Microgrid frequency regulation method for hybrid energy storage system

Abstract

The application discloses a micro-grid frequency modulation method of a hybrid energy storage system, and belongs to the technical field of power supply and distribution. The frequency modulation method comprises the following steps: obtaining operation data of a micro-grid; obtaining a secondary drop risk index of the micro-grid based on the operation data of the micro-grid; obtaining secondary drop support power demand and safe standby energy of the micro-grid based on energy storage and load data; obtaining a judgment result of the secondary drop support demand based on the secondary drop support power demand and the safe standby energy of the micro-grid; constructing a collaborative support scheme of the hybrid energy storage system based on the judgment result of the secondary drop support demand; obtaining optimal support power of energy storage and load in the micro-grid based on the collaborative support scheme of the hybrid energy storage system; verifying the optimal support power of the energy storage and the load in the micro-grid, and judging whether feedback correction is needed. The problems that it is difficult to realize rapid support, continuous compensation and orderly participation of backup resources in micro-grid frequency modulation in the prior art are solved.

Description

Technical Field

[0001] This application belongs to the field of power supply and distribution technology, specifically, it relates to a microgrid frequency regulation method for a hybrid energy storage system. Background Technology

[0002] Autonomous microgrids have relatively small inertia and limited frequency regulation reserve resources. With the integration of a high proportion of renewable energy, the system frequency becomes more sensitive to active power disturbances. After the end of a frequency support period, the relevant frequency regulation units may cause the active power support to drop in order to restore their own operating status, resulting in a power gap in the system again, which in turn leads to a secondary frequency drop, affecting the frequency stability and continuous operation capability of the microgrid.

[0003] Existing technologies mostly improve frequency regulation performance from the perspectives of energy storage frequency division control, power smooth recovery, or power allocation based on state of charge. However, they lack a unified description of the support capabilities, response time, dynamic weights, and power constraints among flywheel energy storage, lithium battery energy storage, backup power, and controllable loads during secondary drops. They also lack optimal target allocation methods for secondary drop support requirements. This results in unclear coordination relationships among various frequency regulation resources, making it difficult to achieve rapid support, continuous compensation, and orderly participation of backup resources. Summary of the Invention

[0004] To address the challenges of achieving rapid support, continuous compensation, and orderly participation of backend resources in microgrid frequency regulation in existing technologies, this application discloses a microgrid frequency regulation method using a hybrid energy storage system, specifically:

[0005] A microgrid frequency regulation method for a hybrid energy storage system, the frequency regulation method comprising:

[0006] Acquire microgrid operating data;

[0007] Based on the microgrid's operational data, the secondary drop risk index of the microgrid is obtained;

[0008] Based on energy storage and load data, the secondary sag support power demand and safe reserve energy of the microgrid are obtained;

[0009] Based on the secondary dip-slip support power demand and safety reserve energy of the microgrid, the judgment result of the secondary dip-slip support demand is obtained.

[0010] Based on the assessment of the secondary drop support requirements, a collaborative support scheme for the hybrid energy storage system is constructed.

[0011] Based on a collaborative support scheme using a hybrid energy storage system, the optimal support power for energy storage and load within a microgrid is obtained;

[0012] The optimal power support for energy storage and load within the microgrid is verified, and it is determined whether feedback correction is needed.

[0013] Optionally, acquiring the microgrid's operational data includes:

[0014] The microgrid's operational data includes power operation data, frequency regulation equipment operation status data, and energy storage system energy storage status data.

[0015] Optionally, obtaining the microgrid's secondary voltage drop risk index based on microgrid operating data includes:

[0016] Based on the microgrid's operational data, the current frequency deviation and frequency change rate of the microgrid are obtained, as shown in the equations:

[0017] ,

[0018] in, f represents the current frequency deviation of the microgrid at time t; n The frequency is denoted by f(t); f(t) represents the measured frequency of the microgrid. represents the rate of frequency change; t represents the frequency acquisition time of the microgrid. Indicates time difference;

[0019] Based on the current frequency deviation and frequency change rate of the microgrid, normalized values ​​of risk factors are obtained, and the equations are as follows:

[0020] ,

[0021] Where, r P p represents the normalized value of active power. w (t) represents the active power at the current moment; This indicates the active power at the previous moment; Indicates the power deviation safety threshold; r f This represents the frequency normalization value; Indicates the frequency deviation safety threshold; r v This represents the normalized value of the rate of change of frequency. Indicates the safety threshold for frequency variation; This represents the normalized value of the rotational speed; Indicates the optimal rotational speed; Indicates the current rotational speed; [·] + Represents the positive part function;

[0022] Based on the normalized values ​​of risk factors, the secondary drop risk index of the microgrid is obtained, and the equation is as follows:

[0023] ,

[0024] Where a1, a2, a3 and a4 represent the weights of the normalized values ​​of active power, frequency, rate of change of frequency and speed, respectively. This indicates the risk index of a second drop.

[0025] Optionally, obtaining the microgrid's secondary sag support power demand and safe reserve energy based on energy storage and load data includes:

[0026] Based on the microgrid's wind turbine reference power and current active power, the power dip after the microgrid's wind turbines are removed from primary frequency support is obtained, as shown in the equation:

[0027] ,

[0028] in, This indicates a secondary power drop during the wind turbine speed recovery phase; This represents the reference active power of the wind turbine when the speed recovery derating has not occurred;

[0029] Based on the power dip, the secondary drop power requirement is obtained by the following equation:

[0030] ,

[0031] in, Indicates the supporting power required for a second drop; k p Indicates the power dip compensation coefficient; k f Indicates the frequency correction factor; k r Indicates the inhibition coefficient of the rate of change of frequency;

[0032] Based on the wind turbine speed deviation in the microgrid, the expected speed recovery time is determined by the following equation:

[0033]

[0034] in, Indicates the estimated speed recovery time; This indicates the lower limit of the expected speed recovery time; This indicates the upper limit of the expected speed recovery time; This indicates the conversion factor for rotational speed recovery time; This represents the limiting function, used to limit the amplitude of the amplitude. Limit to preset upper and lower limits;

[0035] The secondary fall safety reserve energy is obtained by integrating the secondary fall power demand over the expected speed recovery time, as shown in the equation:

[0036]

[0037] in, This indicates the safety reserve energy required for a second fall; This represents the safety reserve factor, used to compensate for forecast errors, wind power fluctuations, and load uncertainties.

[0038] Optionally, the determination result of the secondary sag support power requirement and safety reserve energy based on the microgrid includes:

[0039] Based on the existing available power of all subsystems in the microgrid, the executable secondary sag support power and safety reserve energy of the microgrid are obtained, as shown in the equations:

[0040] in, This indicates the secondary drop support power that the current system can perform under existing reserve conditions; This indicates the maximum power that the flywheel can currently output; This indicates the maximum output power of the lithium battery at present; This indicates the remaining power that the backup power supply can generate. This indicates the maximum power that can be cut off from the controllable load; This indicates the equivalent available supporting energy of the backup power supply; This indicates the equivalent available supporting energy for a controllable load; Indicates the duration of continuous backup power generation; Indicates the allowable continuous shearing time under controllable load; This represents the safe reserve energy that the current system can provide under existing reserve conditions; This indicates the flywheel's currently available energy; This indicates the current available energy of the lithium battery; This indicates the power that the flywheel-lithium battery hybrid energy storage can support;

[0041] Based on the executable secondary sag support power and safety reserve energy of the microgrid, the power support margin of all subsystems and the overall support margin of the microgrid are obtained, as shown in the equation:

[0042]

[0043] in, The comprehensive support margin refers to the system's secondary drop support capability index, which is obtained by comprehensively considering the power margin, energy margin, and safety constraints of flywheel energy storage, lithium battery energy storage, backup power supply, and controllable load. This indicates the combined power, energy, and safety margin of the flywheel and lithium battery; This indicates the power support margin for backup power supplies and controllable loads; Indicates the minimum safe operating speed of the flywheel; This indicates the safest minimum state of charge for a lithium battery. These represent the margin weights for flywheel, lithium battery, backup power supply, and controllable load, respectively.

