Microgrid differentiated emergency control method and device based on power imbalance level

Abstract

The application discloses a micro-grid differentiated emergency control method and device based on power imbalance level, and belongs to the technical field of micro-grid emergency control. The method collects micro-grid operation parameters in real time, dynamically evaluates and marks the off-grid risk of key equipment; in combination with the action state of a public connection point switch, internal equipment switch information of the micro-grid and a system frequency offset, a sequential diagnosis mode is adopted to identify and classify the direction and severity of a power imbalance event; and accordingly, a corresponding control strategy is called to implement differentiated control. The application combines multi-source information fusion diagnosis and hierarchical control, can take targeted control measures according to different emergency working conditions, and overcomes the problem that the existing emergency control method relies on a single criterion and has a single control mode. Without the need of adding additional hardware, the application can improve the emergency response capability and the safe and stable operation level of the micro-grid under complex operation conditions, and is suitable for the emergency control of a high-proportion new energy micro-grid.

Description

Technical Field

[0001] This invention relates to the field of microgrid emergency control, and more particularly to a method and apparatus for differentiated emergency control of microgrids based on power imbalance levels. Background Technology

[0002] With the large-scale integration of distributed renewable energy, microgrids, as an important technological carrier for absorbing new energy on the distribution side, have experienced rapid development in recent years. However, the grid connection of new energy equipment in microgrids via power electronic converters results in low inertia and high volatility in the system's operation. Compared with traditional power grids, microgrids have weaker inertial support capabilities, and when subjected to power disturbances, the system frequency and voltage change more rapidly, significantly shortening the response time for the control system. Simultaneously, the intermittent and fluctuating power output of new energy sources further increases the probability of power imbalance in microgrids, posing challenges to the safe and stable operation of the system.

[0003] Currently, emergency control in microgrids primarily relies on protection schemes based on frequency or voltage limits. The decision-making trigger of such strategies depends solely on whether the system frequency / voltage, a terminal state variable, exceeds a threshold, failing to detect the type and severity of the disturbance. This leads to an inherent mismatch between the control output and the actual disturbance. For minor power imbalances that can be absorbed by internal regulation resources, traditional strategies lack a preventative measure that lies between "no action" and "load shedding," primarily relying on calling upon backup resources. This results in overly sensitive frequency action settings, easily leading to unnecessary load shedding during transient processes and causing overreaction; conversely, overly conservative settings completely lack the ability to proactively intervene in minor faults and maintain high-quality power supply. Furthermore, existing active emergency frequency regulation methods applied to energy storage units also have design limitations. For example, early emergency regulation schemes used constant power control, instructing the energy storage to output a fixed power once the frequency limit is exceeded. This method completely ignores the magnitude of the disturbance, easily causing secondary impacts on the system, triggering more severe oscillations or even system collapse. Another type of drooping emergency control may still cause excessive energy storage response and affect system stability when the system encounters excessive unbalanced shocks.

[0004] Therefore, there is an urgent need for a method that can comprehensively utilize multi-source information, accurately identify the direction and severity of power imbalance, and implement differentiated emergency control accordingly, so as to improve the safe and stable operation capability of microgrids under complex disturbance conditions. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a differentiated emergency control method for microgrids based on power imbalance levels. This method rapidly and accurately quantifies and classifies power imbalance events, and invokes corresponding preventive or corrective control measures based on the classification results. This enables precise identification and efficient handling of microgrid emergency events, effectively improving the overall resilience and operational level of the system.

[0006] One of the objectives of this invention is achieved through the following technical solution: a differentiated emergency control method for microgrids based on power imbalance levels, comprising the following steps:

[0007] S1. During the operation of the microgrid, the Microgrid Central Controller (MGCC) continuously monitors the key operating parameters of the microgrid system and performs real-time, adaptive assessment and marking of potential failure risks of key equipment units as input for emergency control decisions.

[0008] S2, when a change in key operating parameters is detected in S1, causing the microgrid system state to deviate from the normal range, the microgrid central controller dynamically identifies and quantifies power imbalance events such as islanding, internal device disconnection, and frequency anomalies according to the preset diagnostic sequence, and immediately determines whether the power imbalance event is a power shortage or power redundancy and whether it is a first-level or second-level operating condition.

[0009] S3. Based on the operating condition level determined in step S2, initiate and execute the corresponding differentiated control strategy to restore the power balance of the microgrid system. Specifically, a preventive power redistribution strategy is implemented for Level 1 operating conditions, and a corrective composite control strategy that maximizes internal regulation and optimal cut-off is implemented for Level 2 operating conditions. After the control is completed, the microgrid system will automatically reset the operating condition level flag.

[0010] Furthermore, the specific process of step S1 is as follows:

[0011] S1.1, System operating parameter monitoring: MGCC monitors the system operating parameters according to a preset control cycle. Real-time acquisition and updating of microgrid operating parameter sets This set includes at least the switching states of the point of common coupling (PCC) between the microgrid and the main grid. and switching power Real-time output of the kth device unit The positive direction of power flow is into the microgrid; the microgrid currently has a total available backup capacity that can be increased. Total capacity reduction Real-time system frequency of microgrids and the bus voltage at the MGCC connection point ;

[0012] S1.2, Dynamic Assessment of Potential Equipment Risks: In each control cycle, for different types of critical equipment units k within the system, matching logic is used to assess the potential power imbalance risk caused by their sudden disconnection from the grid, and their dynamic risk flags are updated. .

