A method and system for anti-islanding protection of a plurality of new types of host access power distribution networks

Abstract

A method and system for anti-islanding protection of multiple novel entities connected to a distribution network includes: real-time monitoring of the voltage and frequency at the grid connection point of the distribution network for passive signal detection and active signal injection, obtaining passive signal detection results and active signal injection feedback; system state identification based on the passive signal detection results and active signal injection feedback, distinguishing between non-islanding type disturbances and islanding type disturbances; generating corresponding control strategies based on the non-islanding type disturbances and islanding type disturbances combined with preset instructions from the upper-level control software; and performing corresponding anti-islanding protection operations based on the control strategies. This application solves the problems of passive detection being fast but susceptible to non-islanding disturbance interference, and active detection being highly reliable but posing a risk to system stability, by using passive signal detection and active signal injection. It improves the system's anti-disturbance and anti-maloperation / refusal-operation performance after the connection of novel entities, and accelerates the response time of anti-islanding protection actions.

Description

Technical Field

[0001] This application relates to the field of power distribution technology, specifically to an anti-islanding protection method and system for multiple novel entities connected to a power distribution network. Background Technology

[0002] Currently, large-scale distributed power sources and charging loads are being integrated into the distribution network, forming a symbiotic system of "distribution network-new entities." This fundamentally changes the physical structure of the traditional distribution network and greatly increases system complexity and management difficulty. After these new entities are integrated into the distribution network, when a power outage occurs, distributed photovoltaic and distributed energy storage power sources form islanded systems with local loads. This poses a challenge to the safe and stable operation of the distribution network. For safety reasons, it is necessary to quickly and accurately determine whether distributed photovoltaic and distributed energy storage are in an "islanded" state and to implement anti-islanding protection and active support.

[0003] Existing technologies primarily focus on islanding detection methods, which can be broadly categorized into two types: those based on remote communication and those based on local information. The former relies on communication technology and has no blind spots, but is costly. The latter can be further divided into passive and active islanding detection methods. Passive islanding detection is mainly based on changes in local information before and after islanding; it is simple and easy to implement, but has a large blind spot and fails when the distributed generation system and local load power are approximately matched. Active islanding detection involves injecting disturbances into the system through grid-connected inverters and detecting islanding by measuring the grid connection point's response to the disturbances. This method has the advantage of a small blind spot but can impact power quality. Furthermore, when multiple generators operate in parallel, there is a probability of mutual interference between disturbances, leading to islanding protection failure.

[0004] The prior art provides an island detection method, apparatus, and electronic equipment, such as Figure 1 As shown, it can synchronize the disturbances of a single inverter in a parallel system, effectively avoiding mutual interference between disturbances of different machines when multiple machines are connected in parallel, thereby improving the reliability of islanding protection.

[0005] To address the aforementioned issues, the existing technology employs the following solution: A method for islanding detection is provided for distributed power grids composed of multiple inverters connected in parallel. This method includes: multiple inverters injecting disturbances into the power grid according to a disturbance sequence, including each inverter sequentially injecting disturbances into the power grid according to the disturbance sequence until a total of N disturbances are injected, with each inverter repeating the injection at a fixed period; after each inverter injects a disturbance into the power grid, the change in the power grid frequency or phase during that disturbance phase compared to the previous disturbance phase is detected; if the change in frequency or phase exceeds a first preset threshold, the disturbance sequence is reset; if the change in frequency or phase exceeds a second preset threshold, it is determined that an island exists in the power grid, wherein the second preset threshold is greater than the first preset threshold.

[0006] The change in the power grid frequency or phase during a disturbance phase compared to the previous disturbance phase in the prior art refers to the change in the power grid frequency during a disturbance phase compared to the previous disturbance phase, or the change in the power grid phase during a disturbance phase compared to the previous disturbance phase.

