A design method of rotational speed gear position for axial flow fan blade opening and rotational speed gear position combined adjustment

Abstract

The application discloses a kind of axial flow fan blade opening and rotational speed gear joint design methods of speed gear, comprising: based on the natural static frequency of blade first 3 orders obtained by blade knock test, and the variation curve of the multiple order dynamic frequency of blade and rotational speed is obtained by finite element method;Further based on the air flow excitation characteristics in fan, obtain the dangerous rotational speed band of fan;Develop fan performance test under multiple typical working conditions, obtain the pipe network resistance curve in the whole regulation range, and obtain the variable speed performance curve cluster based on fan performance curve, follow the principle of best operating efficiency and operating safety, the best rotational speed corresponding to each fan performance test working condition point is calculated;With the optimization target of avoiding resonance frequency and portable fan control mode, the optimal rotational speed gear scheme is obtained by optimization design.The application has the characteristics of high efficiency and high reliability, and is suitable for the gear design of large coal-fired unit axial flow fan blade and rotational speed gear joint.

Description

Technical Field

[0001] This invention belongs to the field of wind power generation technology, specifically relating to a speed gear design method for the coordinated adjustment of blade opening and rotational speed of an axial flow wind turbine. Background Technology

[0002] Currently, with the continuous increase in the installed capacity of thermal power units and the continuous improvement in the design and manufacturing level of axial flow fans for power plants, axial flow fans have been widely used due to their good adjustment performance and higher design efficiency. However, with the adjustment of my country's energy structure, the flexible adjustment of thermal power units has become the norm, requiring frequent wide-load adjustments. This results in power plant fans operating at medium and low loads for extended periods or frequently undergoing wide-load variable-condition adjustments. Currently, axial flow fans in my country's power plants generally use blade adjustment for variable-condition adjustment. Even though the design efficiency of axial flow fans has reached over 89%, the actual operating efficiency under medium and low load conditions is still below 70%, resulting in low fan operating efficiency and high energy consumption. Therefore, blade adjustment alone is no longer sufficient to meet the needs of deep peak shaving and deep energy saving of the units. Given the current situation of deep peak shaving and low load rates in domestic wind turbines, variable speed regulation remains the optimal operating mode. However, considering the structure and operating characteristics of axial flow fans, operating with full-range variable speed regulation poses safety risks of blade resonance or rotor system resonance. Furthermore, if dynamically adjustable axial flow fans are not adjusted for extended periods, the blade adjustment mechanism may jam, reducing equipment reliability. Therefore, it is essential to implement segmented adjustment of axial flow fan blade opening and speed. This segmented adjustment prevents the fan from operating at dangerous speeds for extended periods and improves fan efficiency while ensuring the reliability of the blade adjustment system. To ensure optimal performance of segmented adjustment of axial flow fan blade opening and speed, it is crucial to establish a speed segmentation optimization design method to achieve the optimal speed range design, balancing power plant fan operation safety with optimal operating economy. Summary of the Invention

[0003] To achieve coordinated adjustment of blade opening and rotational speed in axial flow fans, this invention proposes a speed range design method for coordinated adjustment of blade opening and rotational speed in axial flow fans.

[0004] This invention is achieved using the following technical solution:

[0005] A method for designing speed settings that coordinates blade opening and rotational speed of an axial flow fan includes the following steps:

[0006] 1) The first three natural static frequencies of the blades were obtained based on field blade impact tests of axial flow fans;

[0007] 2) Establish a three-dimensional finite element model of the blade, and use the finite element method to perform stress analysis and modal analysis on the blade to obtain the multi-order dynamic frequencies of the blade and their variation curves with rotational speed;

[0008] 3) Based on the dynamic frequency-speed curves of each blade, considering the first 6 speed frequencies, the first 3 passing frequencies, and the first 3 airflow excitation frequencies caused by the inlet and outlet guide vanes or support plates, the dangerous speed band of the fan is obtained.

[0009] 4) Conduct field performance tests on axial flow fans under multiple typical operating conditions to obtain the distribution of fan operating points and pipeline resistance curves across the entire wide load adjustment range;

[0010] 5) Discretize the wind turbine performance curves and obtain a cluster of variable speed performance curves based on the variation law of wind turbine performance parameters and speed. Based on the mapping relationship between each actual operating point and the constant opening line and efficiency line, construct an intelligent identification algorithm for the opening, efficiency and theoretical stall boundary point under constant opening at the actual operating point of the wind turbine.