[0044] Based on the comprehensive support margin, the risk threshold of the microgrid is obtained by the following equation:

[0045]

[0046] in, This represents the dynamic threshold for the risk of a second fall at the current moment; This represents the baseline threshold for the risk of a second fall. Represents the amplitude limiting function; This represents the support margin impact coefficient, used to characterize the degree of influence of the comprehensive support margin on the dynamic threshold of the second-fall risk. This represents the influence coefficient of the rate of frequency change, used to characterize the degree of influence of the rate of frequency change on the dynamic threshold of the risk of a second fall. This represents the frequency deviation influence coefficient, used to characterize the degree of influence of frequency deviation on the dynamic threshold of secondary fall risk;

[0047] Based on the risk threshold of the microgrid and the secondary drop risk index, the activation status of secondary drop support is obtained. The equation for judging the activation status of secondary drop support is as follows:

[0048] .

[0049] Optionally, the collaborative support scheme for the hybrid energy storage system, based on the judgment result of the secondary drop support requirement, includes:

[0050] Based on the comprehensive support margin of the microgrid, the power support level of the microgrid is obtained by the following equation:

[0051]

[0052] in, Indicates the support level for a second drop; Indicates the normal support level; Indicates the level of limited support; Indicates the level of endangered status; Indicates the level of failure protection; Indicates the emergency low-frequency protection threshold; Indicates the threshold for the rate of decrease in emergency frequency;

[0053] Based on the power support status level, the dynamic power contribution weights of the microgrid's subsystems are obtained, as shown in the equation:

[0054]

[0055] in, Indicates the original contribution weight of the flywheel; Indicates the original contribution weight of the lithium battery; This represents the flywheel response time constant; This represents the response time constant of a lithium battery; and This represents the safety status correction factor; Represents the amplitude limiting function;

[0056] Based on the dynamic power contribution weights of the subsystems in the microgrid, the corrected dynamic power contribution weights of the subsystems are obtained, and the equation is as follows:

[0057]

[0058] in, This indicates the dynamic power contribution weight of flywheel energy storage at level G; This indicates the dynamic power contribution weight of lithium battery energy storage under level G; This represents the flywheel contribution correction factor at level G; This represents the lithium battery contribution correction factor at level G.

[0059] Based on the corrected dynamic power contribution weights of the subsystems, the power allocation method of the microgrid subsystems is obtained, and the equation is as follows:

[0060]

[0061] in, This represents the reference allocated power for flywheel energy storage at level G; This indicates the reference power allocation for lithium batteries in the G category; This indicates the supported power output of the flywheel-lithium battery hybrid energy storage system at level G. This represents the power limiting factor for the flywheel and lithium battery in Class G.

[0062] Optionally, the collaborative support scheme based on the hybrid energy storage system, which obtains the optimal support power for energy storage and load within the microgrid, includes:

[0063] Based on the hybrid energy storage support capability of the microgrid subsystem, the response time coupling quantity of the subsystem is obtained, and the equation is as follows:

[0064]

[0065] in, This represents the reference contribution coefficient of flywheel-lithium battery energy storage to the secondary drop in level G. Represents the natural exponential function; This represents the reference response time coupling amount determined by the dynamic power contribution weights of the flywheel and lithium battery at level G; This represents the flywheel response time constant; This represents the response time constant of a lithium battery;

[0066] Based on the subsystem response time coupling, the reference value of the equivalent support power formed by the wind turbine recovery derating is obtained, and the equation is:

[0067]

[0068] in, This represents the reference factor for fan speed recovery derating under level G. Represents the amplitude limiting function; This represents the reference value for the fan speed recovery power under level G. This represents the reference value for the equivalent supporting power generated by the wind turbine's recovery derating under level G. This indicates a command to restore the original fan speed to its original power output. The derating participation factor for wind turbines in Class G is used for restoration.

[0069] Obtain the equivalent support power reference value penalty term for the microgrid and combine it with the equivalent support power reference value to obtain the optimal support power.

[0070] Optionally, after obtaining the optimal support power for energy storage and load within the microgrid, the collaborative support scheme based on the hybrid energy storage system further includes:

[0071] Based on the reference range of the equivalent support power formed by the wind turbine recovery derating, a set of judgment equations for the wind turbine derating support power is established. The set of judgment equations is as follows:

[0072]

[0073] in, This refers to the portion of the derated support power that does not exceed the reference value for the equivalent derated support of the wind turbine recovery. This refers to the portion of the derated support power that exceeds the reference value for the wind turbine's restored derating equivalent support.

[0074] Based on the correspondence between secondary drop support levels and frequency regulation response actions, the response modes of hybrid energy storage systems are obtained, including:

[0075] When G(t)=1, the hybrid energy storage system is at the normal support level, and the support power of the flywheel energy storage system and the lithium battery energy storage system is:

[0076]

[0077] in, This indicates the reference support power for a secondary drop that the hybrid energy storage system under Level 1 can withstand in the current state; This indicates the reference support power for flywheel energy storage at Level 1; This indicates the reference support power for lithium battery energy storage under Level 1;

[0078] When G(t)=2, at least one type of resource in the hybrid energy storage system, either the flywheel energy storage system or the battery energy storage system, is insufficient. The secondary drop support requirement is met by adjusting the contribution weight of the flywheel energy storage system or the battery energy storage system. The contribution weight adjustment equation is as follows:

[0079]

[0080] in, express Overall power, energy and safety margin of flywheel energy storage ; express Lithium battery energy storage Overall power, energy, and safety margin; like This reduces the flywheel output power and increases the lithium battery's ramp-up power; if This limits the continuous output of the lithium battery and increases the proportion of short-term flywheel support;

[0081] When G(t)=3, the hybrid energy storage system cannot meet the secondary dropout support power demand. Microgrid adjustments are then jointly performed by the backup energy storage system and the hybrid energy storage system, including:

[0082] The power boundary conditions for the flywheel energy storage system and the battery energy storage system are obtained by the following equations:

[0083]

[0084] in, This indicates the flywheel power limiting factor under the backup support level; This indicates the lithium battery power limiting factor under the backup support level;

[0085] The reference range for the power cut-off of backup power and controllable load is obtained by the following equation:

[0086]

[0087] When G(t)=4, the hybrid energy storage system is in a fail-protection state, and the fail-protection control command is:

[0088]

[0089] in, This indicates the backup power supply protection control command under the failure protection level; This indicates an emergency load shedding control command under the failure protection level; This indicates the maximum output power of the backup power supply; This indicates the load power that needs to be cut off in an emergency.

[0090] Based on the response mode of hybrid energy storage systems, a mixed-integer linear programming objective function for the quadratic drop power of hybrid energy storage systems is established.