[0007] Existing technologies that rely on preset thresholds for judgment may face a trade-off between sensitivity and false positive rate, potentially leading to malfunctions under complex power grid conditions. Layered cyclic perturbation mechanisms increase system complexity and place higher demands on processor computing power and communication synchronization. Accumulated N perturbations may still result in detection blind spots under certain load conditions; existing technologies have not fundamentally eliminated the inherent impact of active perturbations on power quality. Summary of the Invention

[0008] To address the challenges of improving the system's anti-disturbance and anti-maloperation / refusal performance after the integration of new types of entities, accelerating the response time of anti-islanding protection, and enhancing the grid connection / network construction support for new entities, this application proposes an anti-islanding protection method for the integration of multiple types of new entities into the distribution network, including: Real-time monitoring of voltage and frequency at the grid connection point of the distribution network is used to perform passive signal detection and active signal injection, and to obtain passive signal detection results and active signal injection feedback. Based on the passive signal detection results and active signal injection feedback, system state identification is performed to distinguish between non-islanding type disturbances and islanding type disturbances; Based on the non-islanding type disturbances and islanding type disturbances combined with the preset instructions of the upper-level control software, a corresponding control strategy is generated. Based on the control strategy, corresponding anti-islanding protection operations are performed.

[0009] Preferably, the real-time monitoring of the voltage and frequency at the distribution network connection point involves passive signal detection and active signal injection to obtain passive signal detection results and active signal injection feedback, including: Real-time monitoring of voltage and frequency at the grid connection point of the distribution network; passive signal detection; and obtaining passive signal detection results. When the passive signal detects a disturbance, it triggers and coordinates the new type of entity to inject an active disturbance signal into the distribution network, thereby obtaining active signal injection feedback.

[0010] Preferably, the active disturbance signal includes a frequency offset signal and / or a current harmonic signal.

[0011] Preferably, the step of generating a corresponding control strategy based on the non-islanded disturbance and the islanded disturbance combined with preset instructions from the upper-level control software includes: When the disturbance type is an islanding disturbance, determine whether the upper-level control software has preset a lockout command. If so, generate an active support strategy according to the non-islanding disturbance type; otherwise, generate an anti-islanding protection strategy. When the disturbance type is a non-islanding type disturbance, an active support strategy is generated.

[0012] Preferably, the corresponding anti-islanding protection operation based on the control strategy includes: Based on the aforementioned anti-islanding protection strategy, an anti-islanding protection action exit is performed; Based on the aforementioned active support strategy, the protection action time limit is extended and the new main body is controlled to maintain or provide grid connection support.

[0013] Preferred options also include: Before the anti-islanding protection action exits, a new type of main body is used to maintain grid connection support; After the anti-islanding protection action is output, the new main body is used to perform a shutdown operation and determine whether the upper-level control software has preset an autonomous restart command. If so, the new main body is restarted according to the command; otherwise, the operation ends.

[0014] Preferred options also include: After the anti-islanding protection action is output, it is determined whether the upper-level control software has preset the seamless autonomous command. If so, it switches to the network construction mode and starts regional coordination control and islanded power supply; otherwise, the operation ends.

[0015] Preferably, the novel entity includes: distributed photovoltaic, distributed energy storage, and charging piles.

[0016] Based on the same concept, this application also proposes an anti-islanding protection system for multiple types of entities connected to the distribution network, including: The collaborative detection module is used to monitor the voltage and frequency of the distribution network connection point in real time, perform passive signal detection and active signal injection, and obtain passive signal detection results and active signal injection feedback. The state identification module is used to identify the system state based on the passive signal detection results and active signal injection feedback, and to distinguish between non-island type disturbances and island type disturbances. The control strategy generation module is used to generate corresponding control strategies based on the non-islanding type disturbances and islanding type disturbances combined with the preset instructions of the upper-level control software. The control strategy execution module is used to perform corresponding anti-islanding protection operations based on the control strategy.

[0017] Preferably, the collaborative detection module is specifically used for: Real-time monitoring of voltage and frequency at the grid connection point of the distribution network; passive signal detection; and obtaining passive signal detection results. When the passive signal detects a disturbance, it triggers and coordinates the new type of entity to inject an active disturbance signal into the distribution network, thereby obtaining active signal injection feedback.

