A hybrid energy storage auxiliary thermal power unit secondary frequency modulation control method and system based on a multi-layer cooperative architecture

Abstract

The application discloses a kind of hybrid energy storage auxiliary thermal power unit secondary frequency modulation control method and system based on multi-layer cooperative architecture, belong to the technical field of power system frequency modulation control.This method upper layer according to AGC adjustment demand, thermal power unit output margin and hybrid energy storage overall state of charge calculates sharing coefficient, completes the dynamic power distribution between thermal power unit and hybrid energy storage system;Middle layer based on the smooth limiting function of state of charge continuous change calculation energy storage array available power, and according to the frequency modulation capacity index constituted by array average state of charge and internal discrete degree, execute flywheel array priority, lithium battery array supplement least array sequential power distribution;Lower layer with energy storage monomer equivalent state of charge deviation and array power variation amplitude as input, through fuzzy control correction energy storage monomer power distribution proportion.The application can improve AGC tracking performance, energy storage utilization, lithium battery life protection effect and energy storage monomer state of charge consistency simultaneously.

Description

Technical Field

[0001] This invention relates to the field of frequency regulation control technology in power systems, specifically to a method and system for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture. Background Technology

[0002] With the large-scale grid connection of new energy sources and the increasing uncertainty in power system operation, the power grid has placed higher demands on the secondary frequency regulation performance of thermal power units. While traditional thermal power units possess a certain power regulation capability, they are constrained by the dynamic response characteristics of boilers, turbines, and generators, resulting in limited ramp-up rates, response lag, and equipment fatigue due to frequent adjustments. To improve the tracking capability of thermal power units to Automatic Generation Control (AGC) commands, existing technologies typically introduce fast-regulating resources such as battery energy storage and flywheel energy storage to construct a combined thermal power and energy storage secondary frequency regulation system. However, in actual operation, thermal power units, flywheel energy storage, and lithium battery energy storage exhibit significant differences in response speed, energy capacity, cycle life, and state of charge (SOC) constraints. If simple differential allocation, fixed-ratio allocation, or single energy storage compensation strategies are still adopted, it is difficult to fully leverage the frequency regulation advantages of different devices, and this may even lead to frequent thermal power unit operations, accelerated lithium battery life degradation, and a decrease in the available power of the energy storage array. Specifically, existing technologies have at least the following three shortcomings.

[0003] First, existing methods for allocating power commands between thermal power units and energy storage systems mostly employ differential allocation or fixed-ratio allocation strategies. These strategies directly use the deviation between the AGC command and the measured power of the combined thermal power and energy storage system as the energy storage compensation power, or distribute the power between the thermal power unit and the energy storage system according to a preset ratio. While these methods are simple to implement, they typically do not fully consider the real-time output limits of the thermal power unit, its ramp-up capability, the overall state of charge (SOC) of the hybrid energy storage system, and the current frequency regulation capability of the energy storage system. When the thermal power unit is close to its upper or lower output limits, a fixed allocation strategy may still require the unit to undertake a large regulation task, leading to frequent unit actions or command inaction. When the SOC of the energy storage system is too high or too low, simple differential compensation can easily cause the energy storage to continue to bear inappropriate charging and discharging power, increasing the risk of overcharging, over-discharging, and protection lockout. Therefore, the lack of state-adaptive capability in the plant-level power coordination and allocation between the thermal power unit and the energy storage system is the primary challenge facing the secondary frequency regulation control of the combined thermal power and energy storage system.

[0004] Secondly, when existing hybrid energy storage systems participate in secondary frequency regulation, they are often treated as an equivalent whole, or power allocation is based solely on static parameters such as rated power and capacity, failing to fully differentiate the operating characteristics of flywheel energy storage and lithium battery energy storage. Flywheel energy storage has advantages such as high power density, fast response speed, and long cycle life, making it more suitable for handling rapid, frequent, small-amplitude frequency regulation power; lithium battery energy storage has characteristics such as large energy capacity and strong continuous support capability, making it more suitable for handling the remaining regulation needs that flywheel arrays cannot fully cover. If a unified dispatch or average allocation method is adopted without distinguishing the characteristics of the two, it is easy to cause frequent high-power operation of lithium batteries, shortening their cycle life; at the same time, it is difficult to select the most suitable participating array based on the SOC level, internal dispersion, and available power in the current direction of each energy storage array. Therefore, how to comprehensively consider the array frequency regulation capability, power limiting, and differences in energy storage type in mid-level control, and achieve flywheel priority, lithium battery supplementation, and minimal array participation, is a key issue in improving the utilization efficiency and lifespan friendliness of hybrid energy storage.

[0005] Third, within the energy storage array, different energy storage cells are prone to significant SOC deviations due to differences in initial state, operating conditions, aging levels, and charge / discharge histories. In actual operation, if the SOC difference between energy storage cells continues to widen, high-SOC cells may reach their upper limit prematurely during charging, while low-SOC cells may reach their lower limit prematurely during discharging, causing some cells to prematurely exit the frequency regulation process. This not only reduces the actual usable power of the energy storage array but may also cause fluctuations in the array's output power due to random cell exits, weakening the hybrid energy storage system's continuous tracking capability of AGC commands. Existing cell control methods that allocate power based on capacity or power ratios often struggle to simultaneously meet array power commands and ensure cell SOC balance. Therefore, how to dynamically adjust the cell power allocation ratio in the lower-level control based on cell SOC deviations and array power changes to improve the consistency of energy storage cell SOC is another important challenge to ensure the long-term stable participation of the energy storage array in secondary frequency regulation. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a method and system for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture. This method employs a three-layer collaborative control approach: upper-layer coordinated power allocation of thermal power and energy storage, middle-layer sequential power allocation of hybrid energy storage, and lower-layer SOC consistency power correction for individual energy storage units. This approach simultaneously improves the AGC tracking performance of the thermal power and energy storage combined system, the utilization rate of hybrid energy storage frequency regulation capabilities, the lithium battery life protection effect, and the SOC consistency of individual energy storage units.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] On one hand, the present invention provides a method for secondary frequency regulation control of a hybrid energy storage-assisted thermal power unit based on a multi-layer collaborative architecture, applicable to a combined thermal power unit and a hybrid energy storage system, wherein the hybrid energy storage system includes at least one flywheel energy storage array and at least one lithium battery energy storage array, each energy storage array including multiple energy storage cells, and the method includes the following steps:

[0009] S1. Collect the operation data of the combined thermal power and energy storage system and construct a data pool. The data pool includes at least AGC commands, the measured total active power output of the combined thermal power and energy storage system, the measured power of the thermal power unit, the upper and lower limits of the output of the thermal power unit, the ramp rate of the thermal power unit, the state of charge of each energy storage unit, and the overall state of charge of the hybrid energy storage system.

[0010] S2. Calculate the regulation demand of the combined thermal power and energy storage system, the upward adjustment margin of thermal power units, the downward adjustment margin of thermal power units, and the discharge availability coefficient and charging availability coefficient of the hybrid energy storage system based on the data pool.

[0011] S3. The upper-level thermal power coordination and allocation module determines the sharing coefficient between the thermal power unit and the hybrid energy storage system based on the upward or downward adjustment margin of the thermal power unit and the available charging and discharging power of the hybrid energy storage system. The adjustment demand is dynamically allocated between the thermal power unit and the hybrid energy storage system, and the power command of the thermal power unit and the total power command of the hybrid energy storage system are generated.