[0091] Optionally, the objective function for the mixed-integer linear programming of the quadratic drop power of the hybrid energy storage system, based on the response mode of the hybrid energy storage system, includes:

[0092] The power deficit penalty term for the hybrid energy storage system at level G is obtained from the following equation:

[0093]

[0094] in, This represents the power gap linearization penalty term that enters the objective function of the mixed-integer linear programming at level G. This indicates the number of power gap linearization segments at level G; This represents the q-th power gap segment variable under level G; This represents the slope of the q-th power gap segment penalty at level G;

[0095] To obtain the wind turbine recovery depreciation penalty at level G, the equation is:

[0096]

[0097] in, This represents the wind turbine recovery derated linearization penalty term for entering the mixed-integer linear programming objective function at level G. This indicates the number of derating segments restored for wind turbines at level G; This represents the piecewise variable for the recovery of the derating of the s-th wind turbine under level G; This represents the slope of the s-th wind turbine's recovery depreciation segment penalty under level G;

[0098] Based on the optimization variables in the hybrid energy storage system, the response time linear term in the hybrid integer pictographic programming model is obtained, and the equation is:

[0099]

[0100] in, This represents the linearized response time variable at level G; This indicates the secondary drop support power requirement for entering the rolling optimization model; express Flywheel response time constant ; express Lithium battery response time constant ;

[0101] The ramp continuity of the backup power output power and the actual backup power output power in the previous sampling period is constrained by the following equation:

[0102]

[0103] in, Indicates the backup power supply ramp rate;

[0104] Based on the shedding status of all controllable load blocks in the hybrid energy storage system, the controllable load shedding power is obtained, as shown in the equation:

[0105] and

[0106] in, This represents the cut-off power of the Mth controllable load block under level G; This represents the cut-off power of the m-th controllable load block; This indicates the maximum power that can be cut off from the current controllable load;

[0107] Based on the power allocation deviation variable, a linear constraint is established for the hybrid energy storage system, and the equation is as follows:

[0108]

[0109] in, This represents the flywheel energy storage power distribution deviation variable; This represents the variable indicating the deviation in the energy storage power distribution of lithium batteries; This represents the sum of the power distribution deviation variables between the flywheel and the lithium battery storage.

[0110] Based on the available energy constraints of flywheel energy storage and battery energy storage, the available energy of the hybrid energy storage system is updated within the prediction time window, and the equation is as follows:

[0111]

[0112] in, Indicates the energy available to the flywheel at the next moment; Indicates the available energy of the lithium battery at the next moment; This indicates the safe energy threshold for flywheels and lithium batteries;

[0113] The output power range of the battery energy storage system is uniformly divided to obtain the output power of the battery energy storage system, and the equation is as follows:

[0114]

[0115] in, This indicates the maximum allowable power for the first segment;

[0116] Based on the loss slope of the battery energy storage system in the first segment, the linear equation for the loss of the battery energy storage system is obtained as follows:

[0117]

[0118] The objective function for the mixed-integer linear programming problem is:

[0119] in, This represents the linearized objective function of the mixed-integer linear programming problem. This represents the power gap linearization penalty term; Represents the linearized response time variable; This represents a linear function of lithium battery loss. This indicates that the wind turbine has resumed the derating linearization penalty term; Indicates that the backup power supply is in Constant output power; This represents the cut-off power of the Mth controllable load block under level G; This represents the sum of the power distribution deviation variables between the flywheel and the lithium battery storage. Indicates the power gap error weight; Indicates response time weight; Indicates the weight of battery loss; This indicates the weight of the penalty for wind turbine speed recovery. Indicates the penalty weight for calling up backup power; Indicates the controllable load shedding penalty weight; This indicates the penalty weight for the power distribution deviation between the flywheel and the lithium battery.

[0120] Optionally, the verification of the optimal support power of energy storage and load within the microgrid, and the determination of whether feedback correction is needed, includes:

[0121] Based on the optimal support power, the actual frequency at the next sampling time is obtained;

[0122] Based on the actual frequency at the next sampling time, obtain the frequency verification index, and determine whether feedback correction of the optimal support power is needed based on the frequency verification index.

[0123] The beneficial effects of this application include:

[0124] 1. This application constructs a secondary frequency drop risk index by real-time collection of autonomous microgrid frequency, wind power output, wind turbine speed, flywheel speed, lithium battery state of charge, backup power status, and controllable load status. Combined with comprehensive support margin, it dynamically judges the secondary frequency drop support level, which can identify the secondary frequency drop risk that may be caused by the wind turbine primary frequency support withdrawal and speed recovery stage in advance, thereby improving the autonomous microgrid's ability to perceive frequency stability risks.

[0125] 2. This application comprehensively considers the available power, available energy, and safety status of flywheel energy storage, lithium battery energy storage, backup power, and controllable loads, establishes a dynamic power contribution weight for flywheel-lithium battery, and adjusts the participation mode of various frequency regulation resources under different support levels. This allows flywheel energy storage to focus on rapid support, lithium battery energy storage to focus on continuous compensation, and backup power, wind turbine recovery derating equivalent support, and controllable loads to participate in an orderly manner as backup resources, thereby improving the collaborative support capability among multiple frequency regulation resources.

[0126] 3. This application establishes a mixed integer linear programming objective function based on the power demand of secondary drop support. Within the power boundary and safety constraints of each frequency regulation resource, it automatically solves the optimal support power combination. It eliminates the need to manually list a large number of power allocation schemes for comparison, thereby improving the computational efficiency and engineering feasibility of power allocation. It can also avoid prematurely cutting off controllable loads when the wind turbine resumes derating and the backup power supply can still participate in the support.

[0127] 4. This application introduces a frequency verification and feedback correction mechanism after the optimal support power is executed. When the frequency deviation or frequency change rate does not meet the preset stability threshold, the rolling optimization input parameters of the next sampling period are corrected based on the frequency response after execution, the actual output of the equipment, and the changes in resource status. When the system enters an emergency low-frequency state, it exits the regular rolling optimization and executes failure protection control, thereby improving the frequency recovery stability and safety protection capability of the autonomous microgrid under the conditions of wind power fluctuation, load disturbance, and equipment response deviation. Attached Figure Description

[0128] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the embodiments of this application or the prior art will be briefly introduced below. Obviously, the following description is only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are used to provide a further understanding of this disclosure and constitute a part of the specification. They are used together with the following detailed description to explain this disclosure, but do not constitute a limitation of this disclosure. In the drawings:

[0129] Figure 1 A flowchart of a microgrid frequency regulation method for a hybrid energy storage system provided in this application embodiment;

[0130] Figure 2 Enlarged view of frequency response and secondary drop under different frequency regulation strategies in a microgrid frequency regulation method for a hybrid energy storage system provided in this application embodiment;

[0131] Figure 3A graph showing the risk index, dynamic threshold, comprehensive support margin, and support level variation in a microgrid frequency regulation method for a hybrid energy storage system provided in this application embodiment;

[0132] Figure 4 A diagram showing the dynamic weights, wind turbine recovery power, and output power variations of various frequency regulation resources in a microgrid frequency regulation method for a hybrid energy storage system provided in this application embodiment;

[0133] Figure 5 The diagram shows the key frequency control performance indicators under different strategies in a microgrid frequency regulation method for a hybrid energy storage system provided in this application embodiment. Detailed Implementation

[0134] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, in the embodiments of this application, "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0135] like Figure 1 The diagram shown is a flowchart of a microgrid frequency regulation method for a hybrid energy storage system provided in an embodiment of this application. Specifically:

[0136] Acquire microgrid operating data;

[0137] Based on the microgrid's operational data, the secondary drop risk index of the microgrid is obtained;

[0138] Based on energy storage and load data, the secondary sag support power demand and safe reserve energy of the microgrid are obtained;

[0139] Based on the secondary dip-slip support power demand and safety reserve energy of the microgrid, the judgment result of the secondary dip-slip support demand is obtained.