[0011] 6) Based on the cluster of wind turbine performance curves under multiple speeds and intelligent recognition algorithms, the dangerous speed range of wind turbine operation, and wind turbine performance test data under typical operating conditions, the permissible range of wind turbine operating speed corresponding to the typical operating point of each wind turbine is calculated.

[0012] 7) Obtain the pipeline resistance curve based on the fan performance test data under typical operating conditions. Based on the permissible speed range of the fan under typical operating conditions, and taking into account the portability of fan control, the optimal speed grading scheme is obtained through optimization design calculations, taking into account the economic efficiency and safety of fan operation.

[0013] A further improvement of this invention is that, in step 1), an impact test is conducted on the axial flow fan blades using an impact method to obtain the first three natural static frequencies {(f1,f2,f3)} of each blade. i}, i = 1, 2, 3, ..., n.

[0014] A further improvement of the present invention is that, in step 2), the specific implementation method is as follows:

[0015] 201) Establish a three-dimensional finite element model of the blade, and use the finite element method to perform modal analysis on the blade to obtain the first three natural frequencies of the blade;

[0016] 202) By comparing the natural frequencies of the blade obtained from the blade impact test with those obtained through modal analysis, the three-dimensional finite element model of the blade is corrected to ensure the accuracy of the calculation model;

[0017] 203) Within the entire design speed range of the wind turbine, select j speed conditions to perform static strength analysis and prestressed modal analysis of the blade, and obtain the first three dynamic frequencies of the blade and the curves showing the relationship between dynamic frequencies and speed, where j≥6.

[0018] A further improvement of this invention is that, in step 3), the intersection points of the two curves are calculated to obtain the set of dangerous speeds, and the minimum dangerous speed N corresponding to the natural frequency of each order of the wind turbine blades is calculated based on the blade natural frequency dispersion ε. min and maximum dangerous speed N max Construct the dangerous speed band set of the wind turbine {[N] min N max ] l}, l=1,2,3,…,m.

[0019] A further improvement of this invention is that, in step 4), on-site performance tests are conducted on the axial flow fan under k typical operating conditions, where the number of test conditions k ≥ 3, and includes the lowest and highest load conditions during normal operation of the unit, to obtain the set {(Q, P)} of the fan inlet flow rate Q and the fan total pressure P at the typical operating point of the fan within the entire wide load adjustment range. i}, i=1,2,3,…,k, and based on the set of fan operating points, the least squares method is used to fit the pipeline system resistance curve P=f(Q).

[0020] A further improvement of this invention is that, in step 5), the fan performance curve is discretized, and based on the conversion relationship between flow rate Q, pressure P, and rotational speed, a cluster of fan performance curves P at multiple rotational speeds is obtained. Ni =f Ni (Q), and based on the mapping relationship between the wind turbine operating point and each opening line and efficiency line, construct the wind turbine performance curve corresponding to the opening β, efficiency η, and the intersection of the equal opening line and the theoretical stall line (Q). s ,P s The intelligent recognition algorithm.

[0021] A further improvement of this invention is that, in step 6), based on the cluster of wind turbine performance curves under multiple speeds and an intelligent recognition algorithm, the typical operating point (Q, P) of each wind turbine is calculated. i The corresponding available fan operating speed range [N' min ,N' max ] i .

[0022] A further improvement of the present invention is that, in step 6), the specific implementation method is as follows:

[0023] 601) Calculate the fan operating point (Q, P) i At different speeds N sThe characteristic parameters (β, η, Q) corresponding to the wind turbine performance curve s ,P s ) Ns ;

[0024] 602) Based on the fan operating point (Q, P) i and theoretical stall point (Q) s ,P s ) Ns Calculate the stall margin coefficients (k) corresponding to the operating points of the fan at different speeds. p ,k q ,k s ) Ns ;

[0025] The stall pressure margin coefficient of the fan is:

[0026] k p =P s / P

[0027] The stall flow margin coefficient of the fan is:

[0028] k q =Q / Q s

[0029] The stall safety factor of the wind turbine is:

[0030]

[0031] 603) To ensure the safe and stable operation of the wind turbine, the available speed range [N'] corresponding to each typical operating point of the wind turbine is calculated based on the following conditions. min ,N' max ] i :

[0032] 1)k s ≥1.35 and k p ≥1.15, k q ≥1.08;

[0033] 2)

[0034] 3) η≥0.8η max .

