Blade fatigue test method and system of wind generating set

Abstract

The invention provides a blade fatigue testing method and system of a wind generating set. The blade fatigue testing method comprises the steps that the first load mean value of a blade to be tested in the first direction is determined; based on the first load mean value and a second load amplitude of the blade in the second direction, determining a target load for performing a fatigue test on the blade in the second direction; determining a test load for performing a fatigue test on the blade in the second direction, so that the difference between the test load and the target load is within a preset range; and based on the test load, performing a fatigue test on the blade in the second direction. According to the blade fatigue test method and system of the wind generating set, the problem that the fatigue load in a single direction may not reflect the actual running state of the blade is solved, the target load is closer to the actual running state of the blade in the fatigue test process, and the test result is more accurate.

Description

Technical Field

[0001] The present disclosure relates to the field of wind power generation, and more specifically, to a blade fatigue testing method and system for a wind generator set. Background Art

[0002] As the capacity of wind turbines increases, blades continue to grow larger, and blade design values ​​are getting closer and closer to the limits of materials. The safety of blades is facing increasing challenges, which makes static and fatigue testing of full-size blades a key link in verifying the reliability of large blades.

[0003] In related technologies, blade fatigue testing is mainly used to verify the service life of the blade. During the fatigue test, the load applied to the blade can generally be decomposed into a swing direction and a swing direction, so that the fatigue test is performed according to the corresponding load direction.

[0004] However, in actual operation, the thrust acting on the blade may not be single, and the load in the flapping direction and the load in the swing direction may affect each other. Therefore, fatigue testing based on a single direction may not reflect the actual operating status of the blade. Summary of the invention

[0005] In view of the problem that fatigue load in a single direction in existing blade fatigue testing schemes may not reflect the actual operating state of the blade, the present disclosure provides a blade fatigue testing method and system for a wind turbine generator set.

[0006] A first aspect of the present disclosure provides a blade fatigue testing method for a wind turbine generator set, the blade fatigue testing method comprising: determining a first load mean value of a blade to be tested in a first direction; determining a target load for fatigue testing the blade in the second direction based on the first load mean value and a second load amplitude of the blade in the second direction, wherein the first direction is one of a flapping direction and a swing direction, and the second direction is the other of the flapping direction and the swing direction; determining a test load for fatigue testing the blade in the second direction, so that the difference between the test load and the target load is within a predetermined range; and performing a fatigue test on the blade in the second direction based on the test load.

[0007] Optionally, the first load mean is determined in the following manner: based on the fatigue load spectrum of the blade, determining the first load amplitude and the first fatigue load of the blade in the first direction; based on the first load amplitude and the first fatigue load, determining the first load mean.

[0008] Optionally, the first load mean is the load mean at a reference fatigue number in the fatigue load spectrum of the blade, wherein the target load is determined in the following manner: based on the first load mean, the second load amplitude and the reference fatigue number, the target load at a target fatigue test number is determined by converting the loads at different fatigue numbers.

[0009] Optionally, load conversion is performed in the following manner: obtaining material parameters of the blade, wherein the material parameters include ultimate tensile strength, ultimate compressive strength, slope parameters of the fatigue test SN curve, and ultimate reduction coefficient; bringing the first load mean, the second load amplitude, the reference fatigue number, the material parameters, and the target fatigue test number into a preset load conversion relationship to perform load conversion.

[0010] Optionally, the ultimate tensile strength and the ultimate compressive strength are equal.

[0011] Optionally, the ultimate tensile strength and the ultimate compressive strength are determined in the following manner: obtaining a material fatigue tensile curve of the blade; adjusting the intersection value of the material fatigue tensile curve and the coordinate axis so that the material fatigue tensile curve has symmetry, and obtaining an adjusted material fatigue tensile curve; based on the adjusted material fatigue tensile curve, determining the ultimate tensile strength and the ultimate compressive strength.

[0012] Optionally, the target load is determined by: determining a second load mean of the blade in the second direction; and determining a target load for fatigue testing the blade in the second direction based on the first load mean, the second load amplitude and the second load mean.

[0013] Optionally, the step of determining a target load for fatigue testing the blade in the second direction based on the first load mean, the second load amplitude and the second load mean includes: determining a sum of the load means of the first load mean and the second load mean; and determining a target load for fatigue testing the blade in the second direction based on the second load amplitude and the sum of the load means.

[0014] Optionally, the test load is determined in the following manner: by adjusting the position of the excitation point, the position of the counterweight and / or the size of the counterweight, a blade vibration mode that meets the fatigue test requirements is determined; based on the dead weight of the blade and the size of the counterweight, a gravity load of the blade in the fatigue test is obtained; based on the gravity load, a mean value of the test load is determined; based on the mean value of the test load, the test load is determined by adjusting the amplitude of the test load so that the difference between the test load and the target load is within the predetermined range.

[0015] A second aspect of the present disclosure provides a blade fatigue testing system for a wind turbine generator set, the blade fatigue testing system comprising an exciter and a controller, the exciter being installed at an excitation point of a blade to be tested to cause the blade to vibrate; the controller controlling the exciter to apply vibration to the blade so that the difference between a test load and a target load is within a predetermined range, so as to perform a fatigue test on the blade in a second direction based on the test load, wherein the target load is determined in the following manner: determining a first load mean value of the blade in a first direction; determining the target load for fatigue testing the blade in the second direction based on the first load mean value and a second load amplitude of the blade in the second direction, wherein the first direction is one of a flapping direction and a swinging direction, and the second direction is the other of the flapping direction and the swinging direction.

