A fan control method without measuring wind speed

Abstract

The application provides a fan control method without measuring wind speed, comprising the following steps: monitoring the current rotating speed of the fan in real time, and once the rotating speed changes, it indicates that the current wind speed changes; then according to the current rotating speed and the initial rotating speed, the first capture power of the fan under the changed wind speed is calculated by using an additional power control formula; and then the output power of the fan is adjusted according to the calculated first capture power, so that the output power is equal to the current capture power of the fan, and the control of the fan is completed. This method does not depend on the measurement of wind speed, and only needs to calculate the first capture power of the fan under the current wind speed according to the current rotating speed of the fan and the initial rotating speed at the last moment; and then the output power of the fan is adjusted according to the first capture power. The wind speed does not need to be measured, so the error caused by the measurement is reduced, and therefore the control precision is higher than that of the existing adjustment method.

Description

Technical Field

[0001] This invention generally relates to the field of wind turbine control technology, and specifically to a wind turbine control method that does not require wind speed measurement. Background Technology

[0002] Wind turbines, as common power generation devices, are used to convert wind speed into the mechanical kinetic energy of the fan blades, and then into electrical energy through electromagnetic induction. The stable operation of the wind turbine is crucial to the efficiency of electrical energy conversion.

[0003] During operation, the fan blades rotate due to wind power, thus generating captured power. The power output of the fan after conversion needs to match the captured power to ensure stable rotation of the fan blades.

[0004] However, in practice, wind turbines are generally installed in areas with high wind speeds to effectively capture wind energy. Because of these high wind speeds, variations in wind speed are also significant. These significant changes in wind speed cause a corresponding change in the turbine blade speed, which in turn leads to variations in the captured power. If the output power is not adjusted, the turbine blade speed becomes difficult to control.

[0005] To solve the above problems and ensure that the wind turbine can capture more wind energy stably, it is necessary to measure the wind speed in real time and obtain the real-time capture power by looking up a table; then adjust the output power to make the output power equal to the capture power.

[0006] Traditional methods rely heavily on wind speed measurement during operation. However, due to sensor errors, non-uniformity of wind speed spatial distribution, wake effects, and wind speed measurement delays, wind farms often struggle to obtain accurate wind speed values, which affects the control accuracy of fan speed and output power, and consequently, the stable operation of the wind turbine. Summary of the Invention

[0007] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a fan control method that does not require wind speed measurement.

[0008] This invention provides a fan control method that does not require wind speed measurement, comprising:

[0009] S1: Obtain the fan speed at the previous moment to get the initial speed; detect the fan speed at the current moment to get the current speed;

[0010] S2: If the current rotational speed is not equal to the initial rotational speed, proceed to steps S3 to S6; otherwise, proceed to step S6.

[0011] S3: Obtain the additional power control formula; the additional power control formula is used to calculate the magnitude of the captured power when the wind turbine is at the current pitch angle and the current wind speed is based on the current rotational speed and the initial rotational speed; the captured power is the power generated by the wind turbine under the action of external wind force;

[0012] S4: Substitute the initial speed and the current speed into the additional power control formula to calculate the first captured power;

[0013] S5: Adjust the output power of the fan according to the first captured power;

[0014] S6: Repeat steps S1 to S6 at the next time step.

[0015] According to the technical solution provided by the present invention, the additional power control formula is as shown in Formula 5:

[0016] Formula 5;

[0017] in, Indicates capture power, Indicates reference coefficient, Indicates additional power, The proportional gain of the additional power controller, Indicates the integral coefficient of the additional power controller, s Represents the Laplace operator, Indicates the current speed, This indicates the initial rotational speed.

[0018] According to the technical solution provided by the present invention, S5: adjusting the output power of the fan according to the first captured power includes:

[0019] S5-1: Obtain the capture power threshold;

[0020] S5-2: If the first capture power is greater than or equal to the capture power threshold, then adjust the output power of the fan until it is equal to a set multiple of the first capture power; the set multiple is less than 1.

[0021] S5-3: If the first capture power is less than the capture power threshold, then reduce the value of the reference coefficient and calculate the second capture power according to the additional power control formula; adjust the output power of the fan until it is equal to the second capture power; the second capture power is less than the first capture power.

