power limiting controller to start.

[0012] The aforementioned anti-reverse current control system based on flexible DC interconnection of distribution areas includes a photovoltaic power limiting controller whose adjustment range is 30% to 100% of the rated output of the photovoltaic power, and whose adjustment response time does not exceed 200 milliseconds. During the adjustment process, the photovoltaic output is kept stable and power fluctuations are avoided to exceed 10% / second.

[0013] The present invention also provides an anti-reverse current control method based on the above-mentioned anti-reverse current control system based on flexible DC interconnection of transformer substations, comprising the following steps: (1) System initialization: The power generation capacity and grid connection capacity of each transformer area are identified and classified through the transformer area capacity identification module, and the initial state parameters of each transformer area are recorded. (2) The energy monitoring unit collects the power generation output data, load power data, energy storage status data and grid connection point power flow data of each transformer area in real time, and synchronizes the collected data to the transformer area capacity identification module, intelligent dispatch strategy module, flexible DC interconnection dispatch module and anti-reverse flow control module. (3) The intelligent scheduling strategy module performs multi-objective optimization decision-making based on the collected data and historical operation data to determine whether there is redundant power in the power supply type transformer area; (4) If there is redundant power, the flexible DC interconnection scheduling module will allocate the redundant power to each power receiving area through a dynamic allocation algorithm based on the optimization decision results and the real-time load carrying capacity of the power receiving area. (5) The anti-backflow control module monitors the power flow data at the grid connection point in real time. When it is determined that a backflow trend occurs, the energy storage management unit, photovoltaic power limiting controller and grid connection isolation switch are started in sequence according to the preset priority to execute the anti-backflow strategy. (6) The intelligent scheduling strategy module continuously optimizes the scheduling parameters and the execution threshold of the anti-backflow strategy based on the running data from steps (2) to (5) through an intelligent self-learning mechanism, so as to realize the dynamic adaptive closed-loop operation of the system.

[0014] In the above-mentioned anti-reverse current control method, in step (5), when the reverse power value at the grid connection point exceeds 150% of the reverse power judgment threshold for 10 consecutive seconds, and the energy storage charge status reaches 95%, and the photovoltaic power limiting controller is adjusted to 30% of the photovoltaic rated output but still cannot suppress the reverse current, it is judged as an extreme case of uncontrollable reverse current, and the grid connection isolation switch automatically disconnects the grid connection branch.

[0015] The present invention has the following beneficial effects: This invention, through the coordinated operation of various functional modules and a scientifically designed control strategy, enables the system to accurately identify the capabilities of distribution substations, comprehensively collect operational data, efficiently schedule power supply, and effectively prevent reverse flow risks. Distribution substations with different characteristics can operate collaboratively, fully utilizing the redundant power of power supply substations, promoting the local consumption of new energy sources, and reducing the waste of new energy power. The hierarchical anti-reverse flow control system systematically suppresses reverse flow trends, preventing power from flowing back into the public grid and ensuring the safety and stability of the distribution network. The application of dynamic allocation algorithms and intelligent self-learning mechanisms makes power scheduling more precise and rational, allowing the system to continuously adapt to complex and changing operating conditions, improving long-term efficiency and stability. Simultaneously, the system possesses strong adaptability, making it suitable for various complex application scenarios such as highways and industrial parks, providing strong support for the integrated development of distribution networks and new energy sources. Attached Figure Description

[0016] Figure 1 A schematic diagram of the anti-reverse current control system architecture based on flexible DC interconnection of transformer substations provided in an embodiment of the present invention; Figure 2 A flowchart of an anti-reverse current control method based on flexible DC interconnection of transformer substations provided in an embodiment of the present invention. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0018] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0019] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0020] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Example 1 The reverse current prevention control system based on flexible DC interconnection of transformer substations provided in this embodiment, such as... Figure 1 As shown, it includes a transformer area capability identification module, an energy monitoring unit, a flexible DC interconnection scheduling module, an anti-reverse current control module, and an intelligent scheduling strategy module; The energy monitoring unit is used to collect real-time power generation output data, load power data, energy storage status data, and power flow data at the grid connection point for each transformer area; The input terminal of the transformer area capability identification module is connected to the output terminal of the energy monitoring unit. It is used to identify the power generation capacity and grid connection capacity of each transformer area based on the collected data, and to divide the transformer area into power supply type transformer areas with power generation and grid connection capabilities and power receiving type transformer areas without power generation and grid connection capabilities. The input of the intelligent scheduling strategy module is connected to the output signals of the energy monitoring unit and the transformer area capability identification module, respectively, and is used to perform multi-objective optimization decisions based on historical operating data and real-time collected data; The input of the flexible DC interconnection dispatch module is connected to the output signals of the transformer area capability identification module and the intelligent dispatch strategy module, respectively, and is used to prioritize the dispatch of redundant power generated by the power supply transformer area to the power receiving transformer area based on the optimization decision results. The input terminal of the anti-reverse flow control module is connected to the output terminal signals of the energy monitoring unit and the intelligent dispatch strategy module, respectively, and communicates bidirectionally with the flexible DC interconnection dispatch module. It is used to monitor the reverse power flow status based on the power flow direction data at the grid connection point, and execute the anti-reverse flow strategy when a reverse flow trend occurs to prevent power from flowing back to the public grid.

