A wind power energy storage frequency modulation control method and a wind power energy storage frequency modulation control device

Abstract

The present disclosure relates to the field of wind power generation technology, and particularly relates to a wind power energy storage frequency modulation control method and a wind power energy storage frequency modulation control device. The control method comprises: constructing a wind farm multi-working condition real-time identification model, the working conditions comprising a steady-state output working condition, a gust disturbance working condition, a limited power running working condition and a working condition close to a cut-out wind speed; receiving a power grid frequency modulation power demand instruction, and dynamically and adaptively allocating wind turbine frequency modulation power and energy storage frequency modulation power according to the current working condition identified, wherein the gust disturbance working condition preferentially calls energy storage to suppress short-time power fluctuation, and the steady-state output working condition preferentially mobilizes the standby capacity of the wind farm to participate in frequency modulation; a storage charge and discharge life constraint threshold is introduced in the power allocation process, and the frequent reciprocating charge and discharge of the energy storage is inhibited on the premise of meeting the power grid frequency modulation index. The method of the present disclosure greatly improves the working condition adaptation capability and the grid frequency regulation accuracy of wind storage combined frequency modulation, and significantly reduces the attenuation rate of the energy storage device and the mechanical loss of the wind turbine.

Description

Technical Field

[0001] This disclosure relates to the field of wind power generation technology, and in particular to a wind power energy storage frequency regulation control method and a wind power energy storage frequency regulation control device. Background Technology

[0002] In the process of building my country's new power system, the installed capacity of onshore and offshore wind power connected to the grid has been increasing year by year. The inherent intermittency, randomness, and turbulent gust characteristics of wind energy cause the active power output of wind farms to fluctuate constantly, which can easily cause an imbalance between active power supply and demand in the power grid system, leading to frequent grid frequency deviations and significantly reducing the frequency stability margin of the power system. According to the current grid connection operation specifications, large-capacity grid-connected wind farms must have primary frequency regulation capabilities. When the grid frequency deviates from the rated value, they must be able to quickly increase or decrease active power to support the grid frequency to return to the allowable range.

[0003] Existing technologies that rely solely on wind turbine generators for frequency regulation have several drawbacks: the pitch actuators of wind turbines have slow response times, with adjustment times reaching several seconds, making it impossible to smooth out short-term high-frequency power disturbances caused by gusts; when strong winds approach the cut-off wind speed range, wind turbines need to feather and limit speed to ensure the safety of core structures such as blades, main shafts, and gearboxes, essentially losing the frequency regulation margin for active power up and down adjustments; under normal steady-state operating conditions, frequent use of rotor inertia and repeated adjustments of pitch angle for frequency regulation also exacerbate mechanical fatigue wear of the unit. Therefore, the current mainstream technology adopts a combined frequency regulation approach using electrochemical energy storage integrated with wind farms, leveraging the millisecond-level rapid power throughput characteristics of energy storage to compensate for the wind turbine's regulation deficiencies, becoming the primary solution.

[0004] However, most of the current wind farm energy storage coordinated frequency regulation control strategies adopt a fixed ratio power allocation mechanism, that is, under any operating conditions, the frequency regulation output of wind turbines and energy storage is divided according to a preset constant ratio. This control mode has poor adaptability to operating conditions and cannot flexibly adjust the output weight according to the real-time operating status of the wind farm. Wind farms operate under complex and varied scenarios, which can be categorized into four typical operating states: steady-state output, gust disturbance, power-limited operation under grid dispatch with output cap, and near-cutoff wind speed. The available frequency regulation reserve capacity and safe operating boundaries of wind turbines vary significantly under these different conditions. In gust disturbance scenarios, short-term power oscillations force energy storage to continuously charge and discharge repeatedly. Frequent small-cycle charging and discharging of lithium batteries exacerbates electrode polarization, increases internal resistance, and reduces capacity, significantly shortening the overall lifespan of the energy storage system and drastically increasing the cost of energy storage replacement and maintenance in the later stages of the power plant. In near-cutoff wind speed high-wind conditions, wind turbines lack frequency regulation capabilities, yet fixed-ratio allocation still rigidly requires turbine participation in frequency regulation, easily inducing turbine overspeed, blade overload, and other safety faults. In power-limited operation conditions, wind turbines have sufficient frequency regulation reserves, but fixed-ratio allocation still excessively utilizes energy storage output, causing unnecessary energy storage losses.

[0005] In addition, existing coordinated frequency regulation schemes lack a systematic energy storage lifespan management and constraint mechanism. They usually only limit the depth of charge and discharge based on the upper and lower limits of the energy storage state of charge, which cannot suppress the energy storage start-up and shutdown switching behavior caused by small frequency jitters in the power grid. It is difficult to meet the various assessment indicators of the primary frequency regulation of the power grid and ensure the frequency regulation performance while taking into account the long-term lifespan requirements of energy storage equipment.

[0006] Based on the above, the existing technology needs further improvement. Summary of the Invention

[0007] The purpose of this disclosure is to achieve joint frequency regulation control that adapts to all wind conditions and takes into account both grid frequency regulation performance and the safe lifespan of wind turbines and energy storage equipment by means of multi-condition identification, condition-adaptive differentiated power allocation, energy storage charging and discharging frequency and lifespan constraints, and gradual exit strategy.