[0022] According to the technical solution provided by the present invention, obtaining the capture power threshold includes:

[0023] Obtain the maximum captured power of the wind turbine;

[0024] The capture power threshold is set based on the maximum capture power.

[0025] According to the technical solution provided by the present invention, adjusting the output power of the fan until it is equal to a set multiple of the first capture power includes:

[0026] During the process of adjusting the output power, if the fan speed reaches the rated speed, the fan pitch angle is adjusted so that the speed is maintained at the rated speed after reaching the rated speed during the process of adjusting the output power, until the output power is equal to the first capture power.

[0027] According to the technical solution provided by the present invention, adjusting the blade pitch angle of a wind turbine includes:

[0028] Historical data of the wind turbine at its rated speed under various wind speed conditions are acquired; the historical data includes: the power difference between the captured power and the output power, and the corresponding pitch angle;

[0029] Based on the historical data, the least squares method is used to fit the functional relationship between the power difference and the pitch angle to obtain the first function;

[0030] Obtain the current output power of the wind turbine to get the first output power;

[0031] Calculate the difference between the first capture power and the first output power to obtain the first difference;

[0032] Substitute the first difference into the first function to calculate the first pitch angle;

[0033] Adjust the wind turbine pitch angle to the first pitch angle.

[0034] According to the technical solution provided by the present invention, reducing the value of the reference coefficient and calculating the second capture power according to the additional power control formula includes:

[0035] Obtain the value of the reduced reference coefficient to obtain the first reference coefficient;

[0036] Substituting the first reference coefficient, the initial rotational speed, and the current rotational speed into the additional power control formula, the second capture power is calculated.

[0037] According to the technical solution provided by the present invention, adjusting the output power of the fan until it is equal to the second capture power includes:

[0038] Starting from the current speed, gradually reduce the speed until the output power of the fan equals the second capture power.

[0039] The beneficial effects of this invention are as follows:

[0040] The system monitors the current rotational speed of the fan in real time. A change in rotational speed indicates a change in wind speed. Based on the measured current and initial rotational speeds, the system calculates the initial captured power of the fan under the changed wind speed using an additional power control formula. The fan's output power is then adjusted to match the current captured power, thus controlling the fan. This method does not rely on wind speed measurement; it only requires calculating the initial captured power based on the current rotational speed and the initial rotational speed from the previous moment. The output power is then adjusted accordingly. Since wind speed measurement is unnecessary, it reduces measurement errors and offers higher control accuracy compared to existing methods. Attached Figure Description

[0041] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0042] Figure 1 This is a flowchart illustrating a fan control method that does not require wind speed measurement.

[0043] Figure 2 The curve shows the change in captured power of the wind turbine as a function of rotational speed. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] Air movement generates wind energy, and according to Betz's theory, wind turbine blades can capture some of the power generated by the wind.

[0047] Formula 1;

[0048] In the formula, P m The wind turbine's mechanical power, i.e., the captured power, is ρ, where ρ is the air density, and S = πR. 2 R is the swept area of ​​the wind turbine blades, v is the wind speed, and C is the wind speed. p (λ,β) represents the wind energy utilization coefficient, λ is the tip speed ratio, and β is the blade pitch angle. The tip speed ratio λ is defined as follows:

[0049] Formula 2;

[0050] The rotor speed of the wind turbine is C; the characteristics of the wind turbine mainly depend on C. p (λ,β) is generally represented by a fitting function. The fitting function used in this paper is as follows:

[0051] Formula 3;

[0052] in, α For the fitting parameters, e It is the natural logarithm.

[0053] The calculation relationship between output power and speed is as follows:

[0054] Formula 4;

[0055] In the formula, the reference coefficient K opt =0.5C pmax πρR 5 / λ opt 3 C pmax λ is the maximum wind energy utilization coefficient. opt This is the optimal tip speed ratio for the fan.

[0056] To ensure safety and system stability, excessive rotor speed can lead to blade overspeed rotation, generating excessive mechanical stress and potentially causing blade breakage or other structural damage. Furthermore, excessively high speeds increase turbine vibration, affecting its operational smoothness and durability. To ensure efficiency and avoid additional energy loss and overload risks due to excessive speed, most wind turbines limit their speed to the rated speed.