[0022] This solution achieves accurate identification of transformer substation capabilities, comprehensive collection of operational data, targeted power dispatch, and effective prevention and control of reverse flow risks through signal connection and coordinated operation of various functional modules. This enables transformer substations with different characteristics to operate collaboratively, promotes the full utilization of new energy sources locally, prevents power from flowing back into the public power grid, ensures the safe and stable operation of the distribution network, and enhances the system's adaptability to various application scenarios.

[0023] Specifically, in this embodiment, the anti-backflow control module includes an energy storage management unit, a photovoltaic power limiting controller, and a grid-connected isolating switch; The input terminals of the energy storage management unit, the photovoltaic power limiting controller, and the grid-connected disconnect switch are all connected to the output terminal of the anti-reverse current control module. The three respond to the anti-reverse current command issued by the anti-reverse current control module in sequence according to the preset priority order, with the energy storage management unit having the highest response priority, the photovoltaic power limiting controller having the second highest response priority, and the grid-connected disconnect switch having the lowest response priority. The input of the energy storage management unit is also connected to the output signal of the energy monitoring unit to obtain energy storage status data and reverse power data, and to actively absorb redundant power from the power supply area when a reverse trend is detected. The input terminal of the photovoltaic power generation limit controller is connected to the output terminal signals of the energy monitoring unit and the energy storage management unit, respectively, to obtain real-time photovoltaic power output data and energy storage absorption status data, and to dynamically adjust the photovoltaic power output of the power supply area when the absorption capacity of the energy storage management unit is insufficient. The input terminals of the grid-connected disconnect switch are respectively connected to the output signals of the energy monitoring unit, the energy storage management unit, and the photovoltaic power limiting controller. This is used to obtain reverse power data, energy storage absorption limit state data, and photovoltaic regulation limit state data. After the energy storage management unit reaches its upper limit and the photovoltaic power limiting controller is adjusted to its limit, the grid-connected branch of the power supply type transformer area is disconnected from the public power grid.

[0024] This solution constructs a hierarchical anti-backflow control system through the priority response design of energy storage management units, photovoltaic power generation limit controllers, and grid-connected disconnect switches. It gradually suppresses backflow trends, ensures that anti-backflow operations are carried out in an orderly manner, reduces the impact on the new energy power generation system and distribution network during the control process, and ensures the overall stability and reliability of the power supply system.

[0025] Specifically, in this embodiment, the multi-objective optimization decision of the intelligent scheduling strategy module includes three core optimization objectives: maximizing the renewable energy absorption rate, ensuring the safety margin of the public power grid, and improving the utilization rate of the energy storage system. The input of the intelligent scheduling strategy module is connected to the system's historical database signal to retrieve historical operating data. Its output is connected to the input signals of the flexible DC interconnection scheduling module and the anti-reverse current control module, respectively, to transmit the optimization decision results to the two modules in real time. It also communicates bidirectionally with the energy monitoring unit to receive data feedback in real time to dynamically adjust the decision.

[0026] This solution uses an intelligent scheduling strategy module to combine historical operating data with real-time status to conduct multi-objective optimization decisions, making the system's energy scheduling and anti-backflow control more in line with actual operating needs, optimizing resource allocation, improving the overall efficiency of system operation, and enhancing the rationality and pertinence of scheduling and control decisions.

[0027] Specifically, in this embodiment, the intelligent scheduling strategy module has a built-in intelligent self-learning mechanism; The input of the intelligent self-learning mechanism is connected to the output signals of the energy monitoring unit, the anti-reverse current control module, and the flexible DC interconnection scheduling module, respectively, and uses historical operating data, system response data under different operating conditions, and fault handling data as training samples. The output of the intelligent self-learning mechanism is connected to the decision unit signal of the intelligent scheduling strategy module, continuously optimizing the execution threshold of the scheduling parameters and the anti-backflow strategy, and feeding back the optimization results to the decision unit to update the multi-objective optimization decision logic.