[0140] Based on the assessment of the secondary drop support requirements, a collaborative support scheme for the hybrid energy storage system is constructed.

[0141] Based on a collaborative support scheme using a hybrid energy storage system, the optimal support power for energy storage and load within a microgrid is obtained;

[0142] The optimal power support for energy storage and load within the microgrid is verified, and it is determined whether feedback correction is needed.

[0143] The following will provide a detailed explanation of all the steps above:

[0144] The acquisition of microgrid operating data includes:

[0145] The microgrid's operational data includes power operation data, frequency regulation equipment operation status data, and energy storage system energy storage status data.

[0146] In this scenario, the autonomous microgrid is in the speed recovery phase after the primary frequency support of the wind turbine has been withdrawn, and the controller sampling period is... Rated frequency of power grid At the current control time t, the frequency of the autonomous microgrid is collected in real time. Frequency at the previous sampling time Collect current wind power output Wind power output at the previous sampling time Rated capacity of wind power Reference active power when the fan speed has not recovered to its derating level. Collect the optimal fan speed under the current wind speed. Current fan speed Collect the current maximum output power of the flywheel energy storage. The flywheel's current available energy Current flywheel speed Flywheel safe minimum speed Collect the current maximum output power of the lithium battery. The current available energy of lithium batteries Lithium battery state of charge The safe minimum state of charge of lithium batteries Collect the remaining available power of the backup power supply. Backup power supply's sustainable increase time ; Collect the maximum controllable power that can be cut off from the controllable load Controllable load allows for continuous shearing time Double-dip risk index weighting Second fall risk benchmark threshold Risk threshold lower limit Risk threshold upper limit Frequency deviation safety threshold Safety threshold for rate of change of frequency Emergency low-frequency protection threshold Emergency frequency decrease rate threshold Let the support margin influence coefficient be set. Frequency change rate influence coefficient Frequency deviation influence coefficient ; Set the power dip compensation coefficient Frequency deviation correction coefficient Frequency change rate suppression coefficient Set the lower limit of the expected speed recovery time. The upper limit of the expected speed recovery time Rotational speed recovery time conversion factor Safety reserve factor Set the comprehensive support margin weight. Assume the flywheel response time constant. Lithium battery response time constant .

[0147] The formulas for calculating the current frequency deviation and the rate of frequency change are as follows:

[0148]

[0149] Based on the current active power of the wind power and the active power at the previous sampling time, the frequency deviation safety threshold, the frequency change rate safety threshold, the optimal wind turbine speed at the current wind speed, and the current wind turbine speed, the normalized value is calculated:

[0150]

[0151] The formula for calculating the double-fall risk index is:

[0152]

[0153] in,

[0154]

[0155] Based on the power dip, frequency deviation, and frequency change rate, the secondary drop support power requirement is calculated as follows:

[0156]

[0157] The estimated speed recovery time is determined based on the fan speed deviation. The estimated speed recovery time is as follows:

[0158]

[0159] During the controller sampling period At that time, the prediction step size is: .

[0160]

[0161] The required safety reserve energy, equivalent available support energy of backup power supply, and equivalent available support energy of controllable load for a secondary fall are as follows:

[0162]

[0163] The current system's available safety reserve energy and secondary drop protection power under existing reserve conditions are as follows:

[0164] ,

[0165] Based on the current available power of flywheel energy storage and lithium battery energy storage, the executable supported power of flywheel-lithium battery hybrid energy storage is determined as follows:

[0166]

[0167] Based on the current available power and energy of flywheel energy storage, lithium battery energy storage, backup power, and controllable load, the power support margin for each is calculated using the following formula:

[0168]

[0169] in, For the combined power, energy and safety margin of the flywheel and lithium battery;

[0170] For backup power and controllable load power support margin;

[0171]

[0172] Therefore, the current overall support margin at the control moment is This indicates that the system's secondary drop support capability is insufficient, and the flywheel-lithium battery hybrid energy storage cannot independently complete all secondary drop support.

[0173] Based on the comprehensive support margin, the current frequency change rate, and the current frequency deviation, a dynamic threshold for the second fall risk is calculated. The dynamic threshold for the second fall risk is:

[0174]

[0175] because Therefore, it was determined that the autonomous microgrid has a secondary drop risk that needs to be addressed, and it entered the secondary drop support level assessment stage.

[0176] Based on the corrected dynamic power contribution weights of the subsystems, the power allocation method of the microgrid subsystems is obtained, and the equation is as follows:

[0177]

[0178] in, This represents the reference allocated power for flywheel energy storage at level G; This indicates the reference power allocation for lithium batteries in the G category; This indicates the supported power output of the flywheel-lithium battery hybrid energy storage system at level G. This represents the power limiting factor for the flywheel and lithium battery in Class G.

[0179] In Level 3, the power limit boundaries for flywheel energy storage and lithium battery energy storage are calculated based on the power limiting coefficients of flywheel energy storage and lithium battery energy storage, using the following formula:

[0180]

[0181] Therefore, the maximum reference power for flywheel energy storage in Level 3 is 60kW, and the maximum reference power for lithium battery energy storage is 42kW.

[0182] Based on the safety states of flywheel energy storage and lithium battery energy storage, the safety state correction coefficient is calculated using the following formula:

[0183]

[0184] This indicates that the current flywheel speed and lithium battery state of charge are not below the safety limit.

[0185] At Level 3, the available power of flywheel energy storage and lithium battery energy storage after power limiting is used as the current available power in the dynamic power contribution weight calculation, resulting in the original flywheel contribution weight:

[0186]

[0187] Based on the flywheel contribution correction factor at level 3 and lithium battery contribution correction factor ,

[0188] The dynamic power contribution weight of flywheel-lithium battery energy storage under level 3 is calculated as follows:

[0189]

[0190] Based on the power limit boundary under Level 3, the feasible reference supported power for flywheel-lithium battery hybrid energy storage is:

[0191]

[0192] because This indicates that even flywheel energy storage and lithium battery energy storage are within the limits permitted by Level 3.

[0193] Despite full participation within the affected area, there remains a power gap to support secondary drops, necessitating the introduction of wind turbines to restore derating equivalent support, backup power supplies, and controllable loads as backup support resources.

[0194] After obtaining the optimal support power for energy storage and load within the microgrid, the collaborative support scheme based on a hybrid energy storage system further includes:

[0195] Based on the reference range of the equivalent support power formed by the wind turbine recovery derating, a set of judgment equations for the wind turbine derating support power is established. The set of judgment equations is as follows:

[0196]

[0197] in, This refers to the portion of the derated support power that does not exceed the reference value for the equivalent derated support of the wind turbine recovery. This refers to the portion of the derated support power that exceeds the reference value for the wind turbine's restored derating equivalent support.