[0057] Please refer to Figure 1 This invention provides a fan control method that does not require wind speed measurement, comprising:

[0058] S1: Obtain the fan speed at the previous moment to get the initial speed; detect the fan speed at the current moment to get the current speed;

[0059] In some implementations, the interval between two adjacent moments can be any length between 1 and 5 seconds. This allows for real-time adjustment of the fan's output power based on wind speed.

[0060] S2: If the current rotational speed is not equal to the initial rotational speed, proceed to steps S3 to S6; otherwise, proceed to step S6.

[0061] Specifically, if the change in wind speed causes a very small change in rotational speed, and the output power is still adjusted strictly according to the principle of inequality, the number of adjustments will be too frequent. In the actual adjustment process, due to the influence of adjustment accuracy, there may be a situation where the output power does not change after adjustment.

[0062] For example, the wind speed might increase rapidly within a few seconds, then return to its original level. In reality, such rapid increases and decreases in wind speed over a short period have a relatively small impact on the fan speed.

[0063] However, traditional methods of measuring wind speed cause the fan's output power to adjust rapidly based on changing wind speeds. This traditional control method, in turn, leads to rapid changes in fan speed, resulting in unstable fan operation.

[0064] To reduce the frequency of output power adjustments when the speed change is small, thus ensuring the stability of the fan operation, the following method can be used:

[0065] After measuring the initial speed and the current speed, calculate the absolute value of the difference between the initial speed and the current speed to obtain the speed difference;

[0066] Then calculate the ratio of the speed difference to the initial speed;

[0067] If the ratio is greater than or equal to 0.5%, it is considered unequal; if the ratio is less than or equal to 0.5%, it is considered equal.

[0068] Specifically, the typical fan speed is around 13 to 20 rpm; even small fans actually operate at around 100 to 300 rpm. Taking 200 rpm as an example, following the above method, if the change in wind speed causes a change in fan speed of less than or equal to 0.1 revolutions per minute, it can be determined that the wind speed has not changed significantly, thereby reducing the number of times the fan output power needs to be adjusted.

[0069] S3: Obtain the additional power control formula; the additional power control formula is used to calculate the magnitude of the captured power when the wind turbine is at the current pitch angle and the current wind speed is based on the current rotational speed and the initial rotational speed; the captured power is the power generated by the wind turbine under the action of external wind force;

[0070] The additional power control formula is shown in Formula 5:

[0071] Formula 5;

[0072] in, Indicates capture power, Indicates reference coefficient, Indicates additional power, The proportional gain of the additional power controller, Indicates the integral coefficient of the additional power controller, s Represents the Laplace operator, Indicates the current speed, This indicates the initial rotational speed.

[0073] S4: Substitute the initial speed and the current speed into the additional power control formula to calculate the first captured power;

[0074] S5: Adjusting the output power of the fan according to the first captured power includes:

[0075] S5-1: Obtain the capture power threshold, including:

[0076] Obtain the maximum capture power of the wind turbine; the maximum capture power is the maximum capture power that the wind turbine can achieve under full wind speed and full pitch angle conditions.

[0077] The capture power threshold is set based on the maximum capture power.

[0078] Specifically, assume there is a capture power threshold; in order to operate at reduced load, the capture power threshold needs to be multiplied by a set multiple to obtain the reduced load capture power threshold.

[0079] At this point, the maximum speed that the fan can reach when it is at the load capture power threshold is exactly equal to the rated speed.

[0080] Furthermore, when the wind turbine is at its maximum capture power, after load reduction control, the wind turbine has a maximum output power (a known fixed value for the same model of wind turbine); the ratio of the maximum output power to the maximum capture power is used as a set multiple; the set multiple is less than 1 and greater than 0. Since the load reduction ratio is generally fixed, the set multiple is also a known fixed value.

[0081] Furthermore, since there is a one-to-one correspondence between the wind turbine's capture power and the maximum achievable speed, the capture power threshold and the load reduction capture power threshold can be derived based on the above conditions.

[0082] Specifically, when the wind speed is constant, the wind turbine's capture power first increases and then decreases as the rotational speed increases. When the rotational speed is constant, the higher the wind speed, the higher the capture power.