[0028] This scheme uses an intelligent self-learning mechanism to receive multi-module operation data as training samples, continuously optimizes scheduling parameters and anti-backflow strategy execution thresholds, enabling the system to continuously adapt to complex and ever-changing operating conditions, improve scheduling accuracy and the adaptability of anti-backflow control, and ensure the long-term high efficiency and stability of the system.

[0029] Specifically, in this embodiment, the flexible DC interconnection scheduling module adopts a dynamic allocation algorithm based on the real-time load-bearing capacity of the power receiving area when scheduling redundant power. The input end of the flexible DC interconnection dispatch module is connected to the output end of the energy monitoring unit corresponding to each power receiving area, and is used to obtain the load gap size, power supply distance and line loss data of each power receiving area; The flexible DC interconnection dispatch module and the intelligent dispatch strategy module communicate bidirectionally to receive the power allocation principles in the optimization decision and at the same time feed back the actual dispatch execution data. Based on the acquired data and allocation principles, redundant power is accurately allocated to each power receiving area.

[0030] This scheme employs a dynamic allocation algorithm through a flexible DC interconnection scheduling module. It combines real-time load, power supply distance, and line loss data of the receiving transformer area to allocate redundant power, thereby achieving precise power allocation, improving the utilization rate of new energy sources, reducing waste during power transmission, and enhancing the effectiveness of cross-transformer area power dispatch.

[0031] Specifically, in this embodiment, the energy monitoring unit acquires power flow direction data at the grid connection point with an accuracy of no less than 0.5%; The output of the energy monitoring unit is connected to the input of the anti-reverse flow control module in real time, and the collected power flow data at the grid connection point is continuously transmitted to the anti-reverse flow control module. The anti-backflow control module has a built-in reverse power judgment threshold storage unit. When the reverse power value at the grid connection point exceeds the reverse power judgment threshold for 3 consecutive seconds after being collected by the energy monitoring unit, the anti-backflow control module determines that a reverse flow trend has occurred and starts the anti-backflow command.

[0032] This solution achieves timely and accurate identification of backflow trends through real-time signal connection between the energy monitoring unit and the anti-backflow control module, as well as the setting of the reverse power judgment mechanism. This ensures that the anti-backflow command can be activated as needed, guaranteeing the timeliness and effectiveness of the anti-backflow control.

[0033] Specifically, in this embodiment, the charging and discharging control strategy of the energy storage management unit is related to the energy storage state of charge and the magnitude of the reverse current power; The energy storage management unit obtains real-time energy storage state of charge and reverse current power data through a signal connection with the energy monitoring unit. When the energy storage state of charge is below 80%, it absorbs 100% of the reverse current power; when the energy storage state of charge is between 80% and 90%, it absorbs 50% to 80% of the reverse current power; when the energy storage state of charge is above 90%, it stops actively absorbing energy and feeds back the signal to the anti-reverse current control module, triggering the photovoltaic power curtailment controller to start.

[0034] This solution adapts the charging and discharging strategy of the energy storage management unit to its own operating status and reverse current conditions, fully leveraging the regulation potential of the energy storage system, avoiding abnormal operating states such as overcharging and discharging of energy storage devices, extending the service life of energy storage devices, and ensuring that the energy storage system continuously and stably participates in anti-reverse current regulation.

[0035] Specifically, in this embodiment, the adjustment range of the photovoltaic power limiting controller is 30% to 100% of the rated output of the photovoltaic power, and the adjustment response time does not exceed 200 milliseconds; The photovoltaic power curtailment controller obtains real-time photovoltaic output data through a signal connection with the energy monitoring unit. During the adjustment process, it maintains a stable change in photovoltaic output based on this data to avoid power fluctuations exceeding 10% / second. The photovoltaic power limiting controller and the anti-reverse current control module communicate bidirectionally to provide real-time feedback on the adjustment progress and adjustment limit status. When the photovoltaic power is adjusted to 30% of the rated output, a limit signal is sent to the anti-reverse current control module.

[0036] This solution utilizes the rapid response and stable adjustment design of the photovoltaic power generation controller to respond to the backflow prevention requirements while reducing the adverse effects of photovoltaic power output fluctuations on the power supply system and electrical equipment, ensuring the stable operation of the new energy power generation system, and ensuring timely tracking of backflow trend changes.