[0012] S4. The middle-layer hybrid energy storage sequential power allocation module calculates the maximum discharge power and maximum rechargeable power of each energy storage cell based on a smooth limiting function that changes continuously with the state of charge, and accumulates them according to the current power direction to obtain the current available power of each energy storage array.

[0013] S5. The mid-layer hybrid energy storage sequential power allocation module calculates the frequency regulation capability index for each energy storage array. The frequency regulation capability index is jointly determined by the array's average state of charge and the dispersion of the state of charge within the array. The flywheel energy storage arrays are sorted according to the frequency regulation capability index. The minimum number of flywheel energy storage arrays whose sum of available power in the current direction meets the hybrid energy storage power demand amplitude is selected, and a flywheel energy storage array power command is generated. Only when the sum of available power in the current direction of all flywheel energy storage arrays still cannot meet the power demand amplitude, all flywheel energy storage arrays are made to work according to the available power in the current direction. The lithium battery energy storage arrays are sorted according to the frequency regulation capability index. The minimum number of lithium battery energy storage arrays that can bear the remaining power amplitude is selected, and a lithium battery energy storage array power command is generated. Thus, the array power command of each selected energy storage array is obtained.

[0014] S6. The lower-level SOC consistency power correction module takes the energy storage unit equivalent state of charge deviation and the normalized value of the array power change amplitude as the input of the fuzzy controller for each selected energy storage array, and outputs the energy storage unit power correction coefficient. Based on the energy storage unit power correction coefficient and the energy storage unit's current directional available power, the array power command is allocated to each energy storage unit within the energy storage unit's amplitude limit constraint to obtain the energy storage unit power command.

[0015] S7. The power command of the thermal power unit is sent to the thermal power unit for execution, the power command of the energy storage unit is sent to the corresponding energy storage unit for execution, and the execution feedback data is returned to the data pool as the input for the next control cycle.

[0016] Further, in step S2, the regulation demand of the combined thermal power and energy storage system is determined by the difference between the AGC command and the measured total active power output of the combined thermal power and energy storage system; the upward adjustment margin of the thermal power unit is the smaller of the product of the unit's distance from the maximum allowable output and the upward ramp rate and the control step size, and is taken as the larger of the two; the downward adjustment margin of the thermal power unit is the smaller of the product of the unit's distance from the minimum allowable output and the downward ramp rate and the control step size, and is taken as the larger of the two; the discharge availability factor and the charging availability factor are calculated based on the relative position of the overall state of charge of the hybrid energy storage system within the allowable state of charge range, and are limited to the range of 0 to 1.

[0017] Further, in step S3, the available discharge power of the hybrid energy storage system is the product of the discharge availability coefficient and the rated maximum discharge power, and the available charging power is the product of the charging availability coefficient and the rated maximum charging power. When adjusting upwards, the sharing coefficient is determined according to the ratio of the upward adjustment margin of the thermal power unit to the available discharge power of the hybrid energy storage system; when adjusting downwards, the sharing coefficient is determined according to the ratio of the downward adjustment margin of the thermal power unit to the available charging power of the hybrid energy storage system. The adjustment amount of the power command of the thermal power unit does not exceed the margin in its corresponding direction. The adjustment demand not undertaken by the thermal power unit is made up by the hybrid energy storage system, and the total power command of the hybrid energy storage system does not exceed the available charging and discharging power in its current direction.

[0018] Furthermore, in step S4, the smoothing limiting function adopts an S-shaped curve that continuously changes with the state of charge: when the state of charge is in the normal operating range, the energy storage unit can participate in frequency regulation at the rated power; when the state of charge is lower than the low warning value and approaches the lower limit of allowable power, the maximum discharge power continuously decreases to zero along the S-shaped curve; when the state of charge is higher than the high warning value and approaches the upper limit of allowable power, the maximum rechargeable power continuously decreases to zero along the S-shaped curve.

[0019] Further, in step S5, the frequency modulation capability index is the product of the array's average state of charge minus the dispersion penalty coefficient and the standard deviation of the array's internal state of charge; in the discharge state, the frequency modulation capability index is sorted from largest to smallest, and in the charging state, the frequency modulation capability index is sorted from smallest to largest; the power command of the unselected energy storage array is zero.

[0020] Furthermore, in step S6, the fuzzy rules are set as follows: the smaller the range of array power change, the greater the deviation of the energy storage unit power correction coefficient from the reference value 1, so as to enhance the SOC equalization correction effect; the greater the range of array power change, the more the energy storage unit power correction coefficient converges to the reference value 1, so as to prioritize ensuring the array power tracking accuracy; the correction coefficient remains at 1 when the equivalent state of charge deviation is close to zero; the weighted average method is used to resolve fuzziness; if some energy storage units touch the limit, resulting in residual array power, the residual is redistributed only among the energy storage units that have not touched the limit according to the proportion of remaining available power.

[0021] Furthermore, in step S7, if the state of charge exceeds the limit or the equipment fails on the energy storage side, the corresponding energy storage array or energy storage unit will be removed from the candidate set, and the process will return to step S4 to recalculate the power limit and array sorting.

[0022] On the other hand, this invention provides a hybrid energy storage-assisted secondary frequency regulation control system for thermal power units based on a multi-layer collaborative architecture, including a remote control unit, a plant-level coordination controller, a thermal power unit coordination control system, an energy storage management system, and a power conversion system. The remote control unit is used to access AGC commands from the dispatch center. The plant-level coordination controller deploys an upper-level thermal power-storage power coordination and allocation module to perform dynamic power allocation between the thermal power unit and the hybrid energy storage system. The energy storage management system deploys a mid-level hybrid energy storage sequential power allocation module and a lower-level SOC consistency power correction module to perform energy storage array sorting and selection and energy storage unit power allocation. The thermal power unit coordination control system executes power commands from the thermal power unit. The power conversion system executes power commands from individual energy storage units. The control system is configured to execute the aforementioned hybrid energy storage-assisted secondary frequency regulation control method for thermal power units based on a multi-layer collaborative architecture.

[0023] The beneficial effects of this invention are:

[0024] Firstly, the upper-level thermal power coordination and allocation module dynamically determines the sharing coefficient based on the real-time output margin of the thermal power unit and the overall SOC availability coefficient of the hybrid energy storage. When the output margin of the thermal power unit is sufficient, it undertakes more adjustment tasks. When it is close to the output boundary or the ramp-up capability is insufficient, the hybrid energy storage undertakes more compensation power. When the overall SOC of the hybrid energy storage is not suitable for continued charging and discharging, its participation ratio is automatically reduced. This avoids the thermal power unit undertaking unreasonable adjustment tasks when it is close to the output boundary, and also avoids the energy storage system being forced to charge and discharge when the SOC is not suitable. This significantly improves the state adaptive capability of plant-level power allocation and the executability of AGC commands.

[0025] Secondly, the mid-layer hybrid energy storage sequential power allocation module constructs a frequency regulation capability index jointly determined by the array's average state of charge and the dispersion of the state of charge within the array. The sequencing process considers both the array's SOC level and the consistency level of individual cells, avoiding the use of arrays with large internal dispersion and weak actual sustainability. Based on this, a minimum array sequential selection is implemented, prioritizing flywheel energy storage arrays and supplementing with lithium battery energy storage arrays. This fully utilizes the high power density, fast response speed, and long cycle life of flywheels to handle rapid and frequent frequency regulation power. Lithium battery arrays are only used when the entire flywheel array is deployed and still cannot meet the demand, significantly reducing the number of high-power operations of lithium batteries and lowering their lifespan. The minimum array participation strategy also reduces the number of ineffective operations of energy storage devices, improving the overall frequency regulation capability utilization rate of the hybrid energy storage system.