[0016] According to the blade fatigue testing method and system of the wind turbine generator set disclosed in the present invention, the target load of the fatigue test of the blade in the second direction can be determined based on the first load mean value in the first direction of the flapping direction and the swing direction and the second load amplitude in the second direction of the flapping direction and the swing direction. Therefore, the influence of the load mean value in the other direction can be taken into account in the fatigue test in any direction, so that the target load during the fatigue test is closer to the actual operating state of the blade, making the test result more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic cross-sectional view showing a blade of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0018] Figure 2 is a schematic flow chart showing a blade fatigue testing method of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0019] Figure 3 is a schematic flow chart showing the steps of determining a first load mean value in a blade fatigue testing method of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0020] Figure 4 is a schematic flow chart showing the steps of load conversion in a blade fatigue testing method of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0021] Figure 5 is a schematic flow chart showing steps of determining ultimate tensile strength and ultimate compressive strength in a blade fatigue testing method of a wind turbine according to an exemplary embodiment of the present disclosure.

[0022] Figure 6Schematic diagram showing a material fatigue tensile curve of a blade of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0023] Figure 7 is a schematic flow chart showing steps of determining a test load in a blade fatigue test method of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0024] Figure 8 is a schematic flow chart showing steps of determining a target load in a blade fatigue testing method of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0025] Fig. 9 is a schematic block diagram showing a blade fatigue testing system of a wind turbine generator system according to an exemplary embodiment of the present disclosure.

[0026] Fig.10 is a schematic diagram illustrating a blade on which an exciter is mounted according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be clear. For example, the order of operations described herein is only an example and is not limited to those orders set forth herein, but can be changed as will be clear after understanding the disclosure of the present application, except for operations that must occur in a specific order. In addition, for greater clarity and simplicity, the description of features known in the art may be omitted.

[0028] The features described herein can be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided to illustrate only some of the many possible ways to implement the methods, devices, and / or systems described herein, which will be clear after understanding the disclosure of the present application.

[0029] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more.

[0030] Although terms such as "first", "second", and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions should not be limited by these terms. Instead, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, first component, first region, first layer, or first portion referred to in the examples may also be referred to as the second member, second component, second region, second layer, or second portion.

[0031] In the specification, when an element (such as a layer, a region, or a substrate) is described as being “on”, “connected to”, or “coupled to” another element, the element may be directly “on”, “connected to”, or “coupled to” another element, or one or more other elements may be present therebetween. Conversely, when an element is described as being “directly on”, “directly connected to”, or “directly coupled to” another element, there may be no other elements present therebetween.

[0032] The terms used herein are only used to describe various examples and are not intended to limit the disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "comprise", "include" and "have" indicate the presence of the described features, quantities, operations, components, elements and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements and / or combinations thereof.

[0033] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by a person of ordinary skill in the art to which the present disclosure belongs after understanding the present disclosure. Unless explicitly defined as such herein, terms (such as those defined in a general dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal manner.

[0034] Furthermore, in the description of examples, when it is considered that a detailed description of a well-known related structure or function would cause vague interpretation of the present disclosure, such a detailed description will be omitted.

[0035] As wind turbine blades develop towards larger sizes, blade fatigue testing becomes a key step in verifying the reliability of large blades.

[0036] In the blade fatigue test, according to the corresponding relationship between the target bending moment and the test bending moment, the test bending moment can be provided in the form of a bending moment or force loaded on the blade cross section through the form of excitation, and the fatigue damage of the blade can be obtained through the strain data of the material. Therefore, the fatigue test of the blade can establish the relationship between the bending moment and the strain, that is, the relationship between the target bending moment and the test bending moment. Here, the bending moment can also be called load.

[0037] During blade fatigue testing, Figure 1 As shown, the load borne by the blade 10 can be decomposed into two directions, the swing direction 20 and the swing direction 30, and the fatigue test can be performed according to the direction of the load. In addition, since the fatigue load of the blade in the swing direction is relatively large, and the fatigue test is generally an accelerated test, in order to make up for the gap with the actual operating state of the blade, the fatigue test load can be amplified on the basis of the design load, for example, the amplification factor is about 1.3, which will cause the fatigue test load of the blade in the swing direction to be equivalent to the limit load, or even exceed the limit load.

[0038] In the related art, fatigue testing mainly adopts the resonance method. Specifically, the fatigue time series load can be first converted into 10 million times equivalent fatigue load without mean value by rain flow method, and the load can be converted to the test load under the target test number, and the corresponding safety factor is considered. The load conversion process can be expressed by the following formula (1):

[0039]

[0040] Among them, M eq It represents the equivalent fatigue load under the target test fatigue times, that is, the test load, N0 represents 10 million stress cycles, that is, 10 million fatigue times, M0 represents the equivalent fatigue load under 10 million fatigue times, N j represents the target test fatigue times, and m represents the slope parameter of the SN curve of the material fatigue test.

[0041] After determining the test load, the appropriate vibration mode for the required verification area can be obtained by increasing or adjusting the counterweight position or weight, and then the desired test load can be obtained through vibration amplification.

[0042] In the above fatigue test method, the loads in the swing direction and the flapping direction are determined separately from each other. Specifically, when determining the load in the swing direction or the flapping direction, only its own direction is often considered, while ignoring that the other direction will also have a certain influence.