[0013] Furthermore, the process of updating its dynamic risk indicators is as follows:

[0014] (1) Power generation equipment: its current real-time output As a potential power deficit, it is compared with the system's current total up-capacity. If a comparison is made, Then update its risk flag to That is, its risk of disconnection is Level 1; otherwise it is Level 2. This means the risk of being disconnected from the network is level two;

[0015] (2) Energy-consuming equipment: its current real-time power consumption As a potential power redundancy, it is compared with the system's current total down-regulation capacity. If a comparison is made, Then update its risk flag to That is, its risk of disconnection is Level 1; otherwise it is Level 2. This means the risk of being disconnected from the network is level two;

[0016] (3) Energy storage system: Evaluate based on its current operating mode; when it is in a discharge state ( (This is considered as a power generation device, and its current discharge power is compared with the total increased reserve capacity.) Compare to update its risk flag and determine whether the off-grid risk is level one or level two; when it is in a charging state ( (This is considered an energy-consuming device, and its current charging power is compared with the total reduced capacity.) Compare them to update their risk indicators and determine whether the risk of disconnection is level one or level two.

[0017] Furthermore, the specific process of step S2 is as follows:

[0018] S2.1, Prioritize the diagnosis of PCC islanding events: When detected Calculate the initial power imbalance when changing from a closed to an open circuit. ,in This represents the power exchanged with the PCC recorded in the previous control cycle. If This is a power deficit, requiring further assessment. If it is determined to be a Level 1 power deficit condition, otherwise it is a Level 2 power deficit condition; if This is power redundancy. If the condition is positive, it is determined to be a Level 1 power redundancy condition; otherwise, it is a Level 2 power redundancy condition.

[0019] S2.2, then diagnose system equipment disconnection events: If S2.1 is not true, when the kth device is detected to be disconnected from the grid, determine the direction of imbalance based on its equipment type (power generation / energy consumption), and read the dynamic risk flag updated by step S1.2 just before disconnection. If the condition is classified as Level 1 or Level 2, the resulting power imbalance is: ;

[0020] S2.3, Final diagnosis of frequency anomaly events: If neither S2.1 nor S2.2 is true, then the frequency deviation of the monitoring system is considered. Judgment, in which For real-time system frequency, The system's rated frequency; the resulting power imbalance is: ,in This refers to the system's frequency regulation coefficient. Based on the direction of frequency deviation, the permissible frequency deviation boundary for normal system operation, the system's available regulation capacity, and the frequency regulation coefficient, the direction of power imbalance and operating condition level reflected by frequency anomalies in the system are determined. When This indicates that the system has a power redundancy trend, and the frequency rise deviation is obtained. ; compare them with the first-level frequency anomaly start-up boundary in the power redundancy direction respectively. and the second-level frequency abnormal start boundary Comparison: If It is determined to be a Level 1 power redundancy condition; if it meets the requirements... If so, it is determined to be a level 2 redundancy condition.

[0021] when This indicates that the system has a power deficit trend, and the frequency drop deviation is obtained. These are respectively compared with the first-order frequency anomaly start-up boundary in the power deficit direction. and the second-level frequency abnormal start boundary Comparison: If This is determined to be a Level 1 power deficit condition; if the conditions are met... If so, it is determined to be a level two shortage condition.

[0022] Specifically, when MGCC calculates this moment... or At this time, MGCC will directly determine the corresponding direction as a level two operating condition to avoid misjudging it as a level one operating condition when the adjustable capacity is insufficient.

[0023] Furthermore, the frequency anomaly start-up boundary described in S2.3 is dynamically determined by the MGCC based on the current operating status of the microgrid, the normal frequency deviation boundary, the available backup capacity of the system, and the frequency regulation coefficient, specifically including:

[0024] (1) Secondary frequency abnormal start boundary:

[0025] The second-level frequency anomaly start-up boundary in the power deficit direction is The secondary frequency anomaly start-up boundary in the power redundancy direction is ;in This represents the system's frequency regulation coefficient. When the frequency deviation reaches the corresponding secondary frequency abnormality start-up boundary, it indicates that the power imbalance has reached or exceeded the system's capacity to absorb it solely through output regulation, necessitating the implementation of a corrective composite control strategy.

[0026] (2) Level 1 frequency abnormal start boundary:

[0027] set up This is the trigger coefficient for Level 1 operating conditions, and The marginal value of the first-order frequency difference in the direction of power deficit. Marginal value of first-order frequency difference in the direction of power redundancy Then the first-order frequency anomaly start boundary in the power deficit direction is: Level 1 frequency anomaly start-up boundary in the direction of power redundancy The first-level frequency anomaly start boundary is located between the normal frequency deviation boundary and the second-level frequency anomaly start boundary. It is used to characterize the state in which the power imbalance has exceeded the normal operating deviation range but can still be eliminated autonomously by adjusting the output of the internal power generation equipment or energy consumption equipment.

[0028] Furthermore, in a certain detection cycle, when step S2 determines the three types of events, only one type of event occurs, and in the device disconnection event, multiple devices disconnect simultaneously.

[0029] Furthermore, if step S3 determines that the power imbalance condition is level one, a preventative power redistribution strategy is implemented, specifically including the following steps:

[0030] (1) Determine the adjustment direction and demand: Determine the power imbalance based on step S2. When this is a PCC isolated incident, When system device k goes offline, When it is a frequency anomaly event,

[0031] (2) Select adjustment resources: If there is a power deficit, select units with effective upward adjustment margin from all backup units to form an available upward adjustment resource pool; if there is a power redundancy, select units with downward adjustment margin from all controllable power generation equipment and energy storage equipment to form an available downward adjustment resource pool.

[0032] (3) Issuing adjustment command: Issuing a power adjustment command to the i-th adjustment unit. , This is the preset power response weight for the regulating unit. The command is automatically either positive (power deficit) or negative (power redundancy) depending on the direction of the power imbalance.