[0083] like Figure 2 As shown, o is the origin of the coordinate system, the horizontal axis is the rotational speed ω, and 1 on the horizontal axis represents 1 times the rated speed of the fan. The vertical axis is the captured power p, and 1 on the vertical axis represents 1 times the rated power of the fan.

[0084] L1, L2, and L3 are curves showing the change in wind turbine capture power with rotational speed under low, medium, and high wind speed conditions, respectively.

[0085] Point A represents the maximum capture power achievable under low wind speed conditions;

[0086] Point B represents the maximum capture power achievable under medium wind speed conditions;

[0087] Point C represents the maximum capture power achievable under high wind speed conditions;

[0088] In order to enable wind turbines to capture more wind energy and reduce failure rates:

[0089] Referring to L1, when the wind speed is too low, the fan speed needs to be gradually reduced from its rated speed to ensure that the fan has a certain capture power, so that it can convert wind energy into electrical energy even at low wind speeds. At this time, after load reduction control, the corresponding speed has two values; to facilitate a rapid increase in speed as the wind speed subsequently rises, the fan is controlled to operate at a higher speed. That is, the speed is adjusted from point A to point A'.

[0090] Referring to L2, when the maximum capture power corresponding to the wind speed is exactly equal to the capture wind speed threshold, calculate the value of the descent capture power threshold and control the output power of the wind turbine to be equal to the descent capture power threshold. That is, adjust from point B to point B'.

[0091] Referring to L3, when the wind speed is too high, the fan speed needs to be controlled to not exceed the rated speed. Therefore, after controlling the speed to maintain the rated speed and adjusting the pitch angle to complete the load reduction control, the speed is adjusted from point C to point C'.

[0092] The set multiple mentioned in this invention is the load reduction coefficient k in existing load reduction control methods. del It lies within the range [0,1]. The smaller the load factor, the more power is reserved.

[0093] The output power P of the fan after load reduction del =k del P mppt P mppt k represents the maximum capture power that the wind turbine can achieve at the current wind speed. del The smaller the value, the more reserved power there is. Furthermore, by changing the load reduction factor k... del The value enables the release and reservation of wind turbine reserve power.

[0094] As can be seen from Equation 1, under the concept of this invention, since wind speed is not measured, the output power equation of the wind turbine... This is an uncontrollable parameter, and its value depends on the wind turbine's own mechanical structure and the external wind speed. Therefore, the wind turbine's load-reducing control method in this invention essentially controls the wind energy utilization coefficient C by changing the tip speed ratio λ and the blade pitch angle β. p The size of (λ,β) makes:

[0095] Formula Six;

[0096] In the formula, C pmax λ is the maximum wind energy utilization coefficient that the wind turbine can achieve. del With β del To meet the load reduction factor k del The specific values ​​of the required tip speed ratio and blade pitch angle.

[0097] Based on the above concept, the specific implementation steps are as follows:

[0098] Scenario 1: High wind speed

[0099] S5-2: If the first capture power is greater than or equal to the capture power threshold, then adjust the output power of the fan until it is equal to a set multiple of the first capture power, including:

[0100] During the process of adjusting the output power, if the fan speed reaches the rated speed, the fan pitch angle is adjusted so that the speed is maintained at the rated speed after reaching the rated speed during the process of adjusting the output power, until the output power is equal to the first capture power.

[0101] To achieve load reduction, the pitch angle also needs to be adjusted accordingly. The higher the wind speed, the greater the increase in the active power reference value, and the greater the pitch angle movement, with the two tending to change in the same direction.

[0102] By measuring the additional power P add The value directly yields the required load reduction pitch angle action value β. del .

[0103] The specific steps include:

[0104] Historical data of the wind turbine at its rated speed under various wind speed conditions are acquired; the historical data includes: the power difference between the captured power and the output power, and the corresponding pitch angle;

[0105] The historical data refers to the data recorded in the tables used in the traditional lookup method.

[0106] Based on the historical data, the least squares method is used to fit the functional relationship between the power difference and the pitch angle to obtain the first function;

[0107] Obtain the current output power of the wind turbine to get the first output power;

[0108] Calculate the difference between the first capture power and the first output power to obtain the first difference;

[0109] Substitute the first difference into the first function to calculate the first pitch angle;

[0110] Adjust the wind turbine pitch angle to the first pitch angle.