[0008] To address the aforementioned technical issues, this disclosure provides a wind power energy storage frequency regulation control method, comprising: constructing a real-time multi-condition identification model for a wind farm; identifying the current operating condition based on real-time operating parameters of the wind farm, including steady-state output condition, gust disturbance condition, power-limited operation condition, and near-cutoff wind speed condition; receiving a grid frequency regulation power demand command; dynamically and adaptively allocating wind turbine frequency regulation power and energy storage frequency regulation power according to the identified current operating condition, wherein, under the gust disturbance condition, energy storage is prioritized to smooth short-term power fluctuations, and under the steady-state output condition, the wind farm's reserve capacity is prioritized to participate in frequency regulation; introducing an energy storage charge-discharge lifetime constraint threshold during the power allocation process to suppress frequent reciprocating charge-discharge of energy storage while meeting grid frequency regulation targets; and issuing the allocated wind turbine frequency regulation power command and energy storage frequency regulation power command to the wind farm pitch control system and energy storage converter, respectively, to execute joint frequency regulation operations.

[0009] In some embodiments, the real-time operating parameters of the wind farm include the active power output of the wind farm, the measured wind speed, the pitch angle of the wind turbine, the real-time rotor speed, the grid connection frequency, and the real-time state of charge (SOC) of the energy storage. The above operating parameters are selected as feature inputs to build a real-time identification model for multiple operating conditions.

[0010] In some embodiments, a multi-condition real-time identification model is built using the fuzzy comprehensive evaluation method. The current operating condition is determined by calculating the membership degree of the operating parameters to various operating conditions. The single-parameter membership degree calculation formula is as follows: u mi =e A A=-( x m -x mi ) 2 / 2σ mi 2 In the formula: u mi Let m be the membership degree of the m-th operating parameter to the i-th operating condition, where i takes the values ​​1, 2, 3, and 4, corresponding to the steady-state output condition, gust disturbance condition, power-limited operation condition, and near-cutoff wind speed condition, respectively. x m This refers to the m-th real-time operating parameter collected from the wind farm. x mi This refers to the pre-calibrated standard center value of the m-th operating parameter under the i-th type of working condition; σ mi Let be the variance of the m-th operating parameter under the i-th operating condition; Calculate the membership degree values ​​of the real-time parameters for the four operating conditions respectively, and determine the operating condition corresponding to the maximum membership degree as the identified current operating condition.

[0011] In some embodiments, the maximum allowable charge and discharge frequency per unit cycle of energy storage is preset. N max As a threshold for limiting the charge-discharge lifespan of energy storage, the actual number of charge-discharge switching cycles of energy storage within a unit sampling period is counted in real time. N real ;when N real < N max At that time, energy storage participates in frequency regulation normally according to the preset allocation rules for each operating condition. N real ≥ N max At the same time, the blocking range for small frequency fluctuations in the power grid is adaptively expanded to reduce the frequency of energy storage frequency regulation.

[0012] In some embodiments, the cooperative control method under steady-state output conditions is as follows: The total frequency regulation demand of the power grid is denoted as Δ. P total Priority will be given to allocating all frequency regulation power demand to the wind farm's reserve capacity, and the frequency regulation output Δ of the wind turbines will be used to meet this demand. P wt =Δ P total Theoretical output of energy storage Δ P bat =0; only when the wind farm's maximum adjustable reserve capacity Δ P total-max <Δ P total At that time, energy storage makes up for the remaining power gap Δ P bat =Δ P total -Δ P total-max In conjunction with the energy storage lifetime constraint threshold, the amplitude is less than the set micro-power threshold Δ P th1 Power deviations are not responded to, so as to prohibit small repeated charging and discharging of energy storage.

[0013] In some embodiments, the cooperative control method under gust disturbance conditions is as follows: Prioritizing energy storage to mitigate power fluctuations caused by short-term gusts, the energy storage base output Δ P bat =Δ P total The wind turbine only handles the low-frequency steady-state power component; the energy storage charge / discharge switching hysteresis bandwidth Δ is set. fbat As a lifespan constraint, when the power fluctuation amplitude is less than the hysteresis bandwidth, the charging and discharging states of the energy storage are switched between each other to avoid high-frequency reciprocating charging and discharging losses of the energy storage.

[0014] In some embodiments, the cooperative control method under power-limited operating conditions is as follows: The wind farm has sufficient active power reserve capacity. The frequency regulation weighting coefficient k for the wind turbines is set to 0.8 ≤ k ≤ 0.95. The frequency regulation output Δ of the wind turbines... P wt =k·Δ P total Energy storage can handle the remaining power Δ P bat =(1-k)·Δ P total The weighting coefficient k is dynamically adjusted based on the real-time charging and discharging frequency of energy storage to continuously reduce the proportion of energy storage output, thereby reducing the number of energy storage charging and discharging cycles.

[0015] In some embodiments, the collaborative control method under near-cut-out wind speed conditions is as follows: The wind turbine is constrained by the upper limit of wind speed and has no frequency adjustment margin; the wind turbine's frequency adjustment output Δ P wt =0, all frequency regulation needs are met by energy storage, i.e., Δ P bat =Δ P total Disturbance levels are classified based on the energy storage lifespan constraint threshold. Energy storage will start regulation only when the grid frequency deviation exceeds the large disturbance threshold, and the energy storage charging and discharging actions will be blocked for small frequency disturbances.

