Micro-grid system island detection cooperative control method, device, equipment and medium

Abstract

The invention relates to the technical field of distributed micro-grid island detection, and discloses a micro-grid system island detection cooperative control method, device, equipment and medium, during grid-connected operation of a micro-grid system, a main disturbance source and an auxiliary disturbance source are determined based on real-time operation data of each distributed power supply; when the parameters are abnormal, the main disturbance source is controlled to carry out short-period progressive enhanced disturbance, the auxiliary disturbance source and the main disturbance source are introduced to carry out superposed same-direction disturbance if no island is detected in the enhanced disturbance process, and the main disturbance source and the auxiliary disturbance source are controlled to carry out reverse disturbance if no island is detected in the same-direction disturbance process; and circularly executing the enhanced disturbance, superposing the same-direction disturbance and the reverse disturbance until the detection is successful, and further controlling the micro-grid system to be switched to an off-grid operation mode. The offset or conflict problem caused by independent disturbance of multiple distributed power supplies is solved, and rapid and reliable island detection with the minimum influence on system operation is achieved.

Description

Technical Field

[0001] This invention relates to the field of distributed microgrid islanding detection technology, and in particular to a collaborative control method, device, equipment and medium for islanding detection in microgrid systems. Background Technology

[0002] With the popularization of photovoltaic power generation and electric vehicles, residential microgrid systems often connect energy storage inverters and bidirectional V2G charging piles at the same time. Both have the ability to feed power to the grid, so islanding detection function is required.

[0003] Common islanding detection methods include passive detection, frequency disturbance, and reactive power disturbance. Passive detection relies on abnormal changes in grid voltage and frequency to determine islanding, but it cannot accurately and effectively detect islanding when grid parameters fluctuate only slightly. Frequency disturbance and reactive power disturbance methods detect islanding by injecting disturbance signals into the grid, but this may negatively impact grid stability. Therefore, in residential energy storage microgrid systems connected to bidirectional charging piles, islanding detection methods for inverters and charging piles are prone to failure due to disturbances canceling each other out. This demonstrates that existing technologies lack effective collaborative control mechanisms, hindering rapid and reliable islanding identification.

[0004] Therefore, how to solve the problem of reduced effectiveness of island detection caused by the inability to coordinate the control of energy storage and bidirectional V2G charging piles in existing residential energy storage microgrid systems has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a method, device, equipment, and medium for coordinated control of islanding detection in microgrid systems, which solves the problem that the effectiveness of islanding detection is reduced due to the inability to coordinate control between energy storage and bidirectional V2G charging piles in existing residential energy storage microgrid systems.

[0006] To address the aforementioned technical problems, the first aspect of this invention provides a method for collaborative control of island detection in a microgrid system, comprising: When the microgrid system is detected to be in grid-connected operation mode, the main disturbance source and the auxiliary disturbance source are determined based on the real-time operation data of each distributed power source in the microgrid system. When an abnormality is detected in the real-time port electrical parameters of the microgrid system, a first-level disturbance mechanism is triggered to control the main disturbance source to perform short-cycle progressively enhanced disturbance. During the execution of the first-level disturbance mechanism, if the real-time port electrical parameters do not exceed the islanding determination threshold, the second-level disturbance mechanism is triggered to introduce the auxiliary disturbance source and the main disturbance source to perform superimposed disturbance in the same direction. During the execution of the secondary disturbance mechanism, if the real-time port electrical parameters do not trigger the islanding determination threshold, the tertiary disturbance mechanism is triggered to control the primary disturbance source and the secondary disturbance source to perform reverse disturbances. If the real-time port electrical parameters do not trigger the islanding threshold during the execution of the three-level disturbance mechanism, the first-level disturbance mechanism, the second-level disturbance mechanism, and the third-level disturbance mechanism are executed in a loop until the real-time port electrical parameters trigger the islanding threshold, and the microgrid system is controlled to switch to off-grid operation mode.

[0007] As one preferred embodiment, the microgrid system includes residential energy storage and bidirectional V2G charging stations; The step of determining the main disturbance source based on the real-time operating data of each distributed power source in the microgrid system includes: If the bidirectional V2G charging pile is in a high-power charging state, then the household energy storage will be used as the main disturbance source. If the bidirectional V2G charging pile is not in a high-power charging state, the real-time reactive power output margin of the household energy storage and the bidirectional V2G charging pile is obtained, and the bidirectional V2G charging pile is used as the main disturbance source if and only if the real-time reactive power output margin of the bidirectional V2G charging pile is greater than a first preset threshold; otherwise, the household energy storage is used as the main disturbance source.

[0008] As one preferred embodiment, after determining the primary and secondary disturbance sources based on the real-time operating data of each distributed power source, the method further includes: Trigger the grid-connected fixed disturbance mechanism to control the main disturbance source to output a fixed reactive disturbance within a first preset long period, and control the auxiliary disturbance source not to output disturbances for islanding detection.

[0009] As one preferred embodiment, controlling the main disturbance source to perform short-period asymptotic enhancement of the disturbance includes: The main disturbance source is controlled to switch to outputting a first variable reactive power disturbance with a second preset short cycle; the first variable reactive power disturbance starts from an initial disturbance value and gradually increases according to a preset step size until it reaches the maximum reactive power disturbance of the main disturbance source.

[0010] As one preferred embodiment, the step of introducing the auxiliary disturbance source and the main disturbance source to perform superimposed disturbance in the same direction includes: The auxiliary disturbance source is controlled to output a second variable reactive power disturbance in the same direction as the main disturbance source; the second variable reactive power disturbance starts from the initial disturbance value and gradually increases according to the preset step size until it reaches the maximum reactive power disturbance of the auxiliary disturbance source.