[0018] Preferably, the active disturbance signal includes a frequency offset signal and / or a current harmonic signal.

[0019] Preferably, the control strategy generation module is specifically used for: When the disturbance type is an islanding disturbance, determine whether the upper-level control software has preset a lockout command. If so, generate an active support strategy according to the non-islanding disturbance type; otherwise, generate an anti-islanding protection strategy. When the disturbance type is a non-islanding type disturbance, an active support strategy is generated.

[0020] Preferably, the control strategy execution module is specifically used for: Based on the aforementioned anti-islanding protection strategy, an anti-islanding protection action exit is performed; Based on the aforementioned active support strategy, the protection action time limit is extended and the new main body is controlled to maintain or provide grid connection support.

[0021] Preferred options also include: Before the anti-islanding protection action exits, a new type of main body is used to maintain grid connection support; After the anti-islanding protection action is output, the new main body is used to perform a shutdown operation and determine whether the upper-level control software has preset an autonomous restart command. If so, the new main body is restarted according to the command; otherwise, the operation ends.

[0022] Preferred options also include: After the anti-islanding protection action is output, it is determined whether the upper-level control software has preset the seamless autonomous command. If so, it switches to the network construction mode and starts regional coordination control and islanded power supply; otherwise, the operation ends.

[0023] Preferably, the novel entity includes: distributed photovoltaic, distributed energy storage, and charging piles.

[0024] Compared with the prior art, the beneficial effects of this application are as follows: A method and system for anti-islanding protection of multiple novel entities connected to a distribution network includes: real-time monitoring of voltage and frequency at the grid connection point of the distribution network for passive signal detection and active signal injection, obtaining passive signal detection results and active signal injection feedback; system state identification based on the passive signal detection results and active signal injection feedback, distinguishing between non-islanding type disturbances and islanding type disturbances; generating corresponding control strategies based on the non-islanding type disturbances and islanding type disturbances combined with preset instructions from the upper-level control software; and performing corresponding anti-islanding protection operations based on the control strategies. This application, through passive signal detection and active signal injection, can reduce the injection frequency of active disturbances and lower the setting threshold of passive criteria, solving the problems of fast passive detection speed but susceptibility to non-islanding disturbance interference, and high reliability of active detection but system stability risks. It improves the system's anti-disturbance and anti-maloperation / refusal-operation performance after the novel entities are connected, and accelerates the response time of anti-islanding protection actions. By integrating preset instructions from the upper-level software, it achieves remote controllability of protection actions, mode switching, and restart strategies, ensuring intelligent autonomy of the power grid and enhancing the support for the grid connection / construction of novel entities. Attached Figure Description

[0025] Figure 1 This is a flowchart of an island detection method according to this application; Figure 2 This is a flowchart of an anti-islanding protection method for multiple novel entities accessing a distribution network, as described in this application. Figure 3 This is a sequence diagram of the overall solution in this application; Figure 4 This is a schematic diagram illustrating a case study of this application; Figure 5 This is a schematic diagram illustrating Case Study 2 of this application; Figure 6 This is a schematic diagram illustrating Case Study 3 of this application; Figure 7 This is a structural diagram of an anti-islanding protection system for multiple novel entities connected to a distribution network, as described in this application. Detailed Implementation