[0026] Third, the power limiting of individual energy storage cells adopts an S-shaped smooth limiting function that changes continuously with the SOC, avoiding sudden changes in power command near the SOC boundary, reducing the risk of overcharging, over-discharging, and protection lockout of individual cells, and enabling the energy storage array to maintain continuous and controllable adjustment capability within the safety constraints.

[0027] Fourth, the lower-level SOC consistency power correction module uses the equivalent SOC deviation of the energy storage unit and the array power change amplitude as dual inputs to the fuzzy controller. When the array power change is small, it enhances the SOC equalization correction effect. When the array power change is large, it makes the correction coefficient converge to the reference value to prioritize power tracking accuracy, thus forming a dynamic coordination between frequency modulation power tracking and unit SOC equalization. Moreover, the fuzzy correction only changes the power allocation ratio within the feasible domain determined by the energy storage unit's amplitude limit constraint, without breaking the energy storage unit's protection boundary. Combined with the residual redistribution mechanism, it ensures the complete execution of the array power command, enabling the flywheel array and lithium battery array to maintain higher consistency, availability, and power output stability during long-term operation.

[0028] Fifth, by implementing a feedback and fault elimination mechanism to form a closed loop, when the energy storage side experiences a limit violation or fault, the corresponding array or cell is automatically eliminated and the limit and sorting are recalculated, ensuring the continuity and robustness of the control link. Attached Figure Description

[0029] Figure 1 A schematic diagram of the multi-layer collaborative control architecture of the hybrid energy storage-assisted thermal power unit secondary frequency regulation control method based on a multi-layer collaborative architecture provided in an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the charging and discharging power limiting function of a single energy storage cell provided in an embodiment of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be further clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment provides a hybrid energy storage-assisted secondary frequency regulation control method for thermal power units based on a multi-layer collaborative architecture, applicable to a combined thermal power unit and a hybrid energy storage system. The hybrid energy storage system includes at least one flywheel energy storage array and at least one lithium battery energy storage array, each array comprising multiple energy storage units; for the flywheel energy storage array, each energy storage unit is a flywheel energy storage cell, and for the lithium battery energy storage array, each energy storage unit is a lithium battery energy storage cell. Figure 1 As shown, this method relies on a multi-layered collaborative control architecture, which includes an upper-layer thermal power-storage power coordination and allocation module, a middle-layer hybrid energy storage sequential power allocation module, and a lower-layer SOC consistency power correction module. The execution entities of the method include Remote Terminal Units (RTUs), Plant Energy Coordination Control Systems (PECCS), Distributed Control Systems (DCS), Energy Management Systems (EMS), and Power Conversion Systems (PCS). The upper-layer thermal power-storage power coordination and allocation module is deployed in the PECCS, while the middle-layer hybrid energy storage sequential power allocation module and the lower-layer SOC consistency power correction module are deployed in the EMS. This method achieves coordinated response of thermal power units, power-type flywheel energy storage arrays, and energy-type lithium battery energy storage arrays to AGC commands through a control link of "scheduling command access—plant-level thermal power-storage power allocation—hybrid energy storage array sorting—energy storage unit consistency allocation—execution feedback."

[0034] Unlike single-battery energy storage-assisted frequency regulation of thermal power plants, this method prioritizes flywheel energy storage arrays as the primary response resource. Leveraging their high power density, fast response speed, and long cycle life, flywheel arrays handle rapid and frequent frequency regulation power. When the flywheel array is constrained by power limiting or SOC boundaries and cannot fully meet regulation demands, the remaining power is then utilized by the lithium battery array. This reduces the frequency of high-power operations by the lithium battery array, lowers lithium battery lifespan, and improves the thermal power-storage integrated system's ability to track AGC commands.

[0035] The method includes steps S1 to S7, which are described in detail below.

[0036] S1. Collect operational data from the combined fire and energy storage system and construct a data pool.

[0037] The main entities executing this step are RTU, EMS, PCS, and DCS. The input is the real-time status information of the combined fire and energy storage system, and the output is a data pool. The goal is to establish a unified state data pool required for subsequent control calculations.

[0038] Among them, RTU provides AGC instructions. Measured total active power output of the combined thermal power and energy storage system The measured power is obtained directly from the grid connection point power measurement device; the DCS provides the actual measured power of the thermal power unit. The rate of ascent for thermal power units Downhill / climbing speed and the maximum allowable output of thermal power units and minimum allowable output PCS provides the measured power of the energy storage system; EMS provides the state of charge of each flywheel energy storage array, each lithium battery energy storage array, and each energy storage cell. Overall state of charge of hybrid energy storage system And the protection status of energy storage devices. This information is then aggregated into a data pool. .

[0039] Among them, the overall state of charge of the hybrid energy storage system The control step size can be obtained by weighting statistics of each energy storage array according to the rated capacity of EMS. Keep it consistent with the AGC control cycle, for example, take 1 s to 10 s.

[0040] S2. Calculate the regulation demand of the combined thermal power and energy storage system, the output margin of the thermal power unit, and the overall SOC availability factor of the hybrid energy storage system.

[0041] The main entity executing this step is the upper-level thermal power coordination and allocation module, and the input is the data pool. The output is for adjusting the demand. Thermal power unit upward adjustment margin Lowering the margin Discharge availability factor and charging availability factor .

[0042] This step does not directly issue control commands, but instead completes the plant-level frequency regulation capability assessment. If the AGC command is higher than the measured power of the combined system, it indicates that the combined system needs to increase active power output; if the AGC command is lower than the measured power of the combined system, it indicates that the combined system needs to reduce active power output. The adjustability of a thermal power unit is determined by both its output boundary and ramp-up capability, while the adjustability of a hybrid energy storage system is determined by its overall SOC.

[0043] AGC adjustment requirements are expressed as follows:

[0044]

[0045] In the formula, The AGC regulation power that the combined fire and energy storage system needs to undertake; For AGC instructions; This represents the measured total active power output of the combined thermal power and energy storage system. If... This indicates that the system needs to increase its active power output; if This indicates that the system needs to reduce its active power output.

[0046] The upward adjustment margin for thermal power units is expressed as follows:

[0047]

[0048] In the formula, This represents the margin of upward power adjustment that thermal power units can handle. This is the maximum allowable output of the thermal power unit; This represents the measured power output of the thermal power unit. The rate at which the thermal power unit climbs an incline; To control the step size.

[0049] The downward adjustment margin for thermal power units is expressed as follows:

[0050]

[0051] In the formula, This represents the downward power reduction margin that thermal power units can withstand. This is the minimum allowable output of a thermal power unit; This represents the downhill climbing rate of the thermal power unit.

[0052] The discharge availability factor and charge availability factor of hybrid energy storage are expressed as follows:

[0053]

[0054] In the formula, The overall state of charge of the hybrid energy storage system; and These are the lower and upper limits of the permissible state of charge for energy storage, respectively. Characterizes the discharge availability of a hybrid energy storage system; Characterizes the charging availability of hybrid energy storage systems; Indicates will Limited to the interval between 0 and 1, that is, when When 0 is taken, Take 1 if it is true, otherwise take 1. It itself. In a specific example, Take 0.1, Take 0.9.

[0055] S3. Execute dynamic allocation of power between upper-level thermal power and hybrid energy storage.

[0056] The main entity executing this step is the upper-level thermal power coordination and allocation module, and the input is... , , , and The output is the power command of the thermal power unit. Total power command for hybrid energy storage systems .