[0037] Example 2 This embodiment provides an anti-backflow control method based on the system in Embodiment 1, such as... Figure 2 As shown, it includes the following steps: (1) System initialization: The system establishes a signal connection with the energy monitoring unit of each transformer area through the transformer area capacity identification module, completes the identification and classification of the power generation capacity and grid connection capacity of each transformer area, and records the initial state parameters of each transformer area; (2) The energy monitoring unit collects the power generation output data, load power data, energy storage status data and grid connection point power flow data of each transformer area in real time, and synchronizes the collected data to the transformer area capacity identification module, intelligent dispatch strategy module, flexible DC interconnection dispatch module and anti-reverse flow control module. (3) The intelligent scheduling strategy module performs multi-objective optimization decision-making based on the synchronously collected data and the historical operation data retrieved from the system's historical database to determine whether there is redundant power in the power supply type transformer area; (4) If there is redundant power, the flexible DC interconnection scheduling module obtains real-time load carrying capacity data through the signal connection with the energy monitoring unit of each power receiving area, and allocates the redundant power to each power receiving area through a dynamic allocation algorithm based on the optimization decision result of the intelligent scheduling strategy module. (5) The anti-backflow control module monitors the power flow data at the grid connection point through the real-time signal connection with the energy monitoring unit. When it is determined that a backflow trend occurs, it sends instructions to the energy storage management unit, the photovoltaic power limiting controller, and the grid connection isolation switch in sequence according to the preset priority to execute the anti-backflow strategy. (6) The intelligent scheduling strategy module receives the operation data transmitted by the energy monitoring unit, flexible DC interconnection scheduling module and anti-reverse flow control module in steps (2) to (5) through the built-in intelligent self-learning mechanism, continuously optimizes the scheduling parameters and the execution threshold of the anti-reverse flow strategy, and realizes the dynamic adaptive closed-loop operation of the system.

[0038] This solution constructs a complete and orderly closed-loop control process to achieve smooth connection between system initialization, data acquisition, power scheduling, anti-reverse flow execution and parameter optimization. This enables each link to operate in a coordinated and efficient manner, ensuring that redundant power is rationally allocated, reverse flow risks are dealt with in a timely manner, and improving the overall continuity and efficiency of system operation.

[0039] Specifically, in this embodiment, in step (5), the energy monitoring unit transmits the collected grid connection point reverse power data, energy storage charge status data, and photovoltaic regulation status data to the anti-reverse current control module in real time. When the reverse power value at the grid connection point exceeds 150% of the reverse power judgment threshold for 10 consecutive seconds, and the energy storage state of charge reaches 95%, and the photovoltaic power limiting controller is adjusted to 30% of the photovoltaic rated output but still cannot suppress the reverse current, the anti-reverse current control module judges it as an extreme case of uncontrollable reverse current and sends a disconnection command to the grid connection isolating switch, and the grid connection isolating switch automatically disconnects the grid connection branch. After the grid disconnection switch is disconnected, it sends a disconnection status signal to the anti-backflow control module. The anti-backflow control module then synchronizes this signal to the intelligent scheduling strategy module, triggering the system's emergency adjustment mechanism.

[0040] This plan clarifies the criteria for judging extreme backflow situations and the emergency response path, and combines status feedback and emergency adjustment mechanisms. When conventional anti-backflow measures fail, it can quickly activate the ultimate prevention and control measures to avoid severe backflow from impacting the public power grid. This allows the system to adapt to extreme operating conditions in a timely manner, reduces the operational risks caused by extreme situations, and ensures the safety and stability of the overall energy supply system.

[0041] Working Principle: This system achieves anti-reverse current and optimized energy scheduling through the signal connection and coordinated operation of multiple functional modules. The energy monitoring unit continuously collects data on power generation output, load power, energy storage status, and power flow direction at grid connection points for each distribution area, providing data support for subsequent identification, decision-making, and control. The distribution area capacity identification module receives data transmitted from the energy monitoring unit, identifies the power generation and grid connection capabilities of each distribution area, and classifies them into power supply and power receiving types. The intelligent scheduling strategy module combines historical operating data with real-time collected data to conduct multi-objective optimization decisions. Its built-in intelligent self-learning mechanism receives operating data from multiple modules as training samples to continuously optimize scheduling parameters and the execution threshold of the anti-reverse current strategy. Based on the distribution area capacity identification results and the decisions of the intelligent scheduling strategy module, the flexible DC interconnection scheduling module uses a dynamic allocation algorithm to prioritize the allocation of redundant power from power supply type distribution areas to power receiving type distribution areas. The anti-reverse flow control module receives signals from the energy monitoring unit and the intelligent dispatch strategy module, and maintains bidirectional communication with the flexible DC interconnection dispatch module to monitor the power flow direction at the grid connection point in real time. When a reverse flow trend is detected, the energy storage management unit is activated to absorb electrical energy and the photovoltaic power limiting controller is activated to adjust the output in sequence according to the preset priority order. If the above measures still cannot control the reverse flow, the grid connection branch is disconnected through the grid connection isolating switch to prevent electrical energy from flowing back to the public grid.

