Frequency regulation blocking control method for primary frequency regulation transient response of wind turbine generator system

Abstract

The present invention discloses a frequency modulation blocking control method for the primary frequency modulation transient response of a wind turbine generator set, which belongs to the technical field of frequency modulation blocking of a wind turbine generator set grid connection point, and comprises the following steps: S1, starting the determination function of the cause of frequency disturbance; S2, analyzing the cause of the frequency disturbance of the wind farm grid connection point, and obtaining the cause determination result; S3, performing frequency modulation blocking control on the wind turbine generator set according to the cause determination result: when the cause is the active power imbalance in the area where the wind farm access point is located, opening the primary frequency modulation function; when the cause is the local oscillation of the frequency of the wind farm access point, blocking the primary frequency modulation function, and restoring the wind farm active power to the state before the primary frequency modulation; when the cause is the instability of the frequency of the wind farm access point, blocking the primary frequency modulation function, and causing the wind turbine generator set to shut down urgently, and cutting off the load. The present invention can prevent the frequent repeated start-up and malfunction of the primary frequency modulation, and improve the stability of the wind turbine generator set participating in the primary frequency modulation.

Description

Technical Field

[0001] The invention relates to the technical field of frequency modulation interlocking of a wind turbine generator set grid connection point, and in particular to a frequency modulation interlocking control method for a primary frequency modulation transient response of a wind turbine generator set. Background Art

[0002] The stability of the power system is a key factor in ensuring the safe operation of the power grid. With the large-scale grid connection of renewable energy, especially wind power, the frequency regulation capability of wind turbines has become particularly important for the stability of the power system. Primary frequency regulation, as the initial response of power system frequency regulation, plays a key role in quickly restoring the frequency balance of the power grid.

[0003] The deviation between the frequency of the wind farm grid connection point and the rated frequency may exceed the primary frequency regulation dead zone due to various reasons, including unbalanced active power in the area where the wind farm access point is located, local oscillation of the frequency at the wind farm access point, and instability of the frequency at the wind farm access point.

[0004] However, existing wind turbines have limitations when participating in primary frequency modulation. After the transient response of primary frequency modulation is completed, their control systems often lack an effective mechanism to analyze and determine the cause of frequency disturbance in wind turbines. If the wind turbine cannot accurately analyze and determine the cause of frequency disturbance, it cannot decide whether to continue to participate in primary frequency modulation or lock the primary frequency modulation function. Therefore, primary frequency modulation may be frequently started, causing primary frequency modulation malfunctions, resulting in poor frequency modulation effects, affecting the operating efficiency of wind turbines and the stability of the power grid. Summary of the invention

[0005] The purpose of the present invention is to provide a frequency modulation locking control method for the primary frequency modulation transient response of a wind turbine generator set. The frequency modulation locking control method of the present invention can prevent frequent repeated startup and malfunction of the primary frequency modulation, thereby improving the stability of the wind turbine generator set participating in the primary frequency modulation; it can also improve the frequency modulation response accuracy of the wind turbine generator set, optimize the frequency regulation performance of the power system, and provide support for the safe, reliable and economical operation of the power grid.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A frequency modulation locking control method for primary frequency modulation transient response of a wind turbine generator system comprises the following steps:

[0008] S1. Real-time measurement of the frequency of the wind farm grid connection point. When the deviation between the real-time frequency of the grid connection point and the rated frequency of the power grid exceeds the primary frequency regulation dead zone, the primary frequency regulation completes the transient response and the frequency disturbance cause determination function is started;

[0009] S2. Analyze the causes of frequency disturbances at the wind farm grid connection point and obtain the cause determination result;

[0010] S3. Perform frequency modulation locking control on wind turbines according to the cause determination result: when the frequency disturbance at the wind farm grid connection point is caused by active power imbalance in the area where the wind farm access point is located, open the primary frequency modulation function; when the frequency disturbance at the wind farm grid connection point is caused by local oscillation of the frequency at the wind farm access point, lock the primary frequency modulation function, and restore the active power of the wind farm to the level before the primary frequency modulation; when the frequency disturbance at the wind farm grid connection point is caused by frequency instability at the wind farm access point, lock the primary frequency modulation function, shut down the wind turbines urgently, and cut off the load.

