Wind-Storage Combined Primary Frequency Regulation Method Considering Rotor Kinetic Energy Recovery

Abstract

This invention discloses a wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery, belonging to the field of power system frequency stability control and primary frequency regulation for new energy grid connection. The method includes: calculating the frequency regulation power demand; when the frequency fluctuation of the wind-storage system exceeds the frequency regulation dead zone, comparing the calculated frequency regulation power demand with the frequency regulation power provided by the wind turbine; if the frequency regulation power provided by the wind turbine can meet the frequency regulation demand, only the wind turbine participates in primary frequency regulation; otherwise, joint wind-storage primary frequency regulation is performed; when the frequency of the wind-storage system reaches its lowest point or the wind turbine speed reaches a set lower limit, the inertial output and droop output of the wind turbine are withdrawn, and the droop coefficient of the battery energy storage in the wind-storage system changes, assisting the wind turbine in recovering rotor kinetic energy; when the frequency fluctuation of the wind-storage system recovers to within the frequency regulation dead zone, the frequency regulation operation ends. This invention fully utilizes the frequency regulation capability of the wind turbine releasing rotor kinetic energy, as well as the respective frequency regulation advantages of battery energy storage and supercapacitors.

Description

Technical Field

[0001] This invention relates to the field of power system frequency stability control and primary frequency regulation technology for new energy grid connection, and more specifically, to a wind-storage combined primary frequency regulation method that considers rotor kinetic energy recovery. Background Technology

[0002] In current wind-storage combined primary frequency regulation strategies, common control practices for wind turbines and energy storage systems participating in frequency regulation include: (1) Although a combination of droop control and inertial control was adopted in the process of wind turbine participating in frequency regulation, the research on the combination of droop control and inertial control is still limited to the level of control coefficients and has not explored the frequency regulation capability of wind turbine rotor kinetic energy. (2) In the process of using hybrid energy storage system (HESS) to participate in grid frequency regulation, the power allocated to battery energy storage system (BESS) and supercapacitor (SC) is fixed and cannot be dynamically allocated according to the actual situation of the grid, thus failing to give full play to the advantages of hybrid energy storage system. Therefore, the existing wind and energy storage combined primary frequency regulation strategy still has obvious limitations: On the one hand, the integrated inertial control on the wind turbine side mostly stays at the setting and tuning of control coefficients, and fails to establish a refined power allocation and recovery coordination mechanism for the available kinetic energy of the rotor, resulting in insufficient utilization of the wind turbine's frequency regulation capability and causing a large secondary frequency drop during the rotor kinetic energy recovery phase; on the other hand, the power sharing of battery energy storage and supercapacitors on the hybrid energy storage side adopts a fixed allocation method, lacking an adaptive frequency division and coordinated adjustment mechanism based on the dynamic operating conditions of the power grid and the constraints of the state of charge (SOC), making it difficult to fully leverage the complementary advantages of "high power density - high energy density" while taking into account battery life and steady-state frequency quality.

[0003] The aforementioned shortcomings limit the coordination and stability of wind turbines and hybrid energy storage throughout the entire frequency regulation process, thereby restricting the engineering application and promotion of wind-storage combined frequency regulation technology. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a wind-storage combined primary frequency regulation method that takes into account rotor kinetic energy recovery. This method fully utilizes the frequency regulation capability of the wind turbine to release rotor kinetic energy, while also better leveraging the frequency regulation advantages of battery energy storage and supercapacitors.

[0005] The objective of this invention is achieved through the following solution: A wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery includes the following steps: Calculate the frequency regulation power requirement. When the frequency fluctuation of the wind-storage system is greater than the frequency regulation dead zone, compare the calculated frequency regulation power requirement with the frequency regulation power provided by the wind turbine side. If the frequency regulation power provided by the wind turbine side can meet the frequency regulation requirement, the wind turbine will participate in the first frequency regulation. If it does not meet the requirement, the wind and storage will perform a joint first frequency regulation. When the frequency of the wind-storage system reaches its lowest point or the fan speed reaches the set lower limit, the inertial output and droop output of the fan are discontinued, the droop coefficient of the battery energy storage in the wind-storage system changes, and the fan is assisted in restoring the rotor kinetic energy; when the frequency fluctuation of the wind-storage system returns to within the frequency regulation dead zone, the frequency regulation action ends.

[0006] Furthermore, the wind turbine participates in primary frequency regulation, specifically including the following sub-steps: On the wind turbine side, an inertia and droop output weight allocation model is established based on the rotor kinetic energy that can be used for frequency regulation, and the weights are adjusted based on the grid frequency deviation and frequency change rate; comprehensive inertial control with adaptive coefficients is used to leverage the frequency regulation capability of the wind turbine rotor kinetic energy.