[0042] Usage: First, perform system initialization. Establish signal connections between the transformer area capacity identification module and the energy monitoring units of each transformer area to identify and classify their power generation and grid connection capabilities, and record their initial state parameters. Then, the energy monitoring units enter real-time operation, continuously collecting data on power output, load power, energy storage status, and power flow direction at the grid connection point for each transformer area. This data is synchronously transmitted to the transformer area capacity identification module, intelligent dispatch strategy module, flexible DC interconnection dispatch module, and anti-reverse flow control module. The intelligent dispatch strategy module, based on the synchronously received real-time data and historical operating data retrieved from the system's historical database, performs multi-objective optimization decisions to determine whether redundant power exists in the power supply transformer areas. If redundant power exists, the flexible DC interconnection dispatch module obtains real-time load-bearing capacity data for each power receiving transformer area and, combined with the optimization decision results from the intelligent dispatch strategy module, uses a dynamic allocation algorithm to rationally distribute the redundant power to each power receiving transformer area. The anti-reverse flow control module monitors the power flow data at the grid connection point in real time. Once a reverse flow trend is detected, it sends commands sequentially to the energy storage management unit, photovoltaic power limiting controller, and grid-connected isolating switch according to preset priorities to execute the anti-reverse flow strategy. The intelligent scheduling strategy module receives operational data from each link through a built-in intelligent self-learning mechanism, continuously optimizing relevant parameters and strategies to enable the system to achieve dynamic adaptive closed-loop operation. When encountering extreme reverse flow conditions, the anti-reverse flow control module will detect and issue a disconnection command. The grid-connected isolating switch will automatically disconnect the grid-connected branch, and the disconnection status signal will be fed back to the relevant modules, triggering the system's emergency adjustment mechanism.

[0043] In summary, the anti-reverse current control system and method based on flexible DC interconnection of transformer substations provided in this embodiment have the following advantages: Through the coordinated operation of various functional modules and the design of a scientifically sound control strategy, this system achieves accurate identification of distribution area capabilities, comprehensive collection of operational data, targeted and efficient power dispatch, and effective prevention and control of reverse flow risks. Distribution areas with different characteristics can operate collaboratively, fully utilizing the redundant power of power supply-type distribution areas, promoting the local consumption of new energy, and reducing the waste of new energy power. The hierarchical anti-reverse flow control system systematically suppresses reverse flow trends, preventing power from flowing back into the public grid and ensuring the safety and stability of the distribution network. The application of dynamic allocation algorithms and intelligent self-learning mechanisms makes power dispatch more precise and rational, enabling the system to continuously adapt to complex and changing operating conditions, improving long-term efficiency and stability. Simultaneously, the system possesses strong adaptability, making it suitable for various complex application scenarios such as highways and industrial parks, providing strong support for the integrated development of distribution networks and new energy.

[0044] In addition, this application also provides the following example: application of flexible DC interconnection for anti-reverse current in heterogeneous transformer substations along highways.

[0045] I. Implementation Scenarios This example applies to a cluster of power distribution substations along a highway, encompassing five main substations. Three are highway service area substations, equipped with distributed photovoltaic power generation devices and eligible for grid connection (Class A substations). The other two are toll station substations, lacking local power generation devices and not eligible for grid connection (Class B substations). Each Class A substation is equipped with an energy storage system. The five substations are interconnected via flexible DC cables and connected to the regional public power grid. This primarily meets the power needs of charging stations in service areas and office and residential use at toll stations, while mitigating the backflow risk caused by fluctuations in renewable energy output.

[0046] II. Technical Solution (I) System Composition 1. Energy Routing Management Module: By establishing a connection with the signal interfaces of photovoltaic inverters and grid-connected switches in each distribution area, it can detect in real time whether the photovoltaic power generation device is operating normally and whether the grid-connected switch can safely close / open, thereby identifying the power generation capacity and grid connection capacity of each distribution area.

[0047] 2. Energy Monitoring Unit: Monitoring nodes are deployed at the photovoltaic output end, load access end, energy storage system interface and public grid connection point of each transformer area to continuously collect data such as real-time photovoltaic output, load power consumption, energy storage status of charge, power flow direction and voltage frequency at the grid connection point, with data transmission delay controlled in the millisecond level.

