Network-structured energy storage active correction method and system for improving power frequency stability

Abstract

This invention provides a method and system for active power correction of grid-connected energy storage to improve power frequency stability, including: S1, online acquisition of multi-dimensional parameters; S2, online estimation of system equivalent inertia and adaptive threshold generation; S3, dynamic discrimination of control modes under SOC constraints; and S4, adaptive fast power correction with SOC constraints. The adaptive threshold of this invention adjusts the action threshold in real time by estimating the system equivalent inertia and grid strength online. When fluctuations in renewable energy output cause a sudden drop in system inertia, the threshold automatically narrows, triggering preventative power correction in advance, avoiding the problem of delayed response of fixed thresholds in low-inertia scenarios. When inertia recovers, the threshold automatically widens, avoiding energy waste and device lifespan loss caused by frequent unnecessary actions of energy storage.

Description

Technical Field

[0001] This invention relates to the field of power grid correction technology, specifically to a grid-based energy storage active power correction method and system for improving power frequency stability. Background Technology

[0002] The large-scale grid connection of renewable energy sources such as wind power and photovoltaics through converter interfaces has continuously reduced the equivalent inertia of the power system, enabling the traditional power system to gradually transform into a low-inertia power system. Low-inertia systems are prone to problems such as significant frequency drops and abnormally high rate of frequency change (RoCoF) under large disturbances, directly threatening frequency security and stable operation.

[0003] Energy storage systems, as a core technology for improving the frequency stability of low-inertia systems, can quickly absorb / release unbalanced power. Among them, grid-connected energy storage (ESS-GFM) can achieve grid connection without phase-locked loops (PLLs) and can simulate the inertia and damping characteristics of synchronous generators, making it an important piece of equipment for rapid frequency response in low-inertia systems.

[0004] However, existing technologies still have the following significant drawbacks when dealing with large disturbances in low-inertia power grids:

[0005] 1. In existing technologies, the threshold values ​​for mode switching (frequency deviation threshold and RoCoF threshold) are usually preset to fixed values ​​offline, without considering the real-time changes in system inertia. In scenarios where inertia varies over time due to significant fluctuations in renewable energy output, fixed thresholds may lead to delayed response and untimely protection when inertia is too low, while they may lead to frequent triggering of energy storage and unnecessary energy consumption when inertia is high.

[0006] 2. Existing technologies for implementing rapid power correction rely solely on system frequency metrics, failing to incorporate energy storage SOC into control decisions. When the energy storage SOC is near its upper / lower limits, continuing to inject / absorb power at the maximum permissible level can lead to rapid energy storage saturation and loss of resilience to subsequent events, or even overcharge / over-discharge safety incidents. Particularly in scenarios with multiple consecutive disturbances, the energy storage may be depleted in the first event, completely losing its ability to support subsequent cascading events, thus exacerbating the risk of system frequency collapse.

[0007] 3. Existing methods are mostly general strategies and do not provide differentiated designs for regional power grids with excessive renewable energy penetration—such grids experience severe inertia fluctuations and cascading frequency events. If a secondary disturbance occurs during the system recovery period after a single large disturbance triggers frequency protection, the cascading effect will lead to widespread generator and load shedding. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a grid-based energy storage active power correction method to improve power frequency stability, thus solving the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for active power correction in grid-connected energy storage to improve power frequency stability, including online acquisition of S1 and multi-dimensional parameters: real-time acquisition of three-phase voltage and three-phase current at the grid connection point of the grid-connected energy storage, and obtaining the real-time equivalent angular frequency of the coupling point system through a phase-locked loop. The real-time angular frequency deviation was calculated. and real-time frequency change rate The phase-locked loop (PLL) is only used for frequency parameter measurement and extraction and mode switching discrimination, and does not participate in the grid-connected phase synchronization control of grid-connected energy storage; at the same time, it collects the state of charge of the energy storage battery in real time. and grid connection point short-circuit capacity ;

[0011] S2. Online estimation of system equivalent inertia and adaptive threshold generation: Based on historical data of frequency change rate and power disturbance within a sliding data window, the system equivalent inertia is estimated online using the swing equation. And combined with short-circuit capacity Adaptive generation of frequency deviation action threshold and frequency change rate action threshold ;