[0007] Furthermore, the step of establishing an inertia and droop output weight allocation model on the wind turbine side based on the rotor kinetic energy available for frequency regulation, and adjusting the weights based on the grid frequency deviation and frequency change rate, specifically includes the following sub-steps: For grid frequency deviation The frequency change rate ROCOF is normalized, and the normalization expression is: ; ; It is the scaling constant normalized to ROCOF. It is Normalized scaling constant; The following weighting formula is then used to allocate the weights for inertia and droop output: ; ; It is the inertia weighting factor. It is the drooping weight factor. It is the baseline weighting factor without disturbance. It is the inertial output control weighting factor. It is the downward output control weight factor.

[0008] Furthermore, the integrated inertial control using adaptive coefficients, which leverages the frequency regulation capability of the wind turbine rotor kinetic energy, specifically includes the following sub-steps: Establish the following adaptive factor expression: ; ; It is an inertial adaptive factor. It is a drooping adaptive factor. , These are the inertial scaling reference and droop scaling reference under undisturbed conditions. , It is the inertial scaling control factor. and It is the droop scaling control factor; Based on the adaptive factor expression, the following expression for the comprehensive inertia coefficient is determined: ; ; and These are the reference inertia and the droop control coefficient, respectively.

[0009] Furthermore, the step of disengaging the inertial output and droop output of the wind turbine after the frequency of the wind storage system reaches its lowest point or the turbine speed reaches a set lower limit specifically includes the following sub-steps: The maximum grid frequency deviation corresponds to the point where the system frequency reaches its lowest point. Or it reaches the lower limit of the rotor speed set by the system. At this point, the inertial control of the wind turbine immediately disengages, and the droop control begins to disengage as a negative exponential function, subsequently decaying naturally. The specific decay expression is as follows:

[0010] It is the time corresponding to the lowest point of the power grid frequency. It is the decay time constant.

[0011] Furthermore, the combined wind and storage primary frequency regulation specifically includes the following sub-steps: On the hybrid energy storage control side, an adaptive complementary filter frequency division method is adopted. Two low-pass filters with different time constants are connected in parallel and cross-mixed through adaptive weighting coefficients to obtain the low-frequency component and the high-frequency component in a complementary manner. At the same time, adaptive integrated inertial control considering the state of charge (SOC) is used.

[0012] Furthermore, the method of adaptive complementary filtering frequency division involves two low-pass filters with different time constants connected in parallel. Low-frequency components are obtained through cross-mixing using adaptive weighting coefficients, and high-frequency components are obtained in a complementary manner. This is combined with adaptive integrated inertial control considering the state of charge (SOC). Specifically, this includes the following sub-steps: The weights are determined based on the different frequency regulation tasks undertaken by supercapacitor energy storage and battery energy storage at different time scales and with different response speeds, using two low-pass filters with different time constants. and Cross-mixing, the specific expression is as follows: ; ; , These are the time constants of the two filters, and The value is less than The value; Cross-mix weights The expression is as follows: ; It is the frequency change rate response factor. , These are the maximum and minimum values ​​of the mixed weights. This indicates the state of charge (SOC) of a supercapacitor. The high-frequency signal after adaptive complementary filtering and frequency division low-frequency signals The expression is as follows: ; ; The low-frequency signal, after frequency division, is sent to the battery for energy storage, while the high-frequency signal is sent to the supercapacitor.

[0013] Furthermore, the frequency modulation dead zone includes 0.033Hz.

[0014] Furthermore, the aforementioned The value includes 0.2Hz.

[0015] Furthermore, the aforementioned The value includes 0.8 Hz / s.

[0016] The beneficial effects of this invention include: This invention is based on a weighted distribution model of inertial output and droop output constructed using the rotor kinetic energy of a doubly fed wind turbine. The weights are adaptively adjusted according to the grid frequency deviation and frequency change rate, enabling the wind turbine to release rotor kinetic energy as needed during the primary frequency regulation process. This improves the dynamic support capability during the frequency drop phase, raises the minimum frequency point, and improves the smoothness of the recovery process. At the same time, by coordinating the power withdrawal process during the rotor kinetic energy recovery phase, the secondary frequency drop caused by kinetic energy recovery can be effectively suppressed, enhancing the dynamic characteristics and stability of the system frequency.