[0198] Based on the correspondence between secondary drop support levels and frequency regulation response actions, the response modes of hybrid energy storage systems are obtained, including:

[0199] When G(t)=1, the hybrid energy storage system is at the normal support level, and the support power of the flywheel energy storage system and the lithium battery energy storage system is:

[0200]

[0201] in, This indicates the reference support power for a secondary drop that the hybrid energy storage system under Level 1 can withstand in the current state; This indicates the reference support power for flywheel energy storage at Level 1; This indicates the reference support power for lithium battery energy storage under Level 1;

[0202] When G(t)=2, at least one type of resource in the hybrid energy storage system, either the flywheel energy storage system or the battery energy storage system, is insufficient. The secondary drop support requirement is met by adjusting the contribution weight of the flywheel energy storage system or the battery energy storage system. The contribution weight adjustment equation is as follows:

[0203]

[0204] in, express Overall power, energy and safety margin of flywheel energy storage ; express Lithium battery energy storage Overall power, energy, and safety margin; like This reduces the flywheel output power and increases the lithium battery's ramp-up power; if This limits the continuous output of the lithium battery and increases the proportion of short-term flywheel support;

[0205] When G(t)=3, the hybrid energy storage system cannot meet the secondary dropout support power demand. Microgrid adjustments are then jointly performed by the backup energy storage system and the hybrid energy storage system, including:

[0206] The power boundary conditions for the flywheel energy storage system and the battery energy storage system are obtained by the following equations:

[0207]

[0208] in, This indicates the flywheel power limiting factor under the backup support level; This indicates the lithium battery power limiting factor under the backup support level;

[0209] The reference range for the power cut-off of backup power and controllable load is obtained by the following equation:

[0210]

[0211] When G(t)=4, the hybrid energy storage system is in a fail-protection state, and the fail-protection control command is:

[0212]

[0213] in, This indicates the backup power supply protection control command under the failure protection level; This indicates an emergency load shedding control command under the failure protection level; This indicates the maximum output power of the backup power supply; This indicates the load power that needs to be cut off in an emergency.

[0214] Based on the response mode of hybrid energy storage systems, a mixed-integer linear programming objective function for the quadratic drop power of hybrid energy storage systems is established.

[0215] The objective function for the mixed-integer linear programming of the quadratic drop power of the hybrid energy storage system, based on the response mode of the hybrid energy storage system, includes:

[0216] The power deficit penalty term for the hybrid energy storage system at level G is obtained from the following equation:

[0217]

[0218] in, This represents the power gap linearization penalty term that enters the objective function of the mixed-integer linear programming at level G. This indicates the number of power gap linearization segments at level G; This represents the q-th power gap segment variable under level G; This represents the slope of the q-th power gap segment penalty at level G;

[0219] To obtain the wind turbine recovery depreciation penalty at level G, the equation is:

[0220]

[0221] in, This represents the wind turbine recovery derated linearization penalty term for entering the mixed-integer linear programming objective function at level G. This indicates the number of derating segments restored for wind turbines at level G; This represents the piecewise variable for the recovery of the derating of the s-th wind turbine under level G; This represents the slope of the s-th wind turbine's recovery depreciation segment penalty under level G;

[0222] Based on the optimization variables in the hybrid energy storage system, the response time linear term in the hybrid integer pictographic programming model is obtained, and the equation is:

[0223]

[0224] in, This represents the linearized response time variable at level G; This indicates the secondary drop support power requirement for entering the rolling optimization model; express Flywheel response time constant ; express Lithium battery response time constant ;

[0225] The ramp continuity of the backup power output power and the actual backup power output power in the previous sampling period is constrained by the following equation:

[0226]

[0227] in, Indicates the backup power supply ramp rate;

[0228] Based on the shedding status of all controllable load blocks in the hybrid energy storage system, the controllable load shedding power is obtained, as shown in the equation:

[0229] and

[0230] in, This represents the cut-off power of the Mth controllable load block under level G; This represents the cut-off power of the m-th controllable load block; This indicates the maximum power that can be cut off from the current controllable load;

[0231] Based on the power allocation deviation variable, a linear constraint is established for the hybrid energy storage system, and the equation is as follows:

[0232]

[0233] in, This represents the flywheel energy storage power distribution deviation variable; This represents the variable indicating the deviation in the energy storage power distribution of lithium batteries; This represents the sum of the power distribution deviation variables between the flywheel and the lithium battery storage.

[0234] Based on the available energy constraints of flywheel energy storage and battery energy storage, the available energy of the hybrid energy storage system is updated within the prediction time window, and the equation is as follows:

[0235]

[0236] in, Indicates the energy available to the flywheel at the next moment; Indicates the available energy of the lithium battery at the next moment; This indicates the safe energy threshold for flywheels and lithium batteries;

[0237] The output power range of the battery energy storage system is uniformly divided to obtain the output power of the battery energy storage system, and the equation is as follows:

[0238]

[0239] in, This indicates the maximum allowable power for the first segment;

[0240] Based on the loss slope of the battery energy storage system in the first segment, the linear equation for the loss of the battery energy storage system is obtained as follows:

[0241]

[0242] The objective function for the mixed-integer linear programming problem is:

[0243] in, This represents the linearized objective function of the mixed-integer linear programming problem. This represents the power gap linearization penalty term; Represents the linearized response time variable; This represents a linear function of lithium battery loss. This indicates that the wind turbine has resumed the derating linearization penalty term; Indicates that the backup power supply is in Constant output power; This represents the cut-off power of the Mth controllable load block under level G; This represents the sum of the power distribution deviation variables between the flywheel and the lithium battery storage. Indicates the power gap error weight; Indicates response time weight; Indicates the weight of battery loss; This indicates the weight of the penalty for wind turbine speed recovery. Indicates the penalty weight for calling up backup power; Indicates the controllable load shedding penalty weight; This indicates the penalty weight for the power distribution deviation between the flywheel and the lithium battery.

[0244] The power constraints, wind turbine recovery derating penalty term, backup power call penalty term, and controllable load shedding penalty term are input into the mixed-integer linear programming model, and the formula is:

[0245]

[0246] In the mixed-integer linear programming objective function at level 3, the penalty weights are: power gap penalty weights. Flywheel-lithium battery response time penalty weight Lithium battery loss penalty weight Wind turbines resume reduced penalty weighting Backup power supply call penalty weight Controllable load shedding penalty weight Flywheel-lithium battery power distribution deviation penalty weight .

[0247] Solving using a mixed-integer linear programming model, we obtain a set of optimal support powers for the current control time t as follows:

[0248]

[0249] After applying the optimal support power as described above, the actual frequency obtained at the next sampling time is:

[0250]

[0251] Based on the actual frequency deviation and actual frequency change rate after execution, the frequency verification index for level 3 is calculated using the following formula:

[0252]

[0253] because Therefore, the optimal support power obtained at the current control time t is deemed to have a satisfactory frequency support effect after execution. At this point, the controller does not perform additional feedback corrections on the secondary drop support power demand, flywheel-lithium battery dynamic power contribution weight, wind turbine speed recovery derating coefficient, and objective function weight in the next sampling cycle. Instead, it continues to perform rolling optimization based solely on the real-time operating data re-acquired in the next sampling cycle.

[0254] The verification of the optimal power support for energy storage and load within the microgrid, and the determination of whether feedback correction is needed, includes:

[0255] Based on the optimal support power, the actual frequency at the next sampling time is obtained;

[0256] Based on the actual frequency at the next sampling time, obtain the frequency verification index, and determine whether feedback correction of the optimal support power is needed based on the frequency verification index.