[0016] In some embodiments, the frequency regulation task is determined to be over after the grid frequency recovers to the rated allowable range and stabilizes for a preset time. The frequency regulation operation is exited step by step in the order of linearly dropping the energy storage power to zero and slowly resetting the wind turbine pitch angle. A gradual power withdrawal strategy is adopted throughout the process to prevent the energy storage from being recharged and discharged due to the impact of the operation switching.

[0017] On the other hand, the present invention also provides a wind power energy storage frequency regulation control device for executing the above-described wind power energy storage frequency regulation control method, comprising: The operating condition identification module is used to build a real-time identification model of multiple operating conditions in wind farms, collect real-time operating parameters of wind farms, identify the current operating conditions, and output the operating condition identification results. The power demand receiving module is used to receive frequency regulation power demand commands issued by the power grid in real time. The adaptive power allocation module is connected to the operating condition identification module and the power demand receiving module respectively. It is used to dynamically allocate the frequency regulation power of the wind turbine and the frequency regulation power of the energy storage according to the current operating conditions. The module integrates an energy storage charge and discharge life constraint threshold determination unit, which corrects the energy storage output and start-stop timing under each operating condition according to the life constraint conditions. The instruction issuance and execution module is used to issue the allocated wind turbine frequency regulation power instruction to the wind farm pitch control system and the energy storage frequency regulation power instruction to the energy storage converter, driving the wind and energy storage to jointly complete the grid frequency regulation operation.

[0018] By adopting the above technical solution, the present invention has at least the following beneficial effects: This disclosure identifies four typical operating conditions of wind farms and dynamically matches differentiated wind-storage coordinated frequency regulation strategies. It can flexibly adjust the power output division between wind turbines and energy storage according to the real-time operating status of the wind farm, adapting to the complex and ever-changing operating scenarios of wind power. This significantly improves the operating condition adaptability of wind-storage joint frequency regulation and the accuracy of grid frequency regulation. At the same time, by adding an energy storage lifespan constraint mechanism, it effectively suppresses the meaningless reciprocating charging and discharging losses of energy storage. Combined with a gradual frequency regulation exit strategy, it avoids grid-connected power disturbances, significantly reducing the attenuation rate of energy storage equipment and the mechanical losses of wind turbines. It takes into account the safety, stability and long-term economic efficiency of wind power frequency regulation operation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of a wind power energy storage frequency regulation control method according to an embodiment of the present disclosure. Detailed Implementation

[0021] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0022] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0023] It should be noted that, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.

[0025] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure depending on the specific circumstances. When a particular device is described as being located between a first device and a second device, an intermediary device may or may not be present between the particular device and the first or second device.

[0026] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0027] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0028] As mentioned in the background section, existing wind power and energy storage frequency regulation technologies suffer from numerous drawbacks, including poor adaptability to operating conditions, severe energy storage losses, and inability to guarantee wind turbine operational safety. Based on these shortcomings, this application proposes a wind power and energy storage frequency regulation control method and device. The method divides wind turbine operating conditions into four specific categories based on the turbine's operating boundaries. It uses a fuzzy algorithm to identify operating conditions in real time and adaptively allocates frequency regulation loads, resulting in stronger adaptability to operating conditions and effectively mitigating the risk of wind turbine overload. Furthermore, through energy storage charge / discharge lifespan constraint control logic, it significantly suppresses frequent repetitive charge / discharge cycles, extends the lifespan of energy storage lithium batteries, and reduces the later-stage operation and maintenance costs and energy storage replacement costs of wind farms. This solves one or more problems in the existing technologies.

[0029] To address the aforementioned technical problems, this invention provides a wind power energy storage frequency regulation control method, such as... Figure 1 As shown, it includes the following steps: S1. Construct a real-time identification model for multiple operating conditions of wind farms, and identify the current operating conditions based on the real-time operating parameters of wind farms. The operating conditions include steady-state power output conditions, gust disturbance conditions, power limiting conditions, and near-cut-off wind speed conditions. S2. Receive the grid frequency regulation power demand command, and dynamically and adaptively allocate the wind turbine frequency regulation power and energy storage frequency regulation power according to the identified current operating conditions. In the case of gust disturbance, energy storage is prioritized to smooth short-term power fluctuations, and in the case of steady-state output, the wind farm's reserve capacity is prioritized to participate in frequency regulation. In the power allocation process, an energy storage charge and discharge life constraint threshold is introduced to suppress frequent reciprocating charge and discharge of energy storage while meeting the grid frequency regulation index. S3. Based on the allocated wind turbine frequency regulation power command and energy storage frequency regulation power command, send them to the wind farm pitch control system and energy storage converter respectively to perform joint frequency regulation operation.

[0030] In the above method, the real-time operating parameters of the wind farm include the active power output of the wind farm, the measured wind speed, the pitch angle of the wind turbine, the real-time rotor speed, the grid connection frequency, and the real-time state of charge (SOC) of the energy storage. The above multiple operating parameters are selected as feature inputs to build a multi-condition real-time identification model.