[0017] This invention changes the fixed power allocation method within hybrid energy storage from a fixed time constant low-pass filter to an adaptive complementary filter frequency division strategy. This strategy can adaptively generate high and low frequency power components according to the actual operating conditions of the power grid and achieve complementary allocation. This allows supercapacitors to prioritize high-frequency rapid power regulation, while battery energy storage mainly undertakes low-frequency energy support and wind power recovery compensation, thereby fully leveraging the power / energy complementary advantages of the two types of energy storage. This strategy can reduce the impact of high-frequency charging and discharging and power fluctuations in battery energy storage, reduce the equivalent cycle number and lifespan loss, and further improve the steady-state frequency quality and overall frequency regulation efficiency. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the wind-storage combined primary frequency regulation control strategy according to an embodiment of the present invention; Figure 2 The grid frequency for which the wind turbine participates in frequency regulation independently at a wind speed of 9 m / s; Figure 3 The fan speed at which the fan participates in frequency regulation independently at a wind speed of 9 m / s; Figure 4 The power of the fan that participates in frequency regulation alone at a wind speed of 9 m / s; Figure 5 The grid frequency for wind and energy storage to jointly participate in frequency regulation at a wind speed of 9 m / s; Figure 6 The wind turbine speed at which the wind and energy storage system jointly participate in frequency regulation at a wind speed of 9 m / s; Figure 7 The wind turbine power for wind and energy storage to participate in frequency regulation at a wind speed of 9 m / s; Figure 8 The battery energy storage power for wind power and energy storage to participate in frequency regulation at a wind speed of 9 m / s; Figure 9 This refers to a battery energy storage SOC that participates in frequency regulation in conjunction with wind power and energy storage at a wind speed of 9 m / s. Figure 10 The power of the supercapacitor used in frequency regulation by wind and energy storage at a wind speed of 9 m / s; Figure 11 The supercapacitor SOC for wind and energy storage to participate in frequency regulation at a wind speed of 9 m / s; Figure 12 This represents a continuous load disturbance waveform. Figure 13 The grid frequency under continuous load disturbance; Figure 14 This refers to the battery energy storage power under continuous load disturbance. Figure 15 This refers to the power of the supercapacitor under continuous load disturbance. Detailed Implementation

[0020] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0021] The technical solution of this invention specifically relates to the field of wind power and energy storage joint frequency regulation control. In a preferred embodiment, it particularly relates to an adaptive weight allocation of inertial output and droop output for a doubly fed induction generator (DFIG), and an adaptive complementary filtering frequency division and SOC constraint coordinated control for a battery energy storage system (BESS) and a supercapacitor (SC). The control strategy and its system implementation are used to coordinate and compensate the frequency regulation power during the wind turbine rotor kinetic energy recovery process to suppress the secondary frequency drop.

[0022] More specifically, on the wind turbine side, an inertia and droop output weight allocation model is established based on the rotor kinetic energy available for frequency regulation, and the weights are adjusted based on grid frequency deviation and frequency change rate. Adaptive coefficient integrated inertial control is used to fully utilize the frequency regulation capability of the doubly-fed induction generator (DFIG) rotor kinetic energy, while setting a lower limit for rotor speed to prevent the DFIG from disconnecting from the grid due to excessively low speed. On the hybrid energy storage control side, an adaptive complementary filter frequency division method is adopted. Two low-pass filters with different time constants are connected in parallel, and low-frequency components are obtained through cross-mixing using adaptive weight coefficients. High-frequency components are obtained in a complementary manner, and this is combined with an adaptive integrated inertial control strategy considering the state of charge (SOC) to fully utilize the respective frequency regulation advantages. Figure 1 As shown, an adaptive weighted integrated inertia control strategy is first proposed, which includes a grid frequency fluctuation stage control strategy, a grid frequency recovery stage control strategy, a weighted integrated inertia control model, and a hybrid energy storage system control strategy.

[0023] More specifically, the specific sub-processes for establishing a control strategy for power grid frequency fluctuations are as follows: (1) Regarding the frequency deviation of the power grid and the rate of change of frequency (ROCOF) ） Normalization processing The normalized expression is: ; ; in: It is the scaling constant normalized to ROCOF. It is The normalized scaling constant. Specifically, Select 0.2Hz. The setting is 0.8 Hz / s.

[0024] (2) Weighting of inertia and downward output During the weight allocation process, when the system is undisturbed, the weights of inertia and drooping output are equal, and the initial stage of frequency drop occurs. The inertial output is relatively small while the ROCOF is large, so the weight of the inertial output is increased. As the frequency drops, the system's... As the ROCOF continuously increases while the drooping force continuously decreases, it is necessary to increase the weight of the downward force. Therefore, the expression for weight allocation is as follows: ; ; in, It is the inertia weighting factor. It is the drooping weight factor. It is the baseline weighting factor without disturbance. It is the inertial output control weighting factor. It is the downward output control weight factor.

[0025] More specifically, the sub-processes for establishing the control strategy during the power grid frequency recovery phase are as follows: When the system frequency reaches its lowest point Or it reaches the lower limit of the rotor speed set by the system. At this point, the inertial control of the fan immediately disengages to prevent further release of rotor kinetic energy, while the droop control begins to disengage in the form of a negative exponential function. Using a negative exponential function for disengagement ensures continuity in the droop output, avoiding abrupt changes, followed by natural decay, which significantly reduces the frequency of secondary drops. The specific decay expression is as follows:

[0026] in: It is the time corresponding to the lowest point of the power grid frequency. It is the decay time constant.