[0011] As one preferred embodiment, controlling the primary disturbance source and the secondary disturbance source to perform opposite disturbances includes: The auxiliary disturbance source is controlled to gradually reduce the second variable reactive power disturbance to zero according to the preset step size, and the main disturbance source is controlled to gradually reduce the first variable reactive power disturbance to zero according to the preset step size; The main disturbance source and the auxiliary disturbance source are controlled to initiate reverse reactive disturbances, so as to execute the short-cycle progressively enhanced disturbance and the superimposed same-direction disturbance respectively in reverse order.

[0012] As one preferred embodiment, the microgrid system further includes an inverter and an energy management system, and the method is controlled and executed by the energy management system; wherein, the bidirectional V2G charging pile is communicatively connected to the energy management system, or the bidirectional V2G charging pile is communicatively connected to the energy management system after being relayed through the inverter.

[0013] A second aspect of the present invention provides a collaborative control device for island detection in a microgrid system, comprising: The disturbance source determination module is used to determine the main disturbance source and the auxiliary disturbance source based on the real-time operating data of each distributed power source in the microgrid system when the microgrid system is detected to be in grid-connected operation mode. The first-level disturbance module is used to trigger the first-level disturbance mechanism when the real-time port electrical parameters of the microgrid system are detected to be abnormal, so as to control the main disturbance source to perform short-period progressively enhanced disturbance. The secondary disturbance module is used to trigger the secondary disturbance mechanism if the real-time port electrical parameters do not exceed the islanding determination threshold during the execution of the primary disturbance mechanism, so as to introduce the auxiliary disturbance source and the primary disturbance source to perform superimposed same-direction disturbance. The third-level disturbance module is used to trigger the third-level disturbance mechanism if the real-time port electrical parameters do not trigger the islanding determination threshold during the execution of the second-level disturbance mechanism, so as to control the main disturbance source and the auxiliary disturbance source to perform reverse disturbance. The cyclic disturbance module is used to repeatedly execute the first-level disturbance mechanism, the second-level disturbance mechanism, and the third-level disturbance mechanism if the real-time port electrical parameters still do not trigger the islanding determination threshold during the execution of the third-level disturbance mechanism, until the real-time port electrical parameters trigger the islanding determination threshold, and then control the microgrid system to switch to off-grid operation mode.

[0014] A third aspect of the present invention provides an electronic device including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the microgrid system island detection and collaborative control method as described above.

[0015] A fourth aspect of the present invention provides a computer-readable storage medium comprising a stored computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements the microgrid system island detection and collaborative control method as described above.

[0016] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows: The main disturbance source is determined based on the equipment's operating status, balancing detection effectiveness and system operating efficiency, making it particularly suitable for high-power charging scenarios for new energy vehicles. A progressive disturbance amplification strategy designed for islanded detection is adopted, gradually expanding the reactive power disturbance energy of the system from single disturbances to superimposed disturbances, and from positive disturbances to reverse disturbances, completely covering the detection blind spots caused by load and power supply mismatch. At the same time, the main and auxiliary disturbance sources are centrally controlled to ensure that the disturbance directions are consistent and the energy is superimposed, avoiding the conflict and cancellation of independent disturbances from multiple devices, forming a collaborative detection mechanism of master-slave cooperation and orderly enhancement, which significantly improves the reliability and speed of islanded detection. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a structural diagram of a microgrid system provided in a certain embodiment of the present invention; Figure 2 This is a schematic diagram of a communication connection provided in a certain embodiment of the present invention; Figure 3 This is a flowchart of a collaborative control method for island detection in a microgrid system provided in a certain embodiment of the present invention; Figure 4 This is a structural diagram of a microgrid system island detection and collaborative control device provided in a certain embodiment of the present invention; Figure 5 This is a structural diagram of an electronic device provided in a certain embodiment of the present invention; Figure label: Among them, 10 is the disturbance source determination module; 20 is the first-level disturbance module; 30 is the second-level disturbance module; 40 is the third-level disturbance module; 50 is the cyclic disturbance module; 101 is the photovoltaic module; 102 is the lithium battery; 103 is the inverter; 104 is the charging pile, short for bidirectional V2G charging pile; 105 is the grid-connected / off-grid switching switch; 5000 is the electronic equipment; 5001 is the processor; 5002 is the bus; 5003 is the memory; and 5004 is the transceiver. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is merely for describing specific embodiments and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] Due to the renewable and clean nature of solar energy, photovoltaic (PV) power generation technology has developed rapidly. As PV power penetration increases, energy storage is needed to mitigate fluctuations in PV power output and improve user income through time-of-use pricing. With the increasing popularity of new energy vehicles, home charging stations are also becoming more common. To enable the batteries of new energy vehicles to participate in grid dispatch, charging stations need to have bidirectional charging and discharging capabilities; these bidirectional charging stations are called V2G (Vehicle-to-Grid) charging stations.

[0024] As a crucial platform connecting photovoltaic power sources, energy storage devices, loads, and charging piles, the stable operation of residential energy storage microgrid systems is paramount. When a grid fault causes the microgrid system to become isolated from the main grid, failure to detect and implement appropriate measures in a timely manner can adversely affect system equipment, user safety, and grid recovery. If the microgrid system is connected to unidirectional charging piles, only inverter 103 needs to have islanding detection functionality. However, bidirectional charging piles, which feed energy into the grid, also require islanding detection. Therefore, in microgrid systems connected to bidirectional charging piles, both inverter 103 and the bidirectional charging piles will perform islanding detection simultaneously.