[0031] In the above method, a multi-condition real-time identification model is built using fuzzy comprehensive evaluation. The current operating condition is determined by calculating the membership degree of the operating parameters to various operating conditions. The formula for calculating the membership degree of a single parameter is as follows: u mi =e A A=-( x m -x mi ) 2 / 2σ mi 2 In the formula: u mi Let m be the membership degree of the m-th operating parameter to the i-th operating condition, where i takes the values ​​1, 2, 3, and 4, corresponding to the steady-state output condition, gust disturbance condition, power-limited operation condition, and near-cutoff wind speed condition, respectively. x m This refers to the m-th real-time operating parameter collected from the wind farm. x mi This refers to the pre-calibrated standard center value of the m-th operating parameter under the i-th type of working condition; σ mi Let be the variance of the m-th operating parameter under the i-th operating condition; Calculate the membership degree values ​​of the real-time parameters for the four operating conditions respectively, and determine the operating condition corresponding to the maximum membership degree as the identified current operating condition.

[0032] In the above method, the maximum allowable charge and discharge frequency per unit cycle of energy storage is preset. N max As a threshold for limiting the charge-discharge lifespan of energy storage, the actual number of charge-discharge switching cycles of energy storage within a unit sampling period is counted in real time. N real ;when N real < N max At that time, energy storage participates in frequency regulation normally according to the preset allocation rules for each operating condition. N real ≥ N max At the same time, the blocking range for small frequency fluctuations in the power grid is adaptively expanded to reduce the frequency of energy storage frequency regulation.

[0033] In the above method, the cooperative control mode under steady-state output conditions is as follows: The total frequency regulation demand of the power grid is denoted as Δ. P total Priority will be given to allocating all frequency regulation power demand to the wind farm's reserve capacity, and the frequency regulation output Δ of the wind turbines will be used to meet this demand. P wt =Δ P total Theoretical output of energy storage Δ P bat =0; only when the wind farm's maximum adjustable reserve capacity Δ P total-max <Δ P total At that time, energy storage makes up for the remaining power gap Δ Pbat =Δ P total -Δ P total-max In conjunction with the energy storage lifetime constraint threshold, the amplitude is less than the set micro-power threshold Δ P th1 Power deviations are not responded to, so as to prohibit small repeated charging and discharging of energy storage.

[0034] In the above method, the cooperative control mode under gust disturbance conditions is as follows: Prioritizing energy storage to mitigate power fluctuations caused by short-term gusts, the energy storage base output Δ P bat =Δ P total The wind turbine only handles the low-frequency steady-state power component; the energy storage charge / discharge switching hysteresis bandwidth Δ is set. f bat As a lifespan constraint, when the power fluctuation amplitude is less than the hysteresis bandwidth, the charging and discharging states of the energy storage are switched between each other to avoid high-frequency reciprocating charging and discharging losses of the energy storage.

[0035] In some embodiments, the cooperative control method under power-limited operating conditions is as follows: The wind farm has sufficient active power reserve capacity. The frequency regulation weighting coefficient k for the wind turbines is set to 0.8 ≤ k ≤ 0.95. The frequency regulation output Δ of the wind turbines... P wt =k·Δ P total Energy storage can handle the remaining power Δ P bat =(1-k)·Δ P total The weighting coefficient k is dynamically adjusted based on the real-time charging and discharging frequency of energy storage to continuously reduce the proportion of energy storage output, thereby reducing the number of energy storage charging and discharging cycles.

[0036] In the above method, the collaborative control mode under the near-cut-out wind speed condition is as follows: The wind turbine is constrained by the upper limit of wind speed and has no frequency adjustment margin; the wind turbine's frequency adjustment output Δ P wt =0, all frequency regulation needs are met by energy storage, i.e., Δ P bat =Δ P total Disturbance levels are classified based on the energy storage lifespan constraint threshold. Energy storage will start regulation only when the grid frequency deviation exceeds the large disturbance threshold, and the energy storage charging and discharging actions will be blocked for small frequency disturbances.

[0037] In the above method, the frequency regulation task is determined to be over after the grid frequency recovers to the rated allowable range and stabilizes for a preset time. The frequency regulation condition is exited step by step in the order of linearly dropping the energy storage power to zero and slowly resetting the wind turbine pitch angle. A gradual power withdrawal strategy is adopted throughout the process to prevent the energy storage from being recharged and discharged due to the impact of the condition switching.

[0038] On the other hand, the present invention also provides a wind power energy storage frequency regulation control device for executing the above-described wind power energy storage frequency regulation control method, comprising: The operating condition identification module is used to build a real-time identification model of multiple operating conditions in wind farms, collect real-time operating parameters of wind farms, identify the current operating conditions, and output the operating condition identification results. The power demand receiving module is used to receive frequency regulation power demand commands issued by the power grid in real time. The adaptive power allocation module is connected to the operating condition identification module and the power demand receiving module respectively. It is used to dynamically allocate the frequency regulation power of the wind turbine and the frequency regulation power of the energy storage according to the current operating conditions. The module integrates an energy storage charge and discharge life constraint threshold determination unit, which corrects the energy storage output and start-stop timing under each operating condition according to the life constraint conditions. The instruction issuance and execution module is used to issue the allocated wind turbine frequency regulation power instruction to the wind farm pitch control system and the energy storage frequency regulation power instruction to the energy storage converter, driving the wind and energy storage to jointly complete the grid frequency regulation operation.

[0039] The working principle of the wind power energy storage frequency regulation control method disclosed herein is as follows: The overall working principle of this invention revolves around the closed-loop control logic of "precise operating condition identification - differentiated power allocation - multiple lifespan constraint management - smooth and stable exit". It addresses the core pain points of existing wind-storage joint frequency regulation, such as fixed ratio, poor operating condition adaptability, large energy storage loss, wind turbine failure, and large frequency regulation and grid connection disturbance. It constructs a multi-dimensional, adaptive, safe and life-extending joint frequency regulation system with a clear overall operating mechanism, distinct levels, and closed-loop controllability.