[0027] More specifically, the sub-processes for establishing the weighted integrated inertial control model are as follows: In the proposed weighted integrated inertial control strategy, the inertial control coefficients... and droop control coefficient It will also adaptively change with variations in Δf and ROCOF. The specific adaptive factor is expressed as follows: ; ; in: It is an inertial adaptive factor. It is a drooping adaptive factor. , These are the inertial scaling reference and droop scaling reference under undisturbed conditions. , It is the inertial scaling control factor. and It is the droop scaling control factor.

[0028] The above indicates that, with As increases, ROCOF decreases. Gradually reduce the frequency to avoid excessive release of rotor kinetic energy causing a secondary drop in frequency. It gradually increases, providing more continuous support for the power grid.

[0029] Therefore, the expression for the comprehensive inertia coefficient is:

[0030]

[0031] in: and These are the reference inertia and the droop control coefficient, respectively.

[0032] More specifically, the sub-processes for establishing a control strategy for a hybrid energy storage system are as follows: An adaptive complementary filter frequency division is proposed, specifically determining the weights based on the different time scales and response speeds of the supercapacitor energy storage and battery energy storage, using two low-pass filters with different time constants. and Cross-mixing, the specific expression is as follows: ; ; in: , These are the time constants of the two filters, and The value is less than The value of . It is a unit step function, used to ensure that the filter's impulse response is within... When the time is zero, multiply by This means that the filter only responds to current and future inputs and does not affect past time, which is a fundamental characteristic of real physical systems.

[0033] Cross-mix weights The expression is as follows: ; in: It is the frequency change rate response factor. , These are the maximum and minimum values ​​of the mixed weights. It is the SOC of a supercapacitor. This is the maximum value of the supercapacitor's state of charge (SOC). This is the minimum SOC (State of Charge) of the supercapacitor. Because supercapacitors have small capacitance and fast response, their SOC is used as a constraint in the formula. The high-frequency signal after adaptive complementary filtering and frequency division... low-frequency signals The expression is as follows: ; ; The low-frequency signal, after frequency division, is sent to the battery for energy storage, while the high-frequency signal is sent to the supercapacitor.

[0034] in, It is the raw, unprocessed frequency deviation signal. and This represents the output of the frequency deviation signal after passing through two first-order low-pass filters with different time constants.

[0035] Based on the aforementioned adaptive weighted inertia control strategy, this method is applied to the primary frequency regulation process of a wind power and energy storage joint frequency regulation control system. An embodiment proposes a wind power and energy storage joint primary frequency regulation method considering rotor kinetic energy recovery, including the following steps: Setting the system's frequency regulation dead zone to 0.033Hz, frequency fluctuations within this range will not trigger system frequency regulation. When the system's frequency fluctuation exceeds the frequency regulation dead zone, the required frequency regulation power is calculated and compared with the frequency regulation power that the wind turbine can provide. If the available frequency regulation power of the wind turbine is sufficient, only the wind turbine participates in primary frequency regulation; otherwise, joint wind power and energy storage primary frequency regulation is performed. When the system frequency reaches its lowest point or the wind turbine speed reaches the set lower limit, the wind turbine's inertial output immediately withdraws, and the droop output withdraws in the form of a negative exponential function. Furthermore, the droop coefficient of the battery energy storage changes to assist the wind turbine in recovering rotor kinetic energy. When the system's frequency fluctuation recovers to within the frequency regulation dead zone, the frequency regulation operation ends.

[0036] The embodiment of the present invention makes full use of the kinetic energy of the wind turbine rotor. Based on the available rotor kinetic energy of the wind turbine, an inertia and droop output weight allocation model is established. The weights are adjusted based on the grid frequency deviation and frequency change rate, and combined with comprehensive inertial control, so as to give full play to the frequency regulation capability of the wind turbine to release rotor kinetic energy.

[0037] The present invention proposes a fixed power allocation method for hybrid energy storage. In terms of power allocation within the hybrid energy storage, the low-pass filter with a fixed time constant is replaced with an adaptive complementary filter, which adaptively allocates power according to the actual situation of the power grid, thereby better leveraging the frequency regulation advantages of battery energy storage and supercapacitors.

[0038] To verify the effectiveness of the strategy proposed in the embodiments of the present invention, the analysis and verification were carried out in two parts: the wind turbine side and the hybrid energy storage side. Figures 2-15 As shown.

[0039] (a) Wind turbine side With a fixed step load, wind speeds of 9 m / s and 11 m / s were set, and three control methods were compared and analyzed. Method 3 is the method of this invention, and the others are comparative methods.