[0026] This application is adaptable to scenarios where various new types of entities (distributed photovoltaic, distributed energy storage, charging piles, etc.) are connected to the distribution network on a large scale. It not only improves the system's anti-disturbance and anti-maloperation / refusal performance after the new entities are connected, but also accelerates the response time of anti-islanding protection actions, and enhances the grid connection / network construction support for new entities. Specifically: 1) The timing coordination between fast and accurate anti-islanding protection and the active support of the new main body for the distribution network is achieved through millisecond-level passive detection and active injection complementarity. Based on accurate state identification and strategy generation, corresponding timing logic is set for different disturbance types. During islanding disturbances, accurate anti-islanding protection action is achieved within 1 second. During non-islanding disturbances, the active support capability of the new main body is enhanced, thereby improving the system's anti-disturbance and anti-maloperation performance and rapid response to islanding events, and realizing the coordination of anti-islanding protection and active support. 2) It provides hierarchical support for the stability of the distribution network, maintaining grid connection support for the new main body before anti-islanding protection actions, shutting down within 10 milliseconds after the action, and supporting upper-level autonomous restart and grid mode switching commands to improve transient / steady-state coordinated control capabilities; 3) It realizes autonomous intelligent operation of islanded systems, supporting minute-level balance scheduling and hour-level islanded power supply through regional coordinated control and energy management to meet the continuous support needs of different SOC energy storage systems; 4) It obeys multi-level command coordination, integrating preset commands from upper-level control software (such as islanding interlocking, seamless autonomy, and autonomous restart) to achieve remote controllability of protection actions, mode switching, and restart strategies, ensuring intelligent autonomy of the distribution network. To better understand this application, the following description, in conjunction with the accompanying drawings and embodiments, further illustrates the content of this application.

[0027] Example 1: A novel anti-islanding protection method for multiple types of entities connected to a distribution network, the specific process of which is as follows: Figure 2 As shown, it includes: Step 1: Real-time monitoring of voltage and frequency at the grid connection point of the distribution network to perform passive signal detection and active signal injection, and obtain passive signal detection results and active signal injection feedback; Step 2: Based on the passive signal detection results and active signal injection feedback, perform system state identification to distinguish between non-islanding type disturbances and islanding type disturbances; Step 3: Based on the non-islanding type disturbances and islanding type disturbances combined with the preset instructions of the upper-level control software, generate corresponding control strategies; Step 4: Perform corresponding anti-islanding protection operations based on the control strategy.

[0028] Step 1 involves real-time monitoring of the voltage and frequency at the distribution network connection point, performing passive signal detection and active signal injection to obtain passive signal detection results and active signal injection feedback. Specifically, this includes: Anti-islanding protection strategies include passive signal detection and active signal injection. Passive signal detection relies on real-time monitoring of grid voltage and frequency, judging islanding status through over / under voltage and over / under frequency thresholds, with a response time typically within hundreds of milliseconds. Active signal injection, on the other hand, injects small disturbances (such as frequency shifts or current harmonics) and observes the system response to identify islanding, also requiring signal generation and feedback acquisition within hundreds of milliseconds. These two methods work together: the passive anti-islanding protection at the grid connection point actively triggers and coordinates active anti-islanding injection from distributed energy storage and distributed photovoltaic systems after a disturbance occurs. This reduces the injection frequency of active disturbances and lowers the setting threshold for passive criteria, solving the problems of passive detection being fast but susceptible to non-islanding disturbances, and active detection being highly reliable but posing system stability risks.

[0029] Step 2, which involves system state identification based on the passive signal detection results and active signal injection feedback to distinguish between non-islanding and islanding disturbances, specifically includes: After the detection is completed, system status identification is performed. Status identification can distinguish between non-islanded type disturbances and islanded type disturbances. Accurate identification can improve the system's ability to resist disturbances and prevent false alarms.

[0030] Step 3, based on the non-islanded and islanded disturbances combined with preset instructions from the upper-level control software, generates a corresponding control strategy, specifically including: When a non-islanding disturbance is identified, a control strategy will be generated within 100 milliseconds, thereby adjusting the anti-islanding protection action time threshold to a long delay of seconds. That is, if the disturbance is identified at this moment, there is no need to immediately take anti-islanding protection action. This requires distributed photovoltaic, distributed energy storage and other power sources to maintain output to support grid operation and improve the system disturbance tolerance. When an islanding-type disturbance is identified, a strategy is generated within 100 milliseconds, and then an anti-islanding protection action is initiated within 10 milliseconds, directly driving the circuit breaker or inverter to lock out. From signal detection, state identification, strategy generation to the anti-islanding protection action, the entire process takes no more than 1 second, ensuring rapid action under real islanding conditions, i.e., the anti-islanding protection time is no more than 1 second.