[0025] Based on this, in one embodiment, the first aspect of the present invention provides a method for island detection and collaborative control in a microgrid system; wherein the structure of the microgrid system is as follows: Figure 1 As shown, the system includes two types of distributed power sources: household energy storage (inverter 103 and connected photovoltaic modules 101 and lithium batteries 102) and bidirectional V2G charging piles 104, an energy management system (EMS), a power grid, a grid-connected / off-grid switching switch 105, and household loads. The household energy storage includes two ports: household loads and the power grid. The bidirectional V2G charging piles 104 are connected to the grid port of the household energy storage and are connected to the power grid together. When the power grid is normal, the inverter 103 provides energy from the photovoltaic modules 101 and lithium batteries 102 to the household loads. The bidirectional V2G charging piles 104 can charge new energy vehicles or feed the battery energy of new energy vehicles back to the power grid. At this time, the grid-connected / off-grid switching switch 105 is in the closed state. When the power grid is interrupted and an islanded operation is formed, the EMS controls the output of the two distributed power sources according to the system status to quickly and reliably detect the islanded state and switch to the off-grid state to continue supplying power to the household loads. In the microgrid system, both the inverter 103 and the bidirectional V2G charging pile 104 need to be dispatched by the energy management system (EMS). Their communication connection diagram is shown below. Figure 2 As shown, the EMS selects the main disturbance source based on the system status and issues island detection and control commands to the two types of distributed power sources based on the dual-path redundant communication architecture to achieve coordinated control.

[0026] Depend on Figure 2It is known that the EMS is connected to the distributed power supply in the system through a "dual-path redundancy" architecture. Path A: The bidirectional V2G charging pile 104 is directly connected to the EMS via an independent communication module (RS485 / CAN) for periodic exchange of disturbance synchronization information, power feed, and battery SOC status. Path B: The bidirectional V2G charging pile 104 communicates with the EMS via RS485 / CAN and other communication modules after being relayed by the inverter 103. This is also used for periodic exchange of disturbance synchronization information, power feed, and battery SOC status. The microgrid system can select one of three communication connection methods—Path A, Path B, or dual-path redundancy—based on the actual project application and wiring optimization. When the system has high requirements for communication reliability, the dual-path redundancy connection method is preferred. When Path A is interrupted or the delay is >50ms, the EMS immediately sends a "reduce power to zero" gradual command through Path B, causing the bidirectional V2G charging pile 104 to automatically reduce the reverse power feed ramp to zero within 100ms. Then, the inverter 103 performs the remaining islanding detection steps.

[0027] The EMS (Electronic Management System) monitors the grid status, the power generation and energy storage of photovoltaic modules 101 and lithium batteries 102, the charging and discharging status of the bidirectional V2G charging pile 104, and the needs of household loads. Based on this information, the EMS issues commands to schedule the operation of the inverter 103 and the bidirectional V2G charging pile 104, ensuring the rational allocation and efficient utilization of energy. The inverter 103 and the bidirectional V2G charging pile 104 exchange information and status via communication to achieve a dual-path redundancy communication architecture. When a communication connection failure occurs between the EMS and the inverter 103 or the bidirectional V2G charging pile 104, communication interaction and system control can be achieved through the redundant path, increasing system reliability. This is suitable for complex on-site operating environments with high communication reliability requirements. The communication connection method adopted in this invention simplifies on-site communication wiring requirements, reduces communication costs, and is suitable for on-site operating environments with good communication quality.

[0028] When a grid fault or anomaly occurs, the inverter 103 monitors key parameters of the microgrid system in real time, such as voltage, frequency, and power, and makes a comprehensive judgment based on the operating status of the bidirectional V2G charging pile 104. If islanding is detected, the inverter 103 will quickly disconnect from the grid to protect the system and household loads from damage. Simultaneously, the bidirectional V2G charging pile 104 will adjust its operating status based on the islanding detection results to ensure that the charging process of new energy vehicles is not affected or can be safely stopped. Furthermore, the inverter 103 and the bidirectional V2G charging pile 104 share information and coordinate control through a communication connection to ensure the accuracy and reliability of islanding detection. In this way, embodiments of the present invention can effectively guarantee the safe and stable operation of the residential energy storage microgrid system under islanding conditions. The present invention adopts a centralized control strategy, entrusting the islanding detection control of the inverter 103 and the bidirectional V2G charging pile 104 to a unified central energy controller (EMS). Under this strategy, EMS will intelligently adjust the output of inverter 103 and bidirectional V2G charging pile 104 according to the real-time status of the system to ensure that the injection of disturbance signals is both effective and does not interfere with each other, thereby ensuring the effectiveness of islanding detection.

[0029] The method is controlled and executed by a power management system, which, as follows: Figure 3 As shown, it includes: S1. When the microgrid system is detected to be in grid-connected operation mode, the main disturbance source and the auxiliary disturbance source are determined based on the real-time operation data of each distributed power source in the microgrid system. First, the microgrid system starts and initializes. The EMS then begins monitoring the entire microgrid system's status, including key parameters such as grid port voltage amplitude and frequency, current, and power factor. The EMS determines whether the system is operating within a specific time window. Within (preferred value 0.2s, i.e., maintaining continuous operation for 10 grid cycles), are the voltage amplitude and frequency at the grid port within the normal range? (According to grid standard settings, the normal range of grid voltage is generally set to 0.85~1.1 rated grid voltage, and the normal range of grid frequency is 48.5~50.5Hz). If yes, it indicates that the grid is in a normal state. Under this state, the main disturbance source and auxiliary disturbance source are determined based on the real-time operation data of the bidirectional V2G charging pile 104 and household energy storage in the microgrid system. If no, it indicates that the grid is abnormal and enters the suspected islanding enhanced monitoring mode (i.e., multi-level disturbance).