[0012] S3, Dynamic Discrimination of Control Mode under SOC Constraints: Defining SOC constraint factors for discharge and charging directions. and and set energy reserve targets. ;when and Maintain the drooping pattern; when or When it enters fast power correction mode, switch to S4;

[0013] S4. Adaptive Fast Power Correction with SOC Constraints: Power boundaries are determined based on converter hardware safety constraints and mapped to angular frequency safety boundaries; according to... Calculate the fundamental virtual power at the location within the angular frequency boundary. The actual injected virtual power is obtained after directional modulation by the SOC constraint factor. ;Will Inject reference power commands into the active power control loop; after frequency recovery, exit the fast power correction mode and start SOC energy reserve recovery.

[0014] Furthermore, in S2, the system's equivalent inertia The online estimation expression is:

[0015]

[0016] Where N is the number of sampling points within the sliding data window. Under normal operating conditions, the data window is 2 to 5 seconds, and during periods of large disturbances, it is shortened to 0.5 to 1 second.

[0017] Furthermore, in S2, the expression for the adaptively generated action threshold is:

[0018]

[0019]

[0020] in and As the baseline action threshold, and These are the reference values ​​for rated inertia and rated short-circuit capacity, respectively. and This is the sensitivity coefficient; and The setting principle is to set the relay protection trigger threshold below that specified in the power grid connection specification.

[0021] Furthermore, in S3, the discharge direction SOC constraint factor Defined as:

[0022]

[0023] Charging direction SOC constraint factor Defined as:

[0024]

[0025] in For the safe zone, This is the alarm range, and .

[0026] Furthermore, in S3, the energy reserve target If the SOC deviates after each exit from the power fast correction mode. The SOC is gradually restored to a value not exceeding 10% of the rated power. .

[0027] Furthermore, in S4, the base virtual power The calculation method is as follows:

[0028]

[0029] in This is the active power droop coefficient. and These are the upper and lower bounds of the limiting angular frequency within the safety region, respectively. , , The maximum / minimum allowable active power of the converter. Rated active power, This is the rated angular frequency.

[0030] Furthermore, in S4, the actual injected virtual power The SOC modulation method is as follows:

[0031]

[0032] A grid-based energy storage active power correction system for improving power frequency stability, the system comprising a power hardware loop and a core control architecture;

[0033] The power hardware circuit includes an energy storage battery cluster, a DC / DC converter, a DC bus capacitor, a DC / AC converter, an LCL filter circuit, and a step-up transformer, which are connected in sequence.

[0034] The core control architecture is deployed in a digital signal processor and includes: a frequency state monitoring and inertia estimation module: acquiring voltage and current, and calculating... and Online estimation of equivalent inertia of the system SOC Status Assessment and Energy Management Module: Collects SOC, terminal voltage, and temperature; calculates SOC constraint factor; and executes energy reserve recovery control. Adaptive Threshold Generation Module: Receives... and short-circuit capacity Real-time generation and The module includes: Mode Selection and SOC Constraint Module: Based on frequency indicators, adaptive thresholds, and SOC status, it determines the operating mode and outputs the SOC constraint factor; Droop Controller Module: Generates reference voltage amplitude and phase in droop mode; Power Control Correction Module: Calculates and injects virtual power modulated by SOC in power fast correction mode; Voltage Generator Module: Generates reference signals for voltage loop and current loop; PWM Signal Conversion Module: Converts the modulated signal into switching transistor drive pulses.

[0035] Furthermore, the DC / AC converter employs fully controlled switching devices and achieves DC-to-AC power conversion through insulated gate bipolar transistors; the LCL filter circuit is used to filter out high-order harmonics of the switching frequency and its integer multiples.

[0036] Furthermore, in droop mode, the power control correction module is not activated; in fast power correction mode, the power control correction module superimposes the virtual power constrained by the SOC onto the original droop command, and updates the inner loop reference voltage amplitude and phase angle.