[0011] Furthermore, in step S2, the steps of determining the cause of the frequency disturbance at the wind farm grid connection point are as follows:

[0012] S21. Create and record a time series of frequency deviation, a time series of frequency change rate, and a time series of frequency change acceleration based on the real-time measurement of the frequency of the wind farm grid connection point within a fixed time period, wherein the time series of frequency deviation refers to the difference between the frequency of the wind farm grid connection point measured in real time under the time series and the rated frequency of the power grid;

[0013] S22. Create a product function: record the duration of a frequency modulation transient response as , then the fixed duration Set to , the starting time of the fixed duration is , the frequency deviation , frequency change rate , frequency change acceleration Multiplying the product factor gives the product function. The product function The specific formula is as follows:

[0014] ,

[0015] in, Indicates the multiplication factor, set , by adjusting , can be increased or decreased Frequency Deviation , frequency change rate and frequency change acceleration Response sensitivity;

[0016] S23. Utilizing frequency deviation , frequency change rate , frequency change acceleration Sum and product functions To determine the cause of frequency disturbance at the wind farm grid connection point.

[0017] Further, in step S23, when the frequency deviation Periodic changes occur, the frequency change rate The absolute value of is non-monotonically decreasing, and the frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function When the frequency disturbance at the wind farm grid connection point is caused by the local oscillation of the frequency at the wind farm access point, the frequency deviation is zero or negative. Non-periodic changes, frequency change rate The absolute value of is monotonically decreasing, and the frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function When it changes non-periodically and its first-order derivative is continuously positive, the cause of the frequency disturbance at the wind farm grid connection point is the unbalanced active power in the area where the wind farm access point is located; if it is neither of the above two, the cause of the frequency disturbance at the wind farm grid connection point is the instability of the frequency at the wind farm access point.

[0018] Furthermore, in step S21, the frequency change rate is the frequency deviation Calculated using the difference method and recorded in time series. The specific calculation formula for the frequency change rate is:

[0019] ,in, is the sampling time interval.

[0020] Further, in step S21, the time series of frequency change acceleration is to convert the frequency change rate Frequency-varying acceleration calculated using the differential method Recorded in time series, at time Frequency change acceleration The specific calculation formula is:

[0021] ,in, is the sampling time interval.

[0022] Further, in step S21, the rated frequency of the power grid is 50 Hz.

[0023] Furthermore, the frequency deviation The specific formula for periodic changes is:

[0024] and

[0025] in, Refers to the frequency deviation The period when periodic changes occur, At the start time A fixed period of time Any time in .

[0026] Furthermore, the frequency change rate The specific formula for the non-monotonically decreasing absolute value of is:

[0027] , , , , so that

[0028] ;

[0029] in, and At the start time A fixed period of time For any two different moments in time, It's at the time and Some time in between.

[0030] Furthermore, the product function changes periodically and the product function The specific formula for the first-order derivative of to be zero or negative is:

[0031] and ,

[0032] ,

[0033] in, is the product function The period when periodic changes occur, Denotes the product function The first derivative of .

[0034] Furthermore, the frequency deviation The specific formula for non-periodic changes is:

[0035] ,

[0036] in, It means that the starting time is A fixed period of time A time interval of any length in ;

[0037] The frequency change rate The specific formula for the monotonically decreasing absolute value of is:

[0038] ;

[0039] The frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function The specific formula for non-periodic changes and its first-order derivative is continuously positive is:

[0040] ,

[0041] .