[0030] In one embodiment, determining the main disturbance source based on the real-time operating data of each distributed power source in the microgrid system includes: If the bidirectional V2G charging pile 104 is in a high-power charging state, then the household energy storage will be used as the main disturbance source. If the bidirectional V2G charging pile 104 is not in a high-power charging state, the real-time reactive power output margin of the household energy storage and the bidirectional V2G charging pile 104 is obtained, and the bidirectional V2G charging pile 104 is used as the main disturbance source if and only if the real-time reactive power output margin of the bidirectional V2G charging pile 104 is greater than a first preset threshold; otherwise, the household energy storage is used as the main disturbance source.

[0031] This invention selects the primary disturbance source based on the operating status of two types of distributed power sources (whether they are online, charging / discharging power, and reactive power margin) to avoid detection failure caused by disordered disturbances from distributed power sources. The selection rules are as follows: If only one type of distributed power source is online, it is assumed to be the primary disturbance source. When both types of power sources are online: if the V2G bidirectional charging pile 104 is in a high-power charging state, then the household energy storage is selected as the main disturbance source to prioritize vehicle charging; if the reactive power margin of both is greater than the first preset threshold (the ratio of the current real-time output reactive power margin to its maximum reactive power margin, preferably 20%), then the household energy storage is preferred as the main disturbance source to improve system stability; if only one has a reactive power margin greater than the first preset threshold, then that one is selected as the main disturbance source; if the reactive power margin of both is not greater than the first preset threshold, the household energy storage is instructed to reduce its charging power to increase its reactive power margin, and the household energy storage is still selected as the main disturbance source; and the classified power sources that are not the main disturbance sources are used as auxiliary disturbance sources.

[0032] This invention achieves conditional intelligent selection of the main disturbance source through a judgment logic that prioritizes state and verifies margin, taking into account system stability, equipment safety, and operational reliability.

[0033] In one embodiment, after determining the primary and secondary disturbance sources based on the real-time operating data of each distributed power source, the method further includes: Trigger the grid-connected fixed disturbance mechanism to control the main disturbance source to output a fixed reactive disturbance within a first preset long period, and control the auxiliary disturbance source not to output disturbances for islanding detection.

[0034] Specifically, for microgrid systems, in order for the reactive power disturbance detection islanding algorithm to have no detection blind spots under certain load conditions, the reactive power energy of the disturbance must satisfy the following formula: In the formula, This represents the total reactive power disturbance currently output by the system. P This represents the current active power output of the system. This is the difference between the active power of inverter 103 and the load. , Determine the upper and lower limits for the island detection frequency; C is a resistive load; C is a capacitive load; L is an inductive load.

[0035] As can be seen from the above formula, the larger the injected reactive disturbance, the smaller the non-detection zone of islanding detection, so as to achieve reliable islanding detection. Then, the EMS needs to intelligently adjust the output of the auxiliary disturbance source according to the monitoring results of voltage, current, power factor, etc. If the output reactive power of the main disturbance source has not yet reached its limit value, the auxiliary disturbance source does not need to output disturbance until the output reactive disturbance of the main disturbance source reaches its limit value.

[0036] Therefore, this invention triggers a grid-connected fixed disturbance mechanism after selecting the main disturbance source, that is, the EMS controls the main disturbance source through command issuance for a first preset long period. The system outputs a fixed reactive power disturbance (i.e., the initial disturbance amount, preferably not exceeding 2% of the rated power) within a period of 5 grid cycles (preferably no more than 0.1s, i.e., a disturbance is generated once every 5 grid cycles and the system waits for stabilization). This maintains only a low-intensity disturbance on standby, does not affect grid stability, and controls the auxiliary disturbance source to maintain normal working state (such as charging, discharging, or standby). There is no need to output reactive power disturbance, so as to avoid the disturbance superposition and interference to the grid.

[0037] This invention constructs a stable, controllable, and low-impact pre-detection environment during the grid connection period through a grid-connected fixed disturbance mechanism, thereby bringing the detection preparation stage forward. This achieves comprehensive optimization of detection speed, reliability, equipment lifespan, and resource utilization efficiency while ensuring system safety and power quality, thus improving the overall performance of the microgrid island protection system.

[0038] S2. When an abnormality is detected in the real-time port electrical parameters of the microgrid system, a first-level disturbance mechanism is triggered to control the main disturbance source to perform short-cycle progressively enhanced disturbance. Specifically, when a power grid outage creates an island, the fixed reactive power disturbance from the main disturbance source will cause the microgrid system voltage / frequency to deviate from the normal range. Therefore, when the EMS detects that the voltage amplitude and frequency at the grid port exceed the normal range, it determines that the grid may be out of power, immediately triggers the first-level disturbance mechanism, and issues a command to control the main disturbance source to perform short-cycle progressively enhanced disturbances, so as to rapidly amplify the system anomaly within the time required by the islanding detection standard.

[0039] In one embodiment, controlling the main disturbance source to perform short-period asymptotic enhancement of the disturbance includes: The main disturbance source is controlled to switch to outputting a first variable reactive power disturbance with a second preset short cycle; the first variable reactive power disturbance starts from an initial disturbance value and gradually increases according to a preset step size until it reaches the maximum reactive power disturbance of the main disturbance source.