[0037] This invention provides a method and system for active power correction in grid-based energy storage to improve power frequency stability. Compared with existing technologies, it has the following advantages:

[0038] 1. The adaptive threshold of this invention adjusts the action threshold in real time by estimating the system's equivalent inertia and grid strength online. When fluctuations in renewable energy output cause a sharp drop in system inertia, the threshold automatically narrows, triggering preventative power correction in advance and avoiding the lag in response of a fixed threshold in low-inertia scenarios. When inertia recovers, the threshold automatically widens, avoiding energy waste and device lifespan loss caused by frequent and unnecessary actions of energy storage. This mechanism makes this invention particularly suitable for regional power grids with excessively high renewable energy penetration and drastic fluctuations in inertia levels.

[0039] 2. The SOC constraint layer ensures the operational safety and continuous disturbance response capability of the energy storage system. The SOC constraint factor of this invention... A directional, gradual power correction depth modulation mechanism is formed—as the State of Charge (SOC) approaches its boundary, the correction depth in the corresponding direction is gradually reduced until it is locked, while maintaining an unconstrained response in the opposite direction to help the SOC return to the safe zone. Combined with an energy storage strategy and a slow-charge / slow-discharge recovery mechanism after FPC exit, this invention can rationally allocate limited energy storage in consecutive disturbance scenarios, preventing energy depletion in the first event and loss of support capability in subsequent cascading events.

[0040] 3. Synergistic effect of adaptive inertia threshold and SOC constraint. Under the worst-case operating conditions where the system inertia is extremely low and the SOC is in the boundary range, the adaptive threshold mechanism ensures that the system detects large disturbances as early as possible, while the SOC constraint mechanism ensures that frequency support is still provided in the most feasible way when the energy storage state is limited. The synergy between the two achieves the optimal trade-off between early warning and response within the limits of available resources, which is not available in existing single-mechanism strategies. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0042] Figure 1 A schematic diagram of the active power correction method for grid-type energy storage to improve power frequency stability according to the present invention is shown;

[0043] Figure 2 A schematic diagram of the grid-type energy storage active power correction system for improving power frequency stability according to the present invention is shown. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] This implementation method is specifically designed for application scenarios in low-inertia regional power grids with excessively high renewable energy penetration rates. Under the interaction of fluctuating wind and solar power output and sudden load changes, the equivalent inertia level of such power grids can fluctuate drastically within minutes or even seconds, with both single disturbances and continuous cascading disturbances coexisting: a single large disturbance may cause a deep frequency drop triggering load shedding protection, while secondary disturbances during system recovery will cause a cascading effect, leading to widespread power outages. To address these issues, this embodiment provides the following solution:

[0047] Reference Figure 1 The active power correction method for grid-type energy storage to improve power frequency stability provided by this invention includes the following steps:

[0048] S1. Online acquisition of multi-dimensional parameters: Real-time acquisition of three-phase voltage and three-phase current at the grid-connected point of the grid-type energy storage system, and acquisition of the real-time equivalent angular frequency of the coupling point system through a phase-locked loop. The real-time angular frequency deviation was calculated. and real-time frequency change rate The phase-locked loop (PLL) is only used for frequency parameter measurement and extraction and mode switching discrimination, and does not participate in the grid-connected phase synchronization control of grid-connected energy storage; at the same time, it collects the state of charge of the energy storage battery in real time. and grid connection point short-circuit capacity ;

[0049] The purpose of setting up S1 is to achieve real-time acquisition of multi-dimensional, full-parameter data on grid status, energy storage device, and grid structure characteristics, providing a complete and real-time raw data foundation for subsequent inertia estimation, adaptive threshold generation, mode discrimination, and power correction. The phase-locked loop (PLL) is only used for frequency measurement and mode discrimination and does not participate in the grid-connected phase synchronization control of the grid-connected energy storage. This avoids phase coupling interference caused by the dynamic characteristics of the PLL, ensuring the grid-connected phase stability of the grid-connected energy storage and preventing grid-connected oscillations and instability.

[0050] S2. Online estimation of system equivalent inertia and adaptive threshold generation: Based on historical data of frequency change rate and power disturbance within a sliding data window, the system equivalent inertia is estimated online using the swing equation. And combined with short-circuit capacity Adaptive generation of frequency deviation action threshold and frequency change rate action threshold ;

[0051] System equivalent inertia The online estimation expression is:

[0052]

[0053] Where N is the number of sampling points within the sliding data window. Under normal operating conditions, the data window is 2 to 5 seconds, and during periods of large disturbances, it is shortened to 0.5 to 1 second.