[0042] The beneficial effects of the present invention are:

[0043] The existing primary frequency modulation technology of wind turbines does not consider the problem that system oscillation may cause primary frequency modulation to malfunction, resulting in frequent erroneous startup of primary frequency modulation of wind turbines, affecting the normal operation of wind turbines. The frequency modulation locking control method of the present invention can accurately determine the cause of frequency disturbance, and perform corresponding locking operations according to different causes, thereby preventing frequent repeated startup and malfunction of primary frequency modulation, improving the stability of wind turbines participating in primary frequency modulation; it can also improve the frequency modulation response accuracy of wind turbines, optimize the frequency regulation performance of the power system, and provide support for the safe, reliable and economical operation of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of the frequency modulation locking control method of the primary frequency modulation transient response of the wind turbine generator set of the present invention;

[0045] Figure 2 It is a system frequency diagram obtained by MATLAB-simulink simulation provided by the present invention when active power imbalance occurs in the area where the wind farm access point is located;

[0046] Figure 3 The present invention provides a primary frequency modulation active power variation instruction diagram of a wind turbine generator set obtained by MATLAB-simulink simulation when active power imbalance occurs in the area where the wind farm access point is located;

[0047] Figure 4 The present invention provides an active power diagram of a wind turbine generator set obtained by MATLAB-simulink simulation when active power imbalance occurs in the area where the wind farm access point is located;

[0048] Figure 5 It is a system frequency diagram obtained by MATLAB-simulink simulation provided by the present invention when a local frequency oscillation occurs at a wind farm access point;

[0049] Figure 6 The present invention provides a primary frequency modulation active power variation instruction diagram of a wind turbine generator set obtained by MATLAB-simulink simulation when a local frequency oscillation occurs at a wind farm access point but the wind turbine generator set does not have an oscillation blocking function;

[0050] Figure 7 The present invention provides an active power diagram of a wind turbine generator set obtained by MATLAB-simulink simulation when a local frequency oscillation occurs at a wind farm access point but the wind turbine generator set does not have an oscillation blocking function;

[0051] Figure 8 The present invention provides a primary frequency modulation active power variation instruction diagram of a wind turbine generator set obtained by MATLAB-simulink simulation when a local frequency oscillation occurs at a wind farm access point and the wind turbine generator set has an oscillation blocking function;

[0052] Fig. 9 The present invention provides an active power diagram of a wind turbine generator set obtained by MATLAB-simulink simulation when a local frequency oscillation occurs at a wind farm access point and the wind turbine generator set has an oscillation blocking function. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0054] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper surface", "lower surface", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "forward", "reverse", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0055] like Figure 1 As shown, a frequency modulation locking control method for primary frequency modulation transient response of a wind turbine generator system comprises the following steps:

[0056] S1. Measure the frequency of the wind farm grid connection point in real time. When the deviation between the real-time frequency of the grid connection point and the rated frequency of the power grid exceeds the primary frequency regulation dead zone and the primary frequency regulation completes the transient response, the function of determining the cause of the frequency disturbance is started.

[0057] S2. Analyze the causes of frequency disturbances at the wind farm grid connection point and obtain the cause determination results. The specific steps are as follows:

[0058] S21. Within a fixed period of time, based on the real-time measurement of the frequency of the wind farm grid connection point, create and record a time series of frequency deviation, a time series of frequency change rate, and a time series of frequency change acceleration.

[0059] The time series of frequency deviation refers to the difference between the frequency of the wind farm grid connection point measured in real time under the time series and the rated frequency of the grid. In other words, the time series of frequency deviation is obtained by recording the difference between the frequency of the wind farm grid connection point measured in real time by the target wind farm using the frequency measuring device and the rated frequency of the grid into the time series. Frequency deviation The specific calculation formula is:

[0060] ,

[0061] in, The real-time frequency of the power grid can be measured in real time using a frequency measuring device at the target wind farm. The rated frequency of the power grid is 50Hz.

[0062] The time series of the frequency change rate, the frequency deviation Calculated using the difference method and recorded in time series. Frequency change rate The specific calculation formula is:

[0063] ,in, is the sampling time interval.

[0064] The time series of the frequency change acceleration is the frequency change rate Frequency-varying acceleration calculated using the differential method Recorded in time series, at time Frequency change acceleration The specific calculation formula is:

[0065] ,in, is the sampling time interval.