[0057] The upper-level thermal power coordination and allocation module determines the sharing ratio of regulation demand between the thermal power unit and the hybrid energy storage system based on the adjustable space of the thermal power unit and the overall state of the energy storage: when the output margin of the thermal power unit is sufficient, the unit undertakes more regulation tasks; when the thermal power unit is close to the output boundary or has insufficient ramping ability, the hybrid energy storage undertakes more compensation power; when the overall SOC of the hybrid energy storage is not suitable for continued charging and discharging, its participation ratio automatically decreases.

[0058] The available discharge power and available charging power of a hybrid energy storage system are expressed as follows:

[0059]

[0060] In the formula, and These refer to the available discharge power and available charging power of the hybrid energy storage system, respectively. and These are the rated maximum discharge power and rated maximum charging power of the hybrid energy storage system, respectively.

[0061] when At that time, the thermal power unit performs upward adjustment, and the hybrid energy storage system performs discharge. The sharing factor between the two is:

[0062]

[0063] In the formula, This refers to the thermal power unit sharing coefficient under the upward adjustment state; The discharge sharing factor for hybrid energy storage; To prevent extremely small positive numbers with a denominator of zero, for example, take .

[0064] The power command for thermal power units under the upward adjustment state is:

[0065]

[0066] In the formula, This is the power command for thermal power units. This formula ensures that the upward adjustment of thermal power units does not exceed their available upward adjustment margin.

[0067] The total power command for the hybrid energy storage system under the upward adjustment state is:

[0068]

[0069] In the formula, This is the total power command for the hybrid energy storage system. This formula indicates that the increased demand not undertaken by the thermal power units will be supplemented by the hybrid energy storage system, but it must not exceed the available discharge power of the hybrid energy storage.

[0070] when At that time, the thermal power unit implements a power reduction, and the hybrid energy storage system implements charging. The sharing factor between the two is:

[0071]

[0072] In the formula, The sharing factor of the thermal power unit under the reduced state; The charging sharing factor for hybrid energy storage.

[0073] The power command for thermal power units under reduced power conditions is as follows:

[0074]

[0075] In the formula, This formula is used to reduce the power demand. It ensures that the reduction in power demand for thermal power units does not exceed their available reduction margin.

[0076] The total power command for the hybrid energy storage system under reduced power conditions is:

[0077]

[0078] In the formula, the negative sign indicates that the hybrid energy storage system is in a charging state.

[0079] It should be noted that when the sum of the thermal power unit's margin and the available charging and discharging power of the hybrid energy storage is still less than the adjustment demand amplitude, the thermal power-storage combined system operates at its maximum executable capacity, and the remaining deviation is left to be absorbed in subsequent control cycles, thereby ensuring that the issued commands are always within the executable range. At that time, the power command of the thermal power unit remains at the current measured power, and the total power command of the hybrid energy storage system is zero.

[0080] S4. Calculate the power limiting of individual energy storage cells and energy storage arrays.

[0081] The main entity executing this step is the mid-layer hybrid energy storage sequential power allocation module, and the input is the total power command of the hybrid energy storage system. and data pool The state of charge of each energy storage cell is represented by the output, which is the maximum discharge power of each energy storage cell. Maximum rechargeable power and the The available power of an energy storage array under the current power direction .

[0082] To prevent overcharging and over-discharging of energy storage, boundary constraints on energy storage output need to be established, and an energy storage power limiting function is designed for this purpose. This limiting function adopts an S-shaped smooth curve that changes continuously with the State of Charge (SOC): when the SOC is in the normal operating range, the energy storage unit can participate in frequency regulation according to its rated power; when the SOC approaches the lower limit, the maximum discharge power gradually decreases; when the SOC approaches the upper limit, the maximum chargeable power gradually decreases.

[0083] The maximum discharge power of a single energy storage cell is expressed as:

[0084]

[0085] In the formula, For the first The first energy storage array The maximum discharge power of each energy storage cell; This represents the state of charge of the individual energy storage unit; This is the rated discharge power of the energy storage unit; This is a low-level warning value for the state of charge. This is the smoothing coefficient for the discharge transition region; It is an exponential function with the natural constant as its base.

[0086] The maximum rechargeable power of a single energy storage cell is expressed as:

[0087]

[0088] In the formula, For the first The first energy storage array The maximum rechargeable power of each energy storage unit; This is the rated charging power of the energy storage unit; This is a high-level warning value for the state of charge. This is the smoothing coefficient for the charging transition region.

[0089] The above power limiting function graph is as follows Figure 2 As shown. In a specific example, Take 0.1, Take 0.2, Take 0.8, Take 0.9, and All are set to 10. The above parameters can be adjusted according to the type of energy storage device and project requirements. For example, for flywheel energy storage cells whose cycle life is almost unaffected by the depth of charge and discharge, and , and The spacing can be set to be even smaller.

[0090] The power command for a single energy storage cell must meet the following requirements:

[0091]

[0092] In the formula, To ultimately issue power commands to individual energy storage cells, the discharge power is specified as positive and the charging power as negative. This constraint ensures that neither the flywheel energy storage cell nor the lithium battery energy storage cell exceeds their safe operating boundaries.

[0093] The available power in the current direction of the energy storage array is expressed as:

[0094]

[0095] In the formula, For the first The available power of each energy storage array in the current power direction. If the hybrid energy storage system is in a discharging state, the maximum discharge power of each energy storage cell in the array is accumulated; if it is in a charging state, the maximum chargeable power of each energy storage cell in the array is accumulated. Accordingly, the available power of each energy storage cell in the current direction is denoted as... Take during discharge Take out while charging .

[0096] This smooth attenuation mechanism avoids abrupt changes in power command near the SOC boundary, reduces the risk of overcharging, over-discharging, and protection lockout of individual cells, and enables the energy storage array to maintain continuous and controllable regulation capability within safety constraints, thereby improving the reliability of subsequent array sequencing and individual cell power allocation.

[0097] S5. Perform mid-layer hybrid energy storage array sorting and minimum array selection.

[0098] The main entity executing this step is the mid-level hybrid energy storage sequential power allocation module. The PECCS provides the EMS with the total power command of the hybrid energy storage system output by S3. The EMS receives the available power of the energy storage array in the current direction output by S4, and internally completes the frequency regulation capability calculation, array sorting and minimum array selection of the flywheel energy storage array and lithium battery energy storage array, forming an array-level power command and sending it to the PCS.

[0099] The input for this step is the total power command of the hybrid energy storage system. and the available power in the current direction of each energy storage array The output is the power command for the flywheel energy storage array. Power commands for lithium battery energy storage array The selected set of energy storage arrays and the array power command in a unified notation. .

[0100] The mid-layer hybrid energy storage sequential power allocation module first calculates the frequency regulation capability index for both the flywheel energy storage array and the lithium battery energy storage array. Then, based on the characteristics of flywheels—long lifespan, fast response speed, and suitability for frequent power adjustments—the flywheel energy storage array is prioritized. If the power demand still cannot be met after all flywheel energy storage arrays are deployed, the lithium battery energy storage array is further utilized, and selection continues within the lithium battery energy storage array based on frequency regulation capability index. This strategy essentially prioritizes the flywheel energy storage array as the primary response resource and uses the lithium battery energy storage array as a supplementary energy resource, thus balancing response speed and energy storage lifespan.

[0101] The frequency modulation capability of an energy storage array is expressed as follows:

[0102]

[0103] In the formula, For the first Frequency modulation capability indicators of an energy storage array; The average state of charge of the energy storage array is obtained directly from the EMS or through statistical analysis. This represents the degree of dispersion of the state of charge within the energy storage array; This is the dispersion penalty coefficient, for example, 0.5. Under discharge conditions, A larger value indicates a higher array SOC level and lower dispersion, making it more suitable for preferential discharge; during charging, The smaller the value, the lower the array's SOC level and the larger the charging space, making it more suitable for priority charging.