[0054] The adaptively generated action threshold expression is:

[0055]

[0056]

[0057] in and As the baseline action threshold, and These are the reference values ​​for rated inertia and rated short-circuit capacity, respectively. and This is the sensitivity coefficient; and The setting principle is to set the relay protection trigger threshold below that specified in the power grid connection specification.

[0058] The purpose of setting S2 is to: identify the equivalent inertia of the system online based on the swing equation and sliding data window, adapting to the time-varying characteristics of system inertia caused by the high proportion of new energy and the switching of grid operation modes, and solving the problems of poor adaptability and low frequency regulation control accuracy of traditional fixed inertia parameters. Under normal operating conditions, it ensures smooth and accurate inertia estimation within 2-5 seconds, shortening this to 0.5-1 seconds during large disturbances, quickly capturing frequency transient change characteristics and improving the real-time performance of control response under large disturbances. Combined with short-circuit capacity adaptive generation of frequency deviation and frequency change rate action thresholds, it can dynamically match the control threshold according to the strength of the grid, avoiding excessively high thresholds leading to control lag under weak grids and excessively low thresholds causing frequent malfunctions under strong grids. The action threshold is set lower than the grid relay protection trigger threshold, enabling grid-connected energy storage to suppress frequency disturbances in advance, smoothing frequency offsets early, avoiding frequency degradation triggering grid relay protection tripping, and improving the safety margin of grid operation. By introducing a rated reference value and sensitivity coefficient, the threshold can be flexibly set to adapt to different regional grids and different energy storage grid connection scenarios, making the solution highly versatile and engineering portable.

[0059] S3, Dynamic Discrimination of Control Mode under SOC Constraints: Defining SOC constraint factors for discharge and charging directions. and and set energy reserve targets. ;when and Maintain the drooping pattern; when or When it enters fast power correction mode, switch to S4;

[0060] Discharge direction SOC constraint factor Defined as:

[0061]

[0062] Charging direction SOC constraint factor Defined as:

[0063]

[0064] in For the safe zone, This is the alarm range, and .

[0065] Energy reserve target If the SOC deviates after each exit from the power fast correction mode. The SOC is gradually restored to a value not exceeding 10% of the rated power. .

[0066] The purpose of setting S3 is to define bidirectional SOC constraint factors for charging and discharging, and to divide the safe and alarm ranges to accurately define the operating range for frequency regulation of the energy storage battery. This prevents overcharging and over-discharging from a control logic perspective, protecting the battery's lifespan and operational safety. It uses frequency indicators, adaptive thresholds, and SOC status for mode discrimination. Under normal operating conditions, it maintains a droop mode to ensure grid-connected steady-state stability. When the frequency exceeds the limit but the SOC is permissible, it automatically switches to a fast power correction mode, balancing steady-state grid-connected stability with rapid transient frequency support. A fixed energy reserve target is set, forcing the energy storage to reserve dedicated frequency regulation backup capacity to prevent the loss of subsequent frequency regulation capability due to depleted energy storage capacity, ensuring long-term frequency backup support for the power system. After power correction exits, SOC is gradually restored with a small power level not exceeding 10% of the rated power to avoid secondary frequency fluctuations in the grid caused by high-power backlash, achieving a smooth return of SOC to the target value without disturbing the grid's steady-state frequency.

[0067] S4. Adaptive Fast Power Correction with SOC Constraints: Power boundaries are determined based on converter hardware safety constraints and mapped to angular frequency safety boundaries; according to... Calculate the fundamental virtual power at the location within the angular frequency boundary. The actual injected virtual power is obtained after directional modulation by the SOC constraint factor. ;Will Inject reference power command into the active power control loop; after frequency recovery, exit fast power correction mode and start SOC energy reserve recovery;

[0068] Basic virtual power The calculation method is as follows:

[0069]

[0070] in This is the active power droop coefficient. and These are the upper and lower bounds of the limiting angular frequency within the safety region, respectively. , , The maximum / minimum allowable active power of the converter. Rated active power, This is the rated angular frequency.