[0031] Furthermore, if the upper-level control software has pre-set islanding interlocking instructions, then even if the disturbance is identified as an islanding type, it will not generate an anti-islanding protection action output, but will be treated as a non-islanding type disturbance.

[0032] Step 4, which involves performing corresponding anti-islanding protection operations based on the control strategy, specifically includes: Based on the aforementioned anti-islanding protection strategy, an anti-islanding protection action exit is performed; Based on the aforementioned active support strategy, the protection action time limit is extended and the new main body is controlled to maintain or provide grid connection support.

[0033] This also includes proactive support: Before the anti-islanding protection action is triggered, the new types of entities (distributed photovoltaic, distributed energy storage) need to maintain grid connection support to improve the system's anti-disturbance capability. Once the anti-islanding protection action is triggered, the new types of entities should complete shutdown within 10 milliseconds to achieve anti-islanding protection. If the upper-level control software has a pre-set autonomous restart command, after a certain time delay (this delay refers to the time required for system initialization or reconnection; this delay is used to ensure grid stability before reconnection, avoiding repeated islanding or grid-connection disruptions), the new types of entities should restart according to the command.

[0034] It also includes autonomous operation: When an islanding-type disturbance is confirmed, i.e., the anti-islanding protection action is triggered, if the upper-level control software has a seamless autonomous command pre-set, the direct-controlled inverter should be completed within 100 milliseconds. On the one hand, it achieves minute-level energy balance through regional coordination control function, and on the other hand, it switches distributed photovoltaic and distributed energy storage to grid mode within 30 milliseconds, and achieves hour-level (depending on the current SOC of the energy storage system) active support for islanding operation, maintaining local power supply through energy management.

[0035] The strategy described in this application, from such Figure 3 The overall timing framework shown comprises three parts: anti-islanding protection, autonomous operation, and active support. These three parts, combined with pre-set instructions from the upper-level control software, work together according to corresponding timing logic to form a rapid anti-islanding protection and active support strategy for the safe access of various new types of entities to the distribution network. For distribution substations with multiple new entities such as distributed photovoltaic, distributed energy storage, and charging loads, anti-islanding protection, as the core security protection mechanism, needs to coordinate multiple stages, including passive signal detection, active signal injection, state identification, and strategy execution. The logical coordination across different time scales (from milliseconds to hours) reflects the synergy between transient and steady-state control, the balance between the speed and reliability of anti-islanding protection actions, and the conflicting balance between the time scales of anti-islanding protection and active support.

[0036] The anti-islanding protection and active support strategy proposed in this application is a complex control strategy that coordinates multiple levels and time scales. It enables rapid detection at the millisecond level and islanding operation at the hour level, ensuring the distribution network's resistance to disturbances and prevention of maloperation under non-islanding disturbances, while achieving rapid anti-islanding protection and active support for new types of entities under islanding disturbances.

[0037] The strategy proposed in this invention is illustrated using high-voltage disturbance as an example, as described in the example below. Figure 4 As shown. The passive signal detection of anti-islanding protection triggers active signal injection after the system disturbance occurs. It completes system state identification and strategy generation within hundreds of milliseconds. In the case of Case 1, the voltage disturbance is too large and is judged to be an islanding type disturbance, so anti-islanding protection action output is required. At this time, the whole time does not exceed 1 second, and then the inverter is shut down within 10ms.

[0038] The strategy proposed in this invention is illustrated using high-voltage disturbance as an example. Example 2 is as follows: Figure 5 As shown. The passive signal detection of anti-islanding protection triggers active signal injection after the system disturbance occurs, and completes system state identification and strategy generation within hundreds of milliseconds. In the case of Case 2, the voltage disturbance is small and is determined to be a non-islanding type disturbance. It is only necessary to adjust the anti-islanding protection action time threshold to a long delay, which calls the energy storage system for active support. The maximum active support time is 2 seconds, and the voltage recovers after support.

[0039] The strategy proposed in this invention is illustrated using high-voltage disturbance as an example, with case study three as follows. Figure 6 As shown. The timing logic coordination between active support and its preceding steps is the same as in Case Study 2. If the voltage still cannot be restored after 2 seconds of active support, the anti-islanding protection action needs to be activated to shut down the inverter.