[0257] Specifically, when the frequency verification index does not meet the preset stability threshold, it indicates that the current optimal support power is...

[0258] The frequency support effect after execution did not meet the frequency regulation requirements. At this time, based on the frequency response results after execution, the actual output results of the frequency regulation equipment, and the changes in the status of each frequency regulation resource, the controller performs feedback correction on the secondary drop support power demand, support level, flywheel-lithium battery dynamic power contribution weight, wind turbine speed recovery derating factor, equipment available power boundary, and mixed integer linear programming objective function weight for the next sampling period, and re-executes the rolling optimization for the next sampling period.

[0259] Furthermore, if the actual frequency is detected to be lower than the emergency low-frequency protection threshold or the actual frequency decline rate exceeds the emergency frequency decline rate threshold during the feedback verification process, the system is determined to enter the failure protection level, and the conventional flywheel-lithium battery power allocation and mixed integer linear programming rolling optimization are stopped. The backup power protection control command and emergency load shedding control command are executed first to ensure the power supply to the core load of the autonomous microgrid and the safe operation of the system.

[0260] Through the aforementioned feedback correction process, this application does not overwrite the optimal support power already executed in the current sampling period. Instead, it uses the frequency response results, actual equipment output results, and resource status change results after execution as the input correction basis for the rolling optimization in the next sampling period. This forms a closed-loop frequency modulation control process of "real-time acquisition—risk identification—support requirement calculation—support level judgment—mixed integer linear programming optimal allocation—frequency verification—feedback correction—rolling optimization in the next period" until both frequency deviation and frequency change rate meet the preset stability threshold.

[0261] Furthermore, to verify the effectiveness of the frequency regulation strategy of this application in suppressing secondary frequency drops, an autonomous microgrid simulation model was established, including wind turbines, flywheel energy storage, lithium battery energy storage, backup power, and controllable loads. Under the same wind power, load disturbance, initial energy storage state, equipment capacity, and safety constraints, the conventional independent control strategy, the fixed-proportion collaborative support strategy, the feedback-free hierarchical optimization strategy, and the frequency regulation strategy of this application were compared. In the simulation, the wind turbine enters the speed recovery phase after completing one frequency support cycle, with the expected speed recovery time set at 6.1 s.

[0262] like Figure 2The image shown is a magnified view of the frequency response and secondary frequency drop under different frequency regulation strategies in a microgrid frequency regulation method for a hybrid energy storage system provided in this application embodiment. After the wind turbine enters the speed recovery phase, a significant secondary frequency drop occurs under the conventional independent control strategy. The fixed-proportion coordinated support strategy can compensate for the power gap during the recovery phase to some extent, but it cannot adjust the power allocation between flywheel energy storage and lithium battery energy storage in a timely manner according to changes in energy storage status. The feedbackless hierarchical optimization strategy can improve the frequency response, but it cannot correct subsequent control quantities based on actual execution deviations. The frequency regulation strategy of this application can further increase the minimum secondary frequency, reduce the depth of the secondary frequency drop, and shorten the frequency recovery time.

[0263] like Figure 3 The diagram shows the changes in risk index, dynamic threshold, comprehensive support margin, and support level in a microgrid frequency regulation method for a hybrid energy storage system provided in this application embodiment. When the secondary drop risk index reaches the dynamic risk threshold, the controller initiates secondary drop support and determines the support level based on the comprehensive support margin. As the flywheel speed, flywheel available energy, lithium battery state of charge, and lithium battery available energy change, the comprehensive support margin and support level are adjusted accordingly, indicating that this application can dynamically select the support mode based on system risk and frequency regulation resource status.

[0264] like Figure 4 The diagram illustrates the dynamic weights, wind turbine recovery power, and output power variations of various frequency regulation resources in a microgrid frequency regulation method for a hybrid energy storage system provided in this application embodiment. In the initial stage of a secondary voltage drop, flywheel energy storage prioritizes providing rapid power support, followed by lithium battery energy storage increasing its output power to compensate for the continuous power gap during the recovery phase. When the overall support margin of either flywheel or lithium battery energy storage decreases, the controller adjusts their dynamic power contribution weights accordingly. When the hybrid energy storage support capacity is insufficient, a power recovery command is used to reduce wind turbine speed to form a recovery derating equivalent support power, and backup power is allowed to participate in power compensation; controllable loads are only invoked when the aforementioned resources still cannot meet the support requirements. This achieves orderly coordination among flywheel energy storage, lithium battery energy storage, wind turbine recovery derating, backup power, and controllable loads.

[0265] like Figure 5 The diagram shows the key frequency control performance indicators under different strategies in a microgrid frequency regulation method for a hybrid energy storage system provided in this application. Compared with other frequency regulation strategies, the frequency regulation strategy of this application has a higher secondary frequency minimum point, a smaller secondary drop depth, and a larger maximum frequency change rate, and can shorten the frequency recovery time. Simultaneously, the flywheel speed and lithium battery state of charge are maintained within a preset safe range, and the amount of backup power called up and controllable load cut-off is effectively controlled.

[0266] In summary, the frequency regulation strategy of this application can accurately identify the risk of secondary frequency drop caused by wind turbine speed recovery, and dynamically adjust the support level and power allocation based on the comprehensive support margin and the real-time status of frequency regulation resources. Compared with conventional independent control, fixed-proportion collaborative support, and feedback-free hierarchical optimization strategies, this application can improve the minimum secondary frequency, reduce the depth of secondary frequency drop, and shorten the frequency recovery time while meeting equipment safety constraints, thus verifying the effectiveness and engineering feasibility of the frequency regulation strategy.

[0267] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to computer program instructions. The aforementioned computer program can be stored in a non-volatile storage medium, and when executed, it performs the steps of the above method embodiments. Alternatively, if the integrated unit of the present invention is implemented as a software functional module and sold or used as an independent product, it can also be stored in a non-volatile storage medium. Based on this understanding, the technical solution of the embodiments of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a non-volatile storage medium and includes several instructions to cause an electronic device (which may be a personal computer, server, network device, etc.) to execute all or part of the methods described in the various embodiments of the present invention.

[0268] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A microgrid frequency regulation method for a hybrid energy storage system, characterized in that, The frequency modulation method includes: Acquire microgrid operating data; Based on the microgrid's operational data, the secondary drop risk index of the microgrid is obtained; Based on energy storage and load data, the secondary sag support power demand and safe reserve energy of the microgrid are obtained; Based on the secondary dip-slip support power demand and safety reserve energy of the microgrid, the judgment result of the secondary dip-slip support demand is obtained. Based on the assessment of the secondary drop support requirements, a collaborative support scheme for the hybrid energy storage system is constructed. Based on a collaborative support scheme using a hybrid energy storage system, the optimal support power for energy storage and load within a microgrid is obtained; The optimal power support for energy storage and load within the microgrid is verified, and it is determined whether feedback correction is needed.

2. The microgrid frequency regulation method for a hybrid energy storage system according to claim 1, characterized in that, The acquisition of microgrid operating data includes: The microgrid's operational data includes power operation data, frequency regulation equipment operation status data, and energy storage system energy storage status data.