[0035] A further improvement of this invention is that, in step 7), based on the pipeline system resistance curve P=f(Q) and the set of available speed ranges corresponding to each typical operating point of the fan {[N' min ,N' max ] i (i = 1, 2, 3, ..., k), taking into account the convenience of fan control, the optimal number of speeds I and the speed N of each speed are calculated for the entire wide load adjustment range.d , d=1,2,3,…,I.

[0036] A further improvement of the present invention is that, in step 7), the specific implementation method is as follows:

[0037] 701) Based on the set of available speed ranges corresponding to each typical operating point of the wind turbine {[N' min ,N' max ] i} and the dangerous speed zone of the fan {[N min N max ] l Based on the principle of avoiding dangerous speed ranges, multiple safe and efficient speed ranges are obtained. i=1,2,3,…,k, l=1,2,3,…,m, j=1,2,3,…,m;

[0038] 702) Based on the pipeline system resistance curve P=f(Q), the entire wide load adjustment range is divided into I sub-ranges, and the efficiency of the fan operating point in each sub-range is used as the optimization objective within the speed range. Internal optimization is performed to obtain the optimal number of gears I and the corresponding speed set N. i , i=1,2,3,…,I, 3≤I≤6.

[0039] The present invention has at least the following beneficial technical effects:

[0040] This invention provides a speed range design method for the coordinated adjustment of blade opening and rotational speed of an axial flow fan. The static frequency of the blades is obtained through blade impact tests, and the relationship between the dynamic frequency and rotational speed is obtained using finite element analysis. Based on the main excitation frequencies present during axial flow fan operation, the dangerous speed range of the axial flow fan is identified. Performance tests are conducted on the fan to obtain the fan operating point parameters and pipeline resistance curves under typical operating conditions. By discretizing the fan performance curves, a cluster of fan performance curves at different speeds and a fan operating status evaluation model are constructed. Then, the usable speed range under each typical operating condition is calculated. Based on avoiding the dangerous range and achieving optimal operating efficiency, while also considering ease of control and safety, an optimization algorithm is used to obtain the optimal number of speed ranges and the optimal speed for each range. This provides a basis for the coordinated operation of the fan blades and rotational speed, improving the peak-shaving flexibility of the unit and enhancing the operational safety and economy of the fan.

[0041] In summary, this invention is characterized by high efficiency and high reliability, and is suitable for the geared design of axial flow fan blades and speed geared adjustment in large coal-fired power units, providing a theoretical basis for the subsequent logical implementation of automatic geared adjustment of power plant fans. Attached Figure Description

[0042] Figure 1 This is a schematic diagram illustrating the principle of the present invention.

[0043] Figure 2 This is a schematic diagram showing the distribution of the wind turbine operating points and corresponding stall points on the wind turbine performance curve according to the present invention.

[0044] Figure 3 This is a distribution diagram of the actual operating points of the wind turbine on its performance curve under typical operating conditions.

[0045] in, Figure 1 In this context, Q represents the inlet volumetric flow rate of the fan, in cubic meters per second (m³). 3 / s, P is the total pressure of the fan in Pa, f is the static frequency of the fan blades in Hz. d The dynamic frequency of the wind turbine blades, in Hz, f act The main excitation frequency during wind turbine operation is expressed in Hz, N is the wind turbine operating speed in r / min, and Q is the frequency of vibration. s The theoretical stall point flow rate corresponding to the operating point of the wind turbine, in cubic meters per second (m³). 3 / s, Ps is the theoretical stall point total pressure corresponding to the wind turbine operating point, in Pa; β is the opening value of the performance curve corresponding to the wind turbine operating point, in °. max The maximum opening value on the wind turbine performance curve, in degrees, β min η represents the minimum opening value on the wind turbine performance curve, in degrees; η represents the efficiency value of the performance curve corresponding to the wind turbine operating point, in percentage; i represents the wind turbine blade number (i = 1, 2, 3, ..., n); j represents the speed range (j = 1, 2, ..., m); and i represents the number of wind turbine test load conditions (i = 1, 2, 3, ..., k). s Kp is the stall safety factor, kq is the stall pressure margin factor, kq is the stall flow margin factor, and I is the optimal number of gears. Detailed Implementation

[0046] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] like Figure 1 As shown, the present invention provides a speed range design method for the coordinated adjustment of blade opening and speed of an axial flow fan, comprising the following steps:

[0048] 1. An impact test was conducted on the blades of an axial flow fan using the impact method to obtain the first three natural static frequencies {(f1,f2,f3)} of each blade. i}, i = 1, 2, 3, ..., n.

