A pitch control method for a combined vertical-axis wind turbine based on fuzzy control

Abstract

The present invention relates to a pitch control method for a combined vertical-axis wind turbine based on fuzzy control, comprising: S1. When the wind turbine starts, the control system is initialized, and information on wind speed V, the actual rotational speed ω of the generator of the combined vertical-axis wind turbine, and the pitch angle β of the H-type wind turbine blades is obtained through a sensor module; S2. If the measured wind speed < cut-in wind speed, the wind turbine does not operate; if the measured wind speed > cut-in wind speed, according to the actual rotational speed information of the generator, the overlap ratio of the two blades of the S-type wind turbine is adjusted; S3. Taking the pitch angle of the H-type wind turbine as the controlled object, the deviation e between the actual rotational speed of the generator and the rated rotational speed and the wind speed change rate ec as fuzzy input quantities, a fuzzy control algorithm is used to calculate the control output quantity, i.e., the pitch angle change value Δβ, and this control output quantity is input into the pitch control system to control the pitch angle change of the H-type wind turbine. The present invention has the advantages of good starting performance and can quickly and effectively control the pitch angle, further improving the power generation efficiency of the vertical-axis wind turbine.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and particularly relates to a pitch control method for a combined vertical-axis wind turbine based on fuzzy control. Background Art

[0002] As a renewable energy source, wind energy has the advantages of being clean and pollution-free, rich in reserves, low in investment, and quick in effect. A wind turbine is an energy conversion device that converts wind energy into mechanical energy and then converts the mechanical energy into electrical energy, and is divided into two categories: vertical-axis wind turbines and horizontal-axis wind turbines. Among them, vertical-axis wind turbines have the advantages of good wind direction adaptability, simple structure, and easy maintenance, and are widely used.

[0003] Vertical-axis wind turbines can be divided into drag-type vertical-axis wind turbines and lift-type vertical-axis wind turbines. Drag-type vertical-axis wind turbines have the advantages of low wind speed requirements, good starting performance, and easy installation, but their wind energy utilization efficiency is low. Lift-type vertical-axis wind turbines have a relatively high wind energy utilization rate, but have the disadvantages of unstable power generation and poor self-starting performance. Therefore, a combined vertical-axis wind turbine composed of a drag-type vertical-axis wind turbine and a lift-type vertical-axis wind turbine can reasonably solve the problems of poor self-starting performance and low power generation efficiency of vertical-axis wind turbines.

[0004] In order to further improve the power generation efficiency of wind turbines, wind turbines often use a pitch angle adjustment device to perform pitch control, so as to keep the wind turbine generating electricity at the rated power as much as possible to improve the power generation capacity. However, after the existing combined vertical-axis wind turbine relies on the drag-type vertical-axis wind turbine to reduce the starting conditions and work normally, the drag-type vertical-axis wind turbine cannot be automatically retracted, often forming a new wind resistance. At the same time, when the existing combined vertical-axis wind turbine enters the high-speed operation state, if the pitch angle is not adjusted actively in real time, there is often a possibility of low wind energy utilization rate or wind turbine stall. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a pitch control method for a combined vertical-axis wind turbine based on fuzzy control in view of the above-mentioned deficiencies of the existing technology. The method can actively adjust the drag-type vertical-axis wind turbine to automatically retract and work according to the changes in wind speed and generator speed, and can adjust the pitch angle of the wind turbine in real time based on fuzzy control to ensure that the wind turbine is as close as possible to the optimal power generation power, with good starting performance and the ability to quickly and effectively control the pitch angle, further improving the power generation efficiency of the vertical-axis wind turbine.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A pitch control method for a combined vertical-axis wind turbine based on fuzzy control, the combined vertical-axis wind turbine includes an S-type wind turbine and an H-type wind turbine arranged coaxially, and the method includes the following steps:

[0008] S1. The fan starts, the control system is initialized, and information on wind speed V, the actual rotational speed ω of the combined vertical-axis wind turbine generator, and the pitch angle β of the H-type wind turbine blades is obtained through the sensor module.

[0009] S2. According to the wind speed measured in S1, if the measured wind speed < cut-in wind speed, the fan does not operate.