[0040] First, based on the actual operating characteristics of wind power, this invention selects six core operating parameters: active power output of the wind farm, measured wind speed, turbine pitch angle, rotor speed, grid connection frequency, and energy storage SOC. Utilizing a Gaussian fuzzy comprehensive evaluation algorithm combined with big data clustering calibration, it identifies four typical operating states: steady-state output, gust disturbance, power-limited operation, and near-cutoff wind speed. This provides accurate state information for subsequent differentiated frequency regulation strategy switching.

[0041] Secondly, based on real-time identification of wind farm operating conditions, an adaptive and differentiated wind-storage coordinated frequency regulation strategy is implemented: under steady-state conditions, the wind turbine's reserve capacity is maximized to dominate frequency regulation, reducing energy storage start-up and shutdown losses; under gust conditions, the millisecond-level rapid response characteristics of energy storage are used to smooth high-frequency power fluctuations, while the wind turbine undertakes the low-frequency steady-state component, compensating for the wind turbine's mechanical response lag; under power-limited conditions, the wind-storage frequency regulation weights are dynamically and adaptively adjusted to fully utilize the wind turbine's surplus reserve capacity and reduce ineffective energy storage cycle charging and discharging; under near-cutoff wind speed conditions, the wind turbine's frequency regulation action is completely locked, and all frequency regulation needs are undertaken by energy storage, thereby avoiding wind turbine overload and overspeed safety faults under high wind conditions and achieving the optimal coordinated ratio under different wind conditions.

[0042] Meanwhile, this invention establishes a hierarchical multi-constraint control system, which differs from the traditional control mode that relies solely on the single-dimensional protection of the energy storage SOC. It accurately suppresses the small-scale reciprocating charging and discharging behavior of energy storage caused by minor frequency fluctuations in the power grid, thus solving the technical problem that existing technologies cannot simultaneously address frequency regulation control and energy storage life extension.

[0043] Furthermore, the working condition identification and calibration algorithm of the present invention is as follows:

[0044] 1. Standard center values ​​of each parameter are determined by clustering and calibrating historical operational big data of the wind farm. x mi With volatility and variance σ mi We collected 30 consecutive days of full-condition operation data from the wind farm. K-means clustering was performed on steady-state power output, gust disturbance, power-limited operation, and near-cutoff wind speed conditions. The cluster center point of each parameter under each condition was taken as the standard center value xmi, and the square of the standard deviation of the cluster data was taken as the parameter fluctuation variance for the corresponding condition. x mi For wind farms of different capacities and turbine models, adaptive calibration can be achieved through clustering of historical operating data.

[0045] 2. Considering the sensitivity of wind power frequency regulation operation, the correlation degree of six types of parameters to the operating condition is calculated using the grey relational analysis algorithm. After normalization, the optimal weights are obtained: wind speed has the highest sensitivity and the largest weight, followed by active power output, while energy storage SOC has the lowest direct impact on wind farm operation. The final weights are determined as follows: w 1 =0.25 (work output) w 2 =0.3 (wind speed) w 3 =0.15 (pitch angle) w 4 =0.15 (rotor speed) w 5 =0.1 (grid connection frequency) w6 =0.05 (storage SOC), all weights satisfy the normalization constraint.

[0046] 3. The preset minimum threshold value for the comprehensive membership degree is 0.3. When the comprehensive membership degree of the four types of working conditions... U 1 、U 2 、U 3 、U 4 When all values ​​are below 0.3, the current operating state is determined to be a transitional state. The operating condition identified at the previous moment remains unchanged, and frequent changes in operating condition are prohibited to ensure the continuous and stable control strategy.

[0047] 4. Operating condition identification and calculation process: Step 1: Real-time acquisition of six-dimensional operating parameters, and analysis through clustering and labeling. x mi , σ mi First, substitute the Gaussian formula to calculate the membership degree of a single parameter; second, obtain the comprehensive membership degree of the four types of operating conditions by weighted fusion with fixed weights, and determine the final operating condition. The formula for single-parameter membership is as follows: w m x u mi u mi =

[0048] A=-( x m -x mi ) 2 / 2σ mi 2 The formula for the overall membership degree is as follows: U i = w 1 x u 1i + w 2 x u 2i + w 3 x u 3i + w 4 x u 4i + w 5 x u 5i+ w 6 x u 6i

[0049] Furthermore, the energy storage charging and discharging constraint strategy of the present invention is as follows:

[0050] 1. A fixed statistical period of 15 minutes is used to count only the number of bidirectional switching between energy storage charging state and discharging state; continuous charging, continuous discharging, and zero-power standby states are not included in the switching count to avoid statistical errors.

[0051] 2. Maximum allowable switching frequency per unit cycle N max =8 times / 15min; when N real < N max Energy storage participates in frequency regulation normally; when N real ≥ N max The frequency lock-in range is gradually widened by a small increment of 0.02Hz. The upper limit of the lock-in range is locked at ±0.1Hz. Once the upper limit is reached, the range is no longer widened, thus preserving the basic frequency modulation capability and preventing the frequency modulation function from failing.