[0040] This application enhances the security and resilience of the distribution network. Through a three-pronged multi-timescale collaborative control strategy integrating anti-islanding protection, autonomous operation, and active support, it identifies and rapidly isolates genuine islanding faults within milliseconds based on a precise identification algorithm. It effectively blocks malfunctions under non-islanding disturbances within seconds, significantly improving the speed and reliability of anti-islanding protection. Furthermore, this strategy supports seamless switching to network mode within 30 milliseconds after islanding occurs, achieving hourly autonomous and stable operation. This provides uninterrupted, high-quality power supply to core loads, significantly enhancing the distribution network's security and resilience against disturbances and preventing maloperation or failure to operate.

[0041] Maximizing the synergistic value and utilization efficiency of new energy sources (distributed photovoltaic, distributed energy storage, and charging loads). Through pre-set strategies in the upper-level control software, distributed photovoltaic and distributed energy storage are guided to maintain grid connection support during system disturbances, effectively improving the overall anti-disturbance capability of the distribution network. During islanded operation, minute-level regional energy coordination and hourly proactive support strategies optimize the power output plans of distributed photovoltaic and distributed energy storage, fully tapping their power supply potential within the island and extending the guarantee period for critical loads. This significantly improves the utilization efficiency and reliability of distributed energy in emergency situations, achieving a balance between safety and economy.

[0042] Example 2: A novel anti-islanding protection system for multiple types of entities connected to the distribution network, with the structure as follows: Figure 7 As shown, it includes: The collaborative detection module is used to monitor the voltage and frequency of the distribution network connection point in real time, perform passive signal detection and active signal injection, and obtain passive signal detection results and active signal injection feedback. The state identification module is used to identify the system state based on the passive signal detection results and active signal injection feedback, and to distinguish between non-island type disturbances and island type disturbances. The control strategy generation module is used to generate corresponding control strategies based on the non-islanding type disturbances and islanding type disturbances combined with the preset instructions of the upper-level control software. The control strategy execution module is used to perform corresponding anti-islanding protection operations based on the control strategy.

[0043] The collaborative detection module is specifically used for: Real-time monitoring of voltage and frequency at the grid connection point of the distribution network; passive signal detection; and obtaining passive signal detection results. When the passive signal detects a disturbance, it triggers and coordinates the new type of entity to inject an active disturbance signal into the distribution network, thereby obtaining active signal injection feedback.

[0044] The active disturbance signal includes a frequency offset signal and / or a current harmonic signal.

[0045] The control strategy generation module is specifically used for: When the disturbance type is an islanding disturbance, determine whether the upper-level control software has preset a lockout command. If so, generate an active support strategy according to the non-islanding disturbance type; otherwise, generate an anti-islanding protection strategy. When the disturbance type is a non-islanding type disturbance, an active support strategy is generated.

[0046] The control strategy execution module is specifically used for: Based on the aforementioned anti-islanding protection strategy, an anti-islanding protection action exit is performed; Based on the aforementioned active support strategy, the protection action time limit is extended and the new main body is controlled to maintain or provide grid connection support.

[0047] Also includes: Before the anti-islanding protection action exits, a new type of main body is used to maintain grid connection support; After the anti-islanding protection action is output, the new main body is used to perform a shutdown operation and determine whether the upper-level control software has preset an autonomous restart command. If so, the new main body is restarted according to the command; otherwise, the operation ends.

[0048] Also includes: After the anti-islanding protection action is output, it is determined whether the upper-level control software has preset the seamless autonomous command. If so, it switches to the network construction mode and starts regional coordination control and islanded power supply; otherwise, the operation ends.

[0049] Preferably, the novel entity includes: distributed photovoltaic, distributed energy storage, and charging piles.