[0010] If the measured wind speed > cut-in wind speed, and at the same time according to the actual rotational speed information of the generator measured in S1, the relative positions of the two blades of the S-type wind turbine are adjusted, thereby adjusting the overlap ratio of the two blades; specifically, it includes the following steps:

[0011] S21. Determine the rotational speed range [0, ω max at which the S-type wind turbine operates, and monitor the actual rotational speed of the combined vertical-axis wind turbine generator.

[0012] S22. If the actual rotational speed of the generator is lower than the threshold ω max , the S-type wind turbine operates, and the overlap ratio of the S-type wind turbine is adjusted to a suitable position, which can provide a large starting torque and improve the starting performance of the fan.

[0013] If the actual rotational speed of the generator is higher than the threshold ω max , the overlap ratio of the S-type wind turbine remains 1, that is, the blades are closed and stop working to avoid causing wind resistance; the H-type wind turbine starts.

[0014] S3. According to the information collected in S1, with the pitch angle of the H-type wind turbine as the controlled object, the deviation e between the actual rotational speed of the generator and the rated rotational speed and the wind speed change rate ec as fuzzy input quantities, a fuzzy control algorithm is used to calculate the control output quantity, the pitch angle change value Δβ, and this control output quantity is input into the pitch control system to control the pitch angle change of the H-type wind turbine.

[0015] In the above solution, S3 specifically includes the following steps:

[0016] S31. Determine the fuzzy controller input quantities e, ec and the output quantity Δβ:

[0017] According to the information on the actual rotational speed ω of the generator and the wind speed V measured in S1, the deviation e = Δω = ω - ω0 between the actual rotational speed ω and the rated rotational speed ω0 and the wind speed change rate ec = dV / dt are calculated. The output quantity of the fuzzy controller is the pitch angle change value Δβ.

[0018] S32. Fuzzy processing of the input quantity and output quantity:

[0019] The deviation e between the actual rotational speed ω and the rated rotational speed ω0 and the wind speed change rate ec are fuzzified and transformed into fuzzy quantities E and EC; at the same time, the output quantity Δβ is fuzzily quantified as U.

[0020] S33. Establish fuzzy control rules:

[0021] During the control process, when the deviation between the actual speed and the rated speed of the generator is large, the objective of the pitch angle change is to eliminate the speed deviation as soon as possible; when the speed deviation of the generator is small, in addition to eliminating the speed deviation of the generator, the change of the pitch angle should also consider the stability of the fan system to prevent unnecessary overshoot and oscillation of each variable during the operation of the fan.

[0022] S34. Fuzzy inference:

[0023] Using the look-up table method in Mamdani inference control, based on the fuzzy control rules, the inference statement is as follows:

[0024] If ec = EC i and e = E j then U = U ij

[0025] In the formula, EC i and E j (i, j = 1, 2,..., 6) are respectively the elements in the fuzzy quantity sets of the input variables of the wind speed change rate and the speed deviation, and U ij (i, j = 1, 2,..., 6) is the fuzzy quantity set of the output pitch angle change value;

[0026] S35. Defuzzification:

[0027] Using the weighted summation method to convert the fuzzy value of the output quantity into an exact value;

[0028] S36: Output of the fuzzy controller:

[0029] The fuzzy controller outputs the pitch angle adjustment amount to the pitch-changing device to complete the pitch adjustment.

[0030] In the above scheme, the methods for fuzzy processing of the input and output quantities in step S32 are as follows:

[0031] Fuzzify the input quantity to obtain the fuzzy subsets EC and E of {negative large, negative medium, negative small, zero, positive small, positive medium, positive large}, and record them correspondingly as {NB, NM, NS, ZO, PS, PM, PB}; among them, the change of the speed deviation e is controlled within the range of (-25 r / min, 25 r / min), and the wind speed change rate ec is controlled within the range of (-10 m / s 2 , 10 m / s 2 ). Quantize both the speed deviation e and the wind speed change rate ec into the domain range of [-6, 6];

[0032] Meanwhile, the output quantity is fuzzified to obtain a fuzzy subset U of {Negative Large, Negative Medium, Negative Small, Zero, Positive Small, Positive Medium, Positive Large}, which is correspondingly recorded as {NB, NM, NS, ZO, PS, PM, PB} and quantized within the universe of discourse range of [-6, 6].

[0033] In the above solution, the fuzzy control rule table is established in step S33 as follows:

[0034]

[0035] In the above solution, in step S35, the weighted summation method means that the value obtained by weighted averaging each element in the fuzzy output set of the controller is used as the accurate output value of the control system, and its formula is:

[0036]

[0037] In the formula, U is the final output quantity, U i is the output of the i-th rule, w i is the weight factor, that is, the proportion of the i-th rule in the total output.