[0048] 3. Distribution Area Capability Marking Module: Receives the identification results transmitted by the Energy Routing Management Module, marks the 3 service area distribution areas with power generation and grid connection capabilities as Class A, and the 2 toll station distribution areas without power generation and grid connection capabilities as Class B, and synchronizes the classification results to other functional modules.

[0049] 4. Flexible DC Interconnection Dispatch Module: Maintains bidirectional signal communication with the intelligent dispatch strategy module and energy monitoring unit, receives redundant power data of Class A transformer areas and load data of Class B transformer areas, and distributes redundant power through flexible DC interconnection lines according to the principle of load gap matching and minimum line loss.

[0050] 5. Anti-reverse current control module: This module includes an energy storage management unit, a photovoltaic power limiting controller, and a grid-connected isolating switch. The energy storage management unit is directly connected to the energy storage system in the Class A distribution area and is responsible for controlling the charging and discharging of the energy storage. The photovoltaic power limiting controller is interconnected with the photovoltaic inverter signal to regulate the photovoltaic output. The grid-connected isolating switch is connected in series in the connection branch between the Class A distribution area and the public power grid and is responsible for emergency isolation.

[0051] 6. Intelligent Dispatch Strategy Module: It has a built-in historical database that stores data such as the photovoltaic output curve, the load change pattern of the distribution area, and the reverse current occurrence record of the past 6 months in the region. Combined with the real-time data of the energy monitoring unit, it performs multi-objective optimization decisions. At the same time, it has a built-in intelligent self-learning mechanism that continuously optimizes dispatch parameters and anti-reverse current triggering conditions based on daily operating data including the effect of redundant power dispatch, the implementation status of anti-reverse current strategy, and the efficiency of energy storage.

[0052] (II) Control Methods 1. System initialization: The energy routing management module performs capacity detection on each of the five transformer substations, and the substation capacity marking module completes the classification into Class A and Class B, recording initial parameters such as the load peak, rated capacity of the energy storage system, and transmission loss coefficient of the flexible DC line for each substation.

[0053] 2. Real-time data acquisition: The energy monitoring unit collects data from each monitoring node once per second and transmits it synchronously to the energy routing management module, intelligent scheduling strategy module, flexible DC interconnection scheduling module, and anti-reverse flow control module to ensure that each module obtains consistent real-time operating status.

[0054] 3. Redundant Energy Determination and Scheduling: The intelligent scheduling strategy module compares the real-time photovoltaic output of Class A distribution areas with their own load consumption to calculate the amount of redundant energy. If redundant energy exists, a scheduling command is immediately sent to the flexible DC interconnection scheduling module. The flexible DC interconnection scheduling module obtains the real-time load gap of two Class B distribution areas through the energy monitoring unit, and combines the transmission loss of the flexible DC line to accurately allocate the redundant energy of Class A distribution areas to Class B distribution areas with larger load gaps, achieving cross-distribution area energy complementarity.

[0055] 4. Backflow Prevention Monitoring and Control: The backflow prevention control module monitors the power flow direction at the grid connection point in real time. If a trend of power flowing back into the public power grid is detected: The energy storage management unit is activated first to control the energy storage system to enter the charging state and absorb redundant electrical energy. If the energy storage state of charge reaches the upper limit, the energy storage management unit feeds a signal to the anti-reverse current control module, triggering the photovoltaic power limiting controller to gradually reduce the output power of the photovoltaic inverter. If the reverse current trend cannot be curbed after the photovoltaic power generation is limited, the anti-reverse current control module issues a command to control the grid-connected isolating switch to open, disconnecting the Class A distribution area from the public power grid.

[0056] 5. Dynamic Adaptive Optimization: The self-learning mechanism of the intelligent scheduling strategy module summarizes the operation data of each module daily, analyzes the power loss during the scheduling process and the response effect of the anti-reverse flow strategy, and optimizes the subsequent redundant power allocation ratio, energy storage charging and discharging threshold and photovoltaic power generation limitation start-up conditions, so that the system can adapt to the changes in photovoltaic power output in different seasons and the load fluctuations in different time periods.

[0057] III. Technical Effects 1. Achieve coordinated operation of heterogeneous distribution areas: Through flexible DC interconnection and precise scheduling of Class A and Class B distribution areas, the barriers of independent operation of traditional distribution areas are broken, allowing distribution areas with power generation capacity to complement those without power generation capacity, thereby improving the operational flexibility of the entire distribution area cluster.

[0058] 2. Improve the local consumption level of new energy: The redundant photovoltaic power in Class A distribution areas is no longer wasted due to insufficient local load. Instead, it is efficiently utilized by Class B distribution areas through dispatch, reducing curtailment and fully leveraging the environmental value of new energy.