[0033] Furthermore, if step S3 determines that the operating condition is a secondary power imbalance, a corrective composite control strategy is executed, specifically including the following steps:

[0034] (1) Calculate the remaining power imbalance: Based on maximizing the internal regulation, recalculate the remaining imbalance that still exists in the system. If it is a power deficit, then If it is for power redundancy, then ;

[0035] (2) Execute the targeted resection plan: if If so, a two-stage optimized load shedding strategy will be implemented; if If so, an ordered switching strategy based on a preset priority list will be executed.

[0036] (3) Internal adjustment of equipment: If there is a power shortage, instruct all available resources to increase to support it with maximum power capacity; if there is a power redundancy, instruct all available resources to decrease its output to the minimum output level.

[0037] Furthermore, the two-stage optimized load shedding strategy specifically includes:

[0038] (1) First stage: coarse cut-off based on greedy algorithm: based on the remaining power deficit From a pre-defined load list sorted by priority from high to low, loads are disconnected level by level until the cumulative disconnected power is not less than [amount missing]. ;

[0039] (2) Second stage: Fine recovery based on optimal correction: Calculate the power overcut value caused by the first stage, and select load combinations whose total power does not exceed the power overcut value from the already cut-off loads. Do not issue the final cut-off command for the loads in the load combination with the largest total power.

[0040] Furthermore, the ordered switching strategy based on a preset priority list specifically includes:

[0041] (1) First stage: coarse cut-off based on greedy algorithm: starting from the highest priority unit in the cut-off priority list based on factors such as type and restart cost, cut-off instructions are issued one by one in sequence until the power redundancy value is no greater than 0.

[0042] (2) Second stage: Fine recovery based on optimal correction: Calculate the power overcut value caused by the first stage, and select the combination of units whose total power does not exceed the power overcut value from the units to be cut off. Do not issue the final cut-off command to the units in the combination of units with the largest total power.

[0043] Furthermore, the differentiated emergency control method for microgrids based on power imbalance levels is applicable to microgrid systems with the following characteristics:

[0044] (1) Operating mode: The microgrid can support two operating modes: grid-connected and islanded, and is equipped with control logic for mode switching;

[0045] (2) Equipment configuration: The microgrid shall be equipped with at least distributed power sources, energy storage devices as the main backup capacity and frequency regulation unit, and loads classified according to importance, etc.

[0046] (3) Control architecture: At least one converter with grid-forming (GFM) capability is configured in the microgrid to build system voltage and frequency in island mode. The remaining distributed power sources can work in grid-following (GFL) mode. All controllable units are connected to MGCC through the communication network and receive its control commands.

[0047] A second objective of this invention is to provide an electronic device for performing one of the objectives of the invention, comprising a processor, a storage medium, and a computer program, wherein the computer program is stored in the storage medium and, when executed by the processor, implements the aforementioned microgrid differentiated emergency control method based on power imbalance levels.

[0048] A third objective of this invention is to provide a computer-readable storage medium storing one of the objectives of the invention, wherein a computer program is stored thereon, which, when executed by a processor, implements the above-described microgrid differentiated emergency control method based on power imbalance levels.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] (1) This invention breaks through the limitations of traditional emergency control methods that rely solely on the over-limit of terminal state quantities such as system frequency or voltage, ignore the severity of disturbances, and cannot effectively distinguish between different types of emergency conditions by integrating sequential diagnosis of system state quantity monitoring and real-time dynamic assessment mechanism of potential equipment risks. It achieves rapid and accurate quantitative classification of the direction and severity of power imbalance events. Moreover, its diagnostic logic has foresight and adaptability, which can effectively avoid decision-making errors caused by insufficient information and provide a reliable basis for subsequent differentiated control.

[0051] (2) By establishing a hierarchical differentiated control strategy, this invention breaks through the limitations of traditional strategy control methods, which are single and rigid, lack a preventive intermediate level between "no action" and "rigid reduction", and are difficult to balance system safety and operation economy. It achieves hierarchical precise response, ensures system safety, fully covers power deficit and redundancy scenarios, effectively improves the operational resilience of microgrids, and minimizes unnecessary load interruptions.

[0052] (3) This invention introduces a preventive power redistribution strategy under the first-level operating condition and adopts a two-stage optimization reduction strategy under the second-level deficit operating condition. This invention overcomes the limitations of traditional droop control, which cannot prioritize resource adjustment, and traditional load reduction schemes, which are prone to one-size-fits-all or unnecessary excessive cut-off. It achieves optimized scheduling of internal system adjustment resources and refined execution of reduction measures. Moreover, the algorithm is easy to implement and has a fast calculation speed. Attached Figure Description

[0053] Figure 1 This is a flowchart of a microgrid differentiated emergency control method based on power imbalance level in Embodiment 1;

[0054] Figure 2 This is a typical droop control block diagram of Example 1;

[0055] Figure 3 This is the coordinate transformation of Example 1 and a typical PQ control block diagram under a single current loop;

[0056] Figure 4 This is the sequential diagnosis and quantitative classification of power imbalance events in Example 1.

[0057] Figure 5 This is a schematic diagram of the first-level operating condition power command issuance in Example 1;

[0058] Figure 6 This is a schematic diagram of the secondary working condition directional resection in Example 1;

[0059] Figure 7 This is a schematic diagram of the photovoltaic-storage microgrid system connection in Example 2;

[0060] Figure 8 This describes the system frequency variation in Example 2;

[0061] Figure 9 This describes the system bus voltage variation in Example 2;

[0062] Figure 10 This refers to the energy storage and the output active power of the two adjustable photovoltaic units in Example 2.

[0063] Figure 11 This refers to the energy storage and reactive power output of the two adjustable photovoltaic units in Example 2.