[0038] In the above solution, in step S22, when the overlap ratio of the S-type fan is 0.15 - 0.2, a relatively large starting torque can be provided.

[0039] In the above solution, the S-type fan includes a first blade support track, a second blade support track, a first blade, a second blade, a first active control device, and a second active control device; the first blade support track and the second blade support track are symmetrically arranged about the transmission shaft, the first blade is installed on the first blade support track and can slide along it, the second blade is installed on the second blade support track and can slide along it, the first blade and the second blade are symmetrically arranged about the transmission shaft and the blade parts are staggered; the first active control device is carried on the outer end of the first blade support track and contacts the outer end of the first blade, the second active control device is carried on the outer end of the second blade support track and contacts the outer end of the second blade; the two active control devices can change their own lengths according to the wind speed sensing information and the actual rotational speed information of the generator to adjust the relative positions of the corresponding blades, thereby adjusting the overlap ratio of the two blades;

[0040] The blades of the H-type fan are equipped with pitch-changing devices, and the pitch angle can be adjusted according to the output signal of the fuzzy controller.

[0041] In the above solution, the active control device adopts a spring active control device or a hydraulic telescopic active control device.

[0042] In the above solution, the generator of the combined vertical-axis fan is installed at the lower end of the transmission shaft, and the generator is a doubly-fed asynchronous generator.

[0043] In the above solution, the sensor module of the combined vertical axis wind turbine includes... a wind speed sensor, a generator speed sensor, and a blade pitch angle sensor of the wind turbine. The wind speed sensor is installed on the nacelle and is used to input a wind speed signal to the wind speed processing circuit; the generator speed sensor is installed inside the wind turbine engine; the blade pitch angle sensor of the wind turbine is installed on the blade to detect pitch angle information.

[0044] The beneficial effects of the present invention are as follows:

[0045] 1. First, the method of the present invention controls the working state of the S-type wind turbine according to the wind speed information and the generator speed information. When the speed is low, the S-type wind turbine works to provide a starting torque, which is beneficial to the rapid start of the combined vertical axis wind turbine. When the speed is high, the S-type wind turbine retracts to avoid wind resistance. Then, according to the deviation between the actual speed and the rated speed of the generator and the change rate of the wind speed, the pitch angle of the H-type wind turbine is adjusted in real time by fuzzy control to ensure that the generator operates at the optimal power. Therefore, the present invention combines the advantages of the S-type wind turbine and the H-type wind turbine, and has the advantages of good starting performance and high power generation efficiency.

[0046] 2. The present invention adjusts the overlap ratio of the two blades by mounting a spring or a hydraulic telescopic active control device on the S-type wind turbine. When the overlap ratio of the blades is adjusted to 0.15 - 0.2 (preferably 0.17) during the operation of the S-type wind turbine, the starting torque provided by the S-type wind turbine during operation is relatively large, which is beneficial to the rapid start of the vertical axis wind turbine. When the S-type wind turbine stops, the overlap ratio of the blades is adjusted to 1, and the starting torque provided by the S-type wind turbine is zero at this time, avoiding wind resistance and being beneficial to the high-speed operation of the H-type wind turbine.

[0047] 3. The present invention mounts a variable pitch device on the H-type wind turbine to adjust the pitch angle of the H-type wind turbine in real time to ensure that the generator operates at the optimal power.

[0048] 4. The present invention uses a doubly-fed induction motor. By adjusting the rotor winding current, the electromagnetic torque of the generator is changed, and then the motor speed is changed to ensure that the generator operates at the optimal power as much as possible. At the same time, the doubly-fed induction motor has the advantages of large overload capacity, high reliability, and can effectively increase the power generation. Description of the Drawings

[0049] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0050] Figure 1 is the overall structure diagram of the combined vertical axis wind turbine in the present invention;

[0051] Figure 2 is the structural schematic diagram of the S-type wind turbine when the blade overlap ratio is 0.17 in the present invention;

[0052] Figure 3 It is a schematic structural diagram when the overlap ratio of the S-shaped fan blade in the present invention is 1;

[0053] Figure 4 It is a schematic diagram of the pitch angle of the H-shaped fan in the present invention;

[0054] Figure 5 It is a schematic diagram of the principle of the pitch control method for a vertical-axis wind turbine based on fuzzy control in the present invention;

[0055] Figure 6 It is a control flowchart of the pitch control method for a vertical-axis wind turbine based on fuzzy control in the present invention;

[0056] Figure 7 It is a schematic diagram of the fuzzy control principle of the pitch angle controller;

[0057] Figure 8 It is a fuzzy inference diagram of the pitch fuzzy controller in Matlab software.