[0071] Actual injected virtual power The SOC modulation method is as follows:

[0072]

[0073] The purpose of setting S4 is to map the converter hardware power safety constraints to angular frequency safety boundaries, transforming the maximum / minimum active power limits of devices into frequency control constraints. This mitigates the risks of overpower and overcurrent exceeding limits in the converter from a control perspective, ensuring the reliable operation of power electronic hardware. The basic virtual power is calculated based on the position of the angular frequency within the safety boundary, achieving adaptive matching between frequency offset and correction power amplitude. The larger the frequency deviation, the stronger the correction support power, accurately and quickly smoothing grid frequency fluctuations. The basic virtual power is directionally modulated using the SOC constraint factor, and the correction power is dynamically limited based on the remaining battery capacity. While fully participating in grid frequency regulation, it adheres to the SOC safety range, achieving synergistic optimization of grid frequency stability and energy storage battery safety. The modulated virtual power is used as a reference command for the active power control loop, rapidly superimposing and regulating active power output. This significantly improves the dynamic response capability of grid-based energy storage to frequency drops / surges, effectively suppressing frequency deviation and frequency change rate, and enhancing the overall frequency stability of the power system. After the frequency is restored, it automatically exits the correction mode and starts SOC energy recovery, forming a closed-loop control of "frequency disturbance correction - steady-state grid-connected operation - energy storage energy replenishment", realizing the sustainable cyclic operation of the grid-type energy storage frequency regulation function.

[0074] Example 2

[0075] A grid-based energy storage active power correction system for improving power frequency stability, the system comprising a power hardware loop and a core control architecture;

[0076] The power hardware circuit includes an energy storage battery cluster, a DC / DC converter, a DC bus capacitor, a DC / AC converter, an LCL filter circuit, and a step-up transformer, which are connected in sequence.

[0077] The core control architecture is deployed in a digital signal processor and includes: a frequency state monitoring and inertia estimation module: acquiring voltage and current, and calculating... and Online estimation of equivalent inertia of the system SOC Status Assessment and Energy Management Module: Collects SOC, terminal voltage, and temperature; calculates SOC constraint factor; and executes energy reserve recovery control. Adaptive Threshold Generation Module: Receives... and short-circuit capacity Real-time generation and The module includes: Mode Selection and SOC Constraint Module: Based on frequency indicators, adaptive thresholds, and SOC status, it determines the operating mode and outputs the SOC constraint factor; Droop Controller Module: Generates reference voltage amplitude and phase in droop mode; Power Control Correction Module: Calculates and injects virtual power modulated by SOC in power fast correction mode; Voltage Generator Module: Generates reference signals for voltage loop and current loop; PWM Signal Conversion Module: Converts the modulated signal into switching transistor drive pulses.

[0078] In this embodiment, the DC / AC converter uses a fully controlled switching device and achieves DC to AC power conversion through an insulated gate bipolar transistor; the LCL filter circuit is used to filter out high-order harmonics of the switching frequency and its integer multiples.

[0079] In this embodiment, the power control correction module is not activated in droop mode; in fast power correction mode, the power control correction module superimposes the virtual power constrained by SOC onto the original droop command and updates the inner loop reference voltage amplitude and phase angle.

[0080] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for active power correction in grid-based energy storage to improve power frequency stability, characterized in that: S1, multi-dimensional parameter online acquisition: real-time acquisition of three-phase voltage and three-phase current of the grid-connected point of the network-forming energy storage, acquisition of real-time equivalent angular frequency of the coupling point system through a phase-locked loop , calculation of real-time angular frequency deviation and real-time frequency change rate , the phase-locked loop is only used for measurement and extraction of the frequency parameter and basis for discrimination of mode switching, and does not participate in grid phase synchronization control of the network-forming energy storage; at the same time, the state of charge of the energy storage battery and the short-circuit capacity of the grid-connected point are acquired in real time; S2. Online estimation of system equivalent inertia and adaptive threshold generation: Based on historical data of frequency change rate and power disturbance within a sliding data window, the system equivalent inertia is estimated online using the swing equation. And combined with short-circuit capacity Adaptive generation of frequency deviation action threshold and frequency change rate action threshold ; S3, Dynamic Discrimination of Control Mode under SOC Constraints: Defining SOC constraint factors for discharge and charging directions. and and set energy reserve targets. ; when and Maintain the drooping pattern; when or When it enters fast power correction mode, switch to S4; S4. Adaptive Fast Power Correction with SOC Constraints: Power boundaries are determined based on converter hardware safety constraints and mapped to angular frequency safety boundaries; according to... Calculate the fundamental virtual power at the location within the angular frequency boundary. ; The actual injected virtual power is obtained after directional modulation by the SOC constraint factor. ;Will Inject reference power commands into the active power control loop; After frequency recovery, exit the fast power correction mode and start SOC energy reserve recovery.