[0066] S22. Create a product function: record the duration of a frequency modulation transient response as , then the fixed duration Set to , the starting time of the fixed duration is , the frequency deviation , frequency change rate , frequency change acceleration Multiplying the product factor gives the product function. The product function The specific formula is as follows:

[0067] ,

[0068] in, Indicates the multiplication factor, set , by adjusting , can be increased or decreased Frequency Deviation , frequency change rate and frequency change acceleration Response sensitivity.

[0069] S23. Utilizing frequency deviation , frequency change rate , frequency change acceleration Sum and product functions To determine the cause of frequency disturbance at the wind farm grid connection point.

[0070] The specific determination is as follows:

[0071] When the frequency deviation Periodic changes occur, the frequency change rate The absolute value of is non-monotonically decreasing, and the frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function When periodic changes also occur and its first-order derivative is zero or negative, the cause of the frequency disturbance at the wind farm connection point is the local oscillation of the frequency at the wind farm connection point.

[0072] Where: the frequency deviation The specific formula for periodic changes is:

[0073] and ,

[0074] in, Refers to the frequency deviation The period when periodic changes occur, At the start time A fixed period of time Any time in .

[0075] The frequency change rate The specific formula for the non-monotonically decreasing absolute value of is:

[0076] , , , , so that

[0077] ,

[0078] in, and At the start time A fixed period of time For any two different moments in time, It's at the time and Some time in between.

[0079] The product function changes periodically and the product function The specific formula for the first-order derivative of to be zero or negative is:

[0080] and ,

[0081] ,

[0082] in, is the product function The period when periodic changes occur, Denotes the product function The product function The first-order derivative of is zero or negative, indicating that the product value tends to be stable or decrease, and the system is gradually recovering stability.

[0083] When the frequency deviation Non-periodic changes, frequency change rate The absolute value of is monotonically decreasing, and the frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function When it changes non-periodically and its first-order derivative is continuously positive, the cause of the frequency disturbance at the wind farm grid connection point is the unbalanced active power in the area where the wind farm access point is located; if it is neither of the above two, the cause of the frequency disturbance at the wind farm grid connection point is the instability of the frequency at the wind farm access point.

[0084] Among them, the frequency deviation The specific formula for non-periodic changes is:

[0085] ,

[0086] in, It means that the starting time is A fixed period of time A time interval of any length in ;

[0087] The frequency change rate The specific formula for the monotonically decreasing absolute value of is:

[0088] ;

[0089] The frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function The specific formula for non-periodic changes and its first-order derivative is continuously positive is:

[0090] ,

[0091] .

[0092] In the above formula, the product function The first-order derivative of continues to be positive, indicating that the product value is increasing and the system is gradually moving away from the stable point.

[0093] S3. Perform frequency regulation and locking control on the wind turbine according to the cause determination result:

[0094] After obtaining the determination result of the cause of the frequency disturbance at the wind farm grid connection point by using the above method, different frequency modulation blocking control processes are performed according to different determination results:

[0095] First, when the frequency disturbance at the wind farm grid connection point is caused by the unbalanced active power in the area where the wind farm access point is located, the frequency modulation function is enabled. A simulation experiment was conducted on the frequency modulation locking control processing when the active power is unbalanced, and the following chart was obtained:

[0096] Figure 2The system frequency diagram obtained by MATLAB-simulink simulation provided by the present invention when active power imbalance occurs in the area where the wind farm access point is located. The diagram is obtained by simulating the sudden increase of load at the 15th and 45th seconds in the system. Figure 2 It can be seen that the horizontal axis represents time in seconds, the vertical axis represents the per-unit value of the system frequency, and each convex and concave point in the figure represents the fluctuation of the system frequency. The simulation results show that the system frequency exhibits non-periodic fluctuation characteristics. Figure 2 The purpose of this test is to verify the primary frequency regulation function of the wind turbine when the system frequency undergoes non-periodic fluctuations.