3. The microgrid frequency regulation method for a hybrid energy storage system according to claim 1, characterized in that, The second-degree voltage drop risk index of the microgrid, obtained based on the microgrid's operational data, includes: Based on the microgrid's operational data, the current frequency deviation and frequency change rate of the microgrid are obtained, as shown in the equations: ， in, f represents the current frequency deviation of the microgrid at time t; n The frequency is denoted by f(t); f(t) represents the measured frequency of the microgrid. represents the rate of frequency change; t represents the frequency acquisition time of the microgrid. Indicates time difference; Based on the current frequency deviation and frequency change rate of the microgrid, normalized values ​​of risk factors are obtained, and the equations are as follows: ， Where, r P p represents the normalized value of active power. w (t) represents the active power at the current moment; This indicates the active power at the previous moment; Indicates the power deviation safety threshold; r f This represents the frequency normalization value; Indicates the frequency deviation safety threshold; r v This represents the normalized value of the rate of change of frequency. Indicates the safety threshold for frequency variation; This represents the normalized value of the rotational speed; Indicates the optimal rotational speed; Indicates the current rotational speed; [·] + Represents the positive part function; Based on the normalized values ​​of risk factors, the secondary drop risk index of the microgrid is obtained, and the equation is as follows: ， Where a1, a2, a3 and a4 represent the weights of the normalized values ​​of active power, frequency, rate of change of frequency and speed, respectively. This indicates the risk index of a second drop.

4. The microgrid frequency regulation method for a hybrid energy storage system according to claim 1, characterized in that, The process of obtaining the secondary sag support power demand and safe reserve energy of the microgrid based on energy storage and load data includes: Based on the microgrid's wind turbine reference power and current active power, the power dip after the microgrid's wind turbines are removed from primary frequency support is obtained, as shown in the equation: ， in, This indicates a secondary power drop during the wind turbine speed recovery phase; This represents the reference active power of the wind turbine when the speed recovery derating has not occurred; Based on the power dip, the secondary drop power requirement is obtained by the following equation: ， in, Indicates the supporting power required for a second drop; k p Indicates the power dip compensation coefficient; k f Indicates the frequency correction factor; k r Indicates the inhibition coefficient of the rate of change of frequency; Based on the wind turbine speed deviation in the microgrid, the expected speed recovery time is determined by the following equation: ， in, Indicates the estimated speed recovery time; This indicates the lower limit of the expected speed recovery time; This indicates the upper limit of the expected speed recovery time; This indicates the conversion factor for rotational speed recovery time; This represents the limiting function, used to limit the amplitude of the amplitude. Limit to preset upper and lower limits; The secondary fall safety reserve energy is obtained by integrating the secondary fall power demand over the expected speed recovery time, as shown in the equation: ， in, This indicates the safety reserve energy required for a second fall; This represents the safety reserve factor, used to compensate for forecast errors, wind power fluctuations, and load uncertainties.

5. The microgrid frequency regulation method for a hybrid energy storage system according to claim 1, characterized in that, The determination of secondary sag support power demand and safety reserve energy based on the microgrid, and the result of obtaining the secondary sag support demand, include: Based on the existing available power of all subsystems in the microgrid, the executable secondary sag support power and safety reserve energy of the microgrid are obtained, as shown in the equations: in, This indicates the secondary drop support power that the current system can perform under existing reserve conditions; This indicates the maximum power that the flywheel can currently output; This indicates the maximum output power of the lithium battery at present; This indicates the remaining power that the backup power supply can generate. This indicates the maximum power that can be cut off from the controllable load; This indicates the equivalent available supporting energy of the backup power supply; This indicates the equivalent available supporting energy for a controllable load; Indicates the duration of continuous backup power generation; Indicates the allowable continuous shearing time under controllable load; This represents the safe reserve energy that the current system can provide under existing reserve conditions; This indicates the flywheel's currently available energy; This indicates the current available energy of the lithium battery; This indicates the power that the flywheel-lithium battery hybrid energy storage can support; Based on the executable secondary sag support power and safety reserve energy of the microgrid, the power support margin of all subsystems and the overall support margin of the microgrid are obtained, as shown in the equation: ， in, The comprehensive support margin refers to the system's secondary drop support capability index, which is obtained by comprehensively considering the power margin, energy margin, and safety constraints of flywheel energy storage, lithium battery energy storage, backup power supply, and controllable load. This indicates the combined power, energy, and safety margin of the flywheel and lithium battery; This indicates the power support margin for backup power supplies and controllable loads; Indicates the minimum safe operating speed of the flywheel; This indicates the safest minimum state of charge for a lithium battery. These represent the margin weights for flywheel, lithium battery, backup power supply, and controllable load, respectively. Based on the comprehensive support margin, the risk threshold of the microgrid is obtained by the following equation: ， in, This represents the dynamic threshold for the risk of a second fall at the current moment; This represents the baseline threshold for the risk of a second fall. Represents the amplitude limiting function; This represents the support margin impact coefficient, used to characterize the degree of influence of the comprehensive support margin on the dynamic threshold of the second-fall risk. This represents the influence coefficient of the rate of frequency change, used to characterize the degree of influence of the rate of frequency change on the dynamic threshold of the risk of a second fall. This represents the frequency deviation influence coefficient, used to characterize the degree of influence of frequency deviation on the dynamic threshold of secondary fall risk; Based on the risk threshold of the microgrid and the secondary drop risk index, the activation status of secondary drop support is obtained. The equation for judging the activation status of secondary drop support is as follows: 。 6. The microgrid frequency regulation method for a hybrid energy storage system according to claim 1, characterized in that, Based on the assessment of secondary drop support requirements, a collaborative support scheme for the hybrid energy storage system is constructed, including: Based on the comprehensive support margin of the microgrid, the power support level of the microgrid is obtained by the following equation: ， in, Indicates the support level for a second drop; Indicates the normal support level; Indicates the level of limited support; Indicates the level of endangered status; Indicates the level of failure protection; Indicates the emergency low-frequency protection threshold; Indicates the threshold for the rate of decrease in emergency frequency; Based on the power support status level, the dynamic power contribution weights of the microgrid's subsystems are obtained, as shown in the equation: ， in, Indicates the original contribution weight of the flywheel; Indicates the original contribution weight of the lithium battery; This represents the flywheel response time constant; This represents the response time constant of a lithium battery; and This represents the safety status correction factor; Represents the amplitude limiting function; Based on the dynamic power contribution weights of the subsystems in the microgrid, the corrected dynamic power contribution weights of the subsystems are obtained, and the equation is as follows: ， in, This indicates the dynamic power contribution weight of flywheel energy storage at level G; This indicates the dynamic power contribution weight of lithium battery energy storage under level G; This represents the flywheel contribution correction factor at level G; This represents the lithium battery contribution correction factor at level G. Based on the corrected dynamic power contribution weights of the subsystems, the power allocation method of the microgrid subsystems is obtained, and the equation is as follows: ， in, This represents the reference allocated power for flywheel energy storage at level G; This indicates the reference power allocation for lithium batteries in the G category; This indicates the supported power output of the flywheel-lithium battery hybrid energy storage system at level G. This represents the power limiting factor for the flywheel and lithium battery in Class G.