[0049] 2. Based on the blade structural parameters, a three-dimensional finite element model was constructed, and modal analysis with prestress was carried out on each blade to obtain the first three dynamic frequencies of the blade and their variation curves with rotational speed.

[0050] ① Establish a three-dimensional finite element model of the blade, and use the finite element method to perform modal analysis on the blade to obtain the first three natural frequencies of the blade.

[0051] ② By comparing the natural frequency of the blade obtained from the blade impact test with the natural frequency obtained through modal analysis, the three-dimensional finite element model of the blade is corrected to ensure the accuracy of the calculation model.

[0052] ③ Within the entire design speed range of the wind turbine (0~N), select j speed conditions (j≥6) to perform static strength analysis and prestressed modal analysis of the blades, and obtain the first three dynamic frequencies of the blades and the curves showing the relationship between dynamic frequencies and speed.

[0053] 3. Based on the relationship curves between the dynamic frequencies of the blades and their rotational speeds, construct the relationship curves between the main excitation frequencies and rotational speeds during wind turbine operation (the first 6 rotational speed frequencies of the wind turbine, the first 3 passing frequencies, and the first 3 airflow excitation frequencies caused by the inlet and outlet guide vanes or support plates). Calculate the intersection points of the two curves to obtain the set of dangerous rotational speeds. Based on the blade's natural frequency dispersion ε, calculate the set of dangerous rotational speed zones {[N]}. min N max ] l}(l=1,2,3,…,m).

[0054] 4. Conduct on-site performance tests on the axial flow fan under k typical operating conditions (the number of test conditions k ≥ 3, including the lowest and highest load conditions during normal operation of the unit), and obtain the set of typical operating points {(Q, P)} of the fan within the entire wide load adjustment range. i}(i=1,2,3,…,k), and based on the set of fan operating points, the least squares method is used to fit the pipeline system resistance curve P=f(Q).

[0055] 5. Discretize the fan design performance curves and, based on the conversion relationship between flow rate Q, pressure P, and speed, obtain the fan performance curve cluster P at multiple speeds. Ni =f Ni (Q), and based on the mapping relationship between the wind turbine operating point and each opening line and efficiency line, construct the wind turbine performance curve corresponding to the opening β, efficiency η, and the intersection of the equal opening line and the theoretical stall line (Q). s ,Ps The intelligent recognition algorithm.

[0056] 6. Based on the cluster of wind turbine performance curves under multiple speeds and intelligent recognition algorithms, the typical operating points (Q, P) of each wind turbine are calculated. i The corresponding available fan operating speed range [N' min ,N' max ] i .

[0057] ① Calculate the fan operating point (Q, P) i At different speeds N s The characteristic parameters (β, η, Q) corresponding to the wind turbine performance curve s ,P s ) Ns .

[0058] ②Based on the fan operating point (Q, P) i and theoretical stall point (Q) s ,P s ) Ns Calculate the stall margin coefficients (k) corresponding to the operating points of the fan at different speeds. p ,k q ,k s ) Ns .

[0059] The stall pressure margin coefficient of the fan is:

[0060] k p =P s / P

[0061] The stall flow margin coefficient of the fan is:

[0062] k q =Q / Q s

[0063] The stall safety factor of the wind turbine is:

[0064]

[0065] ③ To ensure the safe and stable operation of the wind turbine, the available speed range [N'] corresponding to each typical operating point of the wind turbine is calculated based on the following conditions. min ,N' max ] i :

[0066] 1)k s ≥1.35 and k p ≥1.15, k q ≥1.08;

[0067]

[0068] 3) η≥0.8η max .

[0069] 7. Based on the pipeline system resistance curve P=f(Q) and the set of available speed ranges corresponding to each typical operating point of the fan {[N' min ,N' max ] i (i = 1, 2, 3, ..., k), taking into account the convenience of fan control, the optimal number of speeds I and the speed N of each speed are calculated for the entire wide load adjustment range. d (d = 1, 2, 3, ..., I).

[0070] ①Based on the set of available speed ranges corresponding to each typical operating point of the wind turbine {[N' min ,N' max ] i}(i=1,2,3,…,k) and the dangerous speed band set of the fan {[N min N max ] l Based on the principle of avoiding dangerous speed zones, multiple safe and efficient speed ranges are obtained for the range (l = 1, 2, 3, ..., m).

[0071] ② Based on the pipeline system resistance curve P=f(Q), the entire wide load adjustment range is divided into I sub-ranges (3≤I≤6), and the efficiency of the fan operating point within each sub-range is used as the optimization objective, within the speed range. Internal optimization is performed to obtain the optimal number of gears I and the corresponding speed set N. i , i = 1, 2, 3, ..., I.