[0111] Specifically, the details of the fitting process include:

[0112] Because the baselines for medium and high wind speeds are different, resulting in different curve slopes, the upper limit of medium wind speed is used as the boundary for segmented fitting in different wind speed regions. The threshold value for the additional power cutoff point under a certain load reduction factor is obtained, and the functions on both sides of the threshold value are fitted separately.

[0113] The first curve on the side of the boundary point threshold closer to the origin has a larger curvature, so a sixth-order polynomial is used to fit it.

[0114] The second curve on the side of the boundary point threshold furthest from the origin has a smaller curvature, so a second-order polynomial is used to fit it.

[0115] Formula Sixteen;

[0116] Formula 17;

[0117] In the formula a i b is the coefficient of each term in a sixth-order polynomial. i β represents the coefficients of each term in the second-order polynomial. del1 The first curve corresponds to the reduced load pitch angle, β del2 Let i be the pitch angle corresponding to the second curve, i = 0, 1, 2...

[0118] Change the load reduction factor and repeat the above steps to complete the fitting process. Formulas 16 and 17 together form the first function.

[0119] During the actual operation of the wind turbine, the load reduction pitch angle action value can be obtained by selecting the appropriate fitting curve based on the given load reduction coefficient and the threshold of the dividing point, without the need to measure the wind speed.

[0120] Specifically, under high wind speed conditions, once the turbine reaches its rated speed, the maximum value of the wind energy utilization coefficient is no longer derived from the optimal tip speed ratio, but gradually decreases below it. Therefore, as the wind speed increases, C... pmax The power gradually decreases but continues to increase until it reaches the rated power.

[0121] At this time, the additional power P for load reduction dadd The value is:

[0122] Formula Fourteen.

[0123] The corresponding equation for solving the pitch angle during load reduction is:

[0124] Formula 15.

[0125] Scenario 2: Low wind speed

[0126] When the wind speed is low, the rotor speed is also low, thus providing sufficient speed margin. Load reduction can be achieved by decreasing the reference coefficient.

[0127] S5-3: If the first capture power is less than the capture power threshold, then decrease the value of the reference coefficient and calculate the second capture power according to the additional power control formula; adjust the output power of the fan until it is equal to the second capture power; the second capture power is less than the first capture power;

[0128] In some implementations, the value of the reference coefficient is reduced in the following ways:

[0129] When the fan operates in MPPT mode, it must satisfy the following:

[0130] Formula 7;

[0131] When the wind turbine operates in descent mode, the following conditions must be met:

[0132] Formula 8;

[0133] In the formula, P del K represents the power of the wind turbine after load reduction. del This corresponds to the suboptimal power coefficient. The optimal power coefficient K... del Substituting into Formula 3, we establish the equation as shown in Formula 9, and solve for λ under the current load reduction factor. del .

[0134] Formula Nine;

[0135] Combining formulas seven, eight, and nine, the reference coefficient K can be obtained. opt With the optimal power factor K del The relationship is as follows:

[0136] Formula 10;

[0137] From Formula 10, we can see that the optimal power coefficient K del Size and λ del and k del Regarding this, in low-wind-speed areas, the different k values ​​are first calculated. del λ below del Then substitute it into Formula 10 to get K. del Load reduction operation is achieved by changing the power reference curve.

[0138] The second capture power is calculated, specifically including:

[0139] Obtain the value of the reduced reference coefficient to obtain the first reference coefficient;

[0140] Substituting the first reference coefficient, the initial rotational speed, and the current rotational speed into the additional power control formula, the second capture power is calculated.

[0141] The process of adjusting the fan's output power is as follows: starting from the current speed, gradually reduce the speed until the fan's output power equals the second capture power.

[0142] It should be noted that for different k del The upper limit wind speed v1 for the corresponding low wind speed area is different. This is because k del The smaller the value, the higher the required rotational speed for overspeed unloading, and the lower the wind speed required to reach the rated rotational speed. The expression for v1 is as follows:

[0143] Formula 11.

[0144] In some implementations, for medium and low wind speeds, the wind turbine can also be controlled by adjusting the pitch angle. The process of calculating the pitch angle during load shedding includes:

[0145] For a certain load reduction ratio k del The size of v1 is calculated using formulas nine and eleven.