[0040] At this time, the EMS controls the disturbance period of the main disturbance source to switch from the first preset long period to the second preset short period by issuing a command. (The preferred value is no more than 0.06s, i.e., a disturbance is performed every 3 grid cycles and the system waits for stabilization.) Output the first variable reactive power disturbance, which starts from a fixed initial disturbance value and gradually increases according to a preset step size until it reaches the maximum reactive power disturbance of the main disturbance source; the calculation process of the first variable reactive power disturbance is as follows: In the formula, The first change in reactive power disturbance currently output by the main disturbance source can be, in the current system, [the following is possible]. or ; The increase in reactive power disturbance is calculated in real time for the main disturbance source; The maximum reactive power output capability of the main disturbance source can be, in the current system, or ; The preset step size can also be considered as the step size coefficient required to calculate each disturbance. The value of this coefficient can be calculated based on the second preset short period and the island detection time requirement. The distance is calculated as follows: the disturbance period is 0.06s, and the island detection time is required to be less than 2s. Therefore, the maximum number of disturbances N is... var for: Select N var =32, since it is a bilateral reactive power disturbance, the number of disturbances on one side is 16, and the maximum reactive power disturbance is selected as 0.5 times the rated power. ,but The calculation is as follows: .

[0041] In the above calculation process, the main disturbance source can be residential energy storage or bidirectional V2G charging pile 104. The formula for calculating the maximum reactive power output of the residential energy storage inverter 103 and the bidirectional V2G charging pile 104 is as follows: In the formula, , The maximum reactive power output capability of the household energy storage inverter 103 and the bidirectional V2G charging pile 104 in the system; , The reactive power margin coefficient for inverter 103 and bidirectional V2G charging pile 104 represents the reactive power that can be output, and is generally taken as 0.2-0.5. , These are the maximum apparent power of inverter 103 and bidirectional V2G charging pile 104, respectively.

[0042] When an anomaly is detected in the system data, this invention triggers a first-level disturbance mechanism. This mechanism employs a short-cycle progressively enhanced disturbance strategy (increasing gradually from the initial value in steps) to avoid the system impact risk caused by a direct jump from zero or a low value to the maximum disturbance. This greatly reduces the probability of false detection triggering unnecessary protection actions and improves the caution and safety of detection. At the same time, the short-cycle output disturbance means that the disturbance signal changes at a higher frequency, which can effectively distinguish between islanded states and normal grid fluctuations. This significantly shortens the time from disturbance to generating an identifiable response, thereby accelerating the confirmation speed of islanded states.

[0043] S3. During the execution of the first-level disturbance mechanism, if the real-time port electrical parameters do not exceed the islanding determination threshold, the second-level disturbance mechanism is triggered to introduce the auxiliary disturbance source and the main disturbance source to perform superimposed disturbance in the same direction. During the execution of the primary disturbance mechanism, if the EMS detects that the voltage amplitude and frequency at the grid port exceed the islanding threshold during the disturbance, it immediately determines that the system has become islanded and issues an off-grid switching command to control the microgrid system to switch to off-grid operation mode. If the voltage amplitude and frequency at the grid port still do not exceed the islanding threshold when the primary disturbance source reaches the maximum positive disturbance amount, it indicates that the disturbance from the primary disturbance source alone cannot meet the system requirements, and triggers the secondary disturbance mechanism, which issues a command to control the secondary disturbance source to superimpose the disturbance from the primary disturbance source in the same direction, further amplifying the disturbance effect.

[0044] In one embodiment, the step of introducing the auxiliary disturbance source and the main disturbance source to perform superimposed co-directional disturbance includes: The auxiliary disturbance source is controlled to output a second variable reactive power disturbance in the same direction as the main disturbance source; the second variable reactive power disturbance starts from the initial disturbance value and gradually increases according to the preset step size until it reaches the maximum reactive power disturbance of the auxiliary disturbance source.

[0045] At this time, the EMS controls the auxiliary disturbance source to output a second variable reactive power disturbance in the same direction as the disturbance direction of the main disturbance source, until the maximum reactive power disturbance of the auxiliary disturbance source is reached; the calculation process and period of the second variable reactive power disturbance are the same as those of the first variable reactive power disturbance, and will not be elaborated here.

[0046] When the main disturbance source fails to meet system requirements even with its maximum positive disturbance, this invention introduces an auxiliary disturbance source to perform a superposition and co-directional disturbance mechanism. This ensures that the reactive disturbances output by the main and auxiliary disturbance sources are completely phase-consistent, and their disturbance effects are algebraically added rather than canceling each other out or generating complex interference. This achieves synergistic amplification of the disturbance effect, greatly improving detection sensitivity and speed. The disturbance mode of the auxiliary disturbance source is completely synchronous and isomorphic with that of the main disturbance source, constructing a composite disturbance signal with regularly increasing intensity and highly unified mode. This effectively filters out noise interference, greatly improving the clarity and reliability of the islanding criterion and reducing the risk of misjudgment and missed judgment. Through the strategy of synergistic superposition and synchronous enhancement, the overall anti-disturbance capability of the system is pushed to the limit, thereby creating an irrefutable islanding criterion in the shortest possible time.

[0047] S4. During the execution of the second-level disturbance mechanism, if the real-time port electrical parameters do not trigger the exceeding of the islanding determination threshold, the third-level disturbance mechanism is triggered to control the main disturbance source and the auxiliary disturbance source to perform reverse disturbance. Specifically, during the execution of the secondary disturbance mechanism, if the EMS detects that the voltage amplitude and frequency at the grid port exceed the islanding determination threshold during the disturbance, it immediately determines that the system has become islanded and issues an off-grid switching command to control the microgrid system to switch to off-grid operation mode. If the voltage amplitude and frequency at the grid port still do not exceed the islanding determination threshold when both the positive and auxiliary disturbance sources reach the maximum positive disturbance amount, the secondary disturbance mechanism is triggered. That is, by issuing a command, the auxiliary disturbance source is controlled to perform reverse disturbance with the main disturbance source, so as to avoid the inability of a single positive disturbance to break through the load matching blind zone and to cover the reverse power matching scenario through reverse disturbance.