[0040] Method 1: The wind turbine participates in frequency regulation independently, using a fixed coefficient control strategy.

[0041] Method 2: The wind turbine participates in frequency regulation independently, using a variable coefficient control strategy.

[0042] Method 3: The wind turbine participates in frequency regulation independently, using an adaptive weighting strategy for control.

[0043] Table 1. Partial Results under Wind Turbine Side Control Method 1-3

[0044] The results show that the lowest frequency controlled by Method 3 in Table 1 is 49.84Hz, which is about 0.032% higher than 49.824Hz controlled by Method 1 and about 0.026% higher than 49.827Hz controlled by Method 2. The second drop amplitude is only 0.0035Hz, which is about 84.1% higher than 0.022Hz controlled by Method 1 and about 86.5% higher than 0.026Hz controlled by Method 2. The time to reach the lowest frequency value is 12.82 seconds, which is about 28.6% shorter than 17.95 seconds controlled by Method 1 and about 32.1% shorter than 18.88 seconds controlled by Method 2. This fully demonstrates that, without changing the overall frequency regulation capability of the wind turbine, Method 3 can significantly improve the frequency regulation capability of the wind turbine.

[0045] The lowest rotor speed under Method 3 control is 0.7465 pu, which is basically the same as 0.747 pu under Method 2 control and 2.55% lower than 0.766 pu under Method 1 control. This indicates that Method 3 can extract rotor kinetic energy more fully and smoothly; the descent and recovery slopes are smoother, avoiding the oscillations caused by rapid release and cutoff of rotor kinetic energy in Methods 1 and 2; and the method adopts a negative exponential function form to slowly exit during the grid frequency recovery phase, sacrificing a small amount of recovery speed in exchange for greater system damping and smaller oscillations.

[0046] The peak power output of the wind turbine under Method 3 control was 0.546 pu, which is 5.37% lower than the 0.577 pu controlled by Method 1 and 7.46% lower than the 0.59 pu controlled by Method 2, with no higher instantaneous peak power output. It exhibits more sustained and effective support capability in terms of power output continuity and stability, and the power output fluctuation is significantly reduced. In terms of recovery phase characteristics, the wind turbine power recovery phase is very smooth, effectively suppressing the secondary drop in system frequency. This fully demonstrates that Method 3, through reasonable power allocation, avoids instantaneous power surges while effectively improving the stability and continuity of system frequency regulation by providing sustained and stable power output support and a smooth recovery process.

[0047] At a wind speed of 11 m / s, the wind turbine rotates at a higher speed, resulting in more rotor kinetic energy available for frequency regulation. This leads to a deeper involvement in frequency regulation during grid disturbances, resulting in lower maximum frequency deviation and steady-state frequency compared to the 9 m / s wind speed. Despite this, the control method proposed in this invention still exhibits good applicability and effectiveness. Regarding system frequency, Method 3 can still significantly improve the minimum system frequency. In terms of wind turbine output, the timely disengagement of the inertial element after the minimum frequency point and the slow disengagement of the drooping element according to a negative exponential law effectively suppress secondary frequency drops, smoothing the process of wind turbine exiting frequency regulation and rotor kinetic energy recovery.

[0048] (ii) Hybrid energy storage side This invention analyzes and verifies two types of disturbances: step load disturbance and continuous disturbance load, with a fixed wind speed of 9 m / s.

[0049] (1) Under the condition of step load disturbance, four control methods are compared and analyzed, of which method 4 is the method of the present invention, and the other methods are comparative methods.

[0050] Method 1: Wind and energy storage combined frequency regulation, with the energy storage system using separate battery energy storage.

[0051] Method 2: Wind and storage combined frequency regulation, the energy storage system adopts hybrid energy storage and uses a fixed frequency division control strategy.

[0052] Method 3: Wind and energy storage combined frequency regulation, the energy storage system adopts hybrid energy storage and uses an adaptive complementary filter frequency division strategy for control.

[0053] Method 4: Wind and energy storage combined frequency regulation. The energy storage system adopts hybrid energy storage, uses an adaptive complementary filter frequency division strategy for control, and battery energy storage assists in the recovery of the rotor kinetic energy of the wind turbine.

[0054] Table 2. Partial Results under Hybrid Energy Storage Side Methods 1-4

[0055] The results show that the lowest frequency controlled by Method 3 in Table 2 is 49.868Hz, which is 0.006% higher than the lowest frequency of 49.865Hz in Method 1 and 0.002% higher than the lowest frequency of 49.867Hz in Method 2. The lowest frequency of Method 4 also reaches 49.868Hz, which is on par with the hybrid energy storage adaptive complementary filter frequency division control strategy. With wind and energy storage jointly participating in frequency regulation, the secondary frequency drop in the grid has essentially disappeared, while Method 4 achieves zero secondary frequency drop, completely eliminating the risk of frequency fluctuations. The steady-state frequency controlled by Method 3 is 49.934Hz, while the steady-state frequency controlled by Method 4 is increased to 49.941Hz, an increase of 0.014%, demonstrating superior steady-state frequency performance. The hybrid energy storage adaptive complementary filter frequency division control strategy effectively improves the lowest frequency point and suppresses secondary frequency drops through adaptive power allocation. Furthermore, the battery energy storage-assisted rotor kinetic energy recovery strategy further eliminates secondary frequency drops and significantly improves the steady-state frequency.