[0064] Figure 12 This is the power adjustment command issued by the MGCC in Example 2. ;

[0065] Figure 13 It is the system load cut-off command issued by MGCC in Example 2;

[0066] Figure 14 This is a schematic diagram of a microgrid differentiated emergency control device based on power imbalance level provided by the present invention. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0068] Example 1:

[0069] like Figure 1 As shown, this embodiment provides a differentiated emergency control method for microgrids based on power imbalance levels, executed by a program deployed in the Microgrid Central Controller (MGCC), and includes the following steps:

[0070] S1, Dynamic Assessment of Microgrid System Status and Risk: During microgrid operation, MGCC continuously monitors key operating parameters of the microgrid system and, based on this, performs real-time, adaptive assessment and labeling of potential failure risks of key equipment units, providing accurate input for subsequent emergency control decisions;

[0071] S1.1, Monitoring of key operating parameters of microgrid systems: MGCC uses a preset control cycle. Real-time acquisition and updating of microgrid operating parameter sets This set includes at least the switching states of the point of common coupling (PCC) between the microgrid and the main grid. and switching power Real-time output of the kth device unit The positive direction of power flow is into the microgrid; the microgrid currently has a total available backup capacity that can be increased. Total capacity reduction Real-time system frequency of microgrids and the bus voltage at the MGCC connection point ;

[0072] Furthermore, the microgrid system should have the following characteristics: (1) Operating mode: The microgrid should be able to support both grid-connected and islanded operating modes and be equipped with control logic for mode switching; (2) Equipment configuration: The microgrid should be equipped with at least distributed power sources, energy storage devices as the main backup capacity and frequency regulation unit, and loads divided according to importance, etc.; (3) Control architecture: The microgrid should be equipped with at least one converter with grid-forming (GFM) capability to construct the system voltage and frequency in islanded mode. Its typical droop control block diagram is as follows: Figure 2 As shown; other distributed power sources can operate in grid-following (GFL) mode, and their typical PQ control block diagram is as follows. Figure 3 As shown; all controllable units are connected to the MGCC via a communication network and receive its control commands.

[0073] S1.2, Dynamic Assessment of Potential Equipment Risks: In each control cycle, for different types of key equipment units k within the microgrid system, matching logic is used to assess the potential power imbalance risk to the system caused by their sudden disconnection from the grid, and their dynamic risk flags are updated. :

[0074] (1) Power generation equipment: its current real-time output As a potential power deficit, it is compared with the system's current total up-capacity. If a comparison is made, Then update its risk flag to That is, its risk of disconnection is Level 1; otherwise it is Level 2. This means the risk of being disconnected from the network is level two;

[0075] (2) Energy-consuming equipment: its current real-time power consumption As a potential power redundancy, it is compared with the system's current total down-regulation capacity. If a comparison is made, Then update its risk flag to That is, its risk of disconnection is Level 1; otherwise it is Level 2. This means the risk of being disconnected from the network is level two;

[0076] (3) Energy storage system: Evaluate based on its current operating mode; when it is in a discharge state ( (This is considered as a power generation device, and its current discharge power is compared with the total increased reserve capacity.) Compare to update its risk flag and determine whether the off-grid risk is level one or level two; when it is in a charging state ( (This is considered an energy-consuming device, and its current charging power is compared with the total reduced capacity.) Compare them to update their risk indicators and determine whether the risk of disconnection is level one or level two.

[0077] S2, Sequential diagnosis and quantitative classification of power imbalance events: When a change in relevant parameters is detected in S1, causing the system state to deviate from the normal range, the MGCC dynamically identifies and quantitatively analyzes events such as islanding, internal device disconnection, and frequency anomalies according to a preset diagnostic sequence, and immediately determines the direction (power deficit or power redundancy) and severity level (Level 1 or Level 2) of the power imbalance event. Specifically, when the equipment type... For power generation equipment, the operating conditions are as follows: This corresponds to a shortfall; when If it is an energy-consuming device, then Corresponding to redundancy; subscript Represents the direction of power redundancy "+" or power deficit "-", such as Figure 4 As shown. In particular, during a certain detection cycle, when step S2 determines the three types of events, only one type of event occurs, and multiple devices do not simultaneously disconnect from the network during the device disconnection event.

[0078] S2.1, Prioritize the diagnosis of PCC islanding events: When detected Calculate the initial power imbalance when changing from a closed to an open circuit. ,in This represents the power exchanged with the PCC recorded in the previous control cycle. If This is a power deficit, requiring further assessment. If it is determined to be a Level 1 power deficit condition, otherwise it is a Level 2 power deficit condition; if This is power redundancy. If the condition is positive, it is determined to be a Level 1 power redundancy condition; otherwise, it is a Level 2 power redundancy condition.

[0079] S2.2, then diagnose the disconnection of internal devices in the diagnostic system: If S2.1 is not true, when the kth device is detected to be disconnected from the grid, determine the direction of imbalance based on its device type (power generation / energy consumption), and read the dynamic risk flag updated by step S1.2 just before disconnection. If the condition is classified as Level 1 or Level 2, the resulting power imbalance is: ;

[0080] S2.3, Final diagnosis of frequency anomaly events: If neither S2.1 nor S2.2 is true, then the frequency deviation of the monitoring system is considered. Judgment, in which For real-time system frequency, The system's rated frequency; the resulting power imbalance is: ,in This refers to the system's frequency regulation coefficient. Based on the direction of frequency deviation, the permissible frequency deviation boundary for normal system operation, the system's available regulation capacity, and the frequency regulation coefficient, the direction of power imbalance and operating condition level reflected by frequency anomalies in the system are determined. When This indicates that the system has a power redundancy trend, and the frequency rise deviation is obtained. ; compare them with the first-level frequency anomaly start-up boundary in the power redundancy direction respectively. and the second-level frequency abnormal start boundary Comparison: If It is determined to be a Level 1 power redundancy condition; if it meets the requirements... If so, it is determined to be a level 2 redundancy condition.