[0048] In one embodiment, controlling the primary disturbance source and the secondary disturbance source to perform opposite disturbances includes: The auxiliary disturbance source is controlled to gradually reduce the second variable reactive power disturbance to zero according to the preset step size, and the main disturbance source is controlled to gradually reduce the first variable reactive power disturbance to zero according to the preset step size. The main disturbance source and the auxiliary disturbance source are controlled to initiate reverse reactive disturbances, so as to execute the short-cycle progressively enhanced disturbance and the superimposed same-direction disturbance respectively in reverse order.

[0049] At this point, the EMS first issues a command to control the auxiliary disturbance source to gradually reduce its output second variable reactive power disturbance to zero according to a preset step size and period. Then, it issues a command to control the main disturbance source to gradually reduce its output first variable reactive power disturbance to zero according to a preset step size and period. Subsequently, the EMS issues a command to control the main and auxiliary disturbance sources to start reverse reactive power disturbance: that is, it controls the main disturbance source to start from the initial reverse disturbance amount and increase it step by step to its maximum reverse disturbance amount. If no islanding is detected at this point, the auxiliary disturbance source is activated, so that it superimposes the disturbance amount in the same direction in the opposite direction (consistent with the current main disturbance source) until the auxiliary disturbance source reaches its maximum reverse disturbance amount. It should be noted that the short-period asymptotic enhancement of disturbance and superimposed same-direction disturbance in the reverse disturbance process are implemented in the same way as the short-period asymptotic enhancement of disturbance and superimposed same-direction disturbance in the forward disturbance process, only the disturbance direction is reversed.

[0050] After completing the forward disturbance detection, this invention initiates a disturbance process in the completely opposite direction (e.g., from inductive disturbance to capacitive disturbance), which is equivalent to performing two independent tests of different polarities on the system. This effectively avoids detection blind spots caused by insufficient sensitivity to unidirectional disturbances due to specific network topology, load characteristics, or initial operating conditions, greatly improving the completeness and robustness of the detection. At the same time, it reuses and strengthens the core detection logic—short-cycle progressively enhanced disturbances and superimposed same-direction disturbances—to ensure the judgment capability under extreme conditions. This upgrades the entire active disturbance detection from a unidirectional linear process to a multi-dimensional system process of forward probing → enhanced detection → safe exit → reverse verification, greatly improving the completeness, robustness, and decision confidence of the detection.

[0051] S5. If the real-time port electrical parameters do not trigger the islanding determination threshold during the execution of the three-level disturbance mechanism, the first-level disturbance mechanism, the second-level disturbance mechanism, and the third-level disturbance mechanism are executed in a loop until the real-time port electrical parameters trigger the islanding determination threshold, and the microgrid system is controlled to switch to off-grid operation mode. Specifically, during the execution of the three-level disturbance mechanism, if the EMS detects that the voltage amplitude and frequency of the grid port exceed the islanding determination threshold during the disturbance, it immediately determines that the system has islanded and issues an off-grid switching command to control and disconnect the off-grid switching switch 105, cutting off the connection with the grid. At the same time, the household energy storage and the bidirectional V2G charging pile 104 switch to off-grid operation mode, allocate active power according to load demand, and maintain the stability of household load voltage and frequency. The bidirectional V2G charging pile 104 stops reverse feeding, and if it is in charging state, it adjusts the charging power according to the remaining battery capacity. If the voltage amplitude and frequency at the grid port still do not exceed the islanding threshold when both the positive and auxiliary disturbance sources reach the maximum negative disturbance amount, the first-level disturbance mechanism, the second-level disturbance mechanism, and the third-level disturbance mechanism are executed in a loop. That is, the positive main disturbance → positive superposition → reverse main disturbance → reverse superposition process is repeated until the real-time port electrical parameters trigger the islanding threshold, that is, islanding is detected, or the preset maximum disturbance period (such as 2 seconds to avoid unlimited disturbance from affecting system stability) is reached, and the microgrid system is controlled to switch to off-grid operation mode.

[0052] This invention utilizes an Energy Management System (EMS) to monitor real-time parameters such as voltage, frequency, and power of the microgrid system. Combined with the operating status of the inverter 103 and the bidirectional V2G charging pile 104, a comprehensive judgment is made. When islanding is detected, the system immediately takes corresponding protective measures, such as disconnecting from the grid, to ensure system safety. Furthermore, this method can adaptively adjust the islanding detection strategy based on changes in system status and grid parameters, improving detection accuracy and reliability. In addition, this method considers the mutual influence between the inverter 103 and the bidirectional V2G charging pile 104, avoiding detection failures through coordinated control, thus achieving fast and reliable islanding detection and ensuring the safe and stable operation of the residential energy storage microgrid system.

[0053] This application addresses the issue of reduced islanding detection effectiveness in existing residential energy storage microgrid systems due to the inability to coordinate control between energy storage and bidirectional V2G charging piles. It proposes a collaborative control method for islanding detection in microgrid systems. This method determines the primary disturbance source based on the equipment's operating status, balancing detection effectiveness with system operating efficiency, and is particularly suitable for high-power charging scenarios for new energy vehicles. It employs a progressive disturbance amplification strategy designed for islanding detection, gradually expanding the system's reactive power disturbance energy from single disturbances to superimposed disturbances, and from positive disturbances to reverse disturbances, thoroughly covering the detection blind spot caused by load and power supply mismatch. Simultaneously, it centrally controls the primary and secondary disturbance sources to ensure consistent disturbance directions and energy superposition, avoiding conflicts and cancellations between independent disturbances from multiple devices. This forms a collaborative detection mechanism with primary and secondary sources working together in an orderly manner, significantly improving the reliability and speed of islanding detection.