[0052] 3. Preset fixed constraint priority: SOC over-limit constraint > charge / discharge frequency lifetime constraint > small frequency fluctuation lockout constraint. When multiple constraints are triggered simultaneously, the following rules apply: ① Prioritize the implementation of SOC hard constraints: SOC < 20% forcibly lock out energy storage discharge, SOC > 90% forcibly lock out energy storage charging. Regardless of frequency regulation requirements and frequency status, priority should be given to avoiding battery overcharging and over-discharging. ② When the SOC is normal, frequency lifetime constraints are applied: after the frequency exceeds the limit, small fluctuation frequency modulation needs are blocked first, and only large frequency disturbances are responded to. ③ No SOC exceeding limits, no frequency exceeding limits, basic micro-fluctuation blocking constraints are implemented to suppress ineffective start-up and shutdown of energy storage.

[0053] ④ Constraint conflict power backtracking rule: If the initial power allocation triggers a high-level constraint, the power allocation logic will be automatically backtracked, and the energy storage output will be adjusted first, while the wind turbine frequency regulation capability will be retained, so as to meet the energy storage life constraint under the premise of ensuring that the frequency regulation index meets the standard.

[0054] The technical solution will be further explained below with reference to specific embodiments.

[0055] Example 1: Case study on steady-state output condition determination.

[0056] Actual wind farm conditions: average wind speed 9–13 m / s, wind speed fluctuation less than 1 m / s, stable turbine pitch angle, stable rotor speed, minimal fluctuation in active power output with no severe oscillations, and energy storage SOC within the normal range. Model calculations show the comprehensive membership degree for the four operating conditions. U 1 =0.82、 U 2 =0.11、 U 3 =0.09、 U 4 =0.03, the membership degree of the steady-state condition is the largest, and the current condition is determined to be a steady-state output condition.

[0057] Example 2: Case Study on Gust Disturbance Condition Judgment Actual wind farm conditions: Wind speed fluctuates rapidly between 6 and 18 m / s for short periods, with a fluctuation range greater than 3 m / s within 1 second. Wind turbine output oscillates frequently, and the pitch angle undergoes continuous fine-tuning. Grid-connected power exhibits high-frequency fluctuations. Based on model calculations... U 1 =0.12、 U 2 =0.85、 U 3 =0.08、 U 4 =0.02, the membership degree of the gust condition is the largest, and the current condition is determined to be a gust disturbance condition.

[0058] Example 3: Case Study on Determining Power-Limited Operating Conditions Actual wind farm conditions: Under grid dispatch, the wind farm operates at 70%–80% of its rated power, with a large reserve capacity for the turbines. Wind speed is stable without significant fluctuations, and power output is controllable and limited. Model calculations indicate… U 1 =0.15、 U 2 =0.06、 U 3 =0.81、 U 4 =0.04, the membership degree of the power-limited operating condition is the largest, and the current condition is determined to be the power-limited operating condition.

[0059] Example 4: Case Study on Determining Near-Cut-Out Wind Speed ​​Conditions Actual wind field conditions: Continuous strong winds, with an average wind speed of 23-25 ​​m / s, approaching the turbine's 25 m / s cutoff speed. The turbine gradually feathers and limits its speed, with the rotor speed approaching its upper limit, leaving no active power regulation margin. Model calculations indicate... U 1 =0.05、 U 2 =0.08、U 3 =0.10、 U 4 =0.86, the membership degree of the near-cut-out condition is the largest, and the current condition is determined to be the near-cut-out wind speed condition.

[0060] Example 5: Steady-state output control example Operating conditions: The wind farm operates in a steady state and is stable, and the power grid issues frequency regulation demand Δ P total =600kW, the maximum standby capacity of the wind turbines is sufficient, and the current switching frequency of energy storage has not exceeded the limit. Control strategy: The wind turbines should be given priority to fully meet the frequency regulation requirements, and the wind turbine output Δ P wt =600kW, energy storage output is 0; energy storage only fills the gap when the wind turbine reserve is insufficient; small power deviations with an amplitude of less than 50kW block the energy storage response. This embodiment makes full use of the wind turbine reserve capacity, with no ineffective charging and discharging of energy storage throughout the process, greatly shortening the energy storage life.

[0061] Example 6: Example of Gust Disturbance Control Operating conditions: Frequent gusts of wind cause high-frequency fluctuations in grid-connected power, resulting in continuous frequency regulation demands from the power grid. A first-order low-pass filter algorithm is used to decompose the total frequency regulation power, with a fixed filter cutoff frequency of 0.03Hz, and the total frequency regulation power Δ... P total It is separated into low-frequency steady-state power components and high-frequency pulsating power components; the low-frequency steady-state component is borne by the wind turbine rotor inertia and slow pitch regulation, while the high-frequency pulsating component is entirely smoothed by the rapid throughput of energy storage.

[0062] Control strategy: The energy storage system handles high-frequency pulsating power with a hysteresis bandwidth of 150kW. When the power fluctuation amplitude is less than the hysteresis bandwidth, the switching between charging and discharging states of the energy storage system is locked to avoid repeated start-stop cycles. The wind turbine continuously tracks low-frequency steady-state components, and minor residual power fluctuations are buffered by the turbine's inertia. This strategy addresses the shortcomings of wind turbines, such as slow response and inability to smooth high-frequency disturbances, while also eliminating minor reciprocating losses in the energy storage system.