[0081] when This indicates that the system has a power deficit trend, and the frequency drop deviation is obtained. These are respectively compared with the first-order frequency anomaly start-up boundary in the power deficit direction. and the second-level frequency abnormal start boundary Comparison: If This is determined to be a Level 1 power deficit condition; if the conditions are met... If so, it is determined to be a level two shortage condition.

[0082] Specifically, when MGCC calculates this moment... or At this time, MGCC will directly determine the corresponding direction as a level two operating condition to avoid misjudging it as a level one operating condition when the adjustable capacity is insufficient.

[0083] The frequency anomaly start boundary is dynamically determined by MGCC based on the current operating status of the microgrid, the normal frequency deviation boundary, the available backup capacity of the system, and the frequency regulation coefficient. Specifically, it includes:

[0084] (1) Secondary frequency abnormal start boundary:

[0085] The second-level frequency anomaly start-up boundary in the power deficit direction is The secondary frequency anomaly start-up boundary in the power redundancy direction is ;in This represents the system's frequency regulation coefficient. When the frequency deviation reaches the corresponding secondary frequency abnormality start-up boundary, it indicates that the power imbalance has reached or exceeded the system's capacity to absorb it solely through output regulation, necessitating the implementation of a corrective composite control strategy.

[0086] (2) Level 1 frequency abnormal start boundary:

[0087] set up This represents the allowable frequency deviation boundary for normal system operation, which can be taken as 0.2Hz here. This is the trigger coefficient for Level 1 operating conditions, and The marginal value of the first-order frequency difference in the direction of power deficit. Marginal value of first-order frequency difference in the direction of power redundancy Then the first-order frequency anomaly start boundary in the power deficit direction is: The first-level frequency anomaly start-up boundary in the power redundancy direction is The first-level frequency anomaly start boundary is located between the normal frequency deviation boundary and the second-level frequency anomaly start boundary. It is used to characterize the state in which the power imbalance has exceeded the normal operating deviation range but can still be eliminated autonomously by adjusting the output of the internal power generation equipment or energy consumption equipment.

[0088] In this embodiment, the primary and secondary frequency anomaly start boundaries are not used to simply determine whether the system frequency has reached the fixed limit specified in industry standards, but rather to identify whether the microgrid still possesses the ability to autonomously recover by adjusting the output of its internal equipment. The secondary frequency anomaly start boundary is determined by the system's currently available backup capacity and frequency regulation coefficient, characterizing the limit of the system's internal output regulation capability. The primary frequency anomaly start boundary is dynamically generated based on the interval between the normal frequency deviation boundary and the secondary frequency anomaly start boundary, identifying the intermediate state where the system has deviated from the normal operating range but has not yet exceeded its autonomous regulation capability. Therefore, this method forms a dynamic operating condition identification mechanism composed of the normal frequency boundary, the primary boundary, and the secondary boundary, which can adaptively adjust the operating condition level determination result according to the current operating state of the microgrid.

[0089] S3, Level-Based Differentiated Control and State Reset: Based on the operating condition level determined in step S2, a matching differentiated control strategy is initiated and executed to restore system power balance, ensuring rapid system response and recovery from faults. Specifically, a preventative power redistribution strategy is implemented for Level 1 power imbalance conditions, while a corrective composite control strategy maximizing internal regulation and optimal clearance is implemented for Level 2 power imbalance conditions. After control is completed, the system automatically resets the relevant status flags.

[0090] S3.1 If the condition is determined to be a Level 1 power imbalance, a preventative power redistribution strategy shall be implemented, which includes the following steps:

[0091] (1) Determine the adjustment direction and demand: Determine the power imbalance based on step S2. When this is a PCC isolated incident, When system device k goes offline, When it is a frequency anomaly event,

[0092] (2) Select adjustment resources: If there is a power deficit, select units with effective upward adjustment margin from all backup units to form an available upward adjustment resource pool; if there is a power redundancy, select units with downward adjustment margin from all controllable power generation equipment and energy storage equipment to form an available downward adjustment resource pool.

[0093] (3) Issuing adjustment instructions: such as Figure 5 As shown, a power adjustment command is issued to the i-th adjustment unit. , This is the preset power response weight for the regulating unit. The command is automatically either positive (power deficit) or negative (power redundancy) depending on the direction of the power imbalance.

[0094] S3.2 If the condition is determined to be a level two power imbalance, a corrective composite control strategy is executed, which specifically includes the following steps:

[0095] (1) Calculate the remaining power imbalance: Based on maximizing the internal adjustment, recalculate the remaining imbalance that still exists in the system. If it is a power deficit, then If it is for power redundancy, then ;

[0096] (2) Execute a targeted resection plan: such as Figure 6 As shown, if Then, a two-stage optimized load shedding strategy is implemented; specifically, it includes: the first stage: coarse shedding based on a greedy algorithm: based on the remaining power deficit From a pre-defined load list sorted by priority from high to low, loads are disconnected level by level until the cumulative disconnected power is not less than [amount missing]. The second stage: Fine-tuning recovery based on optimal correction: Calculate the power over-shear value caused by the first stage, and among the already shelved loads, select load combinations whose total power does not exceed the power over-shear value. Do not issue final shelving commands to loads within the load combination with the largest total power. If... If the power redundancy value is not greater than 0, then an ordered tripping strategy based on a preset priority list will be executed. Specifically, this includes: Phase 1: Coarse tripping based on a greedy algorithm: Starting with the highest priority unit in the pre-defined tripping priority list based on factors such as type and restart cost, tripping commands are issued sequentially until the power redundancy value is no greater than 0. Phase 2: Fine recovery based on optimal correction: The power over-trip value caused by Phase 1 is calculated, and among the units to be tripped, combinations of units whose total power does not exceed the power over-trip value are selected. Units within the combination with the largest total power are not issued a final tripping command.