[0043] Taking the fatigue test in the swing direction as an example, the above method only considers the load generated by the vibration amplitude in the swing direction, while the load in the swing direction is not taken into account, for example Figure 1As shown in the figure, the gravity of the blade's own weight and counterweight will generate loads in the swinging direction. Therefore, such a test process cannot truly reflect the actual load level of the blade. Especially as blades tend to be larger, the influence of gravity load on the test is becoming increasingly greater. The same is true for fatigue testing in the swinging direction. The load generated in the swinging direction will also affect the actual load of the blade. For example, in the actual operation of the blade, the swinging direction of the blade may be in the vertical plane or close to the vertical plane. Therefore, it will also be affected by gravity in the swinging direction.

[0044] In actual operation, the thrust acting on the blade may not be single, and the load in the flapping direction and the load in the swing direction may affect each other. Therefore, fatigue testing based on a single direction may not reflect the actual operating status of the blade.

[0045] In addition, in the process of load conversion, the difference between the tensile strength and compressive strength of the composite material may lead to inaccurate load conversion, which amplifies the difference between the target load and the test load, resulting in a large difference between the target load and the test load, which is not conducive to improving the accuracy of the test.

[0046] In view of the above problems, exemplary embodiments of the present disclosure provide a blade fatigue test method and a blade fatigue test system for a wind turbine generator set to solve or alleviate at least one of the above problems. Exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0047] According to a first aspect of the present disclosure, a method for testing blade fatigue of a wind turbine generator set is provided. The method can be executed by a blade fatigue testing system of the wind turbine generator set.

[0048] In an example application scenario, a blade fatigue test system may include an exciter and a controller, and the controller may determine a first load mean value of a blade to be tested in a first direction, and determine a target load for fatigue testing the blade in the second direction based on the first load mean value and a second load amplitude of the blade in the second direction. Here, the first direction may be one of a flapping direction and a swinging direction, and the second direction may be the other of the flapping direction and the swinging direction. In this way, the controller may control the exciter to apply vibration to the blade so that the difference between the test load and the target load is within a predetermined range, so as to perform a fatigue test on the blade in the second direction based on the test load.

[0049] The above describes the blade fatigue test method in an exemplary manner as an execution subject being a blade fatigue test system. However, it is not limited thereto. The method may also be executed on other execution subjects, and the blade fatigue test system may also include other test equipment.

[0050] The following will refer to Figures 2 to 8A blade fatigue testing method for a wind turbine generator system according to an exemplary embodiment of the present disclosure is described in detail.

[0051] like Figure 2 As shown, the blade fatigue testing method may include the following steps:

[0052] In step S210 , a first load mean value of the blade to be tested in a first direction may be determined.

[0053] Here, the first direction may be one of a swing direction and a shimmy direction, and a second direction to be described below may be the other of the swing direction and the shimmy direction.

[0054] According to an embodiment of the present disclosure, when a fatigue test is to be performed on a blade in a second direction, the average value of the first load on the blade in the first direction may be considered to improve the authenticity and accuracy of the fatigue test in the second direction.

[0055] In this step, as an example, Figure 3 As shown, the first load mean can be determined in the following manner: Step S310, the first load amplitude and the first fatigue load of the blade in the first direction can be determined based on the fatigue load spectrum of the blade; Step S320, the first load mean can be determined based on the first load amplitude and the first fatigue load.

[0056] Here, when the basic parameters of the blade (such as the material parameters of the blade) are determined, a corresponding fatigue load spectrum may be provided. The fatigue load spectrum may be predetermined for the blade, and may be in the form of a Markov matrix. In the Markov matrix, corresponding values ​​between load direction, fatigue times, fatigue load, load amplitude of fatigue load, and load mean of fatigue load may be recorded. For example, the load direction may include a swing direction and a flapping direction. By querying the fatigue load spectrum, specific values ​​of fatigue load, load amplitude, and load mean in the swing direction and at a certain fatigue times may be obtained. Here, the fatigue load spectrum may be obtained by any existing method, and the present disclosure does not impose any particular limitation on this.

[0057] In the above step S310, based on the fatigue load spectrum, the first load amplitude and the first fatigue load of the blade in the first direction can be queried, where the first load amplitude and the first fatigue load can be at any fatigue number (hereinafter also referred to as reference fatigue number) in the fatigue load spectrum. In step S320, the first load mean can be determined based on the first load amplitude and the first fatigue load at the reference fatigue number.

[0058] Here, the first load mean value may be a load mean value under a reference fatigue number. For example, the first load mean value may be determined by the following formula (2):

[0059]

[0060] Among them, M eq represents the equivalent fatigue load under the reference fatigue number, S k,A represents the load amplitude (stress or strain) at the reference fatigue number, S k,M Represents the mean load (stress or strain) under the reference fatigue number, R k,t represents the ultimate characteristic tensile strength of the structural member (here the blade), R k,c represents the ultimate characteristic compressive strength of the structural member (here the blade), γ m,short_term Represents the limit verification reduction factor.

[0061] Based on the above formula (2), when the first load amplitude and the first fatigue load at the reference fatigue number are known, the corresponding first load mean value can be determined.

[0062] In the above manner, the relationship between the fatigue load, the load mean and the load amplitude can be used to determine the first load mean at the reference fatigue number of the fatigue load spectrum, so that the target load can be determined using the first load mean.