[0063] Operating conditions: Frequent gusts of wind cause high-frequency fluctuations in grid-connected power, resulting in continuous frequency regulation demands from the grid. Control strategy: Energy storage acts as the primary means to quickly smooth short-term power fluctuations, handling all frequency regulation power while the wind turbine only handles the low-frequency steady-state component; a hysteresis bandwidth of 150kW is set, and energy storage charging and discharging switching is blocked during small fluctuations to avoid repeated start-stop operations; minor residual fluctuations are buffered by the wind turbine's inertia. This embodiment solves the shortcomings of slow wind turbine response and inability to smooth high-frequency disturbances, while eliminating small reciprocating losses in energy storage.

[0064] Example 7: Example of power-limited operation condition control

[0065] 1. Weighting adjustment rules (energy storage frequency exceeding the limit life extension adjustment) The basic weight range is 0.8≤k≤0.95; within a 15-minute statistical period, for every 2 additional energy storage switching times, the weight coefficient k is increased by 0.01; once k reaches its upper limit of 0.95, it is permanently locked and will not be increased further to avoid overload of wind turbine frequency regulation.

[0066] 2. Weighted reverse callback rule (SOC power recovery adjustment) When the real-time SOC of energy storage is less than 25%, the power recovery logic is triggered, and the k value is lowered by 0.02 in a single instance to moderately increase the output of energy storage and accelerate the return of SOC to the normal range; the lower limit of k is lowered by 0.8 to prevent losses caused by excessive energy storage ratio.

[0067] 3. Quantitative control Operating conditions: Wind farm operates under power-limited scheduling, sufficient wind turbine reserve, initial weight k=0.8, frequency regulation demand Δ P total =1000kW. Control process: Initially, the wind turbine output is 800kW and the energy storage output is 200kW; within a 15-minute cycle, the number of energy storage switching times increases by 4, and k is increased by 0.02 to 0.82, with the wind turbine output at 820kW and the energy storage output at 180kW; after continuous losses, it is gradually increased to 0.92, with the wind turbine undertaking 920kW of frequency regulation power and the energy storage output reduced to 80kW; if the energy storage SOC drops to 24%, the callback logic is triggered, and k is slightly reduced to restore the energy storage capacity.

[0068] Example 8: Near-cut-out wind speed control example The compliance basis for the frequency disturbance threshold disclosed in this invention is as follows: the 0.05Hz disturbance threshold is strictly set with reference to the primary frequency regulation dead zone threshold of the power grid in the "Wind Farm Grid Connection Operation Control Specification", which is compatible with the mainstream frequency regulation assessment standards of the domestic power grid, has strong universality and compliance basis.

[0069] Operating conditions: Wind speed 24 m / s, wind turbine feathering speed limit, no frequency regulation margin. Control strategy: Wind turbine frequency regulation output is set to 0, and all frequency regulation needs are handled by energy storage; using 0.05 Hz as the threshold, an absolute frequency deviation of <0.05 Hz is considered a small disturbance, and energy storage charging and discharging are locked throughout to avoid ineffective losses; an absolute frequency deviation of ≥0.05 Hz is considered a large disturbance, and energy storage is activated for full-scale frequency regulation; SOC is monitored in real time throughout the process, and when the upper or lower SOC limits are triggered, frequency regulation is immediately stopped and an alarm is reported to the dispatch terminal to prioritize equipment safety.

[0070] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0071] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A wind power energy storage frequency regulation control method, characterized in that, The wind power energy storage frequency regulation control method includes: A real-time identification model for multiple operating conditions of a wind farm is constructed to identify the current operating condition based on the real-time operating parameters of the wind farm. The operating conditions include steady-state power output condition, gust disturbance condition, power limiting condition, and near-cutoff wind speed condition. Upon receiving the grid frequency regulation power demand command, the wind turbine frequency regulation power and energy storage frequency regulation power are dynamically and adaptively allocated according to the identified current operating conditions. In the case of gust disturbance, energy storage is prioritized to smooth short-term power fluctuations, while in the case of steady-state output, the wind farm's reserve capacity is prioritized to participate in frequency regulation. In the power allocation process, a lifespan constraint threshold for energy storage charging and discharging is introduced to suppress frequent reciprocating charging and discharging of energy storage while meeting the grid frequency regulation target. The wind turbine frequency regulation power command and the energy storage frequency regulation power command are respectively issued to the wind farm pitch control system and the energy storage converter to perform joint frequency regulation operation.

2. The wind power energy storage frequency regulation control method according to claim 1, characterized in that, The real-time operating parameters of the wind farm include the active power output of the wind farm, the measured wind speed, the pitch angle of the wind turbine, the real-time rotor speed, the grid connection frequency, and the real-time state of charge (SOC) of the energy storage. The above operating parameters are selected as feature inputs to build a multi-condition real-time identification model.