[0097] (3) Internal adjustment of equipment: If there is a power shortage, all available resources are instructed to be increased to support it with maximum power capacity; if there is a power redundancy, all available resources are instructed to be decreased to reduce its output to the minimum output level.

[0098] Example 2:

[0099] Example 2 is an experimental simulation performed according to the method described in Example 1.

[0100] To verify the effectiveness of the proposed control strategy, a microgrid consisting of one grid-connected energy storage system and three grid-connected photovoltaic systems was selected and connected to the external power grid via a PCC point switch. Figure 7 As shown. The MGCC collects frequency and voltage information at the bus, output information of each device, and status of each switch, and issues commands to each device. Its control cycle is 50ms, and the communication delay is 20ms. The microgrid's rated frequency is 50Hz, and the voltage level is 10kV / 380V. Different areas are connected to the 10kV bus via transformers. The initial rated power of the energy storage is 50kW, and the rated powers of the three photovoltaic units are 50kW, 100kW, and 100kW, respectively, with a total installed capacity of 450kW. The power sharing ratio of the energy storage, photovoltaic unit 1, and photovoltaic unit 2 when receiving MGCC power regulation commands is 1:1:2. Photovoltaic unit 3 does not receive regulation commands from the MGCC and always maintains a 100kW output. The frequency regulation coefficient of the grid-type energy storage is 150kW / Hz, and the voltage regulation coefficient is 10kVar. Five loads are set in the microgrid, with values ​​of 50kW, 90kW, 40kW, 60kW, and 65kW, respectively. Example 2 was tested using the MATLAB / Simulink simulation platform. The control strategy considered four events, which occurred at the following time points:

[0101] t=7s, MGCC accesses the system;

[0102] At t=8s, the 60kW load equipment switch is disconnected and disconnected from the grid;

[0103] At t=9s, the power output of photovoltaic module 3 decreased by 40kW in a step.

[0104] At t=10s, the switch of photovoltaic device No. 3 is turned off, disconnecting it from the grid;

[0105] At t=11s, a 230kW load was suddenly connected;

[0106] Figure 8 — Figure 13 The simulation results for multiple operating conditions in this second embodiment are as follows. Figure 8 This describes the system frequency variation. Figure 9 This shows the changes in the system bus voltage. Figure 10 For energy storage and the output active power of two adjustable photovoltaic units, Figure 11 For energy storage and the reactive power output of two adjustable photovoltaic units, Figure 12 Active power regulation value issued by MGCC Because the energy storage and No. 1 photovoltaic system maintain the same proportion when receiving the active power regulation value issued by MGCC, their curves overlap. Figure 13The system load operating status value issued by MGCC is used for load i (i=1, 2, 3, 4, 5). When its operating status value is i, it indicates that MGCC has issued a normal operation command, and load i is operating normally; when its operating status value is i-1, it indicates that MGCC has issued a cut-off command, and load i is cut off. That is, when a falling edge appears in the operating status value, it indicates that MGCC has issued a cut-off command. Figures 8 to 13 As can be seen, after the MGCC was put into operation at 7 seconds, the system frequency quickly recovered from 49.85Hz (frequency deviation caused by the first droop control) to 50Hz; at 8 seconds, due to the load disconnection, power redundancy was generated within the microgrid, and the system frequency rose to 50.31Hz. The MGCC detected that the energy-consuming equipment was disconnected from the grid, and it was in a first-level power redundancy condition. It issued a power adjustment command to reduce the output of the adjustable power supply, causing the system frequency to drop rapidly to 49.9Hz; at 9 seconds, the output of photovoltaic device No. 3 in the system dropped by 40kW in a step, and the MGCC detected that the system frequency dropped to 49.78Hz, with a frequency deviation of -0.22Hz, indicating a first-level power deficit condition. The MGCC issued a power adjustment command to increase the output of the adjustable power supply, and the system frequency quickly recovered to 49.9Hz, and gradually recovered to 50Hz; at 10 seconds, due to the disconnection of photovoltaic device No. 3, the system frequency dropped to 40kW, and it was in a first-level power deficit condition. The system frequency rose rapidly to 49.9Hz, and gradually recovered to 50Hz; at 10 seconds, due to the disconnection of photovoltaic device No. 3, the system frequency dropped to 40kW, and it was in a first-level power deficit condition. The system frequency rose to 40.31Hz, and it was in a first-level power deficit condition. The system frequency rose to 50 ... When the photovoltaic equipment switch is disconnected, the MGCC detects that the power generation equipment is disconnected from the grid, indicating a Level 1 power deficit condition. It issues a power regulation command to increase the output of the adjustable power source, and the system frequency quickly recovers to 49.9Hz, gradually returning to 50Hz. At 11 seconds, a sudden connection of 230kW causes the system frequency to drop drastically to 48.97Hz, with a frequency deviation of -1.03Hz, indicating a Level 2 power deficit condition. The MGCC quickly triggers a directional shelving scheme, disconnecting load 1 and issuing a power regulation command to increase the output of the adjustable power source. Due to unavoidable over-shearing during the disconnection process, the system frequency recovers to 50.3Hz. 0.3 seconds later, the MGCC detects that the frequency remains too high, with a frequency deviation of 0.3Hz, indicating a Level 1 power redundancy condition. The MGCC issues a power regulation command to reduce the output of the adjustable power source, and the system frequency recovers to 50Hz. Throughout this multi-condition test, the MGCC consistently and rapidly detects power imbalance events and executes differentiated control based on the severity level, enabling rapid and stable emergency control after a power imbalance event occurs in the microgrid.

[0107] Example 3:

[0108] Corresponding to the aforementioned embodiment of a microgrid differentiated emergency control method based on power imbalance level, the present invention also provides an embodiment of a microgrid differentiated emergency control device based on power imbalance level.