[0146] Compare v1 with the load reduction factor k del Substituting into Formula 1, calculate the additional load reduction power P required at the current wind speed. dadd Size:

[0147] Formula twelve.

[0148] Current wind speed, rated rotational speed, and k del Substituting into Formula 3, we establish a univariate equation regarding the pitch angle, and solve this equation to obtain the corresponding load-reducing pitch angle value β. del .

[0149] Formula Thirteen.

[0150] S6: Repeat steps S1 to S6 at the next time step.

[0151] By employing the aforementioned control methods, the problem of power oscillation can be avoided when regulating the output power of the wind turbine, while simultaneously improving the wind energy utilization coefficient.

[0152] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to the specific combination of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. A fan control method that does not require wind speed measurement, characterized in that, include: S1: Obtain the fan speed at the previous moment to get the initial speed; The current speed of the fan is detected to obtain the current speed. S2: If the current rotational speed is not equal to the initial rotational speed, proceed to steps S3 to S6; Otherwise, proceed to step S6; S3: Obtain the additional power control formula; the additional power control formula is used to calculate the magnitude of the captured power when the wind turbine is at the current pitch angle and the current wind speed is based on the current rotational speed and the initial rotational speed; the captured power is the power generated by the wind turbine under the action of external wind force; S4: Substitute the initial speed and the current speed into the additional power control formula to calculate the first captured power; S5: Adjust the output power of the fan according to the first captured power; S6: Repeat steps S1 to S6 at the next time step; The additional power control formula is shown in Formula 5: Formula 5; in, Indicates capture power, Indicates reference coefficient, Indicates additional power, The proportional gain of the additional power controller, Indicates the integral coefficient of the additional power controller, s Represents the Laplace operator, Indicates the current speed, This indicates the initial rotational speed.

2. The fan control method without wind speed measurement according to claim 1, characterized in that, S5: Adjusting the output power of the fan according to the first captured power includes: S5-1: Obtain the capture power threshold; S5-2: If the first capture power is greater than or equal to the capture power threshold, then adjust the output power of the fan until it is equal to a set multiple of the first capture power; the set multiple is less than 1. S5-3: If the first capture power is less than the capture power threshold, then reduce the value of the reference coefficient and calculate the second capture power according to the additional power control formula; adjust the output power of the fan until it is equal to the second capture power; the second capture power is less than the first capture power.

3. The fan control method without wind speed measurement according to claim 2, characterized in that, To obtain the capture power threshold, including: Obtain the maximum captured power of the wind turbine; The capture power threshold is set based on the maximum capture power.

4. The fan control method without wind speed measurement according to claim 2, characterized in that, Adjusting the output power of the fan until it equals a set multiple of the first capture power includes: During the process of adjusting the output power, if the fan speed reaches the rated speed, the fan pitch angle is adjusted so that the speed is maintained at the rated speed after reaching the rated speed during the process of adjusting the output power, until the output power is equal to the first capture power.

5. A fan control method without wind speed measurement according to claim 4, characterized in that, Adjusting the wind turbine's pitch angle includes: Historical data of the wind turbine at its rated speed under various wind speed conditions are acquired; the historical data includes: the power difference between the captured power and the output power, and the corresponding pitch angle; Based on the historical data, the least squares method is used to fit the functional relationship between the power difference and the pitch angle to obtain the first function; Obtain the current output power of the wind turbine to get the first output power; Calculate the difference between the first capture power and the first output power to obtain the first difference; Substitute the first difference into the first function to calculate the first pitch angle; Adjust the wind turbine pitch angle to the first pitch angle.

6. A fan control method without wind speed measurement according to claim 2, characterized in that, Decrease the value of the reference coefficient and calculate the second capture power according to the additional power control formula, including: Obtain the value of the reduced reference coefficient to obtain the first reference coefficient; Substituting the first reference coefficient, the initial rotational speed, and the current rotational speed into the additional power control formula, the second capture power is calculated.

7. A fan control method without wind speed measurement according to claim 2, characterized in that, Adjusting the fan's output power until it equals the second capture power includes: Starting from the current speed, gradually reduce the speed until the output power of the fan equals the second capture power.

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