3. The wind power energy storage frequency regulation control method according to claim 2, characterized in that, A multi-condition real-time identification model is built using the fuzzy comprehensive evaluation method. The current operating condition is determined by calculating the membership degree of the operating parameters to various operating conditions. The formula for calculating the membership degree of a single parameter is as follows: u mi =e A A=-( x m -x mi ) 2 / 2σ mi 2 In the formula: u mi Let m be the membership degree of the m-th operating parameter to the i-th operating condition, where i takes the values ​​1, 2, 3, and 4 respectively, corresponding to the steady-state output condition, gust disturbance condition, power-limited operation condition, and near-cutoff wind speed condition. x m This refers to the m-th real-time operating parameter collected from the wind farm. x mi This refers to the pre-calibrated standard center value of the m-th operating parameter under the i-th type of working condition; σ mi Let be the variance of the m-th operating parameter under the i-th operating condition; Calculate the membership degree values ​​of the real-time parameters for the four operating conditions respectively, and determine the operating condition corresponding to the maximum membership degree as the identified current operating condition.

4. The wind power energy storage frequency regulation control method according to claim 1, characterized in that, Preset the maximum allowable charge and discharge frequency per unit cycle of energy storage N max As a threshold for limiting the charge-discharge lifespan of energy storage, the actual number of charge-discharge switching cycles of energy storage within a unit sampling period is counted in real time. N real ;when N real < N max At that time, energy storage participates in frequency regulation normally according to the preset allocation rules for each operating condition. N real ≥ N max At the same time, the blocking range for small frequency fluctuations in the power grid is adaptively expanded to reduce the frequency of energy storage frequency regulation.

5. The wind power energy storage frequency regulation control method according to claim 4, characterized in that, The cooperative control method under steady-state output conditions is as follows: The total frequency regulation demand of the power grid is denoted as Δ. P total Priority will be given to allocating all frequency regulation power demand to the wind farm's reserve capacity, and the frequency regulation output Δ of the wind turbines will be used to meet this demand. P wt =Δ P total Theoretical output of energy storage Δ P bat =0; only when the wind farm's maximum adjustable reserve capacity Δ P total-max <Δ P total At that time, energy storage makes up for the remaining power gap Δ P bat =Δ P total -Δ P total-max In conjunction with the energy storage lifetime constraint threshold, the amplitude is less than the set micro-power threshold Δ P th1 Power deviations are not responded to, so as to prohibit small repeated charging and discharging of energy storage.

6. The wind power energy storage frequency regulation control method according to claim 4, characterized in that, The coordinated control method under gust disturbance conditions is as follows: Prioritizing energy storage to mitigate power fluctuations caused by short-term gusts, the energy storage base output Δ P bat =Δ P total The fan only handles the low-frequency steady-state power component; Set the energy storage charge / discharge switching hysteresis bandwidth Δ f bat As a lifespan constraint, when the power fluctuation amplitude is less than the hysteresis bandwidth, the charging and discharging states of the energy storage are switched between each other to avoid high-frequency reciprocating charging and discharging losses of the energy storage.

7. The wind power energy storage frequency regulation control method according to claim 4, characterized in that, The cooperative control method under power-limited operation conditions is as follows: The wind farm has sufficient active power reserve capacity. The frequency regulation weighting coefficient k for the wind turbines is set to 0.8 ≤ k ≤ 0.

95. The frequency regulation output Δ of the wind turbines... P wt =k·Δ P total Energy storage can handle the remaining power Δ P bat =(1-k)·Δ P total The weighting coefficient k is dynamically adjusted based on the real-time charging and discharging frequency of energy storage to continuously reduce the proportion of energy storage output, thereby reducing the number of energy storage charging and discharging cycles.

8. The wind power energy storage frequency regulation control method according to claim 4, characterized in that, The collaborative control method under near-cut-out wind speed conditions is as follows: The wind turbine is constrained by the upper limit of wind speed and has no frequency adjustment margin; the wind turbine's frequency adjustment output Δ P wt =0, all frequency regulation needs are met by energy storage, i.e., Δ P bat =Δ P total Disturbance levels are classified based on the energy storage lifespan constraint threshold. Energy storage will start regulation only when the grid frequency deviation exceeds the large disturbance threshold, and the energy storage charging and discharging actions will be blocked for small frequency disturbances.

9. The wind power energy storage frequency regulation control method according to claim 1, characterized in that, Once the grid frequency returns to the rated allowable range and stabilizes for a preset duration, the frequency regulation task is considered complete. The frequency regulation operation is exited step by step in the order of linearly dropping the energy storage power to zero and slowly resetting the wind turbine pitch angle. A gradual power withdrawal strategy is adopted throughout the process to prevent the energy storage from undergoing secondary charging and discharging due to the impact of the operation mode switching.

10. A wind power energy storage frequency regulation control device, characterized in that, For executing the wind power energy storage frequency regulation control method according to any one of claims 1-9, the wind power energy storage frequency regulation control device comprises: The operating condition identification module is used to build a real-time identification model of multiple operating conditions in wind farms, collect real-time operating parameters of wind farms, identify the current operating conditions, and output the operating condition identification results. The power demand receiving module is used to receive frequency regulation power demand commands issued by the power grid in real time. The adaptive power allocation module is connected to the operating condition identification module and the power demand receiving module respectively. It is used to dynamically allocate the frequency regulation power of the wind turbine and the frequency regulation power of the energy storage according to the current operating conditions. The module integrates an energy storage charge and discharge life constraint threshold determination unit, which corrects the energy storage output and start-stop timing under each operating condition according to the life constraint conditions. The instruction issuance and execution module is used to issue the allocated wind turbine frequency regulation power instruction to the wind farm pitch control system and the energy storage frequency regulation power instruction to the energy storage converter, driving the wind and energy storage to jointly complete the grid frequency regulation operation.

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