[0059] 3. Effectively curb the risk of reverse flow: The anti-reverse flow control module adopts a graded response mechanism of energy storage absorption - photovoltaic power curtailment - grid disconnection, forming a full-process prevention and control from the source to the end, avoiding the impact of power reverse flow on the public power grid and ensuring the safe operation of the power grid.

[0060] 4. Enhanced system adaptability: The intelligent scheduling strategy module combines historical data and real-time status to optimize decisions, and the self-learning mechanism continuously adjusts operating parameters, enabling the system to adapt to photovoltaic output fluctuations in different seasons and load changes in different time periods, significantly improving long-term operational stability.

[0061] 5. Reduce the power supply pressure on the main power grid: By absorbing green energy from Class A distribution areas, Class B distribution areas reduce their dependence on the public power grid and alleviate the power supply burden on the regional main power grid.

[0062] IV. Experimental Data This example system ran continuously for 6 months, and the key performance indicators of the system after operation were compared with those of the traditional standalone operation mode: Renewable energy consumption: The photovoltaic consumption rate of Class A transformer substations has increased from 65% in the traditional model to 92%, and the amount of curtailed solar power has decreased by about 27% compared to before; Green electricity supply: The green electricity utilization rate in Class B transformer substations reached 88%, and the monthly electricity drawn from the public grid decreased by 30% compared to before; Backflow prevention: The backflow rate at the grid connection point has dropped from 8% in the traditional mode to 0.3%. There was only one slight backflow trend in 6 months, which was completely contained within 10 seconds through energy storage absorption, without affecting the power grid. System Adaptation: After the intelligent self-learning mechanism is in operation, the matching degree between energy storage charging and discharging and photovoltaic output and load changes is improved by 40%, and the number of photovoltaic power curtailment start-ups is reduced by 50% compared with the initial operation stage; Operational efficiency: The power transmission loss of the flexible DC interconnection dispatch is controlled within a reasonable range, and the response time of cross-regional power distribution meets the actual use needs. There are no power supply shortages or reverse flow problems caused by dispatch delays.

[0063] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A control system for preventing reverse flow based on flexible DC interconnection of transformer areas, characterized in that, The system comprises a transformer area capacity identification module, an energy monitoring unit, a flexible DC interconnection scheduling module, an anti-backflow control module, and an intelligent scheduling strategy module. The energy monitoring unit is configured to collect real-time power generation output data, load power data, energy storage state data, and grid-connected point power flow direction data of each transformer area. The input end of the transformer area capacity identification module is signal-connected with the output end of the energy monitoring unit, and is configured to identify the power generation capacity and grid-connected capacity of each transformer area based on the collected data, and divide the transformer areas into power supply type transformer areas with power generation and grid-connected capacity and power receiving type transformer areas without power generation and grid-connected capacity. The input end of the intelligent scheduling strategy module is signal-connected with the output end of the energy monitoring unit and the transformer area capacity identification module, and is configured to execute multi-objective optimization decision based on historical operation data and real-time collected data. The input end of the flexible DC interconnection scheduling module is signal-connected with the output end of the transformer area capacity identification module and the intelligent scheduling strategy module, and is configured to schedule redundant power generated by the power supply type transformer areas to the power receiving type transformer areas according to the optimization decision result. The input end of the anti-backflow control module is signal-connected with the output end of the energy monitoring unit and the intelligent scheduling strategy module, and is in bidirectional signal communication with the flexible DC interconnection scheduling module, and is configured to monitor the reverse power flow state based on the grid-connected point power flow direction data, and execute an anti-backflow strategy when a reverse flow trend occurs to prevent the reverse flow of power to the public power grid.

2. The anti-flow control system based on the flexible DC interconnection of the transformer area according to claim 1, characterized in that, The anti-backflow control module comprises an energy storage management unit, a photovoltaic power limiting controller, and a grid-connected isolation switch. The energy storage management unit, the photovoltaic power limiting controller, and the grid-connected isolation switch respond to the anti-backflow instruction in a preset priority order, wherein the response priority of the energy storage management unit is the highest, the response priority of the photovoltaic power limiting controller is the second, and the response priority of the grid-connected isolation switch is the lowest. The energy storage management unit is configured to actively absorb the redundant power of the power supply type transformer area when a reverse flow trend is detected. The photovoltaic power limiting controller is configured to dynamically adjust the photovoltaic output of the power supply type transformer area when the energy storage management unit is insufficient in absorption capacity. The grid-connected isolation switch is configured to disconnect the grid-connected branch of the power supply type transformer area from the public power grid when the energy storage management unit reaches the upper limit of absorption capacity and the photovoltaic power limiting controller is adjusted to the limit. 3.The anti-flow control system based on the flexible DC interconnection of a transformer area according to claim 1, characterized in that, The multi-objective optimization decision of the intelligent scheduling strategy module includes three core optimization objectives, namely maximizing new energy consumption rate, ensuring public power grid safety margin, and improving energy storage system utilization rate, and the intelligent scheduling strategy module executes the decision by using a dynamic optimization algorithm based on supply and demand prediction. 4.The anti-flow control system based on the flexible DC interconnection of a transformer area according to claim 1, characterized in that, The intelligent scheduling strategy module is provided with an intelligent self-learning mechanism, which takes historical operation data, system response data under different working conditions, and fault handling data as training samples to continuously optimize scheduling parameters and execution thresholds of the anti-backflow strategy.