[0058] In the figure: 10, S-shaped fan; 11, first blade support track; 12, second blade support track; 13, first blade; 14, second blade; 15, first active control device; 16, second active control device; 20, H-shaped fan; 21, H-shaped fan blade; 30, transmission shaft; 40, generator; 50, tower base. Specific embodiments

[0059] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0060] As Figure 1 shown, the combined vertical-axis wind turbine provided by the embodiment of the present invention includes an S-shaped fan 10 and an H-shaped fan 20 sequentially installed on a transmission shaft 30 from top to bottom, and further includes a generator 40 installed at the lower end of the transmission shaft 30, and the bottom of the generator 40 is a tower base 50.

[0061] As Figures 2-3As shown in the figure, the S-shaped wind turbine 10 includes a first blade support rail 11, a second blade support rail 12, a first blade 13, a second blade 14, a first active control device 15, and a second active control device 16. The first blade support rail 11 and the second blade support rail 12 are arranged in central symmetry with respect to the transmission shaft 30. The first blade 13 is installed on the first blade support rail 11 and can slide along it, and the second blade 14 is installed on the second blade support rail 12 and can slide along it. Both the first blade 13 and the second blade 14 are semi-cylindrical surface blades, with the cylindrical surfaces facing in opposite directions, arranged in central symmetry with respect to the transmission shaft 30, and the two blades are partially staggered. The first active control device 15 is mounted at the outer end of the first blade support rail 11 and contacts the outer end of the first blade 13, and a buckle is provided at the contact; the second active control device 16 is mounted at the outer end of the second blade support rail 12 and contacts the outer end of the second blade 14, and a buckle is provided at the contact. The blade support rail is a hollow rail. When the S-shaped wind turbine 10 rotates, due to the centrifugal force, the blades of the S-shaped wind turbine 10 can slide out along the blade support rail. The two active control devices adopt spring active control devices (in other embodiments, hydraulic telescopic active control devices can also be used), which can change the elongation of their respective springs according to the wind speed sensing information and the actual rotational speed information of the generator 40 to adjust the position of the buckle at the end, thereby adjusting the relative position of the corresponding blade and achieving the purpose of adjusting the overlap ratio of the two blades. The diameters of the first blade 13 and the second blade 14 are d, the staggered distance is s, and the blade overlap ratio is s / d. Refer to Figure 2 , the blade overlap ratio of the S-shaped wind turbine 10 is 0.17. At this time, the starting torque provided by the S-shaped wind turbine 10 during operation is relatively large, which is beneficial to the quick start of the vertical axis wind turbine. Refer to Figure 3 , the blade overlap ratio of the S-shaped wind turbine 10 is 1. At this time, the blades of the S-shaped wind turbine 10 are closed (forming a circle), and the starting torque provided by the S-shaped wind turbine 10 is zero, which can avoid causing wind resistance and is beneficial to the high-speed operation of the H-shaped wind turbine 20.

[0062] As Figure 4 shown, the H-shaped wind turbine blade 21 is equipped with a pitch control device, which can adjust the pitch angle according to the output signal of the fuzzy controller.

[0063] Further optimized, the S-shaped wind turbine 10 is a Savonius drag-type vertical axis wind turbine.

[0064] Further optimized, the generator 40 of the combined vertical axis wind turbine is a doubly-fed induction generator 40. Using the variable speed constant frequency power generation method, the wind turbine can change from constant speed operation to variable speed operation. In this way, the rotational speed of the wind wheel can change with the change of the wind speed, keeping it at a constant optimal tip speed ratio, so that the wind energy utilization coefficient of the wind turbine is at the maximum value throughout the operating range below the rated wind speed, thereby obtaining more energy than constant speed operation.