[0104] The dispersion of the state of charge within the array is represented by the standard deviation of the state of charge of each energy storage cell within the array:

[0105]

[0106] In the formula, For the first The number of individual energy storage cells in an energy storage array. Introducing a dispersion penalty term into the frequency regulation capability index can avoid prioritizing the use of energy storage arrays with large internal SOC dispersion and some cells that are prone to prematurely reaching the boundary, thereby reducing the risk of array output power fluctuations caused by premature cell exit from the source.

[0107] The power demand amplitude of hybrid energy storage is expressed as follows:

[0108]

[0109] In the formula, This refers to the power demand amplitude that the hybrid energy storage system needs to handle.

[0110] EMS first integrates flywheel energy storage array The order is based on frequency modulation capability: during discharge, according to... Sort by largest to smallest, and charge according to... Sort the data in ascending order. After sorting, select the minimum number of flywheel energy storage arrays required to meet the power demand:

[0111]

[0112] In the formula, The minimum number of flywheel energy storage arrays required to meet power requirements; The first order of flywheel energy storage array Each array number; This represents the current available power in the direction of the flywheel energy storage array.

[0113] If the flywheel energy storage array can meet the power requirements, then only the first element after sorting is called. One flywheel energy storage array; lithium battery energy storage arrays are not included. The power command for the selected flywheel energy storage array is expressed as:

[0114]

[0115] In the formula, For the first Power commands for a flywheel energy storage array; This is a sign function, taking the value 1 when the independent variable is positive and -1 when it is negative, used to maintain the direction of the array power command consistent with the direction of the total power command of the hybrid energy storage system. For the selected flywheel energy storage array, its unified notation array power command is denoted as... .

[0116] If the sum of the available power in the current direction of all flywheel energy storage arrays is still insufficient to meet the power demand, then each flywheel energy storage array will operate according to the available power in the current direction, and the remaining power will be calculated:

[0117]

[0118] In the formula, This refers to the remaining power amplitude that the lithium battery energy storage array still needs to handle after the flywheel energy storage array is fully operational. ; For the first The flywheel energy storage array has available power in the current direction.

[0119] EMS is then integrated into the lithium battery energy storage array. The lithium battery energy storage arrays are sorted according to the same rules based on their frequency regulation capability, and the minimum number of arrays required to meet the remaining power demand is selected:

[0120]

[0121] In the formula, The minimum number of lithium battery energy storage arrays required to meet the remaining power demand; The first after sorting the lithium battery energy storage array Each array number; This represents the current available power in the direction of the lithium battery energy storage array.

[0122] The selected lithium battery energy storage array power command is represented as follows:

[0123]

[0124] In the formula, For the first The power command for each lithium-ion battery energy storage array. The power command for an unselected lithium-ion battery energy storage array is zero. For the selected lithium-ion battery energy storage array, its array power command, in standardized notation, is denoted as... .

[0125] If the power demand cannot be met after all flywheel energy storage arrays and all lithium battery energy storage arrays are put into operation, then all energy storage arrays will operate at the available power in the current direction, and the remaining deviation will be absorbed in subsequent control cycles.

[0126] S6. Perform SOC consistency control on lower-level energy storage units.

[0127] The main execution unit for this step is the lower-level SOC consistency power correction module, and the input is the array power command. State of charge of each energy storage unit The power command of the array in the previous control cycle and the available power in the current direction of the array The output is the power command of the energy storage unit. .in, Take the power command or actual power executed in the previous control cycle of the array, and set it to 0 at the initial moment.

[0128] The lower-level SOC consistency power correction module dynamically adjusts the degree to which a single cell bears power in the current direction based on the relative relationship between the individual cell SOC and the array's average SOC: in discharge mode, cells with higher SOC appropriately increase their output, while cells with lower SOC appropriately decrease their output; in charging mode, cells with lower SOC appropriately increase their power absorption, while cells with higher SOC appropriately decrease their power absorption. Simultaneously, the fuzzy controller incorporates the array power variation amplitude as an auxiliary input: when the power variation is small, it enhances the SOC equalization correction; when the power variation is large, it causes the correction coefficient to converge towards the reference value, prioritizing array power tracking accuracy. Through this design, coordination can be achieved between frequency-modulated power tracking and individual cell SOC equalization, enabling flywheel energy storage arrays and lithium battery energy storage arrays to maintain higher consistency, availability, and power output stability during long-term operation. Since S4 has already calculated the maximum rechargeable power and maximum dischargeable power of each energy storage cell, the fuzzy control only changes the power allocation ratio within the feasible region and does not exceed the protection boundaries of the energy storage cells.

[0129] The normalized value of the power variation amplitude of the energy storage array is expressed as:

[0130]

[0131] In the formula, For the first Normalized values ​​of power variation amplitude of each energy storage array; This is the power command for the energy storage array; This refers to the power command for the array in the previous control cycle. This represents the available power in the current direction for this array.

[0132] The equivalent SOC deviation of a single energy storage cell is expressed as:

[0133]

[0134] In the formula, For the first The first energy storage array The equivalent SOC deviation of each energy storage cell. If This indicates that the single cell is more suitable to handle the power in the current direction; if This indicates that the power of the unit should be reduced in the current direction.

[0135] Fuzzy controller and As input, the energy storage unit power correction coefficient is used. This is the output. The fuzzy sets are NB, NS, ZE, PS, and PB, which represent obviously unsuitable, slightly unsuitable, close to the mean, relatively suitable, and obviously suitable to bear the power in the current direction, respectively. Let the fuzzy sets be S, M, and B, representing small power change, medium power change, and large power change, respectively.

[0136] In a specific example Domain of discourse NB, NS, ZE, PS, and PB use triangular membership functions, with their centers located at -0.2, -0.1, 0, 0.1, and 0.2, respectively. The membership functions of adjacent sets overlap, and the sum of the membership degrees of each set at any input is 1. NB has a membership degree of 1 in the region less than -0.2, and PB has a membership degree of 1 in the region greater than 0.2. Domain of discourse S, M, and B use triangular membership functions, with their centers at 0, 0.5, and 1, respectively. The form and parameters of the membership functions can also be adapted to other forms such as trapezoidal or Gaussian functions, depending on the engineering requirements.

[0137] The fuzzy rule table is shown in Table 1.

[0138] Table 1 Fuzzy Rule Table (Consequence Quantization Value) )

[0139] Equivalent SOC deviation / Power variation amplitude S: Small change M: In flux B: Significant changes NB: Clearly unsuitable 0.55 0.55 0.80 NS: Slightly unsuitable 0.55 0.80 0.80 ZE: Close to the mean 1.00 1.00 1.00 PS: More suitable 1.20 1.20 1.00 PB: Clearly suitable 1.45 1.20 1.20

[0140] The design principle of this fuzzy rule table is as follows: when the power change is small, the SOC consistency correction can be stronger, and the correction coefficient deviates more from the baseline value of 1; when the power change is large, the correction coefficient converges towards 1 to prioritize array power tracking; when the individual unit SOC is close to the array average value, the baseline ratio is maintained regardless of the power change magnitude. The subsequent quantization values ​​in Table 1 are a specific example and can be adjusted according to the characteristics of the energy storage device and engineering needs, provided that the above design principles are met.