5. The anti-inrush control system based on the flexible DC interconnection of the transformer area according to claim 1, characterized in that, The flexible DC interconnection scheduling module adopts a dynamic allocation algorithm based on the real-time load carrying capacity of the power receiving type transformer area when scheduling redundant power, and the dynamic allocation algorithm accurately allocates the redundant power according to the load gap size, power supply distance, and line loss of each power receiving type transformer area. 6.The anti-flow control system based on the flexible DC interconnection of a transformer area according to claim 1, characterized in that, The energy monitoring unit has a collection accuracy of power flow data of the grid-connected point of not less than 0.5%, and the anti-reverse flow control module has a preset reverse power determination threshold value; when the reverse power value of the grid-connected point continuously exceeds the reverse power determination threshold value for 3 seconds, it is determined that a reverse flow trend occurs.

7. The anti-inrush control system based on the flexible DC interconnection of the transformer area according to claim 2, characterized in that, The charge-discharge control strategy of the energy storage management unit is associated with the energy storage state of charge and the reverse flow power size; when the energy storage state of charge is lower than 80%, 100% of the reverse flow power is absorbed; when the energy storage state of charge is between 80% and 90%, 50% to 80% of the reverse flow power is absorbed; when the energy storage state of charge is higher than 90%, active absorption is stopped and the photovoltaic limited generation controller is triggered to start. 8.The anti-flow control system based on the flexible DC interconnection of a transformer area according to claim 2, characterized in that, The adjustment range of the photovoltaic limited generation controller is 30% to 100% of the rated output of the photovoltaic, and the adjustment response time is not more than 200 milliseconds; during the adjustment process, the photovoltaic output is kept smooth, avoiding power fluctuation exceeding 10% / second.

9. A reverse current prevention control method of a reverse current prevention control system based on a flexible DC interconnection based on any one of claims 1 to 8, characterized by, The method comprises the following steps: (1) system initialization, the identification and classification of the power generation capacity and grid connection capacity of each transformer area are completed through the transformer area capacity identification module, and the initial state parameters of each transformer area are recorded; (2) the energy monitoring unit collects the power generation output data, load power data, energy storage state data and grid-connected point power flow data of each transformer area in real time, and synchronizes the collected data to the transformer area capacity identification module, intelligent scheduling strategy module, flexible DC interconnection scheduling module and anti-reverse flow control module; (3) the intelligent scheduling strategy module executes multi-objective optimization decision based on the collected data and historical operation data, and judges whether there is redundant power in the power supply type transformer area; (4) if there is redundant power, the flexible DC interconnection scheduling module distributes the redundant power to each power receiving type transformer area through a dynamic distribution algorithm according to the optimization decision result and the real-time load receiving capacity of the power receiving type transformer area; (5) the anti-reverse flow control module monitors the grid-connected point power flow data in real time, and when it is determined that a reverse flow trend occurs, the energy storage management unit, photovoltaic limited generation controller and grid-connected disconnecting switch are started in turn according to the preset priority to execute the anti-reverse flow strategy; (6) the intelligent scheduling strategy module continuously optimizes the scheduling parameters and the execution threshold value of the anti-reverse flow strategy based on the operation data of steps (2) to (5) through intelligent self-learning mechanism, to realize dynamic self-adaptive closed-loop operation of the system.

10. The anti-regurgitation control method according to claim 9, characterized by, In step (5), when the reverse power value of the grid-connected point continuously exceeds 150% of the reverse power determination threshold value for 10 seconds, and the energy storage state of charge reaches 95% and the photovoltaic limited generation controller is adjusted to 30% of the rated output of the photovoltaic and still cannot suppress the reverse flow, it is determined that it is an extreme case of uncontrollable reverse flow, and the grid-connected disconnecting switch automatically disconnects the grid-connected branch.

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