7. The microgrid frequency regulation method for a hybrid energy storage system according to claim 1, characterized in that, The collaborative support scheme based on the hybrid energy storage system obtains the optimal support power for energy storage and load within the microgrid, including: Based on the hybrid energy storage support capability of the microgrid subsystem, the response time coupling quantity of the subsystem is obtained, and the equation is as follows: ， in, This represents the reference contribution coefficient of flywheel-lithium battery energy storage to the secondary drop in level G. Represents the natural exponential function; This represents the reference response time coupling amount determined by the dynamic power contribution weights of the flywheel and lithium battery at level G; This represents the flywheel response time constant; This represents the response time constant of a lithium battery; Based on the subsystem response time coupling, the reference value of the equivalent support power formed by the wind turbine recovery derating is obtained, and the equation is: ， in, This represents the reference factor for fan speed recovery derating under level G. Represents the amplitude limiting function; This represents the reference value for the fan speed recovery power under level G. This represents the reference value for the equivalent supporting power generated by the wind turbine's recovery derating under level G. This indicates a command to restore the original fan speed to its original power output. The derating participation factor for wind turbines in Class G is used for restoration. Obtain the equivalent support power reference value penalty term for the microgrid and combine it with the equivalent support power reference value to obtain the optimal support power.

8. The microgrid frequency regulation method for a hybrid energy storage system according to claim 1, characterized in that, After obtaining the optimal support power for energy storage and load within the microgrid, the collaborative support scheme based on a hybrid energy storage system further includes: Based on the reference range of the equivalent support power formed by the wind turbine recovery derating, a set of judgment equations for the wind turbine derating support power is established. The set of judgment equations is as follows: ， in, This refers to the portion of the derated support power that does not exceed the reference value for the equivalent derated support of the wind turbine recovery. This refers to the portion of the derated support power that exceeds the reference value for the wind turbine's restored derating equivalent support. Based on the correspondence between secondary drop support levels and frequency regulation response actions, the response modes of hybrid energy storage systems are obtained, including: When G(t)=1, the hybrid energy storage system is at the normal support level, and the support power of the flywheel energy storage system and the lithium battery energy storage system is: ， in, This indicates the reference support power for a secondary drop that the hybrid energy storage system under Level 1 can withstand in the current state; This indicates the reference support power for flywheel energy storage at Level 1; This indicates the reference support power for lithium battery energy storage under Level 1; When G(t)=2, at least one type of resource in the hybrid energy storage system, either the flywheel energy storage system or the battery energy storage system, is insufficient. The secondary drop support requirement is met by adjusting the contribution weight of the flywheel energy storage system or the battery energy storage system. The contribution weight adjustment equation is as follows: ， in, express Overall power, energy and safety margin of flywheel energy storage ; express Comprehensive energy storage of lithium batteries Combined power, energy and safety margin; like This reduces the flywheel output power and increases the lithium battery's ramp-up power; if This limits the continuous output of the lithium battery and increases the proportion of short-term flywheel support; When G(t)=3, the hybrid energy storage system cannot meet the secondary dropout support power demand. Microgrid adjustments are then jointly performed by the backup energy storage system and the hybrid energy storage system, including: The power boundary conditions for the flywheel energy storage system and the battery energy storage system are obtained by the following equations: ， in, This indicates the flywheel power limiting factor under the backup support level; This indicates the lithium battery power limiting factor under the backup support level; The reference range for the power cut-off of backup power and controllable load is obtained by the following equation: ， When G(t)=4, the hybrid energy storage system is in a fail-protection state, and the fail-protection control command is: ， in, This indicates the backup power supply protection control command under the failure protection level; This indicates an emergency load shedding control command under the failure protection level; This indicates the maximum output power of the backup power supply; This indicates the load power that needs to be cut off in an emergency. Based on the response mode of hybrid energy storage systems, a mixed-integer linear programming objective function for the quadratic drop power of hybrid energy storage systems is established.

9. A microgrid frequency regulation method for a hybrid energy storage system according to claim 8, characterized in that, The response method based on the hybrid energy storage system establishes a mixed-integer linear programming objective function for the quadratic drop power of the hybrid energy storage system, including: The power deficit penalty term for the hybrid energy storage system at level G is obtained from the following equation: ， in, This represents the power gap linearization penalty term that enters the objective function of the mixed-integer linear programming at level G. This indicates the number of power gap linearization segments at level G; This represents the q-th power gap segment variable under level G; This represents the slope of the q-th power gap segment penalty at level G; To obtain the wind turbine recovery depreciation penalty at level G, the equation is: ， in, This represents the wind turbine recovery derated linearization penalty term for entering the mixed-integer linear programming objective function at level G. This indicates the number of derating segments restored for wind turbines at level G; This represents the piecewise variable for the recovery of the derating of the s-th wind turbine under level G; This represents the slope of the s-th wind turbine's recovery depreciation segment penalty under level G; Based on the optimization variables in the hybrid energy storage system, the response time linear term in the hybrid integer pictographic programming model is obtained, and the equation is: ， in, This represents the linearized response time variable at level G; This indicates the secondary drop support power requirement for entering the rolling optimization model; express Flywheel response time constant ; express Lithium battery response time constant ; The ramp continuity of the backup power output power and the actual backup power output power in the previous sampling period is constrained by the following equation: ， in, Indicates the backup power supply ramp rate; Based on the shedding status of all controllable load blocks in the hybrid energy storage system, the controllable load shedding power is obtained, as shown in the equation: and , in, This represents the cut-off power of the Mth controllable load block under level G; This represents the cut-off power of the m-th controllable load block; This indicates the maximum power that can be cut off from the current controllable load; Based on the power allocation deviation variable, a linear constraint is established for the hybrid energy storage system, and the equation is as follows: ， in, This represents the flywheel energy storage power distribution deviation variable; This represents the variable indicating the deviation in the energy storage power distribution of lithium batteries; This represents the sum of the power distribution deviation variables between the flywheel and the lithium battery storage. Based on the available energy constraints of flywheel energy storage and battery energy storage, the available energy of the hybrid energy storage system is updated within the prediction time window, and the equation is as follows: ， in, Indicates the energy available to the flywheel at the next moment; Indicates the available energy of the lithium battery at the next moment; This indicates the safe energy threshold for flywheels and lithium batteries; The output power range of the battery energy storage system is uniformly divided to obtain the output power of the battery energy storage system, and the equation is as follows: ， in, This indicates the maximum allowable power for the first segment; Based on the loss slope of the battery energy storage system in the first segment, the linear equation for the loss of the battery energy storage system is obtained as follows: ， The objective function for the mixed-integer linear programming problem is: in, This represents the linearized objective function of the mixed-integer linear programming problem. This represents the power gap linearization penalty term; Represents the linearized response time variable; This represents a linear function of lithium battery loss. This indicates that the wind turbine has resumed the derating linearization penalty term; Indicates that the backup power supply is in Constant output power; This represents the cut-off power of the Mth controllable load block under level G; This represents the sum of the power distribution deviation variables between the flywheel and the lithium battery storage. Indicates the power gap error weight; Indicates response time weight; Indicates the weight of battery loss; This indicates the weight of the penalty for wind turbine speed recovery. Indicates the penalty weight for calling up backup power; Indicates the controllable load shedding penalty weight; This indicates the penalty weight for the power distribution deviation between the flywheel and the lithium battery.

10. A microgrid frequency regulation method for a hybrid energy storage system according to claim 1, characterized in that, The verification of the optimal power support for energy storage and load within the microgrid, and the determination of whether feedback correction is needed, includes: Based on the optimal support power, the actual frequency at the next sampling time is obtained; Based on the actual frequency at the next sampling time, obtain the frequency verification index, and determine whether feedback correction of the optimal support power is needed based on the frequency verification index.

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