[0141] The weighted average method is used to resolve the fuzziness, and the power correction coefficient of the energy storage unit is obtained:

[0142]

[0143] In the formula, For the first The first energy storage array Power correction factor for each energy storage unit; For the equivalent SOC deviation Membership function of a fuzzy set; The power change amplitude Membership function of a fuzzy set; For the equivalent SOC deviation in the fuzzy rule table The fuzzy set and the power change amplitude The quantized value of the consequent of a fuzzy set corresponding to a rule.

[0144] The initial power command of a single energy storage cell after fuzzy correction is expressed as follows:

[0145]

[0146] In the formula, For the first The first energy storage array Initial power command for each energy storage unit; This represents the available power in the current direction of the energy storage cell, taken during discharge. Take out while charging Summation index Iterate through all the individual energy storage cells in the energy storage array.

[0147] The final energy storage unit power command is expressed as follows:

[0148]

[0149] In the formula, This is the final power command issued to the individual energy storage units.

[0150] If some individual energy storage cells reach their limits, resulting in a residual power in the array, the EMS will redistribute this residual power among the energy storage cells that did not reach their limits, based on the proportion of remaining usable power. Taking the discharge state as an example, the array power residual is expressed as:

[0151]

[0152] In the formula, For the first The power residual of each energy storage array. For individual energy storage cells that have not reached the limit, the power command is corrected as follows:

[0153]

[0154] In the formula, For the first The set of energy storage cells in an energy storage array that have not reached their limits. During charging, they are processed in the same way according to power amplitude, that is, the remaining available power is proportionally allocated based on the difference between the maximum rechargeable power and the allocated charging power amplitude. This redistribution process can be performed iteratively until the residual is less than the allowable deviation or all energy storage cells reach their limits.

[0155] S7. Issue control commands and generate the next round of feedback.

[0156] The main entities executing this step are RTU, PECCS, EMS, PCS, and DCS. Specifically, the RTU is responsible for continuing to receive AGC commands from the dispatch center; the PECCS is responsible for issuing plant-level power commands to thermal power units and hybrid energy storage systems; the DCS is responsible for executing power commands from thermal power units; the EMS is responsible for organizing commands for energy storage arrays and individual energy storage units; and the PCS is responsible for executing energy storage power commands.

[0157] The input for this step is the power command for the thermal power unit. and energy storage cell power command The output includes the operating power of the thermal power unit, the operating power of the flywheel energy storage array, the operating power of the lithium battery energy storage array, and the measured total active power output of the thermal power-storage combined system. Measured power of thermal power units Overall state of charge of hybrid energy storage system Energy storage cell state of charge And the protection status of energy storage devices.

[0158] Specifically, PECCS sends the power command of the thermal power unit to DCS and the total power command of the hybrid energy storage system to EMS; EMS sends the power commands of the individual energy storage units of the flywheel energy storage array and the lithium battery energy storage array to PCS; PCS controls the flywheel energy storage array and the lithium battery energy storage array to discharge or charge according to the EMS command; DCS coordinates the thermal power unit to complete the power regulation according to the PECCS command.

[0159] During execution, PECCS uses the measured power of the combined system. and AGC instructions The overall tracking deviation is checked; the EMS checks the safety boundary of the energy storage side based on the SOC and protection status of the individual energy storage units; the PCS feeds back the actual power of the energy storage to the EMS and PECCS; the DCS feeds back the actual power of the thermal power unit to the PECCS. If the energy storage side experiences a state of charge exceeding the limit or equipment failure, the EMS will remove the corresponding energy storage array or individual energy storage unit from the candidate set and return to S4 to recalculate the power limit and array sorting. All execution feedback data is returned to the data pool. This serves as the input for the next control cycle S1, forming a closed-loop control.

[0160] Through the above steps S1 to S7, this embodiment forms a closed-loop control link with RTU, PECCS, EMS, PCS, and DCS as the core execution entities: PECCS avoids thermal power units undertaking unreasonable adjustment tasks when approaching their output limits based on plant-level power coordination; EMS first calculates the frequency regulation capability indicators of the flywheel energy storage array and the lithium battery energy storage array, and then prioritizes calling the power-type flywheel energy storage array to handle the rapid and frequent AGC adjustment needs. Only when the flywheel energy storage array is fully engaged and still cannot meet the demand will the energy-type lithium battery energy storage array be called, thereby reducing the number of high-power operations of the lithium battery; for the flywheel energy storage cells and lithium battery energy storage cells participating in frequency regulation, EMS improves the SOC consistency of the cells through fuzzy control on the basis of amplitude limiting protection, avoiding local cells from prematurely reaching the charge and discharge boundaries. This hierarchical method can simultaneously take into account the operational safety of thermal power units, the rapid response capability of flywheels, the life protection of lithium batteries, the SOC consistency of hybrid energy storage, and the AGC tracking performance.

[0161] Example 2

[0162] This embodiment illustrates the calculation process of the above method with a specific example, so that those skilled in the art can more intuitively understand and implement the present invention.

[0163] Assume the rated parameters of the thermal power unit are: MW, MW, current measured power MW, both uphill and downhill climbing rates are 9 MW / min, control step size s, then The hybrid energy storage system comprises two flywheel energy storage arrays F1 and F2 and two lithium battery energy storage arrays B1 and B2. Each flywheel energy storage array contains 10 flywheel energy storage cells with a rated power of 0.5 MW, and each lithium battery energy storage array has a rated power of 10 MW. The maximum rated discharge power of the hybrid energy storage system is [not specified]. MW. Take , , , , , , The current overall state of charge of the hybrid energy storage system. .

[0164] S1 to S2: AGC instructions for a certain control cycle MW, measured total active power output of the combined system MW, then MW The system needs to increase active power output. Thermal power units need to increase their adjustment margin. MW; Discharge availability factor .

[0165] S3: Available discharge power for hybrid energy storage MW. Sharing factor , Power command for thermal power units MW; Total Power Command for Hybrid Energy Storage Systems MW. It can be seen that although the unit still has 150 MW of space to reach the upper limit of output, due to the limitation of ramping ability, it only undertakes about 0.59 MW of upward adjustment in this cycle. The rapid component is mainly undertaken by hybrid energy storage, which reflects the effect of adaptive allocation of margin.

[0166] S4: The SOC of each individual cell within the flywheel energy storage array F1 is within the normal operating range; available power in the current direction. MW; In the flywheel energy storage array F2, one individual cell has a SOC of 0.15, which is in the discharge transition region. Its maximum dischargeable power is calculated using the limiting function as follows: MW, therefore MW.

[0167] S5: F1 average SOC is 0.55, standard deviation is 0.04, frequency modulation capability index The mean SOC for F2 was 0.50, and the standard deviation was 0.10. Under discharge conditions, the parameters are sorted from largest to smallest as F1 and F2. Power demand amplitude. MW, because and Therefore, the minimum number of flywheel arrays A flywheel energy storage array can meet the requirements, while the power commands for lithium battery energy storage arrays B1 and B2 are zero. The power command for the flywheel energy storage array is... MW, MW. In this example, the lithium battery energy storage array completely avoids operation, demonstrating the protective effect of the flywheel priority strategy on the lifespan of the lithium battery.