[0056] The lowest fan speed controlled by Method 3 was 0.7905 pu, an increase of 0.32% compared to the lowest speed of 0.788 pu controlled by Method 1, and an increase of 0.19% compared to the lowest speed of 0.789 pu controlled by Method 2. The lowest fan speed controlled by Method 4 was further increased to 0.795 pu, an increase of 0.57% compared to Method 3, effectively reducing the excessive release of rotor kinetic energy and facilitating rapid and stable speed recovery. The peak fan output of the three mixed storage-related control methods was lower than that of Method 1 (0.527 pu), with Method 3 achieving a peak output of 0.519 pu, a decrease of 1.52% compared to Method 1. In terms of minimum output, Method 3 achieved a minimum output of 0.222 pu, an increase of 6.22% compared to the minimum output of 0.209 pu controlled by Method 1, and Method 4 achieved a minimum output of 0.2238 pu, a further increase of 0.81%, indicating smaller output fluctuations and more stable continuous support capabilities. In summary, the hybrid storage adaptive complementary filter frequency division control strategy reduces the peak output of the wind turbine while increasing the minimum speed and reducing output fluctuations through adaptive power allocation. On this basis, the BESS auxiliary rotor kinetic energy recovery strategy further optimizes the wind turbine speed recovery characteristics.

[0057] Compared to fixed frequency division, hybrid energy storage employs adaptive complementary filtering and frequency division, which can adaptively allocate high and low frequency signals according to grid frequency fluctuations. This allows for increased supercapacitor output during the initial stages of frequency fluctuations, enhancing the grid's dynamic response. Furthermore, battery energy storage assists in the recovery of wind turbine rotor kinetic energy, fundamentally solving the problem of secondary frequency drops. These two control schemes fully leverage the fast response of supercapacitors and the large capacity of batteries, making more rational use of the advantages of hybrid energy storage systems in suppressing frequency drops and providing steady-state support.

[0058] (2) The disturbance caused by the continuous fluctuation of the load between -6MW and +6MW is adopted. Under the condition of continuous load disturbance, two control methods are compared and analyzed: the fixed frequency division of the wind turbine and the hybrid energy storage and the adaptive complementary filter frequency division of the wind turbine and the hybrid energy storage.

[0059] The results show that when hybrid energy storage employs adaptive complementary filter frequency division control, the amplitude of grid frequency fluctuations is smaller. Compared with the fixed frequency division strategy, the supercapacitor exhibits a larger power waveform amplitude and a more proactive response under the adaptive complementary filter frequency division strategy, following frequency fluctuations more quickly and undertaking more rapid power regulation tasks. Correspondingly, the power variation amplitude of battery energy storage is significantly reduced, which decreases the number of charge-discharge cycles and the depth of charge-discharge, thus extending battery life. In summary, the adaptive complementary filter frequency division control not only fully leverages the advantages of supercapacitors' fast response speed and long cycle life but also considers the lifespan benefits of battery energy storage while suppressing frequency fluctuations, thereby improving the overall dynamic performance of wind and energy storage combined primary frequency regulation.

[0060] It should be noted that, within the scope of protection defined in the claims of this invention, the following embodiments can be combined and / or extended or replaced in any logical manner from the above specific embodiments, such as the disclosed technical principles, disclosed technical features or implicitly disclosed technical features.

[0061] Example 1 A wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery includes the following steps: Calculate the frequency regulation power requirement. When the frequency fluctuation of the wind-storage system is greater than the frequency regulation dead zone, compare the calculated frequency regulation power requirement with the frequency regulation power provided by the wind turbine side. If the frequency regulation power provided by the wind turbine side can meet the frequency regulation requirement, the wind turbine will participate in the first frequency regulation. If it does not meet the requirement, the wind and storage will perform a joint first frequency regulation. When the frequency of the wind-storage system reaches its lowest point or the fan speed reaches the set lower limit, the inertial output and droop output of the fan are discontinued, the droop coefficient of the battery energy storage in the wind-storage system changes, and the fan is assisted in restoring the rotor kinetic energy; when the frequency fluctuation of the wind-storage system returns to within the frequency regulation dead zone, the frequency regulation action ends.