[0063] It should be noted that, although the process of determining the first load mean is described above in an exemplary manner based on formula (2), it is not limited to this. The relationship between the fatigue load, the load mean and the load amplitude can also be expressed in other ways, such as by a variation of formula (2), by a mapping table, by a mapping relationship curve, etc. Therefore, the process of determining the first load mean based on the first load amplitude and the first fatigue load can also be achieved in these ways.

[0064] In step S220, a target load for performing a fatigue test on the blade in the second direction may be determined based on the first load mean value and a second load amplitude of the blade in the second direction.

[0065] As described above, the first direction may be one of the flapping direction and the swinging direction, and the second direction may be the other of the flapping direction and the swinging direction. Thus, in this step, by combining the first load mean in the first direction with the second load amplitude in the second direction to obtain the target load in the second direction, the fatigue test in the second direction can take into account the load influence in the first direction, so that the test result is closer to the actual situation faced by the blade in operation.

[0066] As an example, when the first load mean is the load mean at a reference fatigue number in the fatigue load spectrum of the blade, the target load can be determined in the following manner: based on the first load mean, the second load amplitude and the reference fatigue number, the target load at the target fatigue test number is determined by converting the loads at different fatigue numbers.

[0067] Specifically, for the fatigue life of the same structural component, the equivalent fatigue load is related to the number of fatigue tests. For example, as described in the above formula (1), the relationship between the equivalent fatigue loads under different fatigue test times can be established to convert the load.

[0068] Taking into account the principle of load conversion, in an embodiment of the present invention, based on the convertibility between the fatigue load at a reference fatigue number and the target load at a target fatigue test number, and the relationship between the fatigue load, the load mean and the load amplitude, a method of determining the target load at a target fatigue test number based on the first load mean and the second load amplitude at the reference fatigue number is proposed, so that the load mean and the load amplitude in different directions can be combined to obtain the target load.

[0069] As an example, Figure 4 As shown, load conversion can be performed in the following manner: Step S410, the material parameters of the blade can be obtained; Step S420, the first load mean, the second load amplitude, the reference fatigue number, the material parameters and the target fatigue test number can be brought into a preset load conversion relationship to perform load conversion.

[0070] Here, the material parameters of the blade may include ultimate tensile strength, ultimate compressive strength, a slope parameter of a fatigue test SN curve, and an ultimate reduction factor.

[0071] Specifically, when the material parameters of the blade are known, the material properties used in the blade can be determined. In this case, since the fatigue load can be described by two parameters, the load amplitude and the load mean, the fatigue load under the reference fatigue number can be characterized based on the first load mean and the second load amplitude. In this way, a preset load conversion relationship can be established based on the material parameters, the first load mean, the second load amplitude, the reference fatigue number and the target fatigue test number, so as to determine the target load under the target fatigue test number.

[0072] Here, the preset load conversion relationship can be obtained by modifying or transforming the basic load calculation formula (such as the above formula (2)). As an example, the preset load conversion relationship can be expressed by the following formula (3):

[0073]

[0074] Among them, M eqj Indicates the number of fatigue times N in the target test j Equivalent fatigue load under i Indicates the reference fatigue times, N j represents the target test fatigue times, m represents the slope value of the material fatigue test SN curve, S k,Ai represents the load amplitude under the reference fatigue number, S k,Mi represents the mean load under the reference fatigue number, R k,t represents the ultimate characteristic tensile strength of the structural member (here the blade), R k,c represents the ultimate characteristic compressive strength of the structural member (here the blade), γ m,short_term Represents the limit verification reduction factor.

[0075] Based on Figure 4 The load conversion method shown can determine the target load at the target test fatigue number based on the first load mean, the second load amplitude, the reference fatigue number, the material parameters and the target fatigue test number without calculating the equivalent fatigue load at the reference fatigue number.

[0076] It should be noted that, although the process of determining the target load is described above in an exemplary manner based on formula (3), it is not limited to this. The load conversion relationship between the first load mean, the second load amplitude, the reference fatigue number, the material parameters and the target fatigue test number can also be expressed in other ways, such as by a variation of formula (3), by a mapping table, by a mapping relationship curve, etc. Therefore, the process of determining the target load can also be achieved by these ways.

[0077] In addition, the load conversion relationship shown in formula (3) can be obtained according to the first relationship between the fatigue load, the load amplitude, and the load mean, and the second relationship between the fatigue number and the load amplitude and the load mean, wherein the first relationship can be, for example, as shown in the formula (2) described above, and the second relationship can be, for example, expressed by the following formula (4):

[0078]

[0079] Among them, N i represents the fatigue times, m represents the slope of the SN curve of the material fatigue test, S k,A Indicates the number of fatigue times N i The load amplitude under k,M Indicates the number of fatigue times N i The mean load under k,t represents the ultimate characteristic tensile strength of the structural member (here the blade), R k,crepresents the ultimate characteristic compressive strength of the structural member (here the blade), γ m,short_term represents the limit verification reduction factor, γ m,fatigue Represents the fatigue verification reduction factor.

[0080] It should be noted that, although the process of determining the load conversion relationship is described above in an exemplary manner based on formula (4), it is not limited to this. The first relationship and the second relationship can also be expressed in other ways, such as by a variation of formula (2) or formula (3), by a mapping table, by a mapping relationship curve, etc. Therefore, the process of determining the load conversion relationship can also be implemented in these ways.

[0081] Furthermore, according to an embodiment of the present disclosure, the ultimate tensile strength and the ultimate compressive strength used to determine the target load may be equal.