[0168] S6: Taking F1 as an example, its previous control cycle power command MW, normalized value of power variation Corresponding membership degree , Assuming the SOC of monomer 1 in F1 is 0.60, the equivalent SOC deviation is... Corresponding membership degree , The correction coefficients are obtained by defuzzifying according to Table 1. Assume that the SOC of monomer 2 is 0.50. Defuzzy The SOC of the remaining 8 monomers is 0.55. According to the initial power command formula, the power command for individual cells is approximately 0.431 MW, for individual cells approximately 0.306 MW, and for the remaining cells approximately 0.383 MW each, totaling 3.80 MW. This is consistent with the array power command and none of them exceed the maximum discharge power of 0.5 MW for an individual cell, so no residual redistribution is needed. It can be seen that individual cell 1, with its higher SOC, bears more discharge power, while individual cell 2, with its lower SOC, bears less discharge power, and the SOC difference within the array will gradually converge.

[0169] S7: PECCS sends a 450.59 MW command to DCS. EMS sends the power commands of each energy storage unit to PCS for execution. The execution feedback is returned to the data pool, and the next control cycle begins.

[0170] when At the same time, the control process is symmetrical to the above process: the thermal power unit shares the load according to the downshift margin, the hybrid energy storage system is charged, the array is sorted according to the frequency regulation capability index from small to large, and the individual units with lower SOC absorb more charging power, which will not be elaborated here.

[0171] Example 3

[0172] This embodiment provides a hybrid energy storage-assisted secondary frequency regulation control system for thermal power units based on a multi-layer collaborative architecture, used to execute the control method described in Embodiment 1. The system includes a remote control unit (RTU), a plant-level coordinated controller (PECCS), a thermal power unit coordinated control system (DCS), an energy storage management system (EMS), and a power conversion system (PCS).

[0173] The RTU communicates with the dispatch center to receive AGC commands. The PECCS communicates with the RTU, DCS, and EMS, and deploys an upper-level thermal power-storage power coordination and allocation module. This module performs the plant-level frequency regulation capability judgment and dynamic power allocation between the thermal power unit and the hybrid energy storage system as described in steps S2 and S3, and sends the thermal power unit power command to the DCS and the hybrid energy storage system total power command to the EMS. The EMS communicates with the PECCS and PCS, and deploys a middle-level hybrid energy storage sequential power allocation module and a lower-level SOC consistency power correction module. This module performs the power limiting calculation, array sorting selection, and energy storage unit power allocation as described in steps S4 to S6, and sends the energy storage unit power command to the PCS. The DCS coordinates the thermal power unit to complete power regulation according to the thermal power unit power command. The PCS controls the charging and discharging of each energy storage unit in the flywheel energy storage array and the lithium battery energy storage array according to the energy storage unit power command.

[0174] Each module can be deployed as a software functional module in the processor and memory of the corresponding control device, or it can be implemented using independent controller hardware; PECCS can also be integrated with EMS and deployed in the same plant-level control device. All such variations do not depart from the concept of this invention.

[0175] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for secondary frequency regulation control of a hybrid energy storage-assisted thermal power unit based on a multi-layer collaborative architecture, applied to a combined thermal power unit and a hybrid energy storage system, wherein the hybrid energy storage system includes at least one flywheel energy storage array and at least one lithium battery energy storage array, each energy storage array including multiple energy storage cells, characterized in that, The method includes the following steps: S1. Collect the operation data of the combined thermal power and energy storage system and construct a data pool. The data pool includes at least AGC commands, the measured total active power output of the combined thermal power and energy storage system, the measured power of the thermal power unit, the upper and lower limits of the output of the thermal power unit, the ramp rate of the thermal power unit, the state of charge of each energy storage unit, and the overall state of charge of the hybrid energy storage system. S2. Calculate the regulation demand of the combined thermal power and energy storage system, the upward adjustment margin of thermal power units, the downward adjustment margin of thermal power units, and the discharge availability coefficient and charging availability coefficient of the hybrid energy storage system based on the data pool. S3. The upper-level thermal power coordination and allocation module determines the sharing coefficient between the thermal power unit and the hybrid energy storage system based on the upward or downward adjustment margin of the thermal power unit and the available charging and discharging power of the hybrid energy storage system. The adjustment demand is dynamically allocated between the thermal power unit and the hybrid energy storage system, and the power command of the thermal power unit and the total power command of the hybrid energy storage system are generated. S4. The middle-layer hybrid energy storage sequential power allocation module calculates the maximum discharge power and maximum rechargeable power of each energy storage cell based on a smooth limiting function that changes continuously with the state of charge, and accumulates them according to the current power direction to obtain the current available power of each energy storage array. S5. The mid-layer hybrid energy storage sequential power allocation module calculates the frequency regulation capability index for each energy storage array. The frequency regulation capability index is jointly determined by the array's average state of charge and the dispersion of the state of charge within the array. The flywheel energy storage arrays are sorted according to the frequency regulation capability index. The minimum number of flywheel energy storage arrays whose sum of available power in the current direction meets the hybrid energy storage power demand amplitude is selected, and a flywheel energy storage array power command is generated. Only when the sum of available power in the current direction of all flywheel energy storage arrays still cannot meet the power demand amplitude, all flywheel energy storage arrays are made to work according to the available power in the current direction. The lithium battery energy storage arrays are sorted according to the frequency regulation capability index. The minimum number of lithium battery energy storage arrays that can bear the remaining power amplitude is selected, and a lithium battery energy storage array power command is generated. Thus, the array power command of each selected energy storage array is obtained. S6. The lower-level SOC consistency power correction module takes the energy storage unit equivalent state of charge deviation and the normalized value of the array power change amplitude as the input of the fuzzy controller for each selected energy storage array, and outputs the energy storage unit power correction coefficient. Based on the energy storage unit power correction coefficient and the energy storage unit's current directional available power, the array power command is allocated to each energy storage unit within the energy storage unit's amplitude limit constraint to obtain the energy storage unit power command. S7. The power command of the thermal power unit is sent to the thermal power unit for execution, the power command of the energy storage unit is sent to the corresponding energy storage unit for execution, and the execution feedback data is returned to the data pool as the input for the next control cycle.

2. The method for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture according to claim 1, characterized in that, In step S2: The regulation demand of the combined fire and energy storage system is expressed as follows: ； In the formula, The AGC regulation power that the combined fire and energy storage system needs to bear. For AGC instructions, The measured total active power output of the combined thermal power and energy storage system; The upward and downward adjustment margins of the thermal power unit are expressed as follows: ； ； In the formula, and These refer to the adjustable power margins of thermal power units, which can be increased or decreased. and These are the maximum and minimum allowable outputs of thermal power units, respectively. This represents the measured power output of the thermal power unit. and These refer to the uphill and downhill ramp rates of thermal power units, respectively. To control the step size; The discharge availability factor and the charge availability factor are respectively expressed as: ； In the formula, and These are the discharge availability factor and the charging availability factor of the hybrid energy storage system, respectively. For the overall state of charge of the hybrid energy storage system, and These are the lower and upper limits of the permissible state of charge for energy storage, respectively. Indicates will It is limited to the range of 0 to 1.

3. The method for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture according to claim 2, characterized in that, In step S3: The available discharge power and available charging power of a hybrid energy storage system are expressed as follows: ； In the formula, and These refer to the available discharge power and available charging power of the hybrid energy storage system, respectively. and These are the rated maximum discharge power and rated maximum charging power of the hybrid energy storage system, respectively. when At that time, the thermal power unit performs upward adjustment, the hybrid energy storage system performs discharge, and the thermal power unit shares the coefficient. and hybrid energy storage discharge sharing factor Represented as: ； Thermal power unit power command Total power command for hybrid energy storage systems They are represented as follows: ； ； when At that time, the thermal power unit implements a reduction, the hybrid energy storage system implements charging, and the thermal power unit shares the coefficient. and hybrid energy storage charging sharing factor Represented as: ； The power command for thermal power units and the total power command for hybrid energy storage systems are expressed as follows: ； ； In the formula, To prevent extremely small positive numbers with a denominator of zero, To reduce the power demand, the negative sign indicates that the hybrid energy storage system is in a charging state.