[0062] Example 2 Based on Example 1, the fan participating in primary frequency regulation specifically includes the following sub-steps: On the wind turbine side, an inertia and droop output weight allocation model is established based on the rotor kinetic energy that can be used for frequency regulation, and the weights are adjusted based on the grid frequency deviation and frequency change rate; comprehensive inertial control with adaptive coefficients is used to leverage the frequency regulation capability of the wind turbine rotor kinetic energy.

[0063] Example 3 Based on Example 2, the step of establishing an inertia and droop output weight allocation model on the wind turbine side according to the rotor kinetic energy available for frequency regulation, and adjusting the weights based on the grid frequency deviation and frequency change rate, specifically includes the following sub-steps: For grid frequency deviation The frequency change rate ROCOF is normalized, and the normalization expression is: ; ; It is the scaling constant normalized to ROCOF. It is Normalized scaling constant; The following weighting formula is then used to allocate the weights for inertia and droop output: ; ; It is the inertia weighting factor. It is the drooping weight factor. It is the baseline weighting factor without disturbance. It is the inertial output control weighting factor. It is the downward output control weight factor.

[0064] Example 4 Based on Example 3, the comprehensive inertial control using adaptive coefficients to leverage the frequency regulation capability of the wind turbine rotor kinetic energy specifically includes the following sub-steps: Establish the following adaptive factor expression: ; ; It is an inertial adaptive factor. It is a drooping adaptive factor. , These are the inertial scaling reference and droop scaling reference under undisturbed conditions. , It is the inertial scaling control factor. and It is the droop scaling control factor; Based on the adaptive factor expression, the following expression for the comprehensive inertia coefficient is determined: ; ; and These are the reference inertia and the droop control coefficient, respectively.

[0065] Example 5 Based on Example 1, the step of disengaging the inertial output and droop output of the wind turbine after the frequency of the wind-storage system reaches its lowest point or the turbine speed reaches a set lower limit specifically includes the following sub-steps: The maximum grid frequency deviation corresponds to the point where the system frequency reaches its lowest point. Or it reaches the lower limit of the rotor speed set by the system. At this point, the inertial control of the wind turbine immediately disengages, and the droop control begins to disengage as a negative exponential function, subsequently decaying naturally. The specific decay expression is as follows:

[0066] It is the time corresponding to the lowest point of the power grid frequency. It is the decay time constant.

[0067] Example 6 Based on Example 1, the wind-storage combined primary frequency regulation specifically includes the following sub-steps: On the hybrid energy storage control side, an adaptive complementary filter frequency division method is adopted. Two low-pass filters with different time constants are connected in parallel and cross-mixed through adaptive weighting coefficients to obtain the low-frequency component and the high-frequency component in a complementary manner. At the same time, adaptive integrated inertial control considering the state of charge (SOC) is used.

[0068] Example 7 Based on Example 6, the method of adaptive complementary filtering frequency division involves two low-pass filters with different time constants connected in parallel. Low-frequency components are obtained through cross-mixing using adaptive weighting coefficients, and high-frequency components are obtained in a complementary manner. This is combined with adaptive integrated inertial control considering the state of charge (SOC). Specifically, this includes the following sub-steps: The weights are determined based on the different frequency regulation tasks undertaken by supercapacitor energy storage and battery energy storage at different time scales and with different response speeds, using two low-pass filters with different time constants. and Cross-mixing, the specific expression is as follows: ; ; , These are the time constants of the two filters, and The value is less than The value; Cross-mix weights The expression is as follows: ; It is the frequency change rate response factor. , These are the maximum and minimum values ​​of the mixed weights. This indicates the state of charge (SOC) of a supercapacitor. The high-frequency signal after adaptive complementary filtering and frequency division low-frequency signals The expression is as follows: ; ; The low-frequency signal, after frequency division, is sent to the battery for energy storage, while the high-frequency signal is sent to the supercapacitor.

[0069] Example 8 Based on Example 1, the frequency modulation dead zone includes 0.033Hz.

[0070] Example 9 Based on Example 3, the The value includes 0.2Hz.

[0071] Example 10 Based on Example 3, the The value includes 0.8 Hz / s.

[0072] The units described in the embodiments of the present invention can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the specific unit itself.

[0073] According to one aspect of the present invention, a computer program product or computer program is provided, the computer program product or computer program including computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and executes the computer instructions, causing the computer device to perform the methods provided in the various optional implementations described above.

[0074] In another aspect, embodiments of the present invention also provide a computer-readable medium, which may be included in the electronic device described in the above embodiments; or it may exist independently and not assembled into the electronic device. The computer-readable medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform the methods described in the above embodiments.