[0065] For further optimization, the sensor module of the combined vertical axis wind turbine includes a wind speed sensor, a generator speed sensor, and a blade pitch angle sensor of the wind turbine. The wind speed sensor is installed on the nacelle and is responsible for inputting the wind speed signal to the wind speed processing circuit. The generator speed sensor is installed inside the wind turbine engine, and the blade pitch angle sensor of the wind turbine is installed on the blade to detect the pitch angle information.

[0066] See Figures 5-6 , the present invention proposes a pitch control method for a combined vertical axis wind turbine based on fuzzy control, including the following steps:

[0067] S1. The wind turbine starts, the control system is initialized, and the wind speed V, the actual speed ω of the generator 40 of the combined vertical axis wind turbine, and the blade pitch angle β information of the H-type wind turbine 20 are obtained through the sensor module;

[0068] S2. According to the wind speed measured in S1, if the measured wind speed < cut-in wind speed, the wind turbine does not operate;

[0069] If the measured wind speed > cut-in wind speed, and at the same time according to the actual speed information of the generator 40 measured in S1, the relative positions of the two blades of the S-type wind turbine 10 are adjusted, so as to adjust the overlap ratio of the two blades. Specifically, it includes the following steps:

[0070] S21. Determine the speed range [0, ω max at which the S-type wind turbine 10 operates, and monitor the actual speed of the generator 40 of the combined vertical axis wind turbine;

[0071] S22. If the actual speed of the generator 40 is lower than the threshold ω max , the S-type wind turbine 10 operates. At this time, when the overlap ratio of the S-type wind turbine 10 is maintained at 0.15 - 0.2 (preferably 0.17), a larger starting torque is provided to improve the starting performance of the wind turbine;

[0072] If the actual speed of the generator 40 is higher than the threshold ω max , the overlap ratio of the S-type wind turbine 10 is maintained at 1, that is, the blades are closed and stop working to avoid wind resistance; the H-type wind turbine 20 starts;

[0073] S3. According to the information collected in S1, taking the pitch angle of the H-type wind turbine 20 as the controlled object, and the deviation e between the actual speed and the rated speed of the generator 40 and the wind speed change rate ec as the fuzzy input quantities, a fuzzy control algorithm is used to calculate the control output quantity, the pitch angle change value Δβ, and this control output quantity is input into the pitch control system to control the pitch angle change of the H-type wind turbine 20. Specifically, it includes the following steps:

[0074] S31. Determine the fuzzy controller input quantities e, ec and the output quantity Δβ:

[0075] Based on the actual rotational speed ω of the generator 40 and the wind speed V information measured by S1, the deviation e = Δω = ω - ω0 between the actual rotational speed ω and the rated rotational speed ω0 and the wind speed change rate ec = dV / dt are calculated, and the output of the fuzzy controller is the pitch angle change value Δβ;

[0076] S32. Fuzzification processing of input and output quantities:

[0077] Fuzzify the deviation e between the actual rotational speed ω and the rated rotational speed ω0 and the wind speed change rate ec, and convert them into fuzzy quantities E and EC; at the same time, perform fuzzy quantization processing on the output quantity Δβ to obtain U.

[0078] Fuzzify the input quantities to obtain fuzzy subsets EC and E of {Negative Large, Negative Medium, Negative Small, Zero, Positive Small, Positive Medium, Positive Large}, which are correspondingly recorded as {NB, NM, NS, ZO, PS, PM, PB}; among them, the change of the rotational speed deviation e is controlled within the range of (-25 r / min, 25 r / min), and the wind speed change rate ec is controlled within the range of (-10 m / s 2 , 10 m / s 2 ). The rotational speed deviation e and the wind speed change rate ec are both quantized into the universe of discourse range of [-6, 6];

[0079] Similarly, fuzzify the output quantity to obtain a fuzzy subset U of {Negative Large, Negative Medium, Negative Small, Zero, Positive Small, Positive Medium, Positive Large}, which is correspondingly recorded as {NB, NM, NS, ZO, PS, PM, PB}, and quantize it into the universe of discourse range of [-6, 6].

[0080] S33. Establish fuzzy control rules:

[0081] During the control process, when the deviation between the actual rotational speed of the generator 40 and the rated rotational speed is large, the change target of the pitch angle is to eliminate the rotational speed deviation as soon as possible; when the rotational speed deviation of the generator 40 is small, the change of the pitch angle should not only eliminate the rotational speed deviation of the generator 40, but also consider the stability of the wind turbine system to prevent unnecessary overshoot and oscillation of each variable during the operation of the wind turbine.