[0072] Example

[0073] A 700MW unit is equipped with two dynamically adjustable axial flow induced draft fans, using motor drive and variable load operation with blade adjustment. This unit participates in deep peak shaving operation. The distribution of the fan operating points under typical operating conditions on its performance curve is as follows: Figure 3As shown, the high-efficiency range of the induced draft fan under constant speed operation is between -5° and +10° blade angle, corresponding to a fan blade opening of 67% to 100%. However, the actual full-load range of the fan blade opening (from the lowest operating condition to the fan's TB point opening) is approximately 33% to 84%. Under normal operating conditions (high, medium, and low operating conditions of the unit's normal operation), the fan blade opening is 33% to 56%, and the efficiency at each operating point is not high, especially under low load and deep-load conditions, where the fan efficiency is below 53%, indicating significant energy-saving potential. To improve the fan's operating efficiency and safety, the method of this invention is implemented using a high-level programming language to obtain the optimal gearing scheme, including the number of gears and the speed of each gear. By improving the logic control in the DCS, automatic joint adjustment of the blades and speed of the dynamically adjustable axial flow fan is achieved, improving the unit's adjustment flexibility under deep peak-shaving conditions. The algorithm of this invention is efficient and reliable. The calculation results of the dangerous speed range of the wind turbine are shown in Table 1. The calculation results of the optimal speed under typical test conditions of each wind turbine are shown in Table 2. The optimal gearing scheme for the joint adjustment of the wind turbine blades and speed is shown in Table 3.

[0074] Table 1 Calculation results of dangerous speed band

[0075]

[0076] Table 2 Calculation results of optimal speed for each fan under typical test conditions

[0077]

[0078]

[0079] Table 3 Optimal Gear Scheme for Co-regulation of Wind Turbine Blades and Rotation Speed

[0080]

[0081] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for designing speed ranges that coordinates the blade opening and rotational speed of an axial flow fan, characterized in that, Includes the following steps: 1) Obtain the first three natural static frequencies of the blades based on field blade impact tests of axial flow fans; 2) Establish a three-dimensional finite element model of the blade, and use the finite element method to perform stress analysis and modal analysis on the blade to obtain the multi-order dynamic frequencies of the blade and their variation curves with rotational speed; 3) Based on the dynamic frequency-speed curves of each blade, considering the first 6 speed frequencies, the first 3 passing frequencies, and the first 3 airflow excitation frequencies caused by the inlet and outlet guide vanes or support plates, the dangerous speed band of the fan is obtained. 4) Conduct field performance tests on axial flow fans under multiple typical operating conditions to obtain the distribution of fan operating points and pipeline resistance curves across the entire wide load adjustment range; 5) Discretize the wind turbine performance curves and obtain a cluster of variable speed performance curves based on the variation law of wind turbine performance parameters and speed. Based on the mapping relationship between each actual operating point and the constant opening line and efficiency line, construct an intelligent identification algorithm for the opening, efficiency and theoretical stall boundary point of the actual operating point of the wind turbine under constant opening. 6) Based on the cluster of wind turbine performance curves under multiple speeds and the intelligent identification algorithm, the dangerous speed range of wind turbine operation and the wind turbine performance test data under typical operating conditions, the permissible range of wind turbine operating speed corresponding to the typical operating point of each wind turbine is calculated. 7) Obtain the pipeline resistance curve based on the fan performance test data under typical operating conditions. Based on the permissible speed range of the fan under typical operating conditions, and taking into account the portability of fan control, the optimal speed grading scheme is obtained through optimization design calculations, taking into account the economic efficiency and safety of fan operation. Based on the resistance curve of the pipeline system P = f ( Q ) and the set of available speed ranges corresponding to each typical operating point of the fan {[ N ’ min , N ’ max ] i }, i =1,2,3,…, k Taking into account the ease of fan control, the optimal number of speed settings is calculated across the entire wide load adjustment range. I and the speed N of each gear d , d =1, 2,3,…, I The specific implementation method is as follows: 701) Based on the set of available speed ranges corresponding to each typical operating point of the wind turbine {[ N ’ min , N ’ max ] i } and the dangerous speed zone of the fan {[ N min , N max ] l Based on the principle of avoiding dangerous speed ranges, multiple safe and efficient speed ranges are obtained. , i =1,2,3,…, k , l =1,2,3,…, m , ; 702) Based on the pipeline system resistance curve P = f ( Q The entire wide load adjustment range is divided into: I The system is divided into sub-intervals, with the efficiency of the fan operating point within each sub-interval as the optimization objective, within the speed range. Internal optimization is used to obtain the optimal number of gears. I and the corresponding speed set N i , i =1, 2,3,…, I ,3≤ I ≤6.