[0054] It should be noted that although the steps in the flowchart above are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order requirement for the execution of these steps, and they can be executed in other orders.

[0055] In another embodiment, such as Figure 4 As shown, a second aspect of the present invention provides a collaborative control device for island detection in a microgrid system, comprising: The disturbance source determination module 10 is used to determine the main disturbance source and the auxiliary disturbance source based on the real-time operating data of each distributed power source in the microgrid system when the microgrid system is detected to be in grid-connected operation mode. The first-level disturbance module 20 is used to trigger the first-level disturbance mechanism when the real-time port electrical parameters of the microgrid system are detected to be abnormal, so as to control the main disturbance source to perform short-cycle progressively enhanced disturbance. The secondary disturbance module 30 is used to trigger the secondary disturbance mechanism if the real-time port electrical parameters do not exceed the islanding determination threshold during the execution of the primary disturbance mechanism, so as to introduce the auxiliary disturbance source and the primary disturbance source to perform superimposed same-direction disturbance. The third-level disturbance module 40 is used to trigger the third-level disturbance mechanism if the real-time port electrical parameters do not trigger the islanding determination threshold during the execution of the second-level disturbance mechanism, so as to control the main disturbance source and the auxiliary disturbance source to perform reverse disturbance. The cyclic disturbance module 50 is used to cyclically execute the first-level disturbance mechanism, the second-level disturbance mechanism, and the third-level disturbance mechanism if the real-time port electrical parameters still do not trigger the islanding determination threshold during the execution of the third-level disturbance mechanism, until the real-time port electrical parameters trigger the islanding determination threshold, and then control the microgrid system to switch to off-grid operation mode.

[0056] It should be noted that each module in the aforementioned microgrid system island detection and collaborative control device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the operations corresponding to each module. For specific limitations regarding the microgrid system island detection and collaborative control device, please refer to the limitations of the microgrid system island detection and collaborative control method described above; both have the same function and role, and will not be repeated here.

[0057] A third aspect of the present invention provides an electronic device comprising: Processor, memory, and bus; The bus is used to connect the processor and the memory; The memory is used to store operation instructions; The processor is configured to execute operations corresponding to the microgrid system island detection and collaborative control method shown in the first aspect of this application by invoking the operation instructions.

[0058] In one alternative embodiment, an electronic device is provided, such as Figure 5 As shown, Figure 5 The illustrated electronic device 5000 includes a processor 5001 and a memory 5003. The processor 5001 and the memory 5003 are connected, for example, via a bus 5002. Optionally, the electronic device 5000 may also include a transceiver 5004. It should be noted that in practical applications, the transceiver 5004 is not limited to one type, and the structure of this electronic device 5000 does not constitute a limitation on the embodiments of this application.

[0059] Processor 5001 may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. Processor 5001 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0060] Bus 5002 may include a path for transmitting information between the aforementioned components. Bus 5002 may be a PCI bus or an EISA bus, etc. Bus 5002 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 5 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0061] The memory 5003 may be a ROM or other type of static storage device capable of storing static information and instructions, RAM or other type of dynamic storage device capable of storing information and instructions, or it may be an EEPROM, CD-ROM or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto.

[0062] The memory 5003 is used to store application code that executes the scheme of this application, and its execution is controlled by the processor 5001. The processor 5001 is used to execute the application code stored in the memory 5003 to implement the content shown in any of the foregoing method embodiments.

[0063] Among them, electronic devices include, but are not limited to: mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), and in-vehicle terminals (such as in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers.

[0064] The fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements a microgrid system island detection and collaborative control method as shown in the first aspect of this application.

[0065] Another embodiment of this application provides a computer-readable storage medium storing a computer program that, when run on a computer, enables the computer to execute the corresponding content in the aforementioned method embodiments.

[0066] Furthermore, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0067] In summary, this invention relates to the field of distributed microgrid islanding detection technology, and discloses a collaborative control method, device, equipment, and medium for islanding detection in microgrid systems. When the microgrid system is operating in grid-connected mode, the primary and secondary disturbance sources are determined based on the real-time operating data of each distributed power source. When their parameters are abnormal, the primary disturbance source is controlled to perform short-cycle progressively enhanced disturbance. If no islanding is detected during the enhanced disturbance process, the secondary disturbance source is introduced to superimpose a disturbance in the same direction as the primary disturbance source. If no islanding is detected during the same-direction disturbance process, the primary and secondary disturbance sources are controlled to perform a disturbance in opposite directions. This process of enhancing disturbance, superimposing same-direction disturbance, and reverse disturbance is repeated until successful detection, thereby controlling the microgrid system to switch to off-grid operation mode. This solves the problem of cancellation or conflict caused by independent disturbances from multiple distributed power sources, achieving fast, reliable islanding detection with minimal impact on system operation.

[0068] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0069] The embodiments described above are merely preferred embodiments of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the technical principles of this invention, and these improvements and substitutions should also be considered within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the scope of the claims.