[0097] Figure 3 The present invention provides a primary frequency modulation active power variation instruction diagram of a wind turbine generator set when active power imbalance occurs in the area where the wind farm access point is located, obtained by MATLAB-simulink simulation. Figure 3 and Figure 2 The result is obtained by synchronous simulation, that is, by setting a sudden increase in load at the 15th and 45th seconds in the simulation system. Figure 3 It can be seen that the horizontal axis represents time in seconds, and the vertical axis represents the change in active power of the wind turbine in megawatts. Each raised point in the figure represents a primary frequency regulation instruction issued by the wind turbine, and the size of the raised point represents the active power increment during the primary frequency regulation process. Figure 2 and Figure 3 From the simulation results, we can see that when the system frequency drops, the wind turbine will issue a frequency modulation command to increase the active power, thereby increasing the active power of the system. This figure proves that the wind turbine has an effective primary frequency modulation function when facing non-periodic fluctuations in the system frequency.

[0098] Figure 4 The active power diagram of the wind turbine generator set obtained by MATLAB-simulink simulation provided by the present invention when active power imbalance occurs in the area where the wind farm access point is located. Figure 4 and Figure 2 The result is obtained by synchronous simulation, that is, by setting a sudden increase in load at the 15th and 45th seconds in the simulation system. Figure 4 It can be seen that the horizontal axis represents time in seconds, and the vertical axis represents the active output of the wind turbine in megawatts. Each raised point in the figure represents an increase in the active output of the wind turbine. Figure 2 , Figure 3 and Figure 4 From the simulation results, we can see that when the system frequency drops, the wind turbine will issue a frequency modulation command, and the active output of the wind turbine will increase. This figure proves that the wind turbine has an effective primary frequency modulation function when facing non-periodic fluctuations in the system frequency, and the active output increases after the primary frequency modulation command appears.

[0099] Second, when the frequency disturbance at the wind farm grid connection point is caused by the local oscillation of the frequency at the wind farm access point, the primary frequency modulation function is locked and the wind farm active power is restored to the state before the primary frequency modulation. A simulation experiment was conducted on the frequency modulation locking control process when the frequency is locally oscillating, and the following chart was obtained:

[0100] Figure 5 This is a system frequency diagram obtained by MATLAB-simulink simulation provided by the present invention when a local frequency oscillation occurs at a wind farm access point. This diagram is obtained by simulating a short circuit fault at the 15th second in the system. Figure 5 It can be seen that the horizontal axis represents time in seconds, the vertical axis represents the per-unit value of the system frequency, and each convex and concave point in the figure represents the fluctuation of the system frequency. The simulation results show that the system frequency exhibits periodic oscillation. The purpose of this figure is to verify the primary frequency regulation locking function of the wind turbine when the system frequency oscillates periodically.

[0101] Figure 6 The present invention provides a wind turbine generator set primary frequency modulation active change command diagram obtained by MATLAB-simulink simulation when a local frequency oscillation occurs at a wind farm access point but the wind turbine generator set does not have an oscillation blocking function. The diagram is obtained by setting a short circuit fault in the system at the 15th second and shutting down the primary frequency modulation blocking function of the wind turbine generator set. Figure 6 It can be seen that the horizontal axis represents time in seconds, and the vertical axis represents the change in active power of the wind turbine in megawatts. Each convex and concave point in the figure represents a primary frequency regulation instruction issued by the wind turbine, and the size of the convex and concave points represents the increase or decrease in active power during the primary frequency regulation process. Figure 5 and Figure 6 From the simulation results, we can see that when the system frequency oscillates periodically, the wind turbines frequently issue primary frequency modulation commands, causing the wind turbines to frequently increase or decrease their active power. This figure proves that wind turbines will frequently start primary frequency modulation when the system frequency oscillates and does not have a primary frequency modulation locking function.