2. The active power correction method for grid-type energy storage to improve power frequency stability according to claim 1, characterized in that: In S2, the system's equivalent inertia The online estimation expression is: Where N is the number of sampling points within the sliding data window. Under normal operating conditions, the data window is 2 to 5 seconds, and during periods of large disturbances, it is shortened to 0.5 to 1 second.

3. The active power correction method for grid-type energy storage to improve power frequency stability according to claim 2, characterized in that: In S2, the adaptively generated action threshold expression is: in and As the baseline action threshold, and These are the reference values ​​for rated inertia and rated short-circuit capacity, respectively. and This is the sensitivity coefficient; and The setting principle is to set the relay protection trigger threshold below that specified in the power grid connection specification.

4. The active power correction method for grid-type energy storage to improve power frequency stability according to claim 3, characterized in that: In S3, the discharge direction SOC constraint factor Defined as: Charging direction SOC constraint factor Defined as: in For the safe zone, This is the alarm range, and .

5. The active power correction method for grid-type energy storage to improve power frequency stability according to claim 4, characterized in that: In S3, energy reserve target ; If the SOC deviates after each exit from the power fast correction mode. The SOC is gradually restored to a value not exceeding 10% of the rated power. .

6. The active power correction method for grid-type energy storage to improve power frequency stability according to claim 5, characterized in that: In S4, base virtual power The calculation method is as follows: in This is the active power droop coefficient. and These are the upper and lower bounds of the limiting angular frequency within the safety region, respectively. , , The maximum / minimum allowable active power of the converter. Rated active power, This is the rated angular frequency.

7. The active power correction method for grid-type energy storage to improve power frequency stability according to claim 6, characterized in that: In S4, the actual injected virtual power The SOC modulation method is as follows: 。 8. A grid-type energy storage active power correction system for improving power frequency stability, characterized in that, The system is used to perform the method of claim 1; the system includes a power hardware loop and a core control architecture; The power hardware circuit includes an energy storage battery cluster, a DC / DC converter, a DC bus capacitor, a DC / AC converter, an LCL filter circuit, and a step-up transformer, which are connected in sequence. The core control architecture is deployed in a digital signal processor and includes: a frequency state monitoring and inertia estimation module: acquiring voltage and current, and calculating... and Online estimation of equivalent inertia of the system SOC Status Assessment and Energy Management Module: Collects SOC, terminal voltage, and temperature; calculates SOC constraint factor; and executes energy reserve recovery control. Adaptive Threshold Generation Module: Receives... and short-circuit capacity Real-time generation and The module includes: Mode Selection and SOC Constraint Module: Based on frequency indicators, adaptive thresholds, and SOC status, it determines the operating mode and outputs the SOC constraint factor; Droop Controller Module: Generates reference voltage amplitude and phase in droop mode; Power Control Correction Module: Calculates and injects virtual power modulated by SOC in power fast correction mode; Voltage Generator Module: Generates reference signals for voltage loop and current loop; PWM Signal Conversion Module: Converts the modulated signal into switching transistor drive pulses.

9. The grid-type energy storage active power correction system for improving power frequency stability according to claim 8, characterized in that: The DC / AC converter uses a fully controlled switching device and achieves DC to AC power conversion through an insulated gate bipolar transistor; the LCL filter circuit is used to filter out high-order harmonics of the switching frequency and its integer multiples.

10. The grid-type energy storage active power correction system for improving power frequency stability according to claim 8, characterized in that: In droop mode, the power control correction module is not activated; in fast power correction mode, the power control correction module superimposes the virtual power constrained by the SOC onto the original droop command and updates the inner loop reference voltage amplitude and phase angle.

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