Claims

1. A method for island detection and collaborative control in a microgrid system, characterized in that, include: When the microgrid system is detected to be in grid-connected operation mode, the main disturbance source and the auxiliary disturbance source are determined based on the real-time operation data of each distributed power source in the microgrid system. When an abnormality is detected in the real-time port electrical parameters of the microgrid system, a first-level disturbance mechanism is triggered to control the main disturbance source to perform short-cycle progressively enhanced disturbance. During the execution of the first-level disturbance mechanism, if the real-time port electrical parameters do not exceed the islanding determination threshold, the second-level disturbance mechanism is triggered to introduce the auxiliary disturbance source and the main disturbance source to perform superimposed disturbance in the same direction. During the execution of the secondary disturbance mechanism, if the real-time port electrical parameters do not trigger the islanding determination threshold, the tertiary disturbance mechanism is triggered to control the primary disturbance source and the secondary disturbance source to perform reverse disturbances. If the real-time port electrical parameters do not trigger the islanding threshold during the execution of the three-level disturbance mechanism, the first-level disturbance mechanism, the second-level disturbance mechanism, and the third-level disturbance mechanism are executed in a loop until the real-time port electrical parameters trigger the islanding threshold, and the microgrid system is controlled to switch to off-grid operation mode.

2. The microgrid system island detection and collaborative control method according to claim 1, characterized in that, The microgrid system includes residential energy storage and bidirectional V2G charging piles; The step of determining the main disturbance source based on the real-time operating data of each distributed power source in the microgrid system includes: If the bidirectional V2G charging pile is in a high-power charging state, then the household energy storage will be used as the main disturbance source. If the bidirectional V2G charging pile is not in a high-power charging state, the real-time reactive power output margin of the household energy storage and the bidirectional V2G charging pile is obtained, and the bidirectional V2G charging pile is used as the main disturbance source if and only if the real-time reactive power output margin of the bidirectional V2G charging pile is greater than a first preset threshold; otherwise, the household energy storage is used as the main disturbance source.

3. The microgrid system island detection and collaborative control method according to claim 1, characterized in that, After determining the primary and secondary disturbance sources based on the real-time operating data of each distributed power source, the process also includes: Trigger the grid-connected fixed disturbance mechanism to control the main disturbance source to output a fixed reactive disturbance within a first preset long period, and control the auxiliary disturbance source not to output disturbances for islanding detection.

4. The method for island detection and collaborative control in a microgrid system according to claim 1, characterized in that, The control of the main disturbance source to perform short-period asymptotic enhancement of the disturbance includes: The main disturbance source is controlled to switch to outputting a first variable reactive power disturbance with a second preset short cycle; the first variable reactive power disturbance starts from an initial disturbance value and gradually increases according to a preset step size until it reaches the maximum reactive power disturbance of the main disturbance source.

5. The microgrid system island detection and collaborative control method according to claim 4, characterized in that, The process of introducing the auxiliary disturbance source and superimposing it with the main disturbance source to create a disturbance in the same direction includes: The auxiliary disturbance source is controlled to output a second variable reactive power disturbance in the same direction as the main disturbance source; the second variable reactive power disturbance starts from the initial disturbance value and gradually increases according to the preset step size until it reaches the maximum reactive power disturbance of the auxiliary disturbance source.

6. The microgrid system island detection and collaborative control method according to claim 5, characterized in that, The control of the main disturbance source and the auxiliary disturbance source to perform reverse disturbances includes: The auxiliary disturbance source is controlled to gradually reduce the second variable reactive power disturbance to zero according to the preset step size, and the main disturbance source is controlled to gradually reduce the first variable reactive power disturbance to zero according to the preset step size. The main disturbance source and the auxiliary disturbance source are controlled to initiate reverse reactive disturbances, so as to execute the short-cycle progressively enhanced disturbance and the superimposed same-direction disturbance respectively in reverse order.

7. The microgrid system island detection and collaborative control method according to claim 2, characterized in that, The microgrid system also includes an inverter and an energy management system, and the method is controlled and executed by the energy management system; wherein, the bidirectional V2G charging pile is communicatively connected to the energy management system, or the bidirectional V2G charging pile is communicatively connected to the energy management system after being relayed through the inverter.

8. A microgrid system island detection and collaborative control device, characterized in that, include: The disturbance source determination module is used to determine the main disturbance source and the auxiliary disturbance source based on the real-time operating data of each distributed power source in the microgrid system when the microgrid system is detected to be in grid-connected operation mode. The first-level disturbance module is used to trigger the first-level disturbance mechanism when the real-time port electrical parameters of the microgrid system are detected to be abnormal, so as to control the main disturbance source to perform short-period progressively enhanced disturbance. The secondary disturbance module is used to trigger the secondary disturbance mechanism if the real-time port electrical parameters do not exceed the islanding determination threshold during the execution of the primary disturbance mechanism, so as to introduce the auxiliary disturbance source and the primary disturbance source to perform superimposed and co-directional disturbance. The third-level disturbance module is used to trigger the third-level disturbance mechanism if the real-time port electrical parameters do not trigger the islanding determination threshold during the execution of the second-level disturbance mechanism, so as to control the main disturbance source and the auxiliary disturbance source to perform reverse disturbance. The cyclic disturbance module is used to repeatedly execute the first-level disturbance mechanism, the second-level disturbance mechanism, and the third-level disturbance mechanism if the real-time port electrical parameters still do not trigger the islanding determination threshold during the execution of the third-level disturbance mechanism, until the real-time port electrical parameters trigger the islanding determination threshold, and then control the microgrid system to switch to off-grid operation mode.

9. An electronic device, characterized in that, The system includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the microgrid system island detection and collaborative control method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements the microgrid system island detection and collaborative control method as described in any one of claims 1 to 7.

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