[0109] See Figure 14The present invention provides a microgrid differentiated emergency control device based on power imbalance level, comprising a memory and one or more processors. The memory stores executable code, and when the processor executes the executable code, it is used to implement a microgrid differentiated emergency control method based on power imbalance level in the above embodiment.

[0110] The embodiment of the microgrid differentiated emergency control device based on power imbalance level provided by this invention can be applied to any device with data processing capabilities, such as a computer. The device embodiment can be implemented through software, hardware, or a combination of both. Taking software implementation as an example, as a logical device, it is formed by the processor of any data processing device loading the corresponding computer program instructions from non-volatile memory into memory for execution. From a hardware perspective, such as... Figure 14 The diagram shown is a hardware structure diagram of any device with data processing capabilities, which is the microgrid differentiated emergency control device based on power imbalance level provided by the present invention. Except for... Figure 14 In addition to the processor, memory, network interface, and non-volatile memory shown, any data processing device in the embodiment may also include other hardware depending on the actual function of the data processing device, which will not be described in detail here.

[0111] The specific implementation process of the functions and roles of each unit in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0112] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of the present invention according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0113] This invention also provides a computer-readable storage medium storing a program thereon, which, when executed by a processor, implements a microgrid differentiated emergency control method based on power imbalance levels as described in the above embodiments.

[0114] The computer-readable storage medium can be an internal storage unit of any data processing device described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device of any data processing device, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc., equipped on the device. Furthermore, the computer-readable storage medium can include both internal storage units and external storage devices of any data processing device. The computer-readable storage medium is used to store the computer program and other programs and data required by the data processing device, and can also be used to temporarily store data that has been output or will be output.

[0115] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the aforementioned microgrid differentiated emergency control method based on power imbalance levels.

[0116] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A differentiated emergency control method for microgrids based on power imbalance levels, characterized in that, The method includes the following steps: S1, During the operation of the microgrid, the microgrid central controller MGCC continuously monitors the key operating parameters of the microgrid system and performs real-time, adaptive assessment and marking of potential failure risks of key equipment units as input for emergency control decisions; S2: When a change in key operating parameters is detected in S1, causing the microgrid system state to deviate from the normal range, the microgrid central controller dynamically identifies and quantifies power imbalance events such as islanding, internal device disconnection, and frequency anomalies according to a preset diagnostic sequence, and immediately determines whether the power imbalance event is a power deficit or power redundancy, and whether it is a level one or level two operating condition; specifically as follows: S2.1, Prioritize the diagnosis of PCC islanding events: When the switching status of the PCC, the connection point between the microgrid and the main grid, is detected... Calculate the initial power imbalance when changing from a closed to an open circuit. ;like This is a power deficit; further judgment is needed if... If it is determined to be a Level 1 power deficit condition, otherwise it is a Level 2 power deficit condition; if This is power redundancy. If the condition is determined to be a Level 1 power redundancy condition, then it is a Level 2 power redundancy condition; otherwise, it is a Level 2 power redundancy condition. and The current available total up-adjustment backup capacity and total down-adjustment capacity of the microgrid; S2.2, then diagnose system equipment disconnection events: If S2.1 is not true, when the kth equipment unit is detected to be disconnected from the grid, determine the direction of imbalance based on its power generation or energy consumption equipment type, and read its dynamic risk flag before disconnection. The dynamic risk indicator is determined to be either a Level 1 or Level 2 operating condition. Updates are made by assessing the potential power imbalance risk to the system caused by the sudden disconnection of critical equipment units; S2.3, Final diagnosis of frequency anomaly events: If neither S2.1 nor S2.2 is true, then the frequency deviation of the monitoring system is considered. Based on the direction of frequency deviation, the allowable frequency deviation boundary for normal system operation, the first-level frequency anomaly start-up boundary, the second-level frequency anomaly start-up boundary, the available adjustment capacity of the system, and the frequency modulation coefficient, the direction of power imbalance and the operating condition level reflected by the frequency anomaly are determined. The second-level frequency anomaly start-up boundary in the power deficit direction is The secondary frequency anomaly start-up boundary in the power redundancy direction is , The frequency modulation coefficient of the system; The first-level frequency abnormal start-up boundary is used as the boundary in the direction of power deficit. The first-level frequency anomaly start-up boundary in the power redundancy direction is Marginal value of first-order frequency difference in the direction of power deficit Marginal value of first-order frequency difference in the direction of power redundancy , The frequency deviation boundary allowed for normal system operation. S3 is the trigger coefficient for the first-level operating condition; based on the operating condition level determined in step S2, a differentiated control strategy matching it is initiated and executed to restore the power balance of the microgrid system. Specifically, a preventive power redistribution strategy is implemented for the first-level operating condition, and a corrective composite control strategy that maximizes internal regulation and optimal cut-off is implemented for the second-level operating condition. After the control is completed, the microgrid system will automatically reset the operating condition level flag.

2. The microgrid differentiated emergency control method based on power imbalance level according to claim 1, characterized in that, The specific process of step S1 is as follows: S1.1, System operating parameter monitoring: MGCC monitors the system operating parameters according to a preset control cycle. Real-time acquisition and updating of microgrid operating parameter sets This set includes at least the switching states of the microgrid's connection point to the main grid, PCC. and switching power Real-time output of the kth device unit The current available total backup capacity of the microgrid has been increased. Total capacity reduction Real-time system frequency of microgrids and the bus voltage at the MGCC connection point Power flows into the microgrid in the positive direction. S1.2, Dynamic Assessment of Potential Equipment Risks: In each control cycle, for different types of critical equipment units k within the system, matching logic is used to assess the potential power imbalance risk caused by their sudden disconnection from the grid, and their dynamic risk flags are updated. .