[0102] Figure 7 The present invention provides an active power diagram of a wind turbine when a local frequency oscillation occurs at a wind farm access point but the wind turbine does not have an oscillation blocking function, which is obtained by setting a short circuit fault in the system at the 15th second and shutting down the primary frequency modulation blocking function of the wind turbine. Figure 7 It can be seen that the horizontal axis represents time in seconds, and the vertical axis represents the active output of the wind turbine in megawatts. Each convex and concave point in the figure represents the increase and decrease of the active output of the wind turbine. Figure 5 , Figure 6 and Figure 7From the simulation results, we can see that when the system frequency oscillates, the wind turbine frequently issues a frequency modulation command, and the wind turbine active output fluctuates between increasing and decreasing. This figure proves that when the system frequency oscillates and does not have a frequency modulation locking function, the frequency modulation function will be frequently activated, and the wind turbine active output will fluctuate continuously, affecting the wind turbine power generation and threatening the wind turbine operation stability.

[0103] Figure 8 The present invention provides a wind turbine generator set primary frequency modulation active power variation instruction diagram obtained by MATLAB-simulink simulation when a local frequency oscillation occurs at a wind farm access point and the wind turbine generator set has an oscillation blocking function, which is obtained by setting a short circuit fault to occur at the 15th second and starting the primary frequency modulation blocking function. Figure 8 It can be seen that the horizontal axis represents time in seconds, and the vertical axis represents the change in active power of the wind turbine in megawatts. The concave point in the figure indicates that the wind turbine issues a frequency regulation command, and the size of the concave point indicates the reduction in active power during the frequency regulation. Figure 5 and Figure 8 From the simulation results, it can be observed that when the system frequency oscillates periodically, the wind turbine only issues a primary frequency modulation command once. This figure proves that the wind turbine will not frequently start the primary frequency modulation when the system frequency oscillates and has a primary frequency modulation locking function.

[0104] Fig. 9 The present invention provides an active power diagram of a wind turbine generator set when a local frequency oscillation occurs at a wind farm access point and the wind turbine generator set has an oscillation blocking function, which is obtained by setting a short circuit fault to occur in the system at the 15th second and starting a frequency modulation blocking function. Fig. 9 It can be obtained that: the horizontal axis represents time in seconds, the vertical axis represents the active output of the wind turbine in megawatts, and each concave point in the figure represents a decrease in the active output of the wind turbine. Figure 5 , Figure 8 and Fig. 9 ,It can be observed that when the system frequency oscillates and has a primary frequency modulation locking function, the wind turbine will not frequently start the primary frequency modulation function, and the active power of the wind turbine will not frequently fluctuate, thus achieving the maximum power generation and stable operation of the wind turbine.

[0105] Third, when the frequency disturbance at the wind farm grid connection point is caused by the instability of the frequency at the wind farm access point, the primary frequency regulation function is locked, the wind turbine is shut down urgently, and the load is cut off.

[0106] It can be seen that the frequency regulation locking control method of the primary frequency regulation transient response of the wind turbine set of the present invention can prevent the frequent repeated startup of the primary frequency regulation, thereby improving the stability of the wind turbine set participating in the primary frequency regulation; it can also improve the frequency regulation response accuracy of the wind turbine set, optimize the frequency regulation performance of the power system, and provide support for the safe, reliable and economical operation of the power grid.