[0082] Under the cut-in wind speed, the fuzzy control rules of the fuzzy controller are shown in Table 1 below:

[0083] Table 1 Fuzzy logic rule table

[0084]

[0085] S34. Fuzzy inference:

[0086] Adopt the look-up table method in Mamdani inference control. Based on the fuzzy control rules, the inference statement is as follows:

[0087] If ec = EC iand e = E j then U = U ij

[0088] In the formula, EC i and E j (i, j = 1, 2, ……, 6) are respectively the elements in the fuzzy quantity sets of the input quantity wind speed change rate and the rotational speed deviation quantity, and U ij (i, j = 1, 2, ……, 6) is the fuzzy quantity set of the output pitch angle change value.

[0089] The fuzzy inference of the fuzzy controller is as Figure 8 shown.

[0090] S35. Defuzzification:

[0091] The weighted summation method is used to convert the fuzzy value of the output quantity into an accurate value. The weighted summation method means that the value obtained by weighted averaging each element in the fuzzy output set of the controller is used as the accurate output value of the control system, and its formula is:

[0092]

[0093] In the formula, U is the final output quantity, and U i is the output of the i-th rule, and w i is the weight factor, that is, the proportion of the i-th rule in the total output.

[0094] S36: Output of the fuzzy controller:

[0095] The fuzzy controller outputs the pitch angle adjustment amount to the pitch-changing device to complete the pitch adjustment.

[0096] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. A pitch control method for a combined vertical-axis wind turbine based on fuzzy control, the combined vertical-axis wind turbine comprising an S-type wind turbine and an H-type wind turbine arranged coaxially, characterized in that, The method includes the following steps: S1. The fan starts, the control system is initialized, and information on wind speed V, the actual rotational speed ω of the combined vertical-axis wind turbine generator, and the pitch angle β of the H-type wind turbine blades is obtained through the sensor module. S2. According to the measured wind speed in S1, if the measured wind speed < cut-in wind speed, the fan does not operate. If the measured wind speed > cut-in wind speed, and at the same time according to the actual rotational speed information of the generator measured in S1, the relative positions of the two blades of the S-type fan are adjusted, thereby adjusting the overlap ratio of the two blades; specifically, it includes the following steps: S21. Determine the rotational speed range [0, ω max at which the S-type fan operates, and monitor the actual rotational speed of the generator of the combined vertical-axis fan; S22. If the actual speed of the generator is lower than the threshold ω max , the S-type fan operates, and the overlap ratio of the S-type fan is adjusted to an appropriate position, which can provide a large starting torque and improve the starting performance of the fan; If the actual rotational speed of the generator is higher than the threshold ω max , the overlap ratio of the S-type fan remains 1, that is, the blades close and stop working to avoid wind resistance; the H-type fan starts; S3. According to the information collected in S1, with the pitch angle of the H-type fan as the controlled object, and the deviation e between the actual rotational speed of the generator and the rated rotational speed and the wind speed change rate ec as the fuzzy input quantities, a fuzzy control algorithm is used to calculate the control output quantity, the pitch angle change value Δβ, and this control output quantity is input into the pitch control system to control the pitch angle change of the H-type fan; specifically, it includes the following steps: S31. Determine the fuzzy controller input quantities e, ec, and output quantity Δβ: According to the information on the actual rotational speed ω of the generator and the wind speed V measured in S1, the deviation e = Δω = ω - ω0 between the actual rotational speed ω and the rated rotational speed ω0 and the wind speed change rate ec = dV / dt are calculated, and the output quantity of the fuzzy controller is the pitch angle change value Δβ. S32. Fuzzification processing of the input and output quantities: The deviation e between the actual rotational speed ω and the rated rotational speed ω0 and the wind speed change rate ec are fuzzified and transformed into fuzzy quantities E and EC; at the same time, the output quantity Δβ is fuzzily quantified as U. S33. Establish fuzzy control rules: During the control process, when the deviation between the actual rotational speed of the generator and the rated rotational speed is large, the change target of the pitch angle is to eliminate the rotational speed deviation as soon as possible; when the rotational speed deviation of the generator is small, in addition to eliminating the rotational speed deviation of the generator, the change of the pitch angle also needs to consider the stability of the fan system to prevent unnecessary overshoot and oscillation of each variable during the operation of the fan. S34. Fuzzy inference: Using the look-up table method in Mamdani inference control, based on the fuzzy control rules, the inference statement is as follows: If ec=EC i and e=E j then U=U ij where EC i and E j (i, j = 1, 2, ……, 6) are elements in the fuzzy quantity sets of the input quantity wind speed change rate and rotational speed deviation quantity respectively, and U ij (i, j = 1, 2, ……, 6) is the fuzzy quantity set of the output pitch angle change value; S35. Defuzzification: The weighted summation method is used to convert the fuzzy value of the output quantity into an exact value. S36: Output of the fuzzy controller: The fuzzy controller outputs the pitch angle adjustment amount to the pitch control device to complete the pitch adjustment.