3. The microgrid differentiated emergency control method based on power imbalance level according to claim 2, characterized in that, The process of updating its dynamic risk indicator is as follows: (1) Power generation equipment: its current real-time output As a potential power deficit, it is compared with the system's current total up-capacity. If a comparison is made, Then update its risk flag to That is, its risk of disconnection is Level 1; otherwise it is Level 2. This means the risk of being disconnected from the network is level two; (2) Energy-consuming equipment: its current real-time power consumption As a potential power redundancy, it is compared with the system's current total down-regulation capacity. If a comparison is made, Then update its risk flag to That is, its risk of disconnection is Level 1; otherwise it is Level 2. This means the risk of being disconnected from the network is level two; (3) Energy storage system: Evaluate based on its current operating mode; when it is in a discharging state, it is regarded as a power generation device, and its current discharge power is compared with the total increased backup capacity. The risk level is compared to update the risk flag and determine whether the grid disconnection risk is level one or level two; when it is charging, it is considered an energy-consuming device, and its current charging power is compared with the total reduced capacity. Compare them to update their risk indicators and determine whether the risk of disconnection is level one or level two.

4. A differentiated emergency control method for microgrids based on power imbalance levels according to claim 2, characterized in that, In step S2: when The system exhibits a power redundancy trend, resulting in a frequency rise deviation. ; Compare these with the first-level frequency anomaly start-up boundary in the power redundancy direction, respectively. and the second-level frequency abnormal start boundary Comparison: If It is determined to be a Level 1 power redundancy condition; if it meets the requirements... If so, it is determined to be a level 2 redundancy condition; when The system exhibits a power deficit trend, resulting in a frequency descent deviation. ; Compare these with the first-order frequency anomaly start-up boundary in the power deficit direction, respectively. and the second-level frequency abnormal start boundary Comparison: If This is determined to be a Level 1 power deficit condition; if the conditions are met... If so, it is determined to be a level two shortage condition; When MGCC calculates this moment or At this time, MGCC will directly determine the corresponding direction as a level two operating condition to avoid misjudging it as a level one operating condition when the adjustable capacity is insufficient.

5. A differentiated emergency control method for microgrids based on power imbalance levels according to claim 4, characterized in that, In S2.3: When the frequency deviation reaches the corresponding secondary frequency abnormal start boundary, it indicates that the power imbalance has reached or exceeded the system's capacity to absorb it by output adjustment alone, and a corrective composite control strategy needs to be implemented. The first-level frequency anomaly start boundary is located between the normal frequency deviation boundary and the second-level frequency anomaly start boundary. It is used to characterize the state in which the power imbalance has exceeded the normal operating deviation range but can still be eliminated autonomously by adjusting the output of the internal power generation equipment or energy consumption equipment.

6. A differentiated emergency control method for microgrids based on power imbalance levels according to claim 1, characterized in that, If the condition is determined to be Level 1 in step S3, a preventative power redistribution strategy is executed, which specifically includes the following steps: (1) Determine the adjustment direction and demand: Determine the power imbalance amount based on the different power imbalance events in step S2. ; (2) Select adjustment resources: If there is a power deficit, select units with effective upward adjustment margin from all backup units to form an available upward adjustment resource pool; if there is a power redundancy, select units with downward adjustment margin from all controllable power generation equipment and energy storage equipment to form an available downward adjustment resource pool. (3) Issuing adjustment instructions: Based on the preset power response weight of the adjustment unit and the power deficit or power redundancy, issue power adjustment instructions to the adjustment unit.

7. A differentiated emergency control method for microgrids based on power imbalance levels according to claim 1, characterized in that, If the condition is determined to be a Level 2 operating condition in step S3, a corrective composite control strategy is executed, which specifically includes the following steps: (1) Calculate the remaining power imbalance: Based on maximizing internal regulation, recalculate the remaining imbalance that still exists in the system according to the power deficit or power redundancy. -; (2) Execute the targeted resection plan: if If so, a two-stage optimized load shedding strategy will be executed; if If so, an ordered switching strategy based on a preset priority list will be executed; (3) Internal adjustment of equipment: If there is a power shortage, all available resources are instructed to be increased to support it with maximum power capacity; if there is a power redundancy, all available resources are instructed to be decreased to reduce its output to the minimum output level.

8. A differentiated emergency control method for microgrids based on power imbalance levels according to claim 7, characterized in that, The two-stage optimized load shedding strategy specifically includes: (1) First stage: coarse cut-off based on greedy algorithm: based on the remaining power deficit From a pre-defined load list sorted by priority from high to low, loads are disconnected level by level until the cumulative disconnected power is not less than [amount missing]. ; (2) Second stage: Fine recovery based on optimal correction: Calculate the power overcut value caused by the first stage, and select load combinations whose total power does not exceed the power overcut value from the already cut-off loads. Do not issue the final cut-off command for the loads in the load combination with the largest total power.

9. A differentiated emergency control method for microgrids based on power imbalance levels according to claim 7, characterized in that, The ordered switching strategy based on a preset priority list specifically includes: (1) First stage: coarse cut-off based on greedy algorithm: starting with the highest priority unit in the cut-off priority list based on type and restart cost factors, cut-off instructions are issued one by one in sequence until the power redundancy value is not greater than 0; (2) Second stage: Fine recovery based on optimal correction: Calculate the power overcut value caused by the first stage, and select the combination of units whose total power does not exceed the power overcut value from the units to be cut off. Do not issue the final cut-off command to the units in the combination of units with the largest total power.

10. A microgrid differentiated emergency control device based on power imbalance level, comprising a memory and one or more processors, wherein the memory stores executable code, characterized in that, When the processor executes the executable code, it implements a microgrid differentiated emergency control method based on power imbalance level as described in any one of claims 1-9.

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