[0107] In addition, those skilled in the art may combine and combine the different embodiments or examples and the features of the different embodiments or examples described in this specification without contradiction. Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A frequency modulation locking control method for primary frequency modulation transient response of a wind turbine generator set, characterized in that: The following steps are involved: S1. Real-time measurement of the frequency of the wind farm grid connection point. When the deviation between the real-time frequency of the grid connection point and the rated frequency of the power grid exceeds the primary frequency regulation dead zone, the primary frequency regulation completes the transient response and the frequency disturbance cause determination function is started; S2. Analyze the cause of the frequency disturbance at the wind farm grid connection point and obtain the cause determination result; the steps for determining the cause of the frequency disturbance at the wind farm grid connection point are as follows: S21. Create and record a time series of frequency deviation, a time series of frequency change rate, and a time series of frequency change acceleration based on the real-time measurement of the frequency of the wind farm grid connection point within a fixed time period, wherein the time series of frequency deviation refers to the difference between the frequency of the wind farm grid connection point measured in real time under the time series and the rated frequency of the power grid; S22. Create a product function: record the duration of a frequency modulation transient response as , then the fixed duration Set to , the starting time of the fixed duration is , the frequency deviation , frequency change rate , frequency change acceleration Multiplying the product factor gives the product function. The product function The specific formula is as follows: ， in, Indicates the multiplication factor, set , by adjusting , can be increased or decreased Frequency Deviation , frequency change rate and frequency change acceleration Response sensitivity; S23. Utilizing frequency deviation , frequency change rate , frequency change acceleration Sum and product functions To determine the cause of frequency disturbance at the wind farm grid connection point, when the frequency deviation Periodic changes occur, the frequency change rate The absolute value of is non-monotonically decreasing, and the frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function When the frequency disturbance at the wind farm grid connection point is caused by the local oscillation of the frequency at the wind farm access point, the frequency deviation is zero or negative. Non-periodic changes, frequency change rate The absolute value of is monotonically decreasing, and the frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function When it changes non-periodically and its first-order derivative is continuously positive, the cause of the frequency disturbance at the wind farm grid connection point is the unbalanced active power in the area where the wind farm access point is located; if it is neither of the above two, the cause of the frequency disturbance at the wind farm grid connection point is the instability of the frequency at the wind farm access point; S3. Perform frequency modulation locking control on wind turbines according to the cause determination result: when the frequency disturbance at the wind farm grid connection point is caused by active power imbalance in the area where the wind farm access point is located, open the primary frequency modulation function; when the frequency disturbance at the wind farm grid connection point is caused by local oscillation of the frequency at the wind farm access point, lock the primary frequency modulation function, and restore the active power of the wind farm to the level before the primary frequency modulation; when the frequency disturbance at the wind farm grid connection point is caused by frequency instability at the wind farm access point, lock the primary frequency modulation function, shut down the wind turbines urgently, and cut off the load.

2. The frequency modulation blocking control method for primary frequency modulation transient response of a wind turbine generator set according to claim 1, characterized in that: In step S21, the frequency change rate is the frequency deviation Calculated using the difference method and recorded in the time series; The specific calculation formula for the frequency change rate is: ,in, is the sampling time interval.

3. The frequency modulation blocking control method for primary frequency modulation transient response of a wind turbine generator set according to claim 2, characterized in that: In step S21, the time series of frequency change acceleration is the frequency change rate Frequency-varying acceleration calculated using the differential method Recorded in time series, at time Frequency change acceleration The specific calculation formula is: ,in, is the sampling time interval.

4. The frequency modulation blocking control method for primary frequency modulation transient response of a wind turbine generator set according to claim 2, characterized in that: In step S21, the rated frequency of the power grid is 50 Hz.

5. The frequency modulation blocking control method for primary frequency modulation transient response of a wind turbine generator set according to claim 3, characterized in that: The frequency deviation The specific formula for periodic changes is: and , in, Frequency deviation The period when periodic changes occur, At the start time A fixed period of time Any time in .

6. The frequency modulation blocking control method for primary frequency modulation transient response of a wind turbine generator set according to claim 3, characterized in that: The frequency change rate The specific formula for the non-monotonically decreasing absolute value of is: , , , , so that ， in, and At the start time A fixed period of time For any two different moments in time, It's at the time and Some time in between.

7. The frequency modulation locking control method for primary frequency modulation transient response of a wind turbine generator set according to claim 3, characterized in that: The product function changes periodically and the product function The specific formula for the first-order derivative of to be zero or negative is: and , ， in, is the product function The period when periodic changes occur, Denotes the product function The first derivative of .

8. The frequency modulation blocking control method for primary frequency modulation transient response of a wind turbine generator set according to claim 3, characterized in that: The frequency deviation The specific formula for non-periodic changes is: ， in, It means that the starting time is A fixed period of time A time interval of any length in ; The frequency change rate The specific formula for the monotonically decreasing absolute value of is: ； The frequency deviation , frequency change rate , frequency change acceleration and multiplication factor The product function The specific formula for non-periodic changes and its first-order derivative is continuously positive is: ， 。

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