2. The pitch control method for a combined vertical axis wind turbine based on fuzzy control according to claim 1, wherein, The method for fuzzification processing of the input and output quantities in step S32 is as follows: Fuzzify the input quantities to obtain fuzzy subsets EC and E of {negative large, negative medium, negative small, zero, positive small, positive medium, positive large}, which are correspondingly recorded as {NB, NM, NS, ZO, PS, PM, PB}; among them, the change of the rotational speed deviation e is controlled within the range of (-25 r / min, 25 r / min), and the wind speed change rate ec is controlled within the range of (-10 m / s 2 , 10 m / s 2 ). Quantize both the rotational speed deviation e and the wind speed change rate ec to the universe of discourse range of [-6, 6]; At the same time, the output quantity is fuzzified to obtain a fuzzy subset U of {negative large, negative medium, negative small, zero, positive small, positive medium, positive large}, which is correspondingly recorded as {NB, NM, NS, ZO, PS, PM, PB}, and is quantified to the domain range of [-6, 6].

3. The pitch control method for a combined vertical axis wind turbine based on fuzzy control according to claim 2, wherein, The fuzzy control rule table established in step S33 is as follows: 。 4. The pitch control method for a combined vertical-axis wind turbine based on fuzzy control according to claim 3, characterized in that, The weighted summation method in step S35 refers to taking the value obtained by weighted averaging each element in the fuzzy output set of the controller as the exact output value of the control system, and its formula is: where U is the final output, and U i is the output of the i-th rule, and w i is the weight factor, that is, the proportion of the i-th rule in the total output 5. The pitch control method for a combined vertical axis wind turbine based on fuzzy control according to claim 1, characterized in that In step S22, when the overlap ratio of the S-type fan is 0.15 - 0.2, a relatively large starting torque can be provided.

6. The pitch control method for a combined vertical axis wind turbine based on fuzzy control according to claim 1, characterized in that, The S-type fan includes a first blade support track, a second blade support track, a first blade, a second blade, a first active control device, and a second active control device. The first blade support track and the second blade support track are arranged in central symmetry with respect to the transmission shaft. The first blade is installed on the first blade support track and can slide along it, and the second blade is installed on the second blade support track and can slide along it. The first blade and the second blade are arranged in central symmetry with respect to the transmission shaft and the blade parts are staggered; the first active control device is carried on the outer end of the first blade support track and contacts the outer end of the first blade, and the second active control device is carried on the outer end of the second blade support track and contacts the outer end of the second blade; The two active control devices can change their respective own lengths according to the wind speed sensing information and the actual generator speed information to adjust the relative positions of the corresponding blades, thereby adjusting the overlap ratio of the two blades; The blades of the H-type wind turbine are equipped with a pitch control device, and the pitch angle can be adjusted according to the output signal of the fuzzy controller.

7. The pitch control method for a combined vertical axis wind turbine based on fuzzy control according to claim 6, wherein The active control device adopts a spring active control device or a hydraulic telescopic active control device.

8. The pitch control method for a combined vertical axis wind turbine based on fuzzy control according to claim 1, characterized in that, The generator of the combined vertical axis wind turbine is installed at the lower end of the transmission shaft, and the generator is a doubly-fed asynchronous generator.

9. The pitch control method for a combined vertical axis wind turbine based on fuzzy control according to claim 1, wherein The sensor module of the combined vertical axis wind turbine includes a wind speed sensor, a generator speed sensor and a wind turbine blade pitch angle sensor. The wind speed sensor is installed on the nacelle and is used to input a wind speed signal to the wind speed processing circuit; the generator speed sensor is installed in the wind turbine engine; the wind turbine blade pitch angle sensor is installed on the blade to detect the pitch angle information.

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