Claims

1. A wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery, characterized in that, Includes the following steps: Calculate the frequency regulation power requirement. When the frequency fluctuation of the wind-storage system is greater than the frequency regulation dead zone, compare the calculated frequency regulation power requirement with the frequency regulation power provided by the wind turbine side. If the frequency regulation power provided by the wind turbine side can meet the frequency regulation requirement, the wind turbine will participate in the first frequency regulation. If it does not meet the requirement, the wind and storage will perform a joint first frequency regulation. When the frequency of the wind-storage system reaches its lowest point or the fan speed reaches the set lower limit, the inertial output and droop output of the fan are discontinued, the droop coefficient of the battery energy storage in the wind-storage system changes, and the fan is assisted in restoring the rotor kinetic energy; when the frequency fluctuation of the wind-storage system returns to within the frequency regulation dead zone, the frequency regulation action ends.

2. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 1, characterized in that, The wind turbine participates in primary frequency regulation, specifically including the following sub-steps: On the wind turbine side, an inertia and droop output weight allocation model is established based on the rotor kinetic energy that can be used for frequency regulation, and the weights are adjusted based on the grid frequency deviation and frequency change rate; comprehensive inertial control with adaptive coefficients is used to leverage the frequency regulation capability of the wind turbine rotor kinetic energy.

3. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 2, characterized in that, The step of establishing an inertia and droop output weight allocation model on the wind turbine side based on the rotor kinetic energy available for frequency regulation, and adjusting the weights based on the grid frequency deviation and frequency change rate, specifically includes the following sub-steps: For grid frequency deviation The frequency change rate ROCOF is normalized, and the normalization expression is: ； ； It is the scaling constant normalized to ROCOF. It is Normalized scaling constant; The following weighting formula is then used to allocate the weights for inertia and droop output: ； ； It is the inertia weighting factor. It is the drooping weight factor. It is the baseline weighting factor without disturbance. It is the inertial output control weighting factor. It is the downward output control weight factor.

4. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 3, characterized in that, The integrated inertial control using adaptive coefficients, which leverages the frequency regulation capability of the wind turbine rotor's kinetic energy, specifically includes the following sub-steps: Establish the following adaptive factor expression: ； ； It is an inertial adaptive factor. It is a drooping adaptive factor. , These are the inertial scaling reference and droop scaling reference under undisturbed conditions. , It is the inertial scaling control factor. and It is the droop scaling control factor; Based on the adaptive factor expression, the following expression for the comprehensive inertia coefficient is determined: ； ； and These are the reference inertia and the droop control coefficient, respectively.

5. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 1, characterized in that, When the frequency of the wind-storage system reaches its lowest point or the fan speed reaches the set lower limit, the inertial output and droop output of the fan will cease, specifically including the following sub-steps: The maximum grid frequency deviation corresponds to the point where the system frequency reaches its lowest point. Or it reaches the lower limit of the rotor speed set by the system. At this point, the inertial control of the wind turbine immediately disengages, and the droop control begins to disengage as a negative exponential function, subsequently decaying naturally. The specific decay expression is as follows: It is the time corresponding to the lowest point of the power grid frequency. It is the decay time constant.

6. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 1, characterized in that, The wind-storage combined primary frequency regulation specifically includes the following sub-steps: On the hybrid energy storage control side, an adaptive complementary filter frequency division method is adopted. Two low-pass filters with different time constants are connected in parallel and cross-mixed through adaptive weighting coefficients to obtain the low-frequency component and the high-frequency component in a complementary manner. At the same time, adaptive integrated inertial control considering the state of charge (SOC) is used.

7. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 6, characterized in that, The method employs an adaptive complementary filtering frequency division approach, where two low-pass filters with different time constants are connected in parallel. Low-frequency components are obtained through cross-mixing using adaptive weighting coefficients, and high-frequency components are obtained in a complementary manner. This is combined with adaptive integrated inertial control considering the state of charge (SOC). Specifically, this includes the following sub-steps: The weights are determined based on the different frequency regulation tasks undertaken by supercapacitor energy storage and battery energy storage at different time scales and with different response speeds, using two low-pass filters with different time constants. and Cross-mixing, the specific expression is as follows: ； ； , These are the time constants of the two filters, and The value is less than The value; Cross-mix weights The expression is as follows: ； It is the frequency change rate response factor. , These are the maximum and minimum values ​​of the mixed weights. This indicates the state of charge (SOC) of a supercapacitor. The high-frequency signal after adaptive complementary filtering and frequency division low-frequency signals The expression is as follows: ； ； The low-frequency signal, after frequency division, is sent to the battery for energy storage, while the high-frequency signal is sent to the supercapacitor.

8. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 1, characterized in that, The frequency modulation dead zone includes 0.033Hz.

9. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 3, characterized in that, The The value includes 0.2Hz.

10. The wind-storage combined primary frequency regulation method considering rotor kinetic energy recovery according to claim 3, characterized in that, The The value includes 0.8 Hz / s.

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