[0082] Specifically, the present disclosure finds that when calculating the fatigue load-bearing capacity of a blade, using different tensile strengths and compressive strengths can enable the blade to obtain a higher fatigue load-bearing capacity value, thereby allowing the blade to have a real and higher safety margin. However, when the load is converted in this way, the difference between the tensile strength and the compressive strength will cause the difference between the target load and the test load of the blade to be amplified when the load is converted, thereby causing inaccurate load conversion and further inaccurate test results.

[0083] In this regard, when converting the load and when determining the load conversion relationship, the ultimate tensile strength and the ultimate compressive strength can be set equal, so that the difference between the tensile strength and the compressive strength can be eliminated, thereby eliminating the difference between the target load and the test load.

[0084] As an example, the ultimate tensile strength and the ultimate compressive strength can be determined by direct measurement. Specifically, the ultimate tensile strength and the ultimate compressive strength can be measured by material testing to determine the same ultimate tensile strength and ultimate compressive strength.

[0085] However, the embodiments of the present disclosure are not limited thereto, and the same ultimate tensile strength and ultimate compressive strength may also be determined by calculating the material fatigue SN curve. Specifically, as another example, Figure 5 As shown, the ultimate tensile strength and ultimate compressive strength can be determined as follows:

[0086] In step S510, a material fatigue tensile curve of the blade may be obtained.

[0087] In this step, when the material of the blade is determined, its material fatigue tensile curve can be determined by existing measurement methods, for example, Figure 6Curve S1 in FIG. 1 shows the equal life fatigue curve of a blade measured based on the Gerber model. The equal life fatigue curve refers to the fatigue tensile curve of the material under different stress levels at the same life.

[0088] In step S520, the intersection value of the material fatigue tensile curve and the coordinate axis may be adjusted to make the material fatigue tensile curve symmetrical, thereby obtaining an adjusted material fatigue tensile curve.

[0089] For example, still Figure 6 Taking curve S1 in the figure as an example, the intersection values ​​of the material fatigue tensile curve with the horizontal axis and the vertical axis are σ a and σ b , where σ a and σ b The material fatigue tensile curve can be simplified while keeping the intersection point unchanged. For example, it can be simplified based on the Goodman model to obtain curve S2.

[0090] In this case, due to σ a and σ b are not equal, so curves S1 and S2 are not symmetrical. They can be made symmetrical by adjusting the intersection of the curves with the coordinate axes. For example, b Adjusted to σ a equal.

[0091] In addition, when adjusting the intersection value, it is preferred to adjust the larger of the intersection values ​​of the material fatigue tensile curve and the two coordinate axes, for example, b Adjusted to σ′ b In this way, the values ​​of tensile strength and compressive strength used after adjustment can be made more conservative, so that the load converted using such strength values ​​is also more conservative, ensuring the accuracy of the test results.

[0092] In step S530 , the ultimate tensile strength and the ultimate compressive strength may be determined based on the adjusted material fatigue tensile curve.

[0093] For the adjusted material fatigue tensile curve, the intersection values ​​with the two coordinate axes are equal, that is, the ultimate tensile strength and the ultimate compressive strength are equal.

[0094] The equal ultimate tensile strength and ultimate compressive strength determined in the above manner make the material fatigue tensile curve symmetrical, so that the target load and the test load have a consistent data processing method during the conversion process, and a more accurate load is obtained.

[0095] Return to reference Figure 2In step S230, a test load for fatigue testing the blade in the second direction may be determined such that a difference between the test load and the target load is within a predetermined range.

[0096] In this step, when the target load is determined, a test load can be applied to the blade by adjusting the excitation position, counterweight position and / or counterweight size of the blade, and the difference between the test load and the target load is within a predetermined range.

[0097] Here, the difference between the test load and the target load can be expressed, for example but not limited to, by the ratio of the test load to the target load. In this example, the predetermined range can be used to characterize the ratio range of the test load to the target load, for example, it can be 1.01 to 1.20. In this way, the test load can be slightly amplified relative to the target load to ensure the safety of the test results.

[0098] In the process of determining the test load, the actual gravity load generated by the deadweight of the blade and the counterweight can be considered, and the test load including the mean value can be determined under the condition of equal strength.

[0099] As an example, Figure 7 As shown, the test load can be determined by:

[0100] In step S710, the vibration mode of the blade that meets the fatigue test requirements may be determined by adjusting the position of the excitation point or by adjusting the position of the excitation point and the position and / or size of the counterweight.

[0101] In this step, for example, a vibration exciter can be installed at the excitation position of the blade to be tested, and if a counterweight needs to be added, a counterweight can also be installed at the counterweight position of the blade. Here, the excitation position and the counterweight position can be determined and adjusted according to actual needs. For example, the vibration exciter can be installed in an effective fatigue verification area that causes the blade to vibrate, preferably an area from the root of the blade to 60% of the total length of the blade.

[0102] By turning on the exciter, the blade can be made to vibrate and the vibration mode of the blade can be measured. If the measured vibration mode of the blade does not meet the preset fatigue test requirements, the position of the excitation point can be adjusted (or, if a counterweight is installed, the position of the excitation point and the position and / or size of the counterweight can be adjusted) until the blade vibration mode fatigue test requirements are met.

[0103] In step S720, the gravity load of the blade in the fatigue test may be obtained according to the deadweight of the blade or according to the deadweight of the blade and the counterweight on the blade.

[0104] In this step, the gravity load may be calculated by taking into account the dead weight of the blade and the weight of various devices mounted on the blade.