2. The speed range design method for the coordinated adjustment of blade opening and speed of an axial flow fan according to claim 1, characterized in that, In step 1), an impact test is conducted on the axial flow fan blades using the impact method to obtain the first three natural static frequencies {( f 1, f 2, f 3) i }, i =1,2,3,…, n .

3. The speed range design method for the coordinated adjustment of blade opening and speed of an axial flow fan according to claim 1, characterized in that, In step 2), the specific implementation method is as follows: 201) Establish a three-dimensional finite element model of the blade, and use the finite element method to perform modal analysis on the blade to obtain the first three natural frequencies of the blade; 202) By comparing the natural frequencies of the blade obtained from the blade impact test with those obtained through modal analysis, the three-dimensional finite element model of the blade is corrected to ensure the accuracy of the calculation model; 203) Select the appropriate speed range for the entire wind turbine design speed range. j Static strength analysis and modal analysis with prestress were performed on the blade under various speed conditions to obtain the first three dynamic frequencies of the blade and the curves showing the relationship between dynamic frequencies and speed, where j≥6.

4. The speed range design method for the coordinated adjustment of blade opening and speed of an axial flow fan according to claim 1, characterized in that, In step 3), the intersection points of the two curves are calculated to obtain the set of critical speeds, and the blade's natural frequency dispersion is then determined. ε The minimum critical speed corresponding to the natural frequency of each order of the wind turbine blades was calculated. N min and maximum dangerous speed N max Construct the dangerous speed band set of the wind turbine {[ N min , N max ] l }, l =1,2,3,…, m .

5. The speed range design method for the coordinated adjustment of blade opening and speed of an axial flow fan according to claim 1, characterized in that, In step 4), the axial flow fan is subjected to... k Field performance tests under typical operating conditions, number of test conditions k ≥3, including the lowest and highest load conditions during normal operation of the unit, to obtain the fan inlet flow rate at typical operating points across the entire wide load adjustment range. Q and the total pressure of the blower P The set {( Q , P ) i }, i =1,2,3,…, k Based on the set of wind turbine operating points, the least squares method was used to fit the resistance curve of the pipeline system. P = f ( Q ).

6. The speed range design method for the coordinated adjustment of blade opening and speed of an axial flow fan according to claim 1, characterized in that, In step 5), the wind turbine performance curve is discretized and based on the flow rate. Q ,pressure P The conversion formula between the speed and the fan speed is used to obtain a set of fan performance curves at multiple speeds. P Ni = f Ni ( Q Based on the mapping relationship between the wind turbine operating point and each opening degree line and efficiency line, the corresponding opening degree of the wind turbine performance curve is constructed. β ,efficiency η and the intersection of the constant opening line and the theoretical stall line ( Q s ,P s The intelligent recognition algorithm.

7. The speed range design method for the coordinated adjustment of blade opening and speed of an axial flow fan according to claim 6, characterized in that, In step 6), based on the cluster of wind turbine performance curves at multiple speeds and the intelligent recognition algorithm, the typical operating point of each wind turbine is calculated. Q , P ) i The corresponding available fan operating speed range [ N ’ min , N ’ max ] i .

8. The speed range design method for the coordinated adjustment of blade opening and speed of an axial flow fan according to claim 7, characterized in that, In step 6), the specific implementation method is as follows: 601) Calculate the fan operating point ( Q , P ) i At different speeds N s The characteristic parameters corresponding to the wind turbine performance curve ( β, η, Q s , P s ) Ns ; 602) Based on the fan operating point ( Q , P ) i and theoretical stall point ( Q s , P s ) Ns Calculate the stall margin coefficients corresponding to the operating points of the fan at different speeds. k p , k q , k s ) Ns ; The stall pressure margin coefficient of the fan is: The stall flow margin coefficient of the fan is: The stall safety factor of the wind turbine is: 603) To ensure the safe and stable operation of the wind turbine, the available speed range corresponding to each typical operating point of the wind turbine is calculated based on the following conditions: N ’ min , N ’ max ] i : 1) k s ≥1.35 and k p ≥1.15、 k q ≥1.08; 2） ； 3） 。

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