4. The method for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture according to claim 1, characterized in that, In step S4: The maximum discharge power of a single energy storage cell is expressed as: ； In the formula, For the first The first energy storage array The maximum discharge power of each energy storage cell This refers to the state of charge of the individual energy storage unit. This is the rated discharge power of the energy storage cell. This is the low-level warning value for the state of charge. This is the smoothing coefficient for the discharge transition region; The maximum rechargeable power of a single energy storage cell is expressed as: ； In the formula, For the first The first energy storage array The maximum rechargeable power of each energy storage cell This refers to the rated charging power of the energy storage unit. This is a high-level warning value for the state of charge. This is the smoothing coefficient for the charging transition region; Energy storage cell power command satisfies constraints: ； In the formula, This is the final power command issued to the individual energy storage units; The available power in the current direction of the energy storage array is expressed as: ； In the formula, For the first The available power of each energy storage array in the current power direction. This is the total power command for the hybrid energy storage system. This indicates that the hybrid energy storage system is in a discharging state. This indicates that the hybrid energy storage system is in a charging state.

5. The method for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture according to claim 1, characterized in that, In step S5, the frequency modulation capability index is expressed as: ； In the formula, For the first Frequency modulation capability indicators of an energy storage array For the first The average state of charge of each energy storage array For the first The degree of dispersion of the state of charge within an energy storage array This is the dispersion penalty coefficient; The dispersion of the state of charge within the array is represented by the standard deviation of the state of charge of each energy storage cell within the array: ； In the formula, For the first The number of individual energy storage units in an energy storage array For the first The first energy storage array The state of charge of each energy storage cell; When sorting, in the discharge state, the frequency regulation capability index is sorted from largest to smallest, and in the charging state, the frequency regulation capability index is sorted from smallest to largest.

6. The method for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture according to claim 5, characterized in that, In step S5: The power demand amplitude of hybrid energy storage is expressed as follows: , This is the total power command for the hybrid energy storage system; The minimum number of flywheel energy storage arrays required to meet power requirements is expressed as: ； In the formula, The minimum number of flywheel energy storage arrays required to meet power requirements. The first order of flywheel energy storage array Each array number This represents the current available power in the direction of the flywheel energy storage array; If the flywheel energy storage array can meet the power requirements, then only the first element after sorting is called. A flywheel energy storage array, excluding lithium battery energy storage arrays, has a power command for the selected flywheel energy storage array as follows: ； In the formula, For the first Power commands for each flywheel energy storage array It is a symbolic function; If the entire flywheel energy storage array still cannot meet the power demand, then each flywheel energy storage array will operate according to the available power in the current direction, and the remaining power amplitude is expressed as: ； In the formula, This represents the remaining power amplitude that needs to be handled by the lithium battery energy storage array. It is a flywheel energy storage array collection. For the first The available power in the current direction of the flywheel energy storage array; The minimum number of lithium-ion battery energy storage arrays required to handle the remaining power is expressed as: ； In the formula, The minimum number of lithium-ion battery storage arrays required to handle the remaining power. The first after sorting the lithium battery energy storage array Each array number This represents the current available power in the direction of the lithium battery energy storage array; The selected lithium battery energy storage array power command is represented as follows: ； In the formula, For the first The power command for each lithium battery energy storage array; the power command for an unselected energy storage array is zero.

7. The method for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture according to claim 1, characterized in that, In step S6: The normalized value of the array power variation amplitude is expressed as: ； In the formula, For the first Normalized values ​​of power variation amplitude of each energy storage array This is the power command for the energy storage array. This refers to the power command for the energy storage array in the previous control cycle. This represents the current available power in the direction of the energy storage array. To prevent extremely small positive numbers with a denominator of zero; The equivalent state of charge deviation of the energy storage cell is expressed as: ； In the formula, For the first The first energy storage array Equivalent state of charge deviation of individual energy storage cells This refers to the state of charge of the individual energy storage unit. This represents the average state of charge of the energy storage array. and These are the lower and upper limits of the permissible state of charge for energy storage, respectively. This indicates that the energy storage unit is suitable for handling more power in the current direction. This indicates that the energy storage unit should handle less power in the current direction; Fuzzy controller and As input, with energy storage cell power correction coefficient For output, The fuzzy set is set as {NB, NS, ZE, PS, PB}, which represent obviously unsuitable, slightly unsuitable, close to the mean, relatively suitable, and obviously suitable to bear the power in the current direction, respectively. Let the fuzzy set be {S,M,B}, representing small power change, medium power change, and large power change, respectively.

8. The method for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture according to claim 7, characterized in that, In step S6, the fuzzy rule is set as follows: the smaller the range of array power change, the greater the deviation of the energy storage unit power correction coefficient from the reference value 1; the greater the range of array power change, the more the energy storage unit power correction coefficient converges to the reference value 1. When the equivalent state of charge deviation is positive, the correction factor is not less than 1; when the equivalent state of charge deviation is negative, the correction factor is not greater than 1; when the equivalent state of charge deviation is close to zero, the correction factor remains at 1. The weighted average method is used to resolve the fuzziness, and the power correction coefficient of the energy storage unit is obtained: ； In the formula, For the first The first energy storage array Power correction factor for each energy storage unit The equivalent state of charge deviation is the first Membership function of a fuzzy set The power change amplitude Membership function of a fuzzy set This is the quantized value of the consequent of the corresponding rule in the fuzzy rule table. To prevent extremely small positive numbers with a denominator of zero; The initial power command of a single energy storage cell after fuzzy correction is expressed as follows: ； In the formula, For the first The first energy storage array Initial power command for each energy storage cell The current available power in the direction of the energy storage cell is used; the maximum dischargeable power is taken during discharge. During charging, the maximum rechargeable power is used. .

9. The method for secondary frequency regulation control of hybrid energy storage-assisted thermal power units based on a multi-layer collaborative architecture as described in claim 8, characterized in that: In step S6, the final energy storage unit power command is expressed as follows: ； In the formula, For the final distribution to the first The first energy storage array The power command of each energy storage unit; if some energy storage units reach the limit and cause a residual in the array power, the residual will be redistributed only among the energy storage units that have not reached the limit according to the proportion of the remaining available power. In step S7, if the energy storage side experiences a state of charge exceeding the limit or equipment failure, the corresponding energy storage array or energy storage unit will be removed from the candidate set, and the process will return to step S4 to recalculate the power limit and array sorting.

10. A secondary frequency regulation control system for a hybrid energy storage-assisted thermal power unit based on a multi-layer collaborative architecture, characterized in that, The system includes a remote control unit, a plant-level coordination controller, a thermal power unit coordination control system, an energy storage management system, and a power conversion system. The remote control unit is used to access AGC commands from the dispatch center. The plant-level coordination controller deploys an upper-level thermal power-storage power coordination and allocation module to perform dynamic power allocation between the thermal power unit and the hybrid energy storage system. The energy storage management system deploys a mid-level hybrid energy storage sequential power allocation module and a lower-level SOC consistency power correction module to perform energy storage array sorting and selection and energy storage unit power allocation. The thermal power unit coordination control system executes power commands from the thermal power unit. The power conversion system executes power commands from individual energy storage units. The control system is configured to execute the hybrid energy storage-assisted thermal power unit secondary frequency regulation control method based on a multi-layer collaborative architecture as described in any one of claims 1 to 9.

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