[0105] In one example, the blades may be excited by a rope pulling method, and no weight may be installed on the blades. In this example, only the dead weight of the blades themselves may be considered to calculate the gravity load.

[0106] In another example, the blade may be vibrated by an exciter such as a motor. In this example, the counterweight on the blade may include the weight of the exciter installed at the excitation point, and the gravity load may be calculated considering only the weight of the blade itself and the weight of the exciter.

[0107] Furthermore, in the case where a counterweight is installed, the counterweight on the blade may further include the weight of a counterweight device providing the counterweight.

[0108] In step S730 , a mean value of the test load may be determined based on the gravity load.

[0109] Here, since the mean component of the test load comes from the dead weight of the blade and the counterweight on the blade, when the excitation point position, counterweight position and counterweight size are determined, the actual gravity load in the blade fatigue test can be obtained, thereby determining the mean value of the test load.

[0110] In step S740, the test load may be determined by adjusting the amplitude of the test load based on the mean value of the test load so that the difference between the test load and the target load is within a predetermined range.

[0111] In this step, when the mean value of the test load and the target load have been determined, the amplitude of the test load that can make the difference between the test load and the target load within a predetermined range can be determined based on the relationship between the fatigue load, the load amplitude and the load mean. As an example, the amplitude of the test load can be adjusted based on the blade vibration mode and the excitation amplitude required by the fatigue test. For example, the amplitude of the test load can be equivalent to the amplitude of the centrifugal excitation load, and the test load can be determined based on the amplitude of the test load superimposed on the mean value of the gravity load.

[0112] The test load determined in the above manner can take into account the influence of the deadweight of the blade and the equivalent gravity load generated by the counterweight on the blade on the test load, thereby determining the test load more accurately and improving the accuracy of the fatigue test.

[0113] Return to reference Figure 2 In step S240, a fatigue test may be performed on the blade in a second direction based on the test load.

[0114] When the test load is determined, the blade may be subjected to fatigue testing in the second direction.

[0115] According to the fatigue testing method of the exemplary embodiment of the present disclosure, the target load including the load mean in the first direction can be determined while greatly shortening the time of the blade fatigue test, thereby improving the accuracy and safety of the blade target load, making the target load during the fatigue test closer to the actual operating state of the blade, and making the blade fatigue test more representative.

[0116] In addition, according to the fatigue testing method of the exemplary embodiment of the present disclosure, it is also possible to solve the problem of large deviation between the target load and the test load caused by the difference in material strength by making the tensile strength and the compressive strength consistent, thereby making the blade fatigue test more accurate and the blade fatigue life obtained by the test more realistic.

[0117] An example of determining the target load is described above in step S220, wherein the mean load in the first direction is taken into account when determining the target load in the second direction, but the embodiments of the present disclosure are not limited to this. In the process of determining the target load, in addition to considering the mean load in the first direction, the mean load in the second direction may also be considered.

[0118] Specifically, according to another example of the present disclosure, Figure 8 As shown, the target load can also be determined by:

[0119] In step S810 , a second load mean value of the blade in a second direction may be determined.

[0120] In this step, the second load mean in the second direction may be determined in a manner similar to the above method of determining the first load mean in the first direction. Figure 3 Taking the illustrated method as an example, the first load amplitude and the first fatigue load of the blade in the second direction may be determined based on the fatigue load spectrum of the blade, and the second load mean may be determined based on the second load amplitude and the second fatigue load.

[0121] The above-described method for determining the first load mean value and its variations are applicable to determining the second load mean value here, and thus will not be described in detail here.

[0122] In step S820, a target load for performing a fatigue test on the blade in the second direction may be determined based on the first load mean value, the second load amplitude value, and the second load mean value.

[0123] In this step, when the first load mean, the second load amplitude and the second load mean are determined, the first load mean and the second load mean can be fused to obtain a fused load mean for calculating the target load, so as to determine the target load based on the fused load mean and the second load amplitude, based on the method described in step S230 above. For example, the target load under the target fatigue test number can be determined based on the fused load mean, the second load amplitude and the reference fatigue number by converting the load under different fatigue numbers. The above-described method for determining the target load based on the first load mean and the second load amplitude and its variants are applicable to determining the target load based on the fused load mean and the second load amplitude here, so they will not be repeated here.

[0124] In step S820, the fused load mean may be calculated based on the first load mean and the second load mean, for example, it may be but is not limited to the sum of the first load mean and the second load mean.

[0125] As an example, step S820 may include: determining a load mean sum of the first load mean and the second load mean; and determining a target load for fatigue testing the blade in the second direction based on the second load amplitude and the load mean sum.

[0126] Specifically, the first load mean and the second load mean can be added to obtain the load mean sum (the fused load mean described above), so that the above method of determining the target load based on the first load mean and the second load amplitude and its variations can be used to determine the target load for fatigue testing of the blade in the second direction based on the second load amplitude and the load mean sum.

[0127] In the above example, when determining the target load in the second direction, not only the mean load in the first direction but also the mean load in the second direction itself may be considered. The target load obtained in this way can simultaneously consider the influence of the mean load in both the first direction and the second direction (i.e., the swinging direction and the swinging direction), thereby making the test result more accurate.

[0128] According to a second aspect of the present disclosure, a blade fatigue testing system for a wind turbine generator set is provided. Fig. 9 As shown, the blade fatigue testing system may include a vibration exciter 100 and a controller 200 .

[0129] The vibration exciter 100 may be installed at the excitation point of the blade 10 to be tested, so as to cause the blade 10 to vibrate.