[0050] This application proposes fast anti-islanding protection and active support strategies for multiple types of new entities accessing the distribution network: 1. Composite island detection mechanism: A dual-cooperative composite islanding detection mechanism integrating passive signal detection (voltage / frequency threshold judgment) and active signal injection (harmonic / frequency offset disturbance) was constructed. When the passive anti-islanding protection at the grid connection point is actively triggered after the disturbance occurs, it coordinates the active anti-islanding injection of energy storage and distributed power sources. On the one hand, it can reduce the setting threshold of the passive criterion, and on the other hand, it can reduce the injection frequency of active disturbance.

[0051] 2. Multi-timescale collaborative control architecture: A four-level timescale collaborative mechanism is proposed, encompassing millisecond-level (hundreds of milliseconds) rapid detection, state identification and strategy generation, second-level proactive support strategy adjustment, minute-level regional autonomous energy balance, and hour-level islanded operation. Particularly noteworthy is the differentiated processing logic after state identification: for non-islanded disturbances, the action time limit is extended to the second level, enabling distributed photovoltaic and distributed energy storage to proactively support the distribution network; for islanded disturbances, the entire process is ensured to be completed within 1 second. In weak power grids containing 30% renewable energy, the false trip rate is reduced by 90%, and the anti-islanding protection action time is shortened from the national standard requirement of 2 seconds to 1 second, effectively improving the system's disturbance resistance and prevention of false trips / failures. Dynamic coupling of transient and steady-state control is achieved through preset commands in the upper-level control software, resolving the technical contradiction between speed and reliability in traditional protection strategies.

[0052] 3. Dynamic response system for instruction priority: A mandatory overriding mechanism is established for superior control commands (blocking / autonomy / restart) to override local protection strategies: when a preset islanding blocking command exists, the system is still processed as a non-islanding mode even if islanding characteristics are detected; when a seamless autonomy command is triggered, the network mode switch is completed within 100 milliseconds; when the superior control software issues an autonomous restart command, the system can restart according to the command; this design significantly improves the system's compliance with scheduling commands.

[0053] 4. Rapid switching between multiple modes for new main entities: Protect the transient switching capability of distributed power sources between three operating states: grid-connected support mode (maintaining disturbance-resistant output), forced grid disconnection mode (shutting down within 10ms), and grid-based autonomous mode (completing control reconfiguration within 30ms). Emphasis is placed on protecting the hourly islanding runtime adaptive adjustment algorithm based on energy storage SOC (State of Charge).

[0054] 5. Regionalized collaborative protection logic: Innovatively, the three major modules of anti-islanding protection (security core), active support (transient response), and autonomous operation (steady-state maintenance) are coupled through a time-series framework to form a closed-loop control chain of "detection-identification-execution-recovery". Its technical features are reflected in the fact that the timing coordination accuracy of each module must meet the following requirements: strategy generation ≤ 100ms → action exit ≤ 10ms → mode switching ≤ 30ms.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

[0056] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0057] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0058] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0059] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0060] The above are merely embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application shall be included within the scope of the claims of this application pending approval.

Claims

1. A method for anti-islanding protection of multiple novel entities connected to a distribution network, characterized in that, include: Real-time monitoring of voltage and frequency at the grid connection point of the distribution network is used to perform passive signal detection and active signal injection, and to obtain passive signal detection results and active signal injection feedback. Based on the passive signal detection results and active signal injection feedback, system state identification is performed to distinguish between non-islanding type disturbances and islanding type disturbances; Based on the non-islanding type disturbances and islanding type disturbances combined with the preset instructions of the upper-level control software, a corresponding control strategy is generated. Based on the control strategy, corresponding anti-islanding protection operations are performed.

2. The method according to claim 1, characterized in that, The real-time monitoring of voltage and frequency at the distribution network connection point involves passive signal detection and active signal injection to obtain passive signal detection results and active signal injection feedback, including: Real-time monitoring of voltage and frequency at the grid connection point of the distribution network; passive signal detection; and obtaining passive signal detection results. When the passive signal detects a disturbance, it triggers and coordinates the new type of entity to inject an active disturbance signal into the distribution network, thereby obtaining active signal injection feedback.

3. The method according to claim 2, characterized in that, The active disturbance signal includes a frequency offset signal and / or a current harmonic signal.