[0130] For example, Fig.10As shown, the blade can be installed horizontally, and the exciter 100 can be installed at the initial excitation point position, so that the vibration mode of the blade that meets the fatigue test requirements can be determined by adjusting the excitation point position of the exciter 100. In some cases, a counterweight device 300 can also be installed on the blade, for example, the counterweight device 300 can be installed at the initial counterweight position, and the vibration mode of the blade can be adjusted to meet the fatigue test requirements by adjusting the excitation point position of the exciter 100 and adjusting the counterweight position of the counterweight device 300 and / or the counterweight size of the counterweight device 300.

[0131] The controller 200 may control the vibration exciter 100 to apply vibration to the blade so that the difference between the test load and the target load is within a predetermined range, so as to perform a fatigue test on the blade 10 in the second direction based on the test load.

[0132] Here, the target load can be determined in the following manner: determine a first load mean value of the blade in a first direction; based on the first load mean value and a second load amplitude of the blade in the second direction, determine a target load for fatigue testing the blade in the second direction, wherein the first direction is one of the flapping direction and the swing direction, and the second direction is the other of the flapping direction and the swing direction.

[0133] In an embodiment according to the second aspect of the present disclosure, the target load and the test load may be determined according to the blade fatigue test method of the embodiment of the first aspect of the present disclosure.

[0134] As an example, the first load mean is determined in the following manner: based on a fatigue load spectrum of the blade, a first load amplitude and a first fatigue load of the blade in a first direction are determined; based on the first load amplitude and the first fatigue load, the first load mean is determined.

[0135] As an example, the first load mean is the load mean at a reference fatigue number in the fatigue load spectrum of the blade, wherein the target load can be determined in the following manner: based on the first load mean, the second load amplitude and the reference fatigue number, the target load at the target fatigue test number is determined by converting the loads at different fatigue numbers.

[0136] As an example, load conversion can be performed in the following manner: obtaining material parameters of the blade, where the material parameters include ultimate tensile strength, ultimate compressive strength, slope parameters of the fatigue test SN curve, and ultimate reduction coefficient; bringing the first load mean, the second load amplitude, the reference fatigue number, the material parameters, and the target fatigue test number into a preset load conversion relationship to perform load conversion.

[0137] As an example, the ultimate tensile strength and the ultimate compressive strength may be equal.

[0138] As an example, the ultimate tensile strength and the ultimate compressive strength can be determined in the following manner: obtain the material fatigue tensile curve of the blade; adjust the intersection value of the material fatigue tensile curve and the coordinate axis to make the material fatigue tensile curve symmetrical, and obtain the adjusted material fatigue tensile curve; based on the adjusted material fatigue tensile curve, determine the ultimate tensile strength and the ultimate compressive strength.

[0139] As an example, the target load may be determined by: determining a second load mean of the blade in the second direction; and determining a target load for fatigue testing the blade in the second direction based on the first load mean, the second load amplitude and the second load mean.

[0140] As an example, the target load may also be determined by: determining the mean load sum of the first load mean and the second load mean; and determining the target load for fatigue testing the blade in the second direction based on the second load amplitude and the mean load sum.

[0141] As an example, the test load can be determined in the following ways: by adjusting the position of the excitation point, the position of the counterweight and / or the size of the counterweight, the blade vibration mode that meets the fatigue test requirements is determined; based on the blade's own weight and the size of the counterweight, the gravity load of the blade in the fatigue test is obtained; based on the gravity load, the mean of the test load is determined; based on the mean of the test load, the test load is determined by adjusting the amplitude of the test load so that the difference between the test load and the target load is within a predetermined range.

[0142] The specific manner of executing the operations in each step in the above embodiment has been described in detail in the embodiment of the method, and will not be elaborated here.

[0143] The blade fatigue testing method of a wind turbine generator set according to an embodiment of the present disclosure may be executed by an electronic device, which may include: a processor; a memory, the memory storing computer executable instructions, wherein the computer executable instructions, when executed by the processor, prompt the processor to execute the blade fatigue testing method of a wind turbine generator set according to the exemplary embodiment of the present disclosure.

[0144] As an example, the electronic device can be a PC computer, a tablet device, a personal digital assistant, a smart phone or other devices capable of executing the above-mentioned instruction set. Here, the electronic device is not necessarily a single electronic device, but can also be any device or circuit that can execute the above-mentioned instruction (or instruction set) individually or jointly. The electronic device can also be a part of an integrated control system or a system manager, or can be configured to be a portable electronic device interconnected with an interface locally or remotely (for example, via wireless transmission). In addition, the electronic device can also include a video display (such as, a liquid crystal display) and a user interaction interface (such as, a keyboard, a mouse, a touch input device, etc.). All components of the electronic device can be connected to each other via a bus and / or a network.

[0145] The processor may include a central processing unit (CPU), a graphics processing unit (GPU), a programmable logic device, a dedicated processor system, a microcontroller or a microprocessor. As an example and not limitation, the processor may also include an analog processor, a digital processor, a microprocessor, a multi-core processor, a processor array, a network processor, etc.

[0146] The processor can execute instructions or codes stored in the memory, wherein the memory can also store data. Instructions and data can also be sent and received through the network via the network interface device, wherein the network interface device can adopt any known transmission protocol.