4. The method according to claim 1, characterized in that, The generation of corresponding control strategies based on the non-islanding type disturbances and islanding type disturbances combined with preset instructions from the upper-level control software includes: When the disturbance type is an islanding disturbance, determine whether the upper-level control software has preset a lockout command. If so, generate an active support strategy according to the non-islanding disturbance type; otherwise, generate an anti-islanding protection strategy. When the disturbance type is a non-islanding type disturbance, an active support strategy is generated.

5. The method according to claim 1, characterized in that, The corresponding anti-islanding protection operation based on the control strategy includes: Based on the aforementioned anti-islanding protection strategy, an anti-islanding protection action exit is performed; Based on the aforementioned active support strategy, the protection action time limit is extended and the new main body is controlled to maintain or provide grid connection support.

6. The method according to claim 5, characterized in that, Also includes: Before the anti-islanding protection action exits, a new type of main body is used to maintain grid connection support; After the anti-islanding protection action is output, the new main body is used to perform a shutdown operation and determine whether the upper-level control software has preset an autonomous restart command. If so, the new main body is restarted according to the command; otherwise, the operation ends.

7. The method according to claim 5, characterized in that, Also includes: After the anti-islanding protection action is output, it is determined whether the upper-level control software has preset the seamless autonomous command. If so, it switches to the network construction mode and starts regional coordination control and islanded power supply; otherwise, the operation ends.

8. The method according to claim 5, characterized in that, The new types of entities include: distributed photovoltaics, distributed energy storage, and charging piles.

9. An anti-islanding protection system for multiple types of novel entities connected to a distribution network, characterized in that, include: The collaborative detection module is used to monitor the voltage and frequency of the distribution network connection point in real time, perform passive signal detection and active signal injection, and obtain passive signal detection results and active signal injection feedback. The state identification module is used to identify the system state based on the passive signal detection results and active signal injection feedback, and to distinguish between non-island type disturbances and island type disturbances. The control strategy generation module is used to generate corresponding control strategies based on the non-islanding type disturbances and islanding type disturbances combined with the preset instructions of the upper-level control software. The control strategy execution module is used to perform corresponding anti-islanding protection operations based on the control strategy.

10. The system according to claim 9, characterized in that, The collaborative detection module is specifically used for: Real-time monitoring of voltage and frequency at the grid connection point of the distribution network; passive signal detection; and obtaining passive signal detection results. When the passive signal detects a disturbance, it triggers and coordinates the new type of entity to inject an active disturbance signal into the distribution network, thereby obtaining active signal injection feedback.

11. The system according to claim 10, characterized in that, The active disturbance signal includes a frequency offset signal and / or a current harmonic signal.

12. The system according to claim 9, characterized in that, The control strategy generation module is specifically used for: When the disturbance type is an islanding disturbance, determine whether the upper-level control software has preset a lockout command. If so, generate an active support strategy according to the non-islanding disturbance type; otherwise, generate an anti-islanding protection strategy. When the disturbance type is a non-islanding type disturbance, an active support strategy is generated.

13. The system according to claim 9, characterized in that, The control strategy execution module is specifically used for: Based on the aforementioned anti-islanding protection strategy, an anti-islanding protection action exit is performed; Based on the aforementioned active support strategy, the protection action time limit is extended and the new main body is controlled to maintain or provide grid connection support.

14. The system according to claim 13, characterized in that, Also includes: Before the anti-islanding protection action exits, a new type of main body is used to maintain grid connection support; After the anti-islanding protection action is output, the new main body is used to perform a shutdown operation and determine whether the upper-level control software has preset an autonomous restart command. If so, the new main body is restarted according to the command; otherwise, the operation ends.

15. The system according to claim 13, characterized in that, Also includes: After the anti-islanding protection action is output, it is determined whether the upper-level control software has preset the seamless autonomous command. If so, it switches to the network construction mode and starts regional coordination control and islanded power supply; otherwise, the operation ends.

16. The system according to claim 13, characterized in that, The new types of entities include: distributed photovoltaics, distributed energy storage, and charging piles.

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