[0147] The memory may be integrated with the processor, for example, RAM or flash memory is arranged within an integrated circuit microprocessor or the like. In addition, the memory may include a separate device, such as an external disk drive, a storage array, or any other storage device that can be used by a database system. The memory and the processor may be operatively coupled, or may communicate with each other, such as through an I / O port, a network connection, etc., so that the processor can read files stored in the memory.

[0148] In addition, some operations in the blade fatigue test method of the wind turbine generator set according to the embodiment of the present disclosure can be written as a computer program and stored on a computer-readable storage medium. Examples of computer-readable storage media include: read-only memory (ROM), random access programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, non-volatile memory, CD-ROM, CD-R, CD+R, CD-RW, CD+RW, DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM, BD-ROM, BD-R, BD-R LTH, BD-RE, Blu-ray or optical disk storage, hard disk drive (HDD), solid state drive (SSD), card storage (such as, multimedia card, secure digital (SD) card or extreme digital (XD) card), magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid state disk and any other device, any other device is configured to store computer program and any associated data, data files and data structures in a non-transitory manner and provide the computer program and any associated data, data files and data structures to a processor or computer so that the processor or computer can execute the computer program. In one example, the computer program and any associated data, data files and data structures are distributed on a networked computer system so that the computer program and any associated data, data files and data structures are stored, accessed and executed in a distributed manner by one or more processors or computers.

[0149] The specific implementation methods of the present disclosure have been described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments may be modified and varied without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents. These modifications and variations should also be within the scope of protection of the claims of the present disclosure.

Claims

1. A method for testing blade fatigue of a wind turbine generator set, characterized in that: The blade fatigue testing method comprises: determining a first load mean value of the blade to be tested in a first direction; Determining a target load for fatigue testing the blade in the second direction based on the first load mean value and a second load amplitude of the blade in the second direction, wherein the first direction is one of a flapping direction and a swing direction, and the second direction is the other of the flapping direction and the swing direction; determining a test load for performing a fatigue test on the blade in the second direction so that a difference between the test load and the target load is within a predetermined range; Based on the test load, a fatigue test is performed on the blade in the second direction.

2. The blade fatigue testing method according to claim 1, characterized in that: The first load mean is determined by: Determining a first load amplitude and a first fatigue load of the blade in the first direction based on a fatigue load spectrum of the blade; The first load mean value is determined based on the first load amplitude and the first fatigue load.

3. The blade fatigue testing method according to claim 1, characterized in that: The first load mean is a load mean at a reference fatigue number in a fatigue load spectrum of the blade. The target load is determined by: Based on the first load mean value, the second load amplitude value and the reference fatigue times, a target load at a target fatigue test times is determined by converting loads at different fatigue times.

4. The blade fatigue testing method according to claim 3, characterized in that: Load conversion is performed in the following ways: Acquiring material parameters of the blade, wherein the material parameters include ultimate tensile strength, ultimate compressive strength, slope parameter of fatigue test SN curve and ultimate reduction factor; The first load mean, the second load amplitude, the reference fatigue times, the material parameters and the target fatigue test times are brought into a preset load conversion relationship to perform load conversion.

5. The blade fatigue testing method according to claim 4, characterized in that: The ultimate tensile strength and the ultimate compressive strength are equal.

6. The blade fatigue testing method according to claim 5, characterized in that: The ultimate tensile strength and the ultimate compressive strength are determined by: Obtaining a material fatigue tensile curve of the blade; Adjusting the intersection value of the material fatigue tensile curve and the coordinate axis to make the material fatigue tensile curve symmetrical, thereby obtaining an adjusted material fatigue tensile curve; Based on the adjusted material fatigue tensile curve, the ultimate tensile strength and the ultimate compressive strength are determined.

7. The blade fatigue testing method according to claim 1, characterized in that: The target load is determined by: determining a second load mean of the blade in the second direction; A target load for performing a fatigue test on the blade in the second direction is determined based on the first load mean value, the second load amplitude value, and the second load mean value.

8. The blade fatigue testing method according to claim 7, characterized in that: The step of determining a target load for fatigue testing the blade in the second direction based on the first load mean value, the second load amplitude value and the second load mean value comprises: Determine a load mean sum of the first load mean and the second load mean; A target load for performing a fatigue test on the blade in the second direction is determined based on the second load amplitude and the load mean sum.

9. The blade fatigue testing method according to claim 1, characterized in that: The test load is determined by: Determine the vibration mode of the blade that meets the fatigue test requirements by adjusting the position of the excitation point or by adjusting the position of the excitation point and the position and / or size of the counterweight; Obtaining a gravity load of the blade in a fatigue test according to the deadweight of the blade or according to the deadweight of the blade and a counterweight on the blade; Based on the gravity load, determining a mean value of the test load; The test load is determined by adjusting the amplitude of the test load based on the mean value of the test load so that the difference between the test load and the target load is within the predetermined range.

10. A blade fatigue testing system for a wind turbine generator set, characterized in that: The blade fatigue test system includes a vibration exciter and a controller. The exciter is installed at the excitation point of the blade to be tested to make the blade vibrate; The controller controls the vibration exciter to apply vibration to the blade so that a difference between a test load and a target load is within a predetermined range, so as to perform a fatigue test on the blade in a second direction based on the test load. Wherein, the target load is determined by: determining a first load mean value of the blade in a first direction; determining the target load for fatigue testing the blade in the second direction based on the first load mean value and the second load amplitude of the blade in the second direction, The first direction is one of a swinging direction and a shimmying direction, and the second direction is the other of the swinging